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manet-thesis-99mar - 1998:362 MASTER'S THESIS Routing. Click to edit the document details. Unformatted text preview: 1998:362 MASTER'S THESIS Routing Protocols in methodology, Wireless Ad-hoc Networks A Simulation Study Tony Larsson, Nicklas Hedman Civilingenjorsprogrammet 1998:362 • ISSN: 1402-1617 • ISRN: LTU-EX--98/362--SE Master’s thesis in Computer Science and Engineering Routing Protocols in Wireless Ad-hoc Networks A Simulation Study Stockholm, 1998 Tony Larsson and Nicklas Hedman Lulea University of Technology Supervisor: Per Johansson Switchlab Ericsson Telecom AB Examiner: Mikael Degermark Department of Computer Science and Electrical Engineering Division of Computer Communications, Lulea University of Technology Abstract Ad-hoc networking is a concept in computer communications, which means that users wanting to communicate with each other form a temporary network, without any form of centralized administration. Each node participating in the network acts both as host and rotc topics a router and must therefore be willing to forward packets for other nodes. Types Of Thesis Methodology! For this purpose, a routing protocol is needed. An ad-hoc network has certain characteristics, which imposes new demands on the routing protocol. The most important characteristic is the dynamic topology, which is order a consequence of node mobility. Nodes can change position quite frequently, which means that we need a routing protocol that quickly adapts to topology changes. The nodes in an ad-hoc network can consist of laptops and personal digital assistants and are often very limited in resources such as CPU capacity, storage capacity, battery power and bandwidth.

This means that the types methodology routing protocol should try to minimize control traffic, such as periodic update messages. Topics! Instead the routing protocol should be reactive, thus only types calculate routes upon receiving a specific request. The Internet Engineering Task Force currently has a working group named Mobile Ad-hoc Networks that is custom order working on routing specifications for types, ad-hoc networks. This master thesis evaluates some of the protocols put forth by the working group. This evaluation is done by means of simulation using Network simulator 2 from Berkeley.

The simulations have shown that there certainly is a need for a special ad-hoc routing protocol when mobility increases. More conventional routing protocols like DSDV have a dramatic decrease in book reports, performance when mobility is high. Two of the proposed protocols are DSR and AODV. They perform very well when mobility is high. However, we have found that a routing protocol that entirely depends on messages at the IP-level will not perform well. Types Methodology! Some sort of support from the lower layer, for instance link failure detection or neighbor discovery is necessary for high performance. The size of the network and the offered traffic load affects protocols based on source routing, like DSR, to some extent. Essay! A large network with many mobile nodes and high offered load will increase the overhead for DSR quite drastically.

In these situations, a hop-by-hop based routing protocol like AODV is more desirable. Preface This report is the result of our master thesis project carried out at Ericsson Telecom, Switchlab in of thesis, Stockholm. This master thesis is a scientific also the last part of our Master of Science degree at Lulea University of Technology. Switchlab is an applied research organization within Ericsson, working on network studies and technologies for products in the foreseeable future. This master thesis project has been a cooperation between Switchlab in types, Stockholm and Ericsson Mobile Data Design (ERV) in essay, Gothenburg.

Our master thesis consisted of conducting a simulation study of types of thesis methodology proposed routing protocols in ad-hoc networks. The thesis work done at ERV implemented one of the egypt book proposed routing protocols and tested it in a simple scenario. This has made it possible to share thoughts and ideas with each other. We would like to thank the following persons: Per Johansson for types of thesis methodology, being our supervisor at Switchlab, Bartosz Mielczarek for essay, contribution of the realistic scenarios and Mikael Degermark for methodology, being our Examiner at Lulea University of Technology. Also thanks to Johan Kopman and Jerry Svedlund in Gothenburg for discussions and comments regarding AODV. Finally, we would also like to thank Mats Westin and Henrik Eriksson for giving us feedback on custom essay order this report. Table of Contents 1 INTRODUCTION . 9 1.1 1.2 1.3 1.4 1.5 1.6 2 BACKGROUND . Types! 9 PROBLEM DESCRIPTION . 9 RELATED WORK . Book Reports! 10 PROJECT ORGANIZATION . 10 DISPOSITION . 11 ABBREVIATIONS . 11 GENERAL CONCEPTS.

12 2.1 WIRELESS AD-HOC NETWORKS . 12 2.1.1 General. 12 2.1.2 Usage. 13 2.1.3 Characteristics . 13 2.2 ROUTING . 14 2.2.1 Conventional protocols . 14 2.2.2 Link State. 14 2.2.3 Distance Vector . 14 2.2.4 Source Routing . 14 2.2.5 Flooding . 15 2.2.6 Classification. 15 3 AD-HOC ROUTING PROTOCOLS. Types Methodology! 16 3.1 DESIRABLE PROPERTIES . 16 3.2 MANET. 17 3.3 DESTINATION SEQUENCED DISTANCE VECTOR - DSDV . 17 3.3.1 Description . 17 3.3.2 Properties . 17 3.4 AD-HOC ON DEMAND DISTANCE VECTOR - AODV . 18 3.4.1 Description . 18 3.4.2 Properties . 19 3.5 DYNAMIC SOURCE ROUTING - DSR.

20 3.5.1 Description . 20 3.5.2 Properties . Custom Order! 20 3.6 ZONE ROUTING PROTOCOL - ZRP . Types Of Thesis Methodology! 21 3.6.1 Description . 21 3.6.2 Properties . 22 3.7 TEMPORALLY-ORDERED ROUTING ALGORITHM - TORA . Historical Fiction Report! 22 3.7.1 Description . 22 3.7.2 Properties . 23 3.8 INTERNET MANET ENCAPSULATION PROTOCOL - IMEP. 24 3.8.1 Description . Types Of Thesis Methodology! 24 3.8.2 Properties . 24 3.9 CLUSTER BASED ROUTING PROTOCOL - CBRP. 24 3.9.1 Description . 24 3.9.2 Properties . How To Write Australia! 26 3.10 COMPARISON. 26 4 SIMULATION ENVIRONMENT . 28 4.1 NETWORK SIMULATOR. 28 4.2 MOBILITY EXTENSION . 29 4.2.1 Shared media. 30 4.2.2 Mobile node. 30 4.3 SIMULATION OVERVIEW . 31 4.4 MODIFICATIONS . 32 4.4.1 AODV . 32 4.4.2 DSR. 33 4.4.3 DSDV. 34 4.4.4 Flooding . 34 4.4.5 The simulator.

34 5 SIMULATION STUDY . 35 5.1 MEASUREMENTS . 35 5.1.1 Quantitative metrics . 35 5.1.2 Parameters . 35 5.1.3 Mobility . Of Thesis! 35 5.2 SIMULATION SETUP . Essay Order! 38 5.3 MOBILITY SIMULATIONS . 39 5.3.1 Setup . 39 5.3.2 Fraction of received packets. 40 5.3.3 End-to-end delay . 41 5.3.4 End-to-end throughput . 42 5.3.5 Overhead . 43 5.3.6 Optimal path. 44 5.3.7 Summary mobility simulations. 46 5.4 OFFERED LOAD SIMULATIONS . 46 5.4.1 Setup . 46 5.4.2 Fraction of received packets. 47 5.4.3 End-to-end delay . Types Of Thesis Methodology! 48 5.4.4 End-to-end throughput . 49 5.4.5 Overhead . 49 5.4.6 Optimal path.

51 5.4.7 Summary offered load simulations . 51 5.5 NETWORK SIZE SIMULATIONS. 52 5.6 REALISTIC SCENARIOS . 52 5.6.1 Setup . 52 5.6.2 Conference. Custom Essay Order! 53 5.6.3 Event coverage . 55 5.6.4 Disaster area . 57 5.6.5 Summary realistic scenarios. 60 5.7 OBSERVATIONS . 60 5.7.1 Ability to find routes . 60 5.7.2 Temporary backward routes. 61 5.7.3 Buffers . 62 5.8 DISCUSSION. 62 5.9 CLASSIFICATION. 62 5.9.1 Mobile networks . Types Methodology! 63 5.9.2 Size of networks . 63 5.9.3 Network scenarios . In Essay Quotes! 64 5.10 IMPROVEMENTS . 64 6 IMPLEMENTATION STUDY . 65 DESIGN. 65 6.1.1 Main . 65 6.1.2 Event queue . 66 6.1.3 Route table. 66 6.1.4 Neighbors / senders . 66 6.1.5 Request buffer.

66 6.1.6 Message . 66 6.2 SETUP . 66 6.3 TESTING . 67 6.3.1 Correctness. 67 6.3.2 Performance . 67 6.4 6.5 6.6 7 CONCLUSIONS. 69 7.1 7.2 8 PROBLEMS / LIMITATIONS . 67 IMPROVEMENTS . 68 IMPLEMENTATION CONCLUSIONS . 68 RESULTS. Of Thesis Methodology! 69 FURTHER STUDIES . 69 REFERENCES . 71 APPENDIX A - TERMINOLOGY. 73 A.1 A.2 GENERAL TERMS . 73 AD-HOC RELATED TERMS . 74 APPENDIX B - AODV IMPLEMENTATION FOR NS. Custom Essay Order! 75 B.1 MESSAGE FORMATS. 75 B.1.1 Route Request – RREQ. 75 B.1.2 Route Reply - RREP. 76 B.1.3 Hello . 76 B.1.4 Link failure . 76 B.2 DESIGN . 77 B.3 IMPORTANT ROUTINES.

78 B.3.1 Sending RREQ. 78 B.3.2 Receiving RREQ . 78 B.3.3 Forwarding RREQ. 79 B.3.4 Forwarding RREP . 79 B.3.5 Receiving RREP . Of Thesis Methodology! 79 B.3.6 Hello handling . 80 B.3.7 Forwarding packets. 80 B.3.8 Sending Triggered RREP . 80 B.3.9 Receiving Triggered RREP. 80 APPENDIX C - SIMULATOR SCREENSHOTS . 81 C.1 C.2 NETWORK ANIMATOR . 81 AD-HOCKEY . 82 List of historical book high school Figures Figure 1: Figure 2: Figure 3: Figure 4: Figure 5: Figure 6: Figure 7: Figure 8: Figure 9: Figure 10: Figure 11: Figure 12: Figure 13: Figure 14: Figure 15: Figure 16: Figure 17: Figure 18: Figure 19: Figure 20: Figure 21: Figure 22: Figure 23: Figure 24: Figure 25: Figure 26: Figure 27: Figure 28: Figure 29: Figure 30: Figure 31: Figure 32: Figure 33: Figure 34: Figure 35: Example of a simple ad-hoc network with three participating nodes. Of Thesis! . Historical Fiction Book Report High! 12 Block diagram of a mobile node acting both as hosts and as router. . 13 Network using ZRP. The dashed squares show the routing zones for nodes S and D. Types Methodology! 22 Directed acyclic graph rooted at destination. 23 IMEP in rsvp how to, the protocol stack. . Types Methodology! 24 Bi-directional linked clusters. Book Report School! 25 Network simulator 2. Types Of Thesis! . 28 Shared media model. . 30 A mobile node. . 31 Simulation overview. 32 Example of mobility. Custom Order! . 37 Relation between the number of link changes and types of thesis mobility. In Essay! . 37 Mobility simulations - fraction of received packets. . 40 Mobility simulations - delay. 41 Mobility simulations - throughput. . 42 Mobility simulations - overhead.

43 Mobility simulations - optimal path difference. . 45 Offered load simulations - fraction of received packets. . 47 Offered load simulations - average delay. . 48 Offered load simulations - average throughput. . Of Thesis Methodology! 49 Offered load simulations - overhead. 50 Offered load simulations – optimal path. 51 Conference scenario. . Historical Book! 54 Event coverage scenario. . 56 Disaster area scenario. . Types Of Thesis Methodology! 58 Simple example scenario. Rsvp Write! . 60 Overview of AODV daemon. . 65 Different router identification approaches. From left to types, right: 3a, 3b, 3c. 70 Route request format. . 75 Route reply format. 76 AODV design of implementation for simulator. Mla Citing Quotes! . 77 Screenshot – Network animator. 81 Screenshot – Ad-hockey – Conference scenario. . 82 Screenshot – Ad-hockey – Event coverage scenario. . 83 Screenshot – Ad-hockey – Disaster area. . 83 List of Tables Table 1: Table 2: Table 3: Table 4: Table 5: Table 6: Table 7: Table 8: Table 9: Table 10: Table 11: Table 12: Table 13: Table 14: Table 15: Table 16: Table 17: Table 18: Table 19: Table 20: Table 21: Neighbor table. Types Methodology! . 25 Comparison between ad-hoc routing protocols. . 27 Constants used in the AODV implementation. 33 Constants used in the DSR implementation. . 33 Constants used in the DSDV implementation. . 34 Mobility variables. 36 Parameters used during mobility simulations. 39 Optimal path difference for all protocols. 45 Parameters used during offered load simulations. . 47 Parameters used during realistic simulations.

53 Parameters used during conference scenario. . 53 Conference simulation results. Order! . 54 Packet drops in conference scenario. 55 Parameters used during event coverage scenario. . 55 Event coverage simulation results. . 57 Packet drops in event coverage scenario. . Of Thesis! 57 Parameters used during disaster area scenario. How To Write! 57 Disaster area simulation results. . 59 Packet drops in disaster area. 59 Routing tables for AODV after a route discovery process. Methodology! . 60 Routing caches for how to report australia, DSR, after a route discovery process. 61 1 Introduction 1.1 Background Wireless communication between mobile users is becoming more popular than ever before. This due to recent technological advances in laptop computers and wireless data communication devices, such as wireless modems and wireless LANs. Of Thesis Methodology! This has lead to lower prices and higher data rates, which are the two main reasons why mobile computing continues to enjoy rapid growth.

There are two distinct approaches for enabling wireless communication between two hosts. The first approach is to let the existing cellular network infrastructure carry data as well as voice. The major problems include the in essay problem of handoff, which tries to handle the situation when a connection should be smoothly handed over from one base station to another base station without noticeable delay or packet loss. Another problem is that networks based on the cellular infrastructure are limited to types of thesis, places where there exists such a cellular network infrastructure. The second approach is to form an ad-hoc network among all users wanting to rotc essay topics, communicate with each other. This means that all users participating in the ad-hoc network must be willing to of thesis, forward data packets to make sure that the mla citing in essay packets are delivered from source to destination. This form of types networking is limited in range by the individual nodes transmission ranges and is typically smaller compared to rotc essay, the range of cellular systems. This does not mean that the cellular approach is better than the ad-hoc approach. Ad-hoc networks have several advantages compared to traditional cellular systems. These advantages include: N N N On demand setup Fault tolerance Unconstrained connectivity Ad-hoc networks do not rely on any pre-established infrastructure and can therefore be deployed in places with no infrastructure. This is types of thesis methodology useful in disaster recovery situations and places with non-existing or damaged communication infrastructure where rapid deployment of egypt reports a communication network is types of thesis methodology needed.

Adhoc networks can also be useful on conferences where people participating in the conference can form a temporary network without engaging the services of historical report high any pre-existing network. Types Of Thesis Methodology! Because nodes are forwarding packets for each other, some sort of routing protocol is necessary to make the routing decisions. Currently there does not exist any standard for a routing protocol for ad-hoc networks, instead this is work in progress. Many problems remain to be solved before any standard can be determined. This thesis looks at some of custom essay order these problems and tries to types of thesis, evaluate some of the currently proposed protocols. 1.2 Problem description The objective for custom, this master thesis was to types methodology, evaluate proposed routing protocols for wireless ad-hoc networks based on performance.

This evaluation should be done theoretically and through simulation. It was also desirable to compare the results with the results for routing protocols in a traditional wired network. At the beginning of this master thesis, no implementation of the protocols had been released, so the first main task was to egypt reports, implement some of the protocols. The thesis also included the goal to generate a simulation environment that could be used as a platform for further studies within the area of methodology ad-hoc networks. This simulation environment should if possible, be based on Network simulator 2 from rsvp how to write Berkeley. 9 The goal of types this master thesis was to: N N N N N N Get a general understanding of how to write ad-hoc networks. Types! Generate a simulation environment that could be used for further studies. Implement some of the rsvp write proposed routing protocols for types, wireless ad-hoc networks.

Analyze the protocols theoretically and through simulation. Produce a classification of the protocols with respect to fiction report high school, applicability in combinations of small/large networks, and mobile/semi-mobile nodes. Recommend protocols for specific network scenarios. 1.3 Related work Many routing protocols have been proposed [2][4][6][8][10][11][12][16][19][22][26], but few comparisons between the types methodology different protocols have been made. Of the egypt work that has been done in this field, only the work done by the Monarch1 project at Carnegie Mellon University (CMU) has compared some of the types different proposed routing protocols and evaluated them based on the same quantitative metrics. The result was presented in the article “A performance comparison of multi-hop ad hoc wireless network routing protocols” [3] that was released in the beginning of custom essay order October 1998. There exist some other simulation results [13][17] that have been done on individual protocols. These simulations have however not used the same metrics and are therefore not comparable with each other. Of Thesis! In parallel with our master thesis, a master thesis project in Gothenburg [28] implemented the reports AODV [19] protocol and tested it in a environment that consisted of 5 computers with wireless interfaces. The cooperation between our projects and their project made it possible to share thoughts and ideas with each other. 1.4 Project organization The following persons have been involved in this master thesis project: Simulation study and master thesis authors M.Sc.

Tony Larsson M.Sc. Of Thesis! Nicklas Hedman Supervisor at Ericsson Telecom AB, Switchlab Tekn.Lic. Per Johansson Examiner at egypt reports, Lulea University of Technology Ph. D. Mikael Degermark Implementation study at Ericsson Mobile data design (ERV) in Gothenburg M.Sc. Types! Johan Kopman M.Sc.

Jerry Svedlund Supervisor at ERV M.Sc. Christoffer Kanljung Contribution of realistic scenarios Ph.D. student at Chalmers University of Technology: Bartosz Mielczarek 1 MObile Networking ARCHitectures 10 1.5 Disposition This report consists of 8 chapters and two appendices. Chapters 1 and 2 explain the concept of ad-hoc networks and custom essay order routing in types of thesis, general. How To Write Australia! Chapter 3 describes the different routing protocols, analyzes and compares them. Chapters 4 and types 5 describe the simulator and the simulations that were made. Chapter 6 describes the implementation study of AODV that was made in Gothenburg.

Chapter 7 concludes the whole report and chapter 8 is the references that we have used. The appendices contain some terminology, details about the implementation of AODV that we did for the simulator and fiction report high school some screenshots of the simulator. Types Methodology! 1.6 Abbreviations AODV CBR CBRP DSDV DSR IEEE IETF LAN IP MAC MANET OLSR PDA QoS TCP TORA UDP WINET ZRP Ad-hoc On-demand Distance Vector Constant Bit Rate Cluster Based Routing Protocol Destination Sequenced Distance Vector Dynamic Source Routing Institute of a scientific report Electrical and types methodology Electronics Engineers Internet Engineering Task Force Local Area Network Internet Protocol Media Access Protocol Mobile Ad-hoc NETworks Optimized Link State Routing Protocol Personal Digital Assistant Quality of in essay Service Transmission Control Protocol Temporally Ordered Routing Algorithm User Datagram Protocol Wireless InterNET Zone Routing Protocol 11 2 General Concepts 2.1 Wireless ad-hoc networks 2.1.1 General A wireless ad-hoc network is a collection of mobile/semi-mobile nodes with no pre-established infrastructure, forming a temporary network. Of Thesis Methodology! Each of the rsvp how to write nodes has a wireless interface and communicate with each other over either radio or infrared. Laptop computers and methodology personal digital assistants that communicate directly with each other are some examples of historical book high school nodes in an ad-hoc network.

Nodes in of thesis methodology, the adhoc network are often mobile, but can also consist of stationary nodes, such as access points to the Internet. Semi mobile nodes can be used to deploy relay points in areas where relay points might be needed temporarily. Figure 1 shows a simple ad-hoc network with three nodes. Write Report Australia! The outermost nodes are not within transmitter range of types of thesis each other. However the middle node can be used to egypt reports, forward packets between the outermost nodes.

The middle node is acting as a router and the three nodes have formed an ad-hoc network. Figure 1: Example of methodology a simple ad-hoc network with three participating nodes. An ad-hoc network uses no centralized administration. This is to be sure that the rotc essay topics network wont collapse just because one of the mobile nodes moves out of transmitter range of the types methodology others. Nodes should be able to enter/leave the write network as they wish. Of Thesis Methodology! Because of the limited transmitter range of the nodes, multiple hops may be needed to reach other nodes.

Every node wishing to in essay quotes, participate in an ad-hoc network must be willing to forward packets for other nodes. Thus every node acts both as a host and as a router. A node can be viewed as an types of thesis methodology, abstract entity consisting of a router and a set of affiliated mobile hosts (Figure 2). A router is an entity, which, among other things runs a routing protocol. A mobile host is simply an IP-addressable host/entity in the traditional sense. Ad-hoc networks are also capable of handling topology changes and malfunctions in nodes. It is fixed through network reconfiguration. For instance, if a node leaves the network and causes link breakages, affected nodes can easily request new routes and the problem will be solved. This will slightly increase the essay topics delay, but the network will still be operational.

12 Wireless ad-hoc networks take advantage of the of thesis methodology nature of the wireless communication medium. In other words, in a wired network the physical cabling is done a priori restricting the connection topology of the nodes. This restriction is mla citing not present in the wireless domain and, provided that two nodes are within transmitter range of each other, an instantaneous link between them may form. Host Host Router Host Figure 2: Block diagram of a mobile node acting both as hosts and as router. 2.1.2 Usage There is no clear picture of what these kinds of networks will be used for.

The suggestions vary from document sharing at conferences to infrastructure enhancements and types of thesis military applications. In areas where no infrastructure such as the Internet is available an ad-hoc network could be used by rsvp how to write a group of wireless mobile hosts. Types Methodology! This can be the case in areas where a network infrastructure may be undesirable due to reasons such as cost or convenience. Examples of such situations include disaster recovery personnel or military troops in cases where the normal infrastructure is historical fiction book report school either unavailable or destroyed. Other examples include business associates wishing to share files in an airport terminal, or a class of students needing to methodology, interact during a lecture. If each mobile host wishing to communicate is equipped with a wireless local area network interface, the group of mobile hosts may form an ad-hoc network.

Access to the Internet and access to resources in networks such as printers are features that probably also will be supported. 2.1.3 Characteristics Ad-hoc networks are often characterized by a dynamic topology due to the fact that nodes change their physical location by order moving around. This favors routing protocols that dynamically discover routes over conventional routing algorithms like distant vector and link state [23]. Another characteristic is that a host/node have very limited CPU capacity, storage capacity, battery power and bandwidth, also referred to as a “thin client”. This means that the power usage must be limited thus leading to types of thesis, a limited transmitter range. The access media, the radio environment, also has special characteristics that must be considered when designing protocols for ad-hoc networks. One example of this may be unidirectional links. These links arise when for example two nodes have different strength on their transmitters, allowing only one of the host to egypt book, hear the other, but can also arise from disturbances from the surroundings.

Multihop in a radio environment may result in types of thesis, an overall transmit capacity gain and power gain, due to the squared relation between coverage and required output power. By using multihop, nodes can transmit the packets with a much lower output power. 13 2.2 Routing Because of the fact that it may be necessary to hop several hops (multi-hop) before a packet reaches the write a scientific australia destination, a routing protocol is needed. Types Methodology! The routing protocol has two main functions, selection of routes for rotc topics, various source-destination pairs and the delivery of types of thesis methodology messages to their correct destination. Mla Citing! The second function is conceptually straightforward using a variety of protocols and of thesis methodology data structures (routing tables). This report is focused on selecting and finding routes. 2.2.1 Conventional protocols If a routing protocol is how to write needed, why not use a conventional routing protocol like link state or distance vector? They are well tested and methodology most computer communications people are familiar with them. The main problem with link-state and distance vector is order that they are designed for a static topology, which means that they would have problems to converge to a steady state in types of thesis methodology, an ad-hoc network with a very frequently changing topology. Link state and rotc topics distance vector would probably work very well in an ad-hoc network with low mobility, i.e. a network where the of thesis methodology topology is not changing very often. The problem that still remains is that link-state and distance-vector are highly dependent on periodic control messages.

As the number of network nodes can be large, the potential number of destinations is essay also large. Of Thesis! This requires large and frequent exchange of data among the network nodes. This is in contradiction with the fact that all updates in rsvp, a wireless interconnected ad hoc network are transmitted over the air and thus are costly in resources such as bandwidth, battery power and CPU. Of Thesis Methodology! Because both link-state and distance vector tries to maintain routes to all reachable destinations, it is necessary to maintain these routes and this also wastes resources for the same reason as above. Another characteristic for book reports, conventional protocols are that they assume bi-directional links, e.g. that the transmission between two hosts works equally well in both directions. In the wireless radio environment this is types not always the case. Because many of the proposed ad-hoc routing protocols have a traditional routing protocol as underlying algorithm, it is necessary to understand the basic operation for conventional protocols like distance vector, link state and source routing. 2.2.2 Link State In link-state routing [23], each node maintains a view of the complete topology with a cost for each link. To keep these costs consistent; each node periodically broadcasts the link costs of its outgoing links to all other nodes using flooding. As each node receives this information, it updates its view of the network and applies a shortest path algorithm to choose the next-hop for each destination. Some link costs in a node view can be incorrect because of long propagation delays, partitioned networks, etc.

Such inconsistent network topology views can lead to in essay, formation of methodology routing-loops. These loops are however short-lived, because they disappear in the time it takes a message to traverse the diameter of the network. 2.2.3 Distance Vector In distance vector [23] each node only monitors the cost of its outgoing links, but instead of broadcasting this information to all nodes, it periodically broadcasts to each of its neighbors an estimate of the shortest distance to every other node in a scientific report australia, the network. The receiving nodes then use this information to types of thesis, recalculate the routing tables, by custom essay using a shortest path algorithm. Types Of Thesis Methodology! Compared to link-state, distance vector is how to more computation efficient, easier to implement and requires much less storage space. However, it is well known that distance vector can cause the of thesis methodology formation of both short-lived and long-lived routing loops. The primary cause for this is that the nodes choose their next-hops in custom essay, a completely distributed manner based on information that can be stale. 2.2.4 Source Routing Source routing [23] means that each packet must carry the complete path that the methodology packet should take through the network. The routing decision is therefore made at the source. Essay! The advantage with this approach is of thesis methodology that it is very easy to avoid routing loops.

The disadvantage is that each packet requires a slight overhead. 14 2.2.5 Flooding Many routing protocols uses broadcast to distribute control information, that is, send the control information from an origin node to all other nodes. A widely used form of broadcasting is flooding [23] and operates as follows. The origin node sends its information to its neighbors (in the wireless case, this means all nodes that are within transmitter range). The neighbors relay it to order, their neighbors and so on, until the packet has reached all nodes in the network.

A node will only relay a packet once and to ensure this some sort of sequence number can be used. This sequence number is increased for each new packet a node sends. 2.2.6 Classification Routing protocols can be classified [1] into types of thesis, different categories depending on their properties. N N N Centralized vs. Distributed Static vs.

Adaptive Reactive vs. Proactive One way to categorize the routing protocols is to divide them into centralized and distributed algorithms. In centralized algorithms, all route choices are made at a central node, while in distributed algorithms, the book computation of routes is shared among the network nodes. Of Thesis! Another classification of routing protocols relates to whether they change routes in response to the traffic input patterns. In static algorithms, the route used by source-destination pairs is fixed regardless of how to write traffic conditions. It can only change in methodology, response to a node or link failure. This type of algorithm cannot achieve high throughput under a broad variety of traffic input patterns. Most major packet networks uses some form of adaptive routing where the routes used to route between source-destination pairs may change in response to congestion A third classification that is more related to ad-hoc networks is to classify the routing algorithms as either proactive or reactive. Proactive protocols attempt to quotes, continuously evaluate the routes within the network, so that when a packet needs to be forwarded, the route is already known and can be immediately used. Of Thesis Methodology! The family of in essay Distance-Vector protocols is an example of a proactive scheme.

Reactive protocols, on the other hand, invoke a route determination procedure on demand only. Thus, when a route is needed, some sort of global search procedure is types employed. The family of classical flooding algorithms belongs to the reactive group. Proactive schemes have the advantage that when a route is needed, the delay before actual packets can be sent is rotc essay very small. On the other side proactive schemes needs time to converge to a steady state. Of Thesis Methodology! This can cause problems if the topology is changing frequently. 15 3 Ad-hoc routing protocols This chapter describes the different ad-hoc routing protocols that we have chosen to simulate and analyze.

3.1 Desirable properties If the conventional routing protocols do not meet our demands, we need a new routing protocol. The question is what properties such protocols should have? These are some of the properties [5] that are desirable: Distributed operation The protocol should of course be distributed. It should not be dependent on a centralized controlling node. This is the case even for stationary networks. The difference is that nodes in an ad-hoc network can enter/leave the book reports network very easily and types of thesis because of mobility the custom essay order network can be partitioned. Loop free To improve the types overall performance, we want the routing protocol to egypt book, guarantee that the routes supplied are loop-free. This avoids any waste of bandwidth or CPU consumption. Demand based operation To minimize the control overhead in the network and thus not wasting network resources more than necessary, the protocol should be reactive. This means that the protocol should only react when needed and that the methodology protocol should not periodically broadcast control information. Unidirectional link support The radio environment can cause the formation of unidirectional links.

Utilization of these links and custom not only the methodology bi-directional links improves the routing protocol performance. Security The radio environment is especially vulnerable to egypt, impersonation attacks, so to ensure the wanted behavior from the types routing protocol, we need some sort of preventive security measures. How To Write A Scientific Report Australia! Authentication and encryption is probably the way to go and of thesis methodology the problem here lies within distributing keys among the nodes in the ad-hoc network. How To Write Australia! There are also discussions about using IP-sec [14] that uses tunneling to types, transport all packets. Custom! Power conservation The nodes in an ad-hoc network can be laptops and thin clients, such as PDAs that are very limited in battery power and therefore uses some sort of stand-by mode to save power.

It is therefore important that the routing protocol has support for these sleep-modes. Multiple routes To reduce the number of reactions to topological changes and congestion multiple routes could be used. Of Thesis Methodology! If one route has become invalid, it is possible that another stored route could still be valid and write a scientific report thus saving the routing protocol from initiating another route discovery procedure. Quality of service support Some sort of Quality of Service support is probably necessary to incorporate into the routing protocol. This has a lot to do with what these networks will be used for. It could for instance be real-time traffic support. Of Thesis! None of the mla citing in essay quotes proposed protocols from MANET have all these properties, but it is necessary to remember that the types of thesis protocols are still under development and are probably extended with more functionality. The primary function is still to find a route to the destination, not to find the historical fiction school best/optimal/shortest-path route. The remainder of this chapter will describe the different routing protocols and analyze them theoretically.

16 3.2 MANET IETF has a working group named MANET (Mobile Ad-hoc Networks) [15] that is working in the field of adhoc networks. Of Thesis! They are currently developing routing specifications for ad-hoc IP networks that support scaling to a couple of order hundred nodes. Types Of Thesis! Their goal is to be finished in the end of year 1999 and then introduce these specifications to the Internet standard tracks. Even if MANET currently is working on routing protocols, it also serves as a meeting place and historical fiction book report forum, so people can discuss issues concerning ad-hoc networks. Types! Currently they have seven routing protocol drafts: N N N N N N N N AODV - Ad-hoc On Demand Distance Vector [19] ZRP - Zone Routing Protocol [8] TORA / IMEP - Temporally Ordered Routing Algorithm / Internet MANET Encapsulation Protocol [6][16][17] DSR - Dynamic Source Routing [12][13] CBRP - Cluster Based Routing Protocol [11] CEDAR - Core Extraction Distributed Ad hoc Routing [26] AMRoute – Ad-hoc Multicast Routing Protocol [2] OLSR - Optimized Link State Routing Protocol [10] Of these proposed protocols we have chosen to analyze AODV, DSR, ZRP, CBRP and TORA theoretically. We have also analyzed DSDV, which is a proactive approach, as opposed to the other reactive protocols. We have not analyzed AMRoute because it is a multicast routing protocol, neither CEDAR because it is primary a QoS routing protocol, nor OLSR, because it was submitted as an Internet draft so late. In those cases where a protocol supports both unicast and multicast routing we have only looked at rotc, the unicast routing part.

Of the types methodology theoretically analyzed protocols we have done simulations on AODV and DSR. 3.3 Destination Sequenced Distance Vector - DSDV 3.3.1 Description DSDV [22] is how to a scientific report a hop-by-hop distance vector routing protocol that in each node has a routing table that for all reachable destinations stores the next-hop and types of thesis methodology number of hops for how to, that destination. Like distance-vector, DSDV requires that each node periodically broadcast routing updates. The advantage with DSDV over traditional distance vector protocols is types of thesis methodology that DSDV guarantees loop-freedom. To guarantee loop-freedom DSDV uses a sequence numbers to how to, tag each route. Types! The sequence number shows the freshness of a route and routes with higher sequence numbers are favorable. A route R is a scientific report australia considered more favorable than R' if R has a greater sequence number or, if the routes have the same sequence number but R has lower hop-count. Of Thesis! The sequence number is increased when a node A detects that a route to book reports, a destination D has broken. So the next time node A advertises its routes, it will advertise the route to D with an infinite hop-count and a sequence number that is larger than before. DSDV basically is types of thesis methodology distance vector with small adjustments to make it better suited for ad-hoc networks.

These adjustments consist of triggered updates that will take care of topology changes in the time between broadcasts. To reduce the quotes amount of information in these packets there are two types of update messages defined: full and incremental dump. The full dump carries all available routing information and the incremental dump that only of thesis methodology carries the information that has changed since the how to australia last dump. 3.3.2 Properties Because DSDV is dependent on periodic broadcasts it needs some time to converge before a route can be used. This converge time can probably be considered negligible in a static wired network, where the topology is not changing so frequently. In an ad-hoc network on the other hand, where the topology is expected to be very dynamic, this converge time will probably mean a lot of dropped packets before a valid route is detected. Of Thesis! The periodic broadcasts also add a large amount of overhead into fiction school, the network. 17 3.4 Ad-hoc On Demand Distance vector - AODV 3.4.1 Description The Ad Hoc On-Demand Distance Vector (AODV) [19] routing protocol enables multi-hop routing between participating mobile nodes wishing to establish and types of thesis maintain an book reports, ad-hoc network. AODV is of thesis methodology based upon the distance vector algorithm. The difference is that AODV is rotc reactive, as opposed to proactive protocols like DV, i.e. AODV only requests a route when needed and of thesis methodology does not require nodes to maintain routes to destinations that are not actively used in communications.

As long as the endpoints of a communication connection have valid routes to each other, AODV does not play any role. Topics! Features of this protocol include loop freedom and types of thesis that link breakages cause immediate notifications to be sent to the affected set of essay topics nodes, but only that set. Additionally, AODV has support for multicast routing and avoids the Bellman Ford counting to infinity problem [27]. The use of destination sequence numbers guarantees that a route is fresh. The algorithm uses different messages to discover and maintain links. Whenever a node wants to of thesis, try and how to write find a route to methodology, another node, it broadcasts a Route Request (RREQ) to how to write a scientific, all its neighbors. The RREQ propagates through the network until it reaches the destination or a node with a fresh enough route to the destination. Then the route is of thesis made available by unicasting a RREP back to the source. The algorithm uses hello messages (a special RREP) that are broadcasted periodically to the immediate neighbors. These hello messages are local advertisements for the continued presence of the node and neighbors using routes through the broadcasting node will continue to mark the routes as valid. Rsvp! If hello messages stop coming from types methodology a particular node, the neighbor can assume that the order node has moved away and of thesis methodology mark that link to the node as broken and notify the affected set of nodes by sending a link failure notification (a special RREP) to that set of nodes.

AODV also has a multicast route invalidation message, but because we do not cover multicast in book, this report we will not discuss this any further. Route table management AODV needs to keep track of the following information for each route table entry: N N N N N N N Destination IP Address: IP address for the destination node. Destination Sequence Number: Sequence number for this destination. Hop Count: Number of hops to the destination. Next Hop: The neighbor, which has been designated to forward packets to types, the destination for this route entry. Essay! Lifetime: The time for which the route is considered valid. Active neighbor list: Neighbor nodes that are actively using this route entry. Of Thesis! Request buffer: Makes sure that a request is only processed once. Route discovery A node broadcasts a RREQ when it needs a route to a destination and historical high does not have one available. This can happen if the route to the destination is unknown, or if a previously valid route expires. After broadcasting a RREQ, the of thesis methodology node waits for a RREP.

If the rotc topics reply is not received within a certain time, the types of thesis methodology node may rebroadcast the RREQ or assume that there is no route to the destination. Historical! Forwarding of RREQs is done when the node receiving a RREQ does not have a route to the destination. It then rebroadcast the RREQ. The node also creates a temporary reverse route to the Source IP Address in its routing table with next hop equal to the IP address field of the neighboring node that sent the broadcast RREQ. This is done to keep track of types a route back to the original node making the request, and might be used for an eventual RREP to find its way back to the requesting node. The route is temporary in the sense that it is valid for a much shorter time, than an actual route entry. When the book reports RREQ reaches a node that either is the destination node or a node with a valid route to the destination, a RREP is generated and unicasted back to the requesting node.

While this RREP is methodology forwarded, a route is how to write a scientific australia created to the destination and when the types RREP reaches the source node, there exists a route from the source to the destination. 18 Route maintenance When a node detects that a route to essay topics, a neighbor no longer is valid, it will remove the types methodology routing entry and send a link failure message, a triggered route reply message to the neighbors that are actively using the route, informing them that this route no longer is valid. Historical Fiction Book Report High! For this purpose AODV uses a active neighbor list to keep track of the neighbors that are using a particular route. The nodes that receive this message will repeat this procedure. The message will eventually be received by the affected sources that can chose to either stop sending data or requesting a new route by types of thesis methodology sending out a new RREQ. 3.4.2 Properties The advantage with AODV compared to classical routing protocols like distance vector and link-state is custom that AODV has greatly reduced the number of routing messages in methodology, the network. Mla Citing In Essay! AODV achieves this by using a reactive approach. This is probably necessary in an ad-hoc network to get reasonably performance when the of thesis topology is changing often. AODV is also routing in the more traditional sense compared to a scientific report australia, for instance source routing based proposals like DSR (see 3.5). The advantage with a more traditional routing protocol in an ad-hoc network is that connections from the ad-hoc network to a wired network like the Internet is most likely easier.

The sequence numbers that AODV uses represents the freshness of methodology a route and is increased when something happens in the surrounding area. Book! The sequence prevents loops from being formed, but can however also be the cause for new problems. What happens for instance when the sequence numbers no longer are synchronized in the network? This can happen when the types methodology network becomes partitioned, or the sequence numbers wrap around. AODV only support one route for each destination. It should however be fairly easy to modify AODV, so that it supports several routes per destination. Instead of rotc essay topics requesting a new route when an of thesis, old route becomes invalid, the next stored route to that destination could be tried.

The probability for that route to still be valid should be rather high. Although the Triggered Route Replies are reduced in number by only sending the Triggered Route Replies to affected senders, they need to traverse the whole way from the failure to the senders. This distance can be quite high in numbers of hops. AODV sends one Triggered RREP for every active neighbor in the active neighbor list for all entries that have been affected of a link failure. This can mean that each active neighbor can receive several triggered RREPs informing about the same link failure, but for different destinations, if a large fraction of the network traffic is routed through the custom essay order same node and this node goes down. An aggregated solution would be more appropriate here.

AODV uses hello messages at the IP-level. This means that AODV does not need support from the link layer to work properly. It is however questionable if this kind of protocol can operate with good performance without support from the link layer. The hello messages adds a significant overhead to the protocol. AODV does not support unidirectional links.

When a node receives a RREQ, it will setup a reverse route to the source by using the node that forwarded the RREQ as nexthop. This means that the of thesis route reply, in most cases is unicasted back the same way as the route request used. Order! Unidirectional link support would make it possible to utilize all links and types of thesis methodology not only the bi-directional links. It is however questionable if unidirectional links are desirable in a real environment. The acknowledgements in the MAC protocol IEEE 802.11 would for instance not work with unidirectional links. 19 3.5 Dynamic Source Routing - DSR 3.5.1 Description Dynamic Source Routing (DSR) [3][12][13] also belongs to the class of reactive protocols and allows nodes to dynamically discover a route across multiple network hops to any destination. Source routing means that each packet in its header carries the complete ordered list of nodes through which the packet must pass. DSR uses no periodic routing messages (e.g. no router advertisements), thereby reducing network bandwidth overhead, conserving battery power and rotc essay avoiding large routing updates throughout the ad-hoc network. Instead DSR relies on support from the MAC layer (the MAC layer should inform the routing protocol about link failures). The two basic modes of operation in DSR are route discovery and route maintenance. Route discovery Route discovery is the mechanism whereby a node X wishing to send a packet to Y, obtains the source route to Y. Types Methodology! Node X requests a route by broadcasting a Route Request (RREQ) packet.

Every node receiving this RREQ searches through its route cache for a route to topics, the requested destination. DSR stores all known routes in its route cache. If no route is found, it forwards the RREQ further and adds its own address to the recorded hop sequence. This request propagates through the network until either the destination or a node with a route to of thesis methodology, the destination is reached. When this happen a Route Reply (RREP) is unicasted back to the originator. This RREP packet contains the sequence of network hops through which it may reach the target. In Route Discovery, a node first sends a RREQ with the maximum propagation limit (hop limit) set to zero, prohibiting its neighbors from rebroadcasting it.

At the cost of egypt book a single broadcast packet, this mechanism allows a node to query the route caches of all its neighbors. Nodes can also operate their network interface in promiscuous mode, disabling the interface address filtering and causing the network protocol to receive all packets that the interface overhears. These packets are scanned for useful source routes or route error messages and then discarded. The route back to the originator can be retrieved in several ways. The simplest way is to reverse the hop record in types methodology, the packet. However this assumes symmetrical links. Egypt! To deal with this, DSR checks the route cache of the replying node. If a route is found, it is used instead.

Another way is to piggyback the reply on a RREQ targeted at the originator. This means that DSR can compute correct routes in the presence of asymmetric (unidirectional) links. Once a route is found, it is stored in types of thesis methodology, the cache with a time stamp and the route maintenance phase begins. Route maintenance Route maintenance is the custom mechanism by which a packet sender S detects if the network topology has changed so that it can no longer use its route to the destination D. This might happen because a host listed in a source route, move out of wireless transmission range or is turned off making the route unusable. Types! A failed link is detected by either actively monitoring acknowledgements or passively by write running in promiscuous mode, overhearing that a packet is of thesis forwarded by a neighboring node. When route maintenance detects a problem with a route in use, a route error packet is sent back to the source node. When this error packet is received, the hop in rsvp how to write, error is removed from this hosts route cache, and of thesis all routes that contain this hop are truncated at this point.

3.5.2 Properties DSR uses the book key advantage of source routing. Intermediate nodes do not need to maintain up-to-date routing information in methodology, order to route the packets they forward. There is also no need for periodic routing advertisement messages, which will lead to reduce network bandwidth overhead, particularly during periods when little or no significant host movement is taking place. Battery power is also conserved on the mobile hosts, both by rotc essay not sending the advertisements and by not needing to receive them, a host could go down to sleep instead. This protocol has the advantage of types of thesis learning routes by historical report high scanning for information in packets that are received. A route from A to types of thesis methodology, C through B means that A learns the route to C, but also that it will learn the route to B. The source route will also mean that B learns the route to A and write C and that C learns the route to methodology, A and rotc topics B. This form of active learning is types of thesis very good and reduces overhead in the network. Topics! 20 However, each packet carries a slight overhead containing the source route of the types of thesis packet. This overhead grows when the packet has to go through more hops to reach the destination. So the write packets sent will be slightly bigger, because of the overhead.

Running the interfaces in promiscuous mode is a serious security issue. Since the address filtering of the interface is turned off and all packets are scanned for information. A potential intruder could listen to all packets and scan them for methodology, useful information such as passwords and credit card numbers. Applications have to provide the security by encrypting their data packets before transmission. The routing protocols are prime targets for mla citing quotes, impersonation attacks and must therefore also be encrypted. One way to achieve this is to use IPsec [14]. Of Thesis Methodology! DSR also has support for unidirectional links by the use of how to write piggybacking the source route a new request. This can increase the performance in types, scenarios where we have a lot of unidirectional links.

We must however have a MAC protocol that also supports this. 3.6 Zone Routing Protocol - ZRP 3.6.1 Description Zone Routing Protocol (ZRP) [8] is a hybrid of rsvp how to a reactive and of thesis methodology a proactive protocol. Book! It divides the of thesis network into several routing zones and specifies two totally detached protocols that operate inside and between the routing zones. How To Write A Scientific Report Australia! The Intrazone Routing Protocol (IARP) operates inside the routing zone and learns the minimum distance and types routes to all the nodes within the zone. The protocol is not defined and can include any number of proactive protocols, such as Distance Vector or link-state routing. Different zones may operate with different intrazone protocols as long as the protocols are restricted to those zones. A change in topology means that update information only propagates within the affected routing zones as opposed to affecting the entire network. The second protocol, the write Interzone Routing Protocol (IERP) is reactive and is used for finding routes between different routing zones.

This is methodology useful if the destination node does not lie within the routing zone. The protocol then broadcasts (i.e. bordercasts) a Route REQuest (RREQ) to all border nodes within the routing zone, which in turn forwards the request if the destination node is not found within their routing zone. This procedure is report school repeated until the of thesis requested node is found and rotc a route reply is sent back to the source indicating the methodology route. IERP uses a Bordercast Resolution Protocol (BRP) [8] that is included in how to write a scientific report australia, ZRP. BRP provides bordercasting services, which do not exist in of thesis, IP. Bordercasting is the rotc essay process of sending IP datagrams from one node to all its peripheral nodes.

BRP keeps track of the peripheral nodes and resolves a border cast address to of thesis methodology, the individual IP-addresses of the peripheral nodes. The message that was bordercasted is then encapsulated into a BRP packet and sent to book reports, each peripheral node. Routing Zone A routing zone is defined as a set of nodes, within a specific minimum distance in number of hops from the node in types of thesis methodology, question. The distance is referred to as the zone radius. In the example network (Figure 3), node S, A, F, B, C, G and H, all lie within a radius of rsvp write two from node F. Even though node B also has a distance of methodology 3 hops from node F, it is included in the zone since the shortest distance is only 2 hops. Border nodes or peripheral nodes are nodes whose minimum distance to the node in question is custom order equal exactly to the zone radius. In Figure 3, nodes B and F are border nodes to S. Consider the network in Figure 3. Node S wants to send a packet to node D. Since node D is not in of thesis methodology, the routing zone of S, a route request is sent to the border nodes B and book school F. Each border node checks to see if D is in their routing zone. Types Of Thesis Methodology! Neither B nor F finds the requested node in their routing zone; thus the request is custom order forwarded to the respectively border nodes. F sends the request to S, B, C and H while B sends the types of thesis request to a scientific, S, F, E and G. Now the requested node D is found within the routing zone of both C and E thus a reply is generated and sent back towards the source node S. Of Thesis Methodology! 21 B E A Zone for essay, D C S D F Zone for S G H Zone for F Figure 3: Network using ZRP. The dashed squares show the routing zones for nodes S and D. To prevent the methodology requests from going back to how to a scientific, previously queried routing zone, a Processed Request List is used. This list stores previously processed requests and of thesis if a node receives a request that it already has processed, it is simply dropped.

3.6.2 Properties ZRP is a very interesting protocol and can be adjusted of its operation to the current network operational conditions (e.g. change the routing zone diameter). However this is write not done dynamically, but instead it is suggested that this zone radius should be set by types methodology the administration of the network or with a default value by the manufacturer. The performance of this protocol depends quite a lot on mla citing in essay this decision. Since this is a hybrid between proactive and reactive schemes, this protocol use advantages from both. Routes can be found very fast within the routing zone, while routes outside the methodology zone can be found by efficiently querying selected nodes in the network. One problem is however that the proactive intrazone routing protocol is how to write not specified. The use of different intrazone routing protocols would mean that the nodes would have to support several different routing protocols. This is methodology not a good idea when dealing with thin clients. It is better to use the same intrazone routing protocol in the entire network. ZRP also limits propagation of information about topological changes to the neighborhood of the change only (as opposed to a fully proactive scheme, which would basically flood the australia entire network when a change in topology occurred).

However, a change in topology can affect several routing zones. 3.7 Temporally-Ordered Routing Algorithm - TORA 3.7.1 Description Temporally Ordered Routing Algorithm (TORA) [16][17] is methodology a distributed routing protocol. The basic underlying algorithm is one in mla citing, a family referred to as link reversal algorithms. TORA is designed to minimize reaction to topological changes. Of Thesis! A key concept in mla citing in essay quotes, its design is types of thesis methodology that control messages are typically localized to quotes, a very small set of nodes. It guarantees that all routes are loop-free (temporary loops may form), and types of thesis methodology typically provides multiple routes for any source/destination pair.

It provides only the routing mechanism and topics depends on Internet MANET Encapsulation Protocol (IMEP [6]) for other underlying functions. TORA can be separated into three basic functions: creating routes, maintaining routes, and erasing routes. The creation of routes basically assigns directions to links in methodology, an undirected network or portion of the network, building a directed acyclic graph (DAG) rooted at mla citing quotes, the destination (See Figure 4). 22 D Figure 4: Directed acyclic graph rooted at destination. Of Thesis Methodology! TORA associates a height with each node in the network. Australia! All messages in the network flow downstream, from a node with higher height to a node with lower height. Routes are discovered using Query (QRY) and of thesis Update (UPD) packets. When a node with no downstream links needs a route to fiction report, a destination, it will broadcast a QRY packet. This QRY packet will propagate through the network until it reaches a node that has a route or the destination itself. Such a node will then broadcast a UPD packet that contains the node height. Every node receiving this UPD packet will set its own height to types, a larger height than specified in egypt, the UPD message.

The node will then broadcast its own UPD packet. This will result in types methodology, a number of directed links from the originator of the QRY packet to mla citing, the destination. Methodology! This process can result in multiple routes. Maintaining routes refers to reacting to topological changes in topics, the network in a manner such that routes to types methodology, the destination are re-established within a finite time, meaning that its directed portions return to a destination-oriented graph within a finite time. Upon detection of historical fiction book high a network partition, all links in the portion of the network that has become partitioned from the destination are marked as undirected to erase invalid routes. The erasing of routes is done using clear (CLR) messages.

3.7.2 Properties The protocols underlying link reversal algorithm will react to link changes through a simple localized single pass of the distributed algorithm. Types! This prevents CLR packets to book, propagate too far in the network. A comparison made by the CMU Monarch project has however shown that the overhead in TORA is quite large because of the use of IMEP. The graph is rooted at the destination, which has the lowest height. However, the of thesis source originating the QRY does not necessarily have the highest height. This can lead to the situation, where multiple routes are possible from the source to the destination, but only one route will be discovered. The reason for how to write a scientific, this is that the height is types initially based on the distance in number of hops from the destination.

23 3.8 Internet MANET Encapsulation Protocol - IMEP 3.8.1 Description IMEP [5] is a protocol designed to support the operation of many routing protocols in Ad-hoc networks. The idea is to have a common general protocol that all routing protocols can make use of rsvp write (see Figure 5). Types! It incorporates many common mechanisms that the upper-layer protocol may need. These include: N N N N N Link status sensing Control message aggregation and encapsulation Broadcast reliability Network-layer address resolution Hooks for interrouter security authentication procedures IMEP also provides an architecture for MANET router identification, interface identification and addressing. IMEPs purpose is to improve overall performance by write reducing the number of types of thesis control messages and to put common functionality into essay order, one unified, generic protocol useful to of thesis methodology, all upper-level routing protocols. Routing IMEP IP Figure 5: IMEP in the protocol stack. Of the currently purposed protocols, only mla citing in essay quotes TORA and OLSR use IMEP. It must however be noted that TORA and IMEP where designed by the same author. 3.8.2 Properties The idea to have a general protocol for common basic features is types of thesis good, but from a performance point of view this is not such a good idea. It adds another layer to the protocol stack. As the work by the CMU Monarch projects has shown [3], IMEP generates a lot of overhead, mainly because of IMEPs neighbor discovery mechanism that generates at least one hello message per second, but also because of the reliable in-order delivery of the packets that IMEP provides.

3.9 Cluster Based Routing Protocol - CBRP 3.9.1 Description The idea behind CBRP [11] is to divide the nodes of an essay topics, ad-hoc network into a number of overlapping or disjoint clusters. One node is types of thesis elected as cluster head for each cluster. This cluster head maintains the essay membership information for types, the cluster. Inter-cluster routes (routes within a cluster) are discovered dynamically using the essay membership information. 24 CBRP is based on source routing, similar to DSR. This means that intracluster routes (routes between clusters) are found by flooding the network with Route Requests (RREQ). Types Of Thesis Methodology! The difference is that the cluster structure generally means that the number of essay nodes disturbed are much less. Of Thesis! Flat routing protocols, i.e. only one level of hierarchy, might suffer from excessive overhead when scaled up. CBRP is like the other protocols fully distributed. This is necessary because of the very dynamic topology of the ad-hoc network. Historical Report School! Furthermore, the protocol takes into of thesis methodology, consideration the existence of unidirectional links.

Link sensing Each node in CBRP knows its bi-directional links to its neighbors as well as unidirectional links from its neighbors to itself. To handle this, each node must maintain a Neighbor Table (see Table 1). Table 1: Neighbor ID Neighbor 1 Neighbor 2 … Neighbor n Neighbor table. Link status Bi/unidirectional link to me Bi/unidirectional link to me … Bi/unidirectional link to me Role Is 1 a cluster head or member Is 2 a cluster head or member … Is n a cluster head or member Each node periodically broadcasts its neighbor table in a hello message. The hello message contains the node ID, the nodes role (cluster head, cluster member or undecided) and the neighbor table. The hello messages are used to update the neighbor tables at each node. If no hello message is received from a certain node, that entry will be removed from the table. Clusters The cluster formation algorithm is very simple, the node with lowest node ID is elected as the cluster head. The nodes use the information in the hello messages to decide whether or not they are the cluster heads. The cluster head regards all nodes it has bi-directinal links to as its member nodes.

A node regards itself as a member node to a particular cluster if it has a bi-directinal link to the cluster head. It is custom essay order possible for a node to belong to several clusters. Cluster 1 Cluster 2 3 4 Cluster head Cluster head 1 2 6 Figure 6: 5 Bi-directional linked clusters. 25 Clusters are identified by their respective cluster heads, which means that the cluster head must change as infrequently as possible. The algorithm is types of thesis therefore not a strict lowest ID clustering algorithm. Quotes! A noncluster head never challenges the status of an existing cluster head. Only when two cluster-heads move next to each other, will one of them lose the types role as cluster head. In Figure 6 node 1 is cluster head for cluster 1 and node 2 is cluster head for cluster 2. Routing Routing in CBRP is based on source routing and the route discovery is done, by flooding the network with Route Requests (RREQ). The clustering approach however means that fewer nodes are disturbed. This, because only the cluster heads are flooded.

If node X needs a route to node Y, node X will send out a RREQ, with a recorded source route listing only mla citing in essay quotes itself initially. Any node forwarding this packet will add its own ID in this RREQ. Each node forwards a RREQ only of thesis once and it never forwards it to node that already appears in a scientific australia, the recorded route. In CBRP, a RREQ will always follow a route with the following pattern: Source-Cluster head-Gateway-Cluster head-Gateway- . -Destination A gateway node for a cluster is a node that knows that it has a bi-directional or a unidirectional link to a node in another cluster. In Figure 6, node 6 is gateway node for cluster 1 and node 4 is gateway node for cluster 2. The source unicasts the RREQ to its cluster head. Each cluster-head unicasts the RREQ to each of its bidirectionally linked neighbor clusters, which has not already appeared in the recorded route through the corresponding gateway. Of Thesis! There does not necessarily have to be an actual bi-directional link to a bi-directional linked neighbor cluster. For instance, in Figure 6 cluster 1 has a unidirectional link to cluster 2 through node 3 and rotc essay topics cluster 2 has a unidirectional link to cluster 1 through node 5, and types of thesis the clusters are therefore bidirectional linked neighbor clusters. This procedure continues until the egypt reports target is found or another node can supply the route. When the RREQ reaches the target, the target may chose to of thesis methodology, memorize the reversed route to the source. It then copies the report australia recorded route to a Route Reply packet and sends it back to the source.

3.9.2 Properties This protocol has a lot of common features with the earlier discussed protocols. It has a route discovery and route removal operation that has a lot in common with DSR and AODV. The clustering approach is probably a very good approach when dealing with large ad-hoc networks. The solution is more scalable than the other protocols, because it uses the clustering approach that limits the number of messages that need to methodology, be sent. In Essay! CBRP also has the advantage that it utilizes unidirectional links.

One remaining question is however how large each cluster should be. This parameter is types of thesis critical to how the protocol will behave. 3.10 Comparison So far, the protocols have been analyzed theoretically. Table 2 summarizes and compares the result from these theoretical/qualitative analyses and shows what properties the protocols have and do not have. As it can be seen from Table 2, none of the protocols support power conservation or Quality of Service. This is however work in progress and will probably be added to the protocols. How To! All protocols are distributed, thus none of the protocols is of thesis dependent on a centralized node and can therefore easily reconfigure in the event of topology changes.

26 Table 2: Comparison between ad-hoc routing protocols. DSDV AODV DSR ZRP Loop-free Yes Yes Yes Yes Multiple routes Distributed Reactive Unidirectional link support QoS Support Multicast Security Power conservation Periodic broadcasts No Yes No No No No No No Yes No Yes Yes No No Yes No No Yes Yes Yes Yes Yes No No No No No No Yes Partially No No No No No Yes Requires reliable or sequenced data No No No No TORA/ IMEP No, short lived loops Yes Yes Yes No No No No No Yes (IMEP) Yes CBRP Yes Yes Yes Yes Yes No No No No Yes No DSDV is the only proactive protocol in write, this comparison. It is also the protocol that have most in common with traditional routing protocol in wired networks. The sequence numbers were added to ensure loop-free routes. DSDV will probably be good enough in networks, which allows the protocol to converge in reasonable time. This however means that the mobility cannot be too high. The authors of DSDV came to the same conclusions and designed AODV, which is a reactive version of DSDV. They also added multicast capabilities, which will enhance the performance significantly when one node communicates with several nodes.

The reactive approach in AODV has many similarities with the reactive approach of DSR. They both have a route discovery mode that uses request messages to types of thesis methodology, find new routes. The difference is that DSR is based on a scientific australia source routing and will learn more routes than AODV. DSR also has the advantage that it supports unidirectional links. Types! DSR has however one major drawback and it is the source route that must be carried in rsvp, each packet. This can be quite costly, especially when QoS is going to be used. Types! ZRP and CBRP are two very interesting proposals that divide the network into several zones/clusters. This approach is probably a very good solution for rotc topics, large networks. Within the zones/clusters they have a more proactive scheme and between the zones/clusters they have a reactive scheme that have many similarities with the operation of AODV and DSR. They have for instance a route discovery phase that sends request through the network. The difference between ZRP and CBRP is how the network is divided.

In ZRP all zones are overlapping and in CBRP clusters can be both overlapping and disjoint. None of the types of thesis presented protocols are adaptive, meaning that the protocols do not take any smart routing decisions when the traffic load in the network is taken into consideration. Book High! As a route selection criteria the proposed protocols use metrics such as shortest number of hops and quickest response time to a request. This can lead to methodology, the situation where all packets are routed through the same node even if there exist better routes where the traffic load is not as large. 27 4 Simulation Environment The simulator we have used to simulate the ad-hoc routing protocols in is the Network Simulator 2 (ns) [7] from Berkeley. Rotc Topics! To simulate the mobile wireless radio environment we have used a mobility extension to methodology, ns that is developed by the CMU Monarch project at custom order, Carnegie Mellon University. 4.1 Network Simulator Network simulator 2 is the result of an on-going effort of types of thesis research and development that is administrated by topics researchers at Berkeley. Methodology! It is a discrete event simulator targeted at networking research. It provides substantial support for how to write report, simulation of TCP, routing, and types of thesis methodology multicast protocols. The simulator is written in C++ and rsvp how to write a script language called OTcl2.

Ns uses an Otcl interpreter towards the types user. This means that the user writes an OTcl script that defines the network (number of nodes, links), the egypt book reports traffic in the network (sources, destinations, type of traffic) and types of thesis which protocols it will use. This script is then used by ns during the simulations. The result of the simulations is an output trace file that can be used to do data processing (calculate delay, throughput etc) and to essay, visualize the simulation with a program called Network Animator (NAM). Types Of Thesis! See Appendix C for a screenshot of NAM. Rsvp Write! NAM is a very good visualization tool that visualizes the packets as they propagate through the network. An overview of how a simulation is done in ns is shown in Figure 7. Methodology! Otcl script Network Simulator 2 Output Data processing Network Animator Figure 7: Network simulator 2. Mla Citing! The current version3 of the Network simulator does not support mobile wireless environments. The Network simulator alone is only intended for stationary networks with wired links. This caused us some problems in the beginning of types methodology this master thesis.

We needed mobility and therefore started to historical school, design and types implement a mobility model that would extend the simulator. We also started to implement the how to report AODV protocol. This implementation of types of thesis methodology AODV is compatible with NAM and write a scientific australia therefore gives a good picture of how AODV behaves. It is very easy to follow for instance the route discovery procedure. Methodology! About two months later, in write australia, August 1998, two separate mobility extensions were released. These extensions had everything that we wanted from an types of thesis methodology, extension, so we decided to use one of them. This however meant that the implementation of AODV that we made earlier no longer was compatible and had to rotc, be ported. 2 3 Object Tool Command Language Network simulator 2.1b3 28 4.2 Mobility extension There currently exist two mobility extensions to ns.

These are: N N Wireless mobility extension developed by the CMU Monarch projects [30]. Mobility support, mobile IP and wireless channel support developed by C. Perkins at Sun Microsystems [18]. The ns group at Berkeley has as intention to integrate both these extensions to types, ns. This work is however not complete yet. We have chosen to use the CMU Monarch extension, because this extension is custom essay order targeted at types methodology, ad-hoc networks. The version of the extension that we have worked with4 adds the following features5 to the Network simulator.

Node mobility Each mobile node is an independent entity that is responsible for computing its own position and velocity as a function of time. Topics! Nodes move around according to a movement pattern specified at of thesis, the beginning of the simulation. Realistic physical layers Propagation models are used to decide how far packets can travel in air. Essay! These models also consider propagation delays, capture effects and carrier sense [25]. MAC 802.11 An implementation of the IEEE 802.11 Media Access Protocol (MAC) [9] protocol was included in the extension. The MAC layer handles collision detection, fragmentation and acknowledgements. This protocol may also be used to detect transmission errors. 802.11 is a CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) protocol. Of Thesis! It avoids collisions by checking the fiction book report channel before using it. If the channel is methodology free, it can start sending, if not, it must wait a random amount of time before checking again. For each retry an exponential backoff algorithm will be used.

In a wireless environment it cannot be assumed that all stations hear each other. Historical Fiction! If a station senses the medium, as free, it does not necessarily mean that the medium is free around the receiver area. This problem is known as the hidden terminal problem and to types of thesis, overcome these problems the Collision Avoidance mechanism together with a positive acknowledgement scheme is used. Essay! The positive acknowledgement scheme means that the receiver sends an acknowledgement when it receives a packet. The sender will try to methodology, retransmit this packet until it receives the acknowledgement or the number of rotc essay retransmits exceeds the maximum number of retransmits. 802.11 also support power saving and security. Power saving allows packets to be buffered even if the types system is asleep. Security is provided by an algorithm called Wired Equivalent Privacy (WEP). It supports authentication and encryption. WEP is a Pseudo Random Number Generator (PRNG) and is based on RSAs RC4. Quotes! One of the types of thesis methodology most important features of how to write 802.11 is the ad-hoc mode, which allows users to build up Wireless LANs without an infrastructure (without an access point).

Address Resolution Protocol The Address Resolution Protocol, ARP [24] is implemented. Methodology! ARP translates IP-addresses to hardware MAC addresses. This takes place before the packets are sent down to egypt book, the MAC layer. Ad-hockey Ad-hockey is an application that makes it possible to visualize the mobile nodes as they move around and of thesis methodology send/receives packets. Egypt Book Reports! Ad-hockey can also be used as a scenario generator tool to of thesis, create the how to write report input files necessary for of thesis, the simulations. This is done, by positioning nodes in custom essay, a specified area.

Each node is then given a movement pattern consisting of types of thesis movement directions at different waypoints, speed, pause times and in essay communication patterns. Screenshots of ad-hockey can be seen in Appendix C. 4 Version 1.0.0-beta, released in the middle of August. At the end of types methodology November 1998, the CMU Monarch projects released version 1.1.0 of the extension. This new version contains some bug fixes and how to australia implementations of the AODV and types methodology TORA protocols. 5 29 Radio network interfaces This is a model of the hardware that actually transmits the packet onto the channel with a certain power and modulation scheme [25].

Transmission power The radius of the transmitter with an omni-directional antenna is about 250 meters in this extension. Antenna gain and receiver sensitivity Different antennas are available for custom essay, simulations. Ad-hoc routing protocols Both DSR and types methodology DSDV have been implemented and custom order added to this extension. 4.2.1 Shared media The extension is based on a shared media model (Ethernet in of thesis methodology, the air). This means that all mobile nodes have one or more network interfaces that are connected to a channel (see Figure 8). Rsvp Write! A channel represents a particular radio frequency with a particular modulation and types coding scheme. Channels are orthogonal, meaning that packets sent on one channel do not interfere with the transmission and reception of historical fiction book high school packets on another channel. The basic operation is as follows, every packet that is sent / put on the channel is received / copied to all mobile nodes connected to the same channel.

When a mobile nodes receive a packet, it first determines if it possible for it to receive the methodology packet. Custom Essay! This is determined by types methodology the radio propagation model, based on the transmitter range, the distance that the rsvp packet has traveled and the amount of bit errors. Mobile Node Mobile Node Mobile Node Channel Figure 8: Shared media model. 4.2.2 Mobile node Each mobile node (Figure 9) makes use of types of thesis a routing agent for the purpose of calculating routes to other nodes in the ad-hoc network. Packets are sent from the application and are received by the routing agent. Mla Citing! The agent decides a path that the packet must travel in order to types, reach its destination and stamps it with this information. It then sends the rotc packet down to the link layer. The link layer level uses an Address Resolution Protocol (ARP) to decide the hardware addresses of neighboring nodes and map IP addresses to types, their correct interfaces. When this information is rotc known, the packet is types sent down to the interface queue and awaits a signal from the Multiple Access Control (MAC) protocol.

When the MAC layer decides it is ok to custom essay order, send it onto the channel, it fetches the packet from the types queue and hands it over to rsvp write, the network interface which in turn sends the packet onto the radio channel. This packet is copied and methodology is delivered to all network interfaces at quotes, the time at which the first bit of the types of thesis methodology packet would begin arriving at the interface in a physical system. Each network interface stamps the packet with the receiving interfaces properties and then invokes the propagation model. The propagation model uses the transmit and receive stamps to determine the power with which the interface will receive the packet. The receiving network interfaces then use their properties to determine if they actually successfully received the packet, and sends it to the MAC layer if appropriate. If the MAC layer receives the packet error- and collision- free, it passes the packet to the mobiles entry point. From there it reaches a demultiplexer, which decides if the rotc essay topics packet should be forwarded again, or if it has reached its destination node. If the destination node is reached, the packet is sent to a port demultiplexer, which decides to types methodology, what application the packet should be delivered. If the packet should be forwarded again the routing agent will be called and topics the procedure will be repeated. 30 Entry point M U X Application Routing Agent Link Layer ARP Queue MAC Propagation model Network Interface Channel Figure 9: A mobile node.

4.3 Simulation overview A typical simulation with ns and the mobility extension is shown in Figure 10. Basically it consists of generating the following input files to of thesis methodology, ns: N N A scenario file that describes the movement pattern of the nodes. A communication file that describes the traffic in rotc topics, the network. Methodology! These files can be generated by drawing them by hand using the visualization tool Ad-hockey (see 4.2) or by generating completely randomized movement and communication patterns with a script. These files are then used for mla citing quotes, the simulation and as a result from this, a trace file is generated as output. Prior to the simulation, the parameters that are going to be traced during the simulation must be selected. Of Thesis! The trace file can then be scanned and analyzed for the various parameters that we want to essay, measure.

This can be used as data for plots with for instance Gnuplot. The trace file can also be used to of thesis, visualize the simulation run with either Ad-hockey or Network animator. 31 Scenario generation Scenario file Communication file Mobility extension Network Simulator 2 Output files Data processing Ad-hockey GnuPlot Figure 10: Network animator Simulation overview. 4.4 Modifications To be able to rotc essay, use ns for the simulations, we had to do some modifications. First of all, we did not have the of thesis routing protocols we wanted to how to report, simulate, so one of the first steps was to implement the protocols. 4.4.1 AODV We have implemented the AODV protocol (for more details, see appendix B). Types Methodology! The implementation is done according to the AODV draft [19] released in August 1998. A Scientific Report! It must however be noted that a new version of the draft [20] was released in the end of November 1998. The new draft contains some changes that would enhance the performance. Types! These changes that affect the unicast routing part is primarily: N N Reduced or complete elimination of hello messages. Updates to custom essay, important parameters to types methodology, reflect recent simulation experiences.

To be able to topics, test how the hello messages and link layer support affects the behavior of the protocol we have implemented three versions: N N N AODV with only IP-based hello messages AODV with only Link Layer notification of broken links AODV with both IP-based hello messages and types methodology Link layer notification of broken links The implementation of the different versions has some major differences that will affect the performance. First of all AODV with only MAC-layer support will not get the routes to the neighbors installed in custom order, the routing table, neither will it update the routes to the neighbor who forwarded a message to you. Both AODV versions that have hello messages will have this neighbor detection process that keeps track of the neighbors. This means that the types methodology protocols with this feature will have more information in the 32 routing tables. Without this support, buffering of the packets may be necessary while a request is egypt sent out in search for a node that could be a neighbor. Types Of Thesis Methodology! It must however be noted that the removal of hello messages somewhat changes the a scientific australia behavior of the AODV protocol. The hello messages add overhead to the protocol, but also gives us some prior knowledge of link breakages. Types Of Thesis Methodology! Removing the hello messages makes the protocol completely on-demand, broken links can only topics be detected when actually sending something on of thesis the broken link. Rotc Essay! The DSR implementation that was included in the mobility extension used a sendbuffer that buffered all packets that the application sent while the routing protocol searched for a route. To get a fair comparison of the protocols we implemented the types methodology same feature for AODV. This buffer can hold 64 packets and egypt packets are allowed to stay in the buffer for 8 seconds.

The parameters that can be adjusted for AODV and the values we have used is shown in Table 3. Some of these parameters are very important and affects the performance of the protocol in types of thesis methodology, drastic ways. The hello interval is maybe the quotes most important parameter when dealing with AODV that uses hello messages. If the types methodology interval is too long, link breakages would not be detected fast enough, but if the interval is to short, a great amount of extra control overhead would be added. Most of the parameters in Table 3 are obvious. How To Write! The maximum rate for sending replies prevents a node to do a triggered route reply storm.

This means that AODV in each node is types methodology only allowed to send one triggered RREP per second for each broken route. Book! This could for instance happen if a forwarding node receives a lot of data packets that the node no longer has a route for. In this case the node should only send a triggered RREP, as a response to the first data packet and types of thesis methodology if the node keeps receiving data packets after that, a triggered RREP is only allowed to be sent once per mla citing in essay, second. Table 3: Constants used in the AODV implementation. Types Of Thesis! Parameter Hello interval Active route timeout Route reply lifetime Allowed hello loss Request retries Time between retransmitted requests Time to hold packets awaiting routes Maximum rate for sending replies for a route Value 1,5 s 300 s 300 s 2 3 3s 8s 1/s 4.4.2 DSR The DSR implementation that came with the extension uses promiscuous mode (i.e. eavesdropping), which means that the protocol learns information from packets that it overhears. In Essay! The question is how realistic this is in a real environment. In a real case scenario we will probably have some sort of encryption, probably IP-Sec that uses IP-Sec tunneling to transport messages. We have made some small change to DSR that makes it possible to types, turn the how to write a scientific eavesdropping feature on of thesis and off. How To Write A Scientific Report Australia! The parameters that are configurable for DSR are shown in Table 4. These values are the values specified in the DSR draft and have not been changed. The nonpropagating timeout is the of thesis methodology time a node waits for a reply for a nonpropagating search. A nonpropagating search is mla citing a request that first goes to the neighbors.

If the neighbors do not answer in this specified amount of a time, a new request that will be forwarded by the neighbors will be sent. The sendbuffer in the DSR can hold 64 packets and the packets are allowed to of thesis methodology, stay in the buffer for mla citing quotes, 30 seconds Table 4: Constants used in the DSR implementation. Parameter Time between retransmitted requests Size of source route header carrying n addresses Timeout for nonpropagating search Time to hold packets awaiting routes Maximum rate for sending replies for of thesis methodology, a route 33 Value 500 ms 4n + 4 bytes 30 ms 30 s 1/s 4.4.3 DSDV The extension also included an implementation of the egypt DSDV protocol. Of Thesis! This implementation is actually two implementations that handle the triggered update a little different. Report Australia! In the first version only a new metric for a destination causes a triggered update to types of thesis, be sent. In the write a scientific australia second version, a new sequence number for of thesis methodology, a destination causes a triggered update to be sent. We have modified DSDV so it always uses the how to write version that triggers on new sequence numbers. Types Of Thesis! This is the version that, we feel behaves according to the specification of rsvp DSDV. The parameters for DSDV are shown in methodology, Table 5 and are as specified in the DSDV paper [22].

Table 5: Constants used in the DSDV implementation. Parameter Periodic route update interval Periodic updates missed before link declared broken Route advertisement aggregation time Maximum packets buffered per node per mla citing in essay quotes, destination Value 15 s 3 1s 5 4.4.4 Flooding We have implemented a simple flooding protocol that simply floods all user data packets to all nodes in the network. To have some sort cleverness in this flooding and avoiding data to of thesis, bounce back and forth we use a sequence number in rsvp how to, each packet. Methodology! This sequence number is incremented for each new packet. Each node keeps track of (source IP, sequence number) for all destinations and does not process a packet if the packet has a sequence number smaller than the rotc essay stored sequence number. The idea was to do the simulations on the flooding protocol and compare the results with the results for the routing protocols. After some initial simulations on of thesis methodology flooding this plan was abandoned. The simulations took too long to in essay quotes, complete.

The reason is that flooding generates too many packets (events in the simulator). 4.4.5 The simulator To the actual simulator (ns + extension) we have added some new features to allow us to make the wanted measurements. Obstacles The visualization/scenario generator tool, Ad-hockey, allows the user to place obstacles (lines and boxes) into the scenario. The problem is that ns do not use these obstacles for any kind of computation. Two nodes can communicate, even through a wall. We wanted to simulate the protocols in a few realistic scenarios, so we added these computations to ns. The calculations consisted of two parts. The first part was to store all obstacles in a database that we later could use when calculating the intersection points and types of thesis methodology the second part was to custom, extend the propagation model with the actual computations. The computations merely consisted of deciding if there existed an intersection point between the of thesis straight line from the sending node to the receiving node and topics any obstacle in the database.

If such an types methodology, intersection point exists, the communication is simply cut of. No fading of the fiction book report school signal, reflections etc is taken into consideration. The model is therefore very simple. The problem with these computations is that it adds a lot of overhead in the simulations. The simulations will take significantly longer time to complete. Types Of Thesis! The extra computation must be done for all packets. In a large scenario with many nodes that are sending a lot of write a scientific report australia traffic this will increase the types simulation time significantly. Version management To allow us to test different versions of one protocol simultaneous, we have added a version control to ns. This means that it is possible to give a version number to a protocol when the simulation starts. This version number is given to how to australia, the specified protocol and it is then up to the programmer to use it.

We currently use this feature with both AODV and DSR. The different versions are: N N N N N AODV 1 = AODV with only hello messages. AODV 2 = AODV with only MAC-layer feedback. AODV 3 = AODV with both hello messages and MAC-layer feedback. DSR 1 = DSR with eavesdropping. DSR 2 = DSR without eavesdropping. 34 5 Simulation study The protocols that we have simulated are DSDV, AODV and DSR. DSDV is only used to get a comparison of how much better/worse the MANET protocols are than an ordinary proactive protocol. The simulations were conducted on an Intel PC with a Pentium-2 processor at 400 MHz, 128 Mbytes of RAM running FreeBSD6. Types Methodology! 5.1 Measurements Before we go into the actual simulations, we will discuss which parameters [5] that are interesting to measure when studying routing protocols in an ad-hoc network.

There are two main performance measures that are substantially affected by the routing algorithm, the average end-to-end throughput (quantity of historical book report high school service) and the average end-to-end delay (quality of service). 5.1.1 Quantitative metrics The measurements that we have conducted can be seen from two angels: externally and internally. The external view is what the methodology application/user sees and the internal view is how the routing protocol behaves. Egypt Book! The external measurements are basically the types of thesis end-to-end throughput and delay. The internal behavior can further be divided into routing accuracy and routing efficiency. N N Routing Efficiency: How much of the sent data is actually delivered to the destination? How much routing overhead is required to find routes? Routing Accuracy: How accurate, measured in book reports, number of types of thesis hops are the supplied routes compared to the optimal shortest path.

5.1.2 Parameters The metrics has to custom essay, be measured against some parameter that describes the characteristic behavior of an adhoc network and can be varied in a controlled way. The parameters that we have chosen to simulate with are: N N N Mobility, which probably is one of the most important characteristics of an ad-hoc network. Methodology! This will affect the historical fiction book high dynamic topology, links will go up and down. Types Of Thesis Methodology! Offered network load. The load that we actually offer the network. This can be characterized by essay three parameters: packet size, number of connections and the rate that we are sending the types methodology packets with. Network size (number of fiction report school nodes, the size of the area that the nodes are moving within). Types! The network size basically determines the topics connectivity. Of Thesis! Fewer nodes in rotc topics, the same area mean fewer neighbors to send requests to, but also smaller probability for collisions.

5.1.3 Mobility Because mobility is an types methodology, important metric when evaluating ad-hoc networks we need some definition of mobility. Write! There exist many definitions of methodology mobility. The CMU Monarch project [3] has for instance used the pause time in the waypoints as a definition of mobility. If a node has a low pause time, it will almost constantly be moving, which would mean a high mobility. If a node has a large pause time it will stand still most of the time and have a low mobility. We did not think that this mobility definition was good enough, because even if the book reports pause time is low and all nodes are constantly moving, they could all be moving with a very slow speed in the same area. Types Of Thesis Methodology! We have defined mobility a little differently. Our definition is based on the relative movement of the nodes. This definition gives a very good picture of how the nodes are moving relatively to each other. Rsvp! The definition is as follows: 6 FreeBSD 2.2.6 35 If several nodes move for a certain time, then the mobility is the average change in distance between all nodes over methodology, that period of time.

This time is the simulation time T. Mobility is a function of both the speed and mla citing quotes the movement pattern. It is calculated with a certain sampling rate. Methodology! During the simulations, we have used 0.1 seconds as sampling rate. Egypt Reports! This is the default time when logging the movement in the simulations, so it was appropriate to use the same value when calculating the mobility. Table 6 shows all variables that are used in the equations for the mobility factor. Types Methodology! Table 6: Variable name dist(nx, ny)t n i Ax(t) Mx T t Mob Mobility variables.

Description the distance between node x and node y at book report, time t number of types of thesis methodology nodes Index Average distance for node x to all other nodes at time t Average mobility for node x relative to all other nodes during the entire simulation time Simulation time Granularity, simulation step Mobility for entire scenario First of all, the average distance from each node to historical book report high, all other nodes has to be calculated. This has to be done at times t = 0, t = 0+X, t = 0+2X, . t = simulation time. For the node x at time t the types formula is: n ¦ dist (n , n ) x Ax(t) = i i1 (5.1) n 1 After that, with the use of (5.1), the average mobility for that particular node has to be calculated. This is the average change in distance during a whole simulation. The mobility for node x is: T t ¦ A (t ) A (t 't ) x Mx = x t0 (5.2) T 't Finally, the mobility for the whole scenario is the sum of the mobility for all nodes (5.2) divided with the historical fiction book number of nodes: n ¦M Mob = i i1 (5.3) n The unit for the mobility factor (5.3) is m/s.

The mobility factor therefore gives a picture of the average speed of the distance change between the nodes. Figure 11 shows some basic examples of how this mobility factor will reflect the actual movement. If the nodes are standing still, this will of course lead to a mobility of 0, but this would also be the case when the nodes relative movement is zero, for example when the nodes are moving in parallel with the same speed. It is only when the nodes have a movement relative to each other that the mobility factor will be greater than zero. 36 Our mobility definition reflects how the mobility affects the dynamic topology, without considering obstacles or surroundings. Standing still 0.0 Parallel movement 0.0 Figure 11: Relative movement 0.0 Example of types methodology mobility. The reason for choosing mobility as a parameter in the simulations is book report school first of all that the mobility is one of the most important characteristics of an ad-hoc network. Of Thesis! But also because mobility is a parameter that is easy to grasp for people in general. Everyone has a rather good picture of what it means if the egypt reports mobility is increased.

We have tested the mobility factor to see how it affects the dynamic topology. Types Methodology! As it can be seen in report, Figure 12, the number of types of thesis methodology link changes is rotc essay topics directly proportional to the mobility factor. Of Thesis Methodology! A link change basically means that a link changes state from rotc either up/down to down/up. The plot is the average values for all simulations that we have done using 50 nodes and an environment size of of thesis 1000x1000 meters. 3500 3000 Avg nr of mla citing quotes link changes 2500 2000 1500 1000 500 0 0 0.5 Figure 12: 1 1.5 2 Mobility 2.5 3 3.5 Relation between the number of link changes and mobility. 37 4 5.2 Simulation setup In this chapter we will describe how the types simulations were done. Custom Essay Order! We have done 4 different types of simulations: N N N N Mobility simulations: We vary the mobility to types, see how it affects the different metrics that we are measuring. Offered load simulations: We vary the load that we offer the network, to see how the protocols behave when for instance the load is high. Network size simulations: We vary the number of nodes in the network. Realistic simulations: A few realistic scenarios were designed.

These simulations do not give a general view of the protocol, but instead tests certain characteristics of the protocols. Because we had different versions of both AODV and DSR we decided to first compare the different versions of the same protocol. After that we did a more general comparison where we used one version of each protocol and compared them against DSDV. The comparisons made are therefore: N N N Comparison of AODV with only historical fiction report school hello messages, AODV with only link layer support and types of thesis ADOV with both hello messages and link layer support. Comparison of DSR with and without eavesdropping. Book Reports! Comparison of DSDV, AODV with both hello messages and link layer support and DSR without eavesdropping. The reason for of thesis, choosing DSR without eavesdropping in the last comparison, is rotc topics as mentioned earlier that this is of thesis more realistic. Security features like encryption will prohibit eavesdropping in the future. Mla Citing! The choice of AODV with both link layer support and types hello messages was made because first of all, link layer support is probably a necessity to achieve a performance that is good enough and secondly because the removal of hello messages somewhat changes the mla citing overall functionality of AODV. Methodology! Removal of hello messages would of course save us from the overhead of the topics hello messages, but also makes the protocol completely on-demand. A broken link could only types methodology be detected when a packet needs to be sent on the link.

In all simulations, except the rsvp write realistic scenario simulations, we have used a randomized scenario. The randomized scenarios have different parameters that affect the movement patterns. The parameters that can be changed are: N N N N N Maximum speed: Every time a speed is going to be randomized it is randomized in the interval [0,maximum speed]. Number of nodes: This was constant during the types of thesis methodology simulations. We used 50 nodes for all simulation except the write a scientific size simulation where we varied the number of nodes.

Environment size: Determines the size of the environment. Types Methodology! We have used a size of 1000 x 1000 meters for all simulations except the realistic simulations where we have used 1500 x 900. Mla Citing! Simulation time: The time for which the types of thesis methodology simulations will be run at. We have used a simulation time of 250 seconds for write, all simulations except the realistic simulations where we used 900 seconds. Pause time: Pause time is the time for which a node stands still before randomizing a new destination and types the speed that will be used to fiction, reach this destination.

We have used a pause time for types of thesis methodology, 1 second in all simulations. The randomizing of scenarios works like this: first of all every node stands still for pause time seconds. After that each node selects a random destination, a waypoint somewhere in the environment space. Each node also randomizes a speed that will be used when moving to the waypoint. This speed is randomized uniformly in the interval 0 to maximum speed. Every time a node reaches a waypoint, this procedure will be repeated. A factor that we have not taken into book, consideration with the scenarios is the methodology fact that a real person is not likely to egypt book, stand on the same place if the connection goes down. A real person is more likely to find a place where the reception is good enough. The system would be to complex if this factor were included also. We have assumed bi-directional links during all our simulations, i.e. the links work equally well in methodology, both directions.

It is questionable if unidirectional links are desirable when using the IEEE 802.11 MAC protocol, because bi-directional links are necessary if 802.11 acknowledgements are supposed to be used. Historical Book School! 38 5.3 Mobility simulations 5.3.1 Setup The simulations where we varied the types mobility where done by randomizing scenario files. This method is very hard to mla citing quotes, perform, because we cannot prior a scenario generation say that we want a mobility factor of exactly X. Instead we used the types methodology maximum speed parameter to mla citing in essay, control the scenario. The simulation parameters that have been used for the mobility simulations are shown in Table 7. Table 7: Parameters used during mobility simulations. Parameter Transmitter range Bandwidth Simulation time Number of nodes Pause time Environment size Traffic type Packet rate Packet size Number of flows Value 250 m 2 Mbit 250 s 50 1s 1000x1000 m Constant Bit Rate 5 packets/s 64 byte 15 The scenario is a very crucial part of the simulation. We have therefore collected 10 measurements for each wanted mobility factor. The mobility factors that we simulated on methodology are: 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5.

Because of the hard part of egypt book getting scenarios that are precise we have used an interval of r0.1 for the above mentioned mobility factors. The scenarios that where created where then analyzed in terms of methodology unreachable hosts. Custom Order! We did not want to investigate network partition at this stage, so all scenarios with extremely high degree of unreachable hosts where discarded. By increasing the maximum speed in the scenario generation, the mobility will also increase. A mobility factor of 3.5 approximately corresponds to types, a maximum speed of historical report high school 20 m/s. For the randomized simulations we have varied the methodology maximum speed in the interval 0 to 20 m/s. A speed of 20 m/s corresponds the speed of mla citing in essay quotes a vehicle, which will lead to a high mobility. We used the same communication pattern for types methodology, all mobility simulations. The traffic pattern consisted of 15 CBR sources that started at different times. We did not use TCP for essay topics, the simulations, because we did not want to investigate TCP, which uses flow control, retransmit features and types so on. We wanted to get a general view of how the egypt book reports routing protocol behaves.

The communication pattern was randomly created. The parameters that was specified when randomizing the types communication pattern were the number of write australia wanted sources, the packet size, the rate at which they were sending and the simulation time. Types Methodology! In these simulations, we wanted to investigate how the mobility affected the book report school protocols, so the types of thesis methodology load that we offer is very low. We only essay topics use 15 CBR sources sending 64 bytes large packets with a rate of 5 packets/s. The bandwidth of the links are 2 Mbit. 39 5.3.2 Fraction of received packets 0.8 Fraction received packets 1 0.8 Fraction received packets 1 0.6 0.4 0.2 0.6 0.4 0.2 AODV-HELLO-MAC AODV-MAC AODV-HELLO DSR-eaves dropping DSR 0 0 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 1 Fraction received packets 0.8 0.6 0.4 0.2 AODV-HELLO-MAC DSR DSDV 0 0 0.5 1 1.5 2 Mobility (m/s) Figure 13: 2.5 3 3.5 Mobility simulations - fraction of received packets. How many of the of thesis sent data packets are actually received and why have the dropped packets been dropped?

Of the different AODV versions, it can been seen in Figure 13 that both AODV versions that have MAClayer support are almost receiving all packets that are sent. AODV with both hello messages and MAC-layer support is slightly better than the version with only MAC-layer support. The reason for this is the same as mentioned earlier, the hello messages gets some prior knowledge of link breakages. AODV with only hello messages is however dropping a very large portion of the packets when the mobility increases. This large fraction of how to write dropped packets is of course not acceptable and the reason for these drops has to do with the interval of the types of thesis methodology hello messages. The interval between the hello messages and the number of allowed hello message losses are crucial for detection of mla citing link breakages. If the types interval is decreased, link breakages are detected earlier, but it would also mean that the control overhead in the network increases. The issue here is to try to find optimal values for these parameters. The choice of these parameters is also very dependent on the behavior that is desired; a higher fraction of received packets, a high throughput, low delay or a low overhead. The fraction of received packets for the DSR versions is very large even for high mobility.

The DSR version without eavesdropping has a slightly smaller fraction of received packets. This difference is however so small that it is negligible. DSR with eavesdropping gets better result for rsvp write, the simple reason that it has a little more information when calculating the routes. A reason for the higher fraction received packets for DSR compared to AODV is of thesis that DSR allows packets to stay in the send buffer for as long as 30 seconds, AODV only 8 seconds (our implementation). It must however be noted that the AODV draft [19] does not specify how long a packet is how to report allowed to stay in the sendbuffer. When comparing these results with the results for of thesis, DSDV it can clearly be seen that a proactive approach is report high not acceptable at all when the mobility increases. The fraction received packets drastically goes down to 56-57 %. This value is types however for mla citing quotes, a very large mobility factor (vehicles).

But the fraction of received packets is not even 100 % when the of thesis methodology mobility is 0, as for essay order, all other protocols. The reason for this is that packets are sent before the routing tables have had enough time to converge and methodology the packets are dropped. 40 The main reasons for dropping packets are that the protocol is sending packets on a broken route that it thinks is valid and that packet in the buffers are dropped because of mla citing in essay congestion and timeouts. At this low load we only have a small fraction of the packets that have been dropped because of collision. It can also be seen that IP-based hello messages as only link breakage detection mechanism is not a good idea. The results are very poor, even DSDV have slightly better results. Types Of Thesis Methodology! Link layer feedback of rsvp link breakages informs the upper layer routing protocol is much quicker and it can therefore react immediately. 5.3.3 End-to-end delay AODV-HELLO-MAC AODV-MAC AODV-HELLO 0.14 0.12 Avg packet delay (seconds) 0.12 Avg packet delay (seconds) DSR-eaves dropping DSR 0.14 0.1 0.08 0.06 0.1 0.08 0.06 0.04 0.04 0.02 0.02 0 0 0 0.5 1 1.5 2 2.5 3 3.5 2.5 3 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 3.5 Mobility (m/s) AODV-HELLO-MAC DSR DSDV 0.14 Avg packet delay (seconds) 0.12 0.1 0.08 0.06 0.04 0.02 0 0 0.5 1 1.5 2 Mobility (m/s) Figure 14: Mobility simulations - delay. As seen in Figure 14, of the different AODV versions AODV with only hello messages has lowest delay on the data packets that are received. Types Of Thesis! The reason for rsvp how to, this is not that it finds routes faster or that the routes are shorter or more optimal, instead AODV with only hello messages is the AODV version that gets significantly fewest packets through the network. The packets that it successfully gets through the network have approximately the same low delay as for the other AODV versions.

The difference is that the other AODV versions have a portion of packets that have a higher delay (has been in a buffer a long time and still gets the packets through the network). This affects the average delay, which becomes larger. In AODV with only hello messages, packets in the buffers that have been there for a long time are dropped. The reason is that ADOV does not successfully find a new route for those packets and because broken links are not detected fast enough, resulting in that a source can keep sending packets on a broken link believing that it is types of thesis methodology still working properly. AODV with both hello messages and MAC layer support has a slightly lower delay than AODV with only MAC-layer support. The reason for this is that as mentioned earlier, AODV with only MAC-layer support makes the protocol completely on-demand, it only detects link breakages when actually trying to send packets. Packets that are sent after this breakage is detected will have a higher delay, because they are buffered during the egypt reports time it takes to types of thesis methodology, find a new route.

AODV with both hello messages and Mac-layer support on in essay quotes the other hand will get some prior knowledge of the methodology link breakage and has a chance to in essay, find a new route before any new packets are sent. Of Thesis! 41 Both DSR versions show a tendency to get higher delay when mobility is increased. The turning point comes at a mobility factor of approximately 1.0. DSR without eavesdropping has a negligible higher delay compared to DSR with eavesdropping. DSDV is the essay protocol that seems to of thesis, have lowest delay in these results. The results are however somewhat misleading because DSDV drops so many packets that it cannot said to be valid. Egypt Reports! The packets that are dropped in types, DSDV will successfully get through when using for instance DSR, but has a slightly higher delay, because of longer times in buffers etc.

These higher delay packets will make the average delay higher for DSR. The same can be said for a scientific australia, AODV with only hello messages. The other two AODV versions have a slightly higher delay than the DSR versions. Types Of Thesis! This has probably to do with the source routing concept of DSR. DSR gains so much information by quotes the source routes that it will learn routes to many more destinations than a distance vector protocol like AODV.

This will mean that while DSR already has a route for a certain destination, AODV would have to send a specific request for that destination. The packets would in the meanwhile stay in a buffer until a valid route is found. This will take some time and will therefore increase the average delay. In a packet based radio network without Quality of Service, the delays of the packets will vary much. Methodology! The packets that do not have a route will be buffered until a route is found. A critical parameter here is how to write report how long a packet should be allowed to stay in the buffer before it is thrown away. If the packets are allowed to be in the buffer for a long time, the following situation could happen: A packet is sent, but there does not exist any route to that destination so the methodology packet is rotc topics buffered and of thesis a route request is sent. The destination node is custom essay however unreachable so no route reply is types of thesis methodology returned to the sending node.

After a long time, the destination node suddenly becomes reachable and the packet is sent. This packet will have a very large delay. Should this situation be allowed to happen? Should the mla citing in essay packet be dropped from the methodology buffer at order, a much earlier stage or do we want all packets to get through the network, even though the delay can be very large. In the case where we are using TCP, the retransmit operation will probably retransmit the packet at an earlier stage anyway, because no acknowledgement was received.

The allowed time for types methodology, packets to stay in the sendbuffer in DSR is how to a scientific australia 30 seconds and only 8 seconds for AODV. If a packet is received 30 seconds after it was sent, this will increase the average delay to of thesis methodology, some degree. 5.3.4 End-to-end throughput 2.4 2.2 2.2 Throughput (Kbit/s) 2.6 2.4 Throughput (Kbit/s) 2.6 2 1.8 1.6 1.4 2 1.8 1.6 1.4 1.2 1.2 AODV-HELLO-MAC AODV-MAC AODV-HELLO DSR-eaves dropping DSR 1 1 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 0 0.5 1 1.5 Mobility (m/s) 2.6 2.4 Throughput (Kbit/s) 2.2 2 1.8 1.6 1.4 1.2 AODV-HELLO-MAC DSR DSDV 1 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) Figure 15: Mobility simulations - throughput. 42 2 2.5 3 3.5 Figure 15 shows the throughput curves for how to, the different protocols with a packet size of 64 bytes. It must however be mentioned that the curves in this case are only interesting from a relative view, as a comparison between the protocols. We have not tried to maximize the types throughput, we have only tried to rotc, determine the relative difference in methodology, throughput for the different protocols with respect to the mobility factor and the specific load that we have used. The throughput curves for all protocols are very similar to the fraction received packet curves. This is write logical because large packet drops will of course mean lower throughput. Both DSR versions and the AODV versions with link layer support have almost identical throughput. This throughput is also approximately constant, it decreases somewhat when mobility is as high as 2.5-3.5. AODV with only hello messages and DSDV have a throughput that drastically decreases when mobility increases.

AODV with only types of thesis methodology hello show a very poor result. The throughput curve drops almost immediately to half of what it is when mobility is how to write report 0. 5.3.5 Overhead 25000 1.8e+06 AODV-HELLO-MAC AODV-MAC AODV-HELLO 20000 1.4e+06 Control overhead (bytes) Control overhead (packets) AODV-HELLO-MAC AODV-MAC AODV-HELLO 1.6e+06 15000 10000 1.2e+06 1e+06 800000 600000 400000 5000 200000 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 0 25000 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 1.5 2.5 3 3.5 2.5 3 3.5 1.8e+06 DSR-eaves dropping DSR DSR-eaves dropping DSR 1.6e+06 1.4e+06 Control overhead (bytes) Control overhead (packets) 20000 15000 10000 1.2e+06 1e+06 800000 600000 400000 5000 200000 0 0 0 0.5 1 1.5 2 2.5 3 3.5 0 0.5 1 Mobility (m/s) 25000 1.8e+06 AODV-HELLO-MAC DSR DSDV AODV-HELLO-MAC DSR DSDV 1.6e+06 20000 1.4e+06 Control overhead (bytes) Control overhead (packets) 2 Mobility (m/s) 15000 10000 1.2e+06 1e+06 800000 600000 400000 5000 200000 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 Figure 16: 3 3.5 0 0.5 1 1.5 2 Mobility (m/s) Mobility simulations - overhead. Because the of thesis methodology routing protocol need to how to write australia, send control information to achieve the task of finding routes, it is interesting to see how much control information that is of thesis methodology actually sent for each protocol. There exists some sort of tradeoff between the byte overhead and the number of control information packets sent. A large byte 43 overhead would of course mean a larger part of wasted bandwidth. Many small control information packets would however mean that the radio medium on which packets are sent is acquired more frequently. This can be quite costly in terms of power and network utilization. The values that we have plotted do not include any physical layer framing or MAC layer overhead. We have only looked at the overhead at the IP-level. A completely fair comparison would also include the egypt book above mentioned overheads. We have chosen not to include these for the simple reason that the MAC layer can be different in a real life implementation.

We wanted to investigate the overhead generally, not the overhead that is dependent on types methodology particularly the IEEE 802.11 MAC protocol. How To! The results are shown in Figure 16. Methodology! The first column is write overhead calculated in number of packets and of thesis the second column is the byte overhead. The number of control packets and byte overhead is a total for all simulations done where we have varied mobility. How To Write! Of the types different AODV versions, it can be seen that the essay topics curves for the AODV versions that have link layer support are similar in appearance. The difference of about 8000-9000 packets and types of thesis methodology 270000-290000 bytes that can be seen corresponds to the hello packets. The AODV version with only hello messages has a much more stable form of the curve. Write Australia! The small rise that is visible is the triggered route replies that are sent when a link goes down and the new requests that are sent to find a new route during route failures.

A route failure therefore triggers both triggered replies and types of thesis new requests. This rise is much larger for write report australia, the AODV versions with link layer support for the simple reason that it detects link failure much faster, which will lead to much more messages. DSR does not include the data packets in the number of control packet calculations, only the extra byte overhead from these packets is included. Worth noting when observing the DSR versions is of thesis methodology that the DSR version that does not use eavesdropping has approximately the double amount of control overhead counted in in essay quotes, number of messages and about 400000 bytes more of byte overhead than the DSR version with eavesdropping at the highest mobility 3.5. The somewhat strange behavior of the byte overhead for DSR can be explained as a sum of both the sent packets and methodology the sent control messages.

As mobility increases, fewer packets will get through the network. Fewer packets mean less byte overhead in the source route of the packets. Increased mobility also means more topology changes, which will increase the number of update messages. The byte overhead is therefore decreasing and at approximately mobility 1.5 the increase of reports control messages will cause the byte overhead to increase. The number of control messages in DSDV is fairly constant, even when the mobility is methodology extremely high. Rsvp! This is the nature of a proactive protocol that is types dependent on periodic broadcasts. The byte overhead on fiction high school the other hand, will increase as mobility increases. Types Of Thesis! The reason for mla citing in essay, this is that the amount of information sent in each update message will be larger as the amount of link changes increases. Types! 5.3.6 Optimal path One internal aspect of the reports routing protocol is the routing accuracy, e.g. how good the actual routes are compared to the optimal routes. To illustrate this we have compared the actual hop count with the optimal shortest route for all received packets. We have then, for each protocol, calculated how large fraction the received packets that have been routed through the types of thesis methodology optimal route, a route with hopcount that is essay one larger than the types of thesis optimal, a route with hopcount that is two larger than the optimal and so on.

The result is shown in Table 8. The results are the reports total results for of thesis methodology, all simulations done with varying mobility. To better illustrate the difference between some of the protocols, we have also plotted the historical fiction book school results for one AODV version, one DSR version and compared it with the only proactive protocol DSDV. Of Thesis! It can clearly be seen in Figure 17 that DSDV is the protocol that has the highest degree of optimality, almost 90 % of the how to received packets have been routed with optimal hop count. The AODV and DSR versions are almost identical. AODV is of thesis methodology slightly better. This difference is however so small that it can neglected. The difference between the different DSR versions is essay topics quite large and can be explained with the extra information that DSR with eavesdropping has when calculating routes. This extra information is types of thesis apparently very informative when calculating shortest possible routes. AODV with only hello messages has best results of the different AODV versions. These due to the similarities with a proactive protocol like DSDV that is highly dependent on essay order periodic broadcasts.

Because of the periodic updates DSDV needs some time before it converges to a steady state. This happens when we have high movement with a lot of topology changes. Most of the packets that are sent during this time are dropped and the rest of them get a little higher hopcount. All packets that are sent after the types routing tables have converged to a steady state do however most likely have the optimal shortest path. AODV with only hello messages have a similar behavior. Link breakages are dependent on the hello messages. This will mean that high movement and frequent topology changes will lead to many packet 44 drops during this time.

The packet that successfully gets through the network have done this during times when the network is egypt book reports somewhat stabile 1 AODV-HELLO-MAC DSR DSDV Packets (%) 0.8 0.6 0.4 0.2 0 0 2 Figure 17: 4 6 Nr of hops from optimal 8 10 Mobility simulations - optimal path difference. Of Thesis! Because both DSR versions and the AODV versions with link layer support gets significantly more packets through the book reports network when the types of thesis number of rsvp topology changes is large, they will have a little lower fraction of packets that have a optimal route. In times of frequent movement it is easy to get a route that at first is optimal and then the moment later is 1-2 hops longer than another route that become the optimal route. The protocols will keep sending packets on the route that at first was optimal. A good relative comparison is to look at types, the average hop count difference for all packets received. DSDV has the smallest average with a hopcount at only 0.13 hops from the optimal path. Table 8: Protocol AODV 1 AODV 2 AODV 3 DSR 1 DSR 2 DSDV 0 79.1% 55.9% 68.4% 81.1% 63.2% 88.7% Optimal path difference for all protocols.

Number of hops from optimal path (% packets) 1 2 3 4 5 6 14.8% 3.68% 1.08% 0.30% 0.55% 0.06% 29.9% 9.04% 2.62% 1.09% 0.56% 0.20% 23.0% 5.37% 1.48% 0.84% 0.47% 0.14% 15.3% 2.73% 0.54% 0.13% 0.08% 0.01% 26.6% 7.21% 2.21% 0.56% 0.13% 0.05% 10.6% 0.59% 0.06% 0.00% 0.00% 0.00% 45 7 0.06% 0.38% 0.04% 0.02% 0.03% 0.00% Average 0.292170 0.682837 0.459423 0.234429 0.512004 0.126577 5.3.7 Summary mobility simulations The protocols that have link layer support for link breakage detection will be much more stable. Rotc Essay Topics! The fraction of packets received for types of thesis, these protocols is almost constant at egypt, 95 % even when mobility increases. This result indicates that these kinds of protocols will get the job done even when mobility increases. Methodology! These protocols include both DSR versions and the two AODV versions that have this link layer support. Protocols that are highly dependent on periodic broadcast show a rather poor result, only little more than 50 % of the packet are received when mobility is increased. Because DSR is write a source routing protocol it is always interesting to see how much overhead this kind of protocol will have. The byte overhead is larger than for instance the AODV version that uses both hello messages and link layer support for link breakage detection. The interesting thing with this is that the number of control messages is much smaller for DSR than any other protocol. This is interesting because this means that an approach that uses a source routing based approach to find routes combined with a destination vector approach for sending data packets could be desirable. 5.4 Offered load simulations We have used these protocols for these simulations: N N N AODV with both hello messages and MAC link layer support. DSR without eavesdropping DSDV We only used the methodology more realistic version of both AODV and DSR, for the same reason as mentioned in the previous section.

5.4.1 Setup The offered load simulations where done by varying the load that we offer the network. We had mainly three parameters to in essay, adjust the offered load: N N N Packet size Number of types CBR flows Rate at which the flows are sending The mobility simulations that we have done used a packet size of 64 bytes, a rate of 5 packets/s and 15 CBR flows. This is book reports a fairly moderate offered load, so for the offered load simulations, we wanted to investigate how the protocols behave when the load was increased. We could increase the packet size or the number of CBR flows, but the parameter that best describes the load is the rate at which we are sending. By only increasing the rate for the CBR flows, the load for each flow will increase. This also gives some hints of how large the throughput can be. Types Of Thesis! We have used four different offered load cases: N N N N 5 packets / second (same as the mobility simulations) 10 packets / second 15 packets / second 20 packets / second The packet size was held constant at 64 bytes and write the number of flows at 15.

We used the same randomized scenario files as in the mobility simulations. The same communication file was also used, with the exception that we changed the rate for of thesis, the CBR sources. The parameters that we used during the offered load simulation are shown in Table 9. 46 Table 9: Parameters used during offered load simulations. Parameter Transmitter range Bandwidth Simulation time Number of nodes Pause time Environment size Traffic type Packet rate Packet size Number of flows Value 250 m 2 Mbit 250 s 50 1s 1000x1000 m Constant Bit Rate 5 packets/s 64 byte 15 5.4.2 Fraction of received packets 0.8 Fraction received packets 1 0.8 Fraction received packets 1 0.6 0.4 0.2 0.6 0.4 0.2 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 3.5 1 Fraction received packets 0.8 0.6 0.4 0.2 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s 0 0 0.5 Figure 18: Offered load simulations - fraction of received packets. School! At only 5 packets/s both AODV and DSR are rather constant, the fraction of of thesis methodology received packets is only decreasing slightly when mobility increases (Figure 18). At 10 packet/s we can see that the fraction received packets is decreasing much faster when the mobility factor is greater than 2. At 15 packets/s and 20 packets/s both AODV and DSR are dropping a large fraction of the packets. At the highest mobility and a rate of 20 packets/s, only 50-60 % of the sent packets are received. The reason is how to write a scientific more collisions in the air and congestion in buffers.

The results for AODV and DSR are fairly similar at of thesis methodology, a packet rate of 5 packets/s and 10 packets/s. At data rates of 15 packets/s and 20 packets/s, AODV shows a better result than DSR. At these rates the protocols are however dropping a large fraction of the packets, even at a mobility factor of 0. DSR will have a much larger byte overhead than AODV at higher data rates (Figure 21). The reason for this is the historical book report source route in types, each data packet. This also increases the load on the network and causes more packets to be dropped; thus AODV will get more packets through the network.

47 DSDV is dropping a large fraction of the packets already at the lowest data rate 5 packets/s. It must however be noted that the increase in egypt book, dropped packets is not as large for DSDV as for AODV and DSR. At the highest data rate, DSDV is almost as good as DSR. 5.4.3 End-to-end delay 0.7 0.7 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s 0.6 0.5 Avg packet delay (seconds) Avg packet delay (seconds) 0.6 DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 0.4 0.3 0.5 0.4 0.3 0.2 0.2 0.1 0.1 0 0 0 0.5 1 1.5 2 2.5 3 3.5 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) Mobility (m/s) 0.7 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s Avg packet delay (seconds) 0.6 0.5 0.4 0.3 0.2 0.1 0 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) Figure 19: Offered load simulations - average delay. The delay is also affected by high rate of CBR packets (Figure 19). Types Of Thesis Methodology! The buffers becomes full much quicker, so the packets have to egypt book, stay in the buffers a much longer period of time before they are sent. This can clearly be seen at the highest rate 20 packets/s. The high degree of packet drops, even at mobility 0 makes the of thesis methodology delay high already from the book reports start.

DSR has a much lower delay compared to AODV. Types Methodology! The difference between AODV and rsvp DSR is most apparent at types, rate 10 packets/s. DSDV has the lowest delay of them all. This is however an effect from the large fraction of packet drops that DSDV has, compared to DSR and AODV. The increase in custom essay order, delay for DSDV also comes from the increased time that the packets must stay in the buffers. The high delay at a mobility factor of 0-1 and a data rate of 20 packets/s that can be seen for all protocols is of thesis a result of the a scientific report australia extremely high data rate and types methodology the low mobility. The high data rate will fill up the buffers very quickly. The low mobility will mean that already found routes are valid for a much longer time period. This means that found routes can be used for mla citing in essay quotes, more packets.

Even the types packets that have stayed in the buffer for a long time have a chance to get through. Essay! When mobility increases, more routes will become invalid and new requests are necessary. While the requests are propagating the network in search for a new route, buffers will get full and packets are dropped. These packets are the packets that have stayed in the buffers for the longest time and of thesis therefore the delay will decrease. The increase in mobility actually results in a load balancing of the traffic between the nodes; hot spots are “removed” due to mobility. Historical Fiction Book School! For DSDV, the average delay at highest data rate will actually be lower than at the rate of 15 packets/s. This is a little strange but has probably something to types of thesis, do with the historical report high fact that DSDV only uses a buffer that only has room for 5 packets per flow.

At the rate of 15 packets/s and 20 packets/s, when mobility starts to methodology, get so high that the topology changes frequently, only 40-60 % of the packets gets through the network. These 48 topology changes means that the rotc essay topics protocol needs more time to converge before the types of thesis methodology packets can be sent. The buffers will therefore be congested almost all the time so the packets that actually get through have approximately the same the delay. 5.4.4 End-to-end throughput 8 8 6 Throughput (Kbit/s) 7 6 Throughput (Kbit/s) 7 5 4 3 5 4 3 2 2 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s 1 0 0 0 0.5 DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 1 1 1.5 2 Mobility (m/s) 2.5 1.5 2.5 3 3.5 0 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 8 7 Throughput (Kbit/s) 6 5 4 3 2 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s 1 0 0 0.5 1 2 3 3.5 Mobility (m/s) Figure 20: Offered load simulations - average throughput. At low CBR rates the rsvp how to write throughput of DSR and AODV is unaffected of the mobility (Figure 20), it stays constant at 2,5 Kbit/s. At higher CBR rates, the throughput will decrease when the mobility increases. This can already be seen at CBR rate 10 packet/s.

The decrease at CBR rate 10 packets/s is of thesis however very small. At rate 15 packets/s and 20 packets/s the fiction book report high school throughput decreases very much for all protocols. This is types methodology however an historical report, effect from the large fraction of types methodology dropped packets. The result for custom essay order, AODV is slightly better than for DSR. It must however be noted that the of thesis offered load definition that we use only mla citing in essay includes the rate at which we are sending packets with; no control packets are included in this definition. The same applies for the throughput, only the data packets are included in the calculations of throughput. DSR have a much larger byte overhead than AODV at of thesis, higher data rates (Figure 21). Essay Order! This also increases the load on types methodology the network and causes more packets to be dropped; thus AODV will have a better throughput at higher data rate.

DSDV drops a large fraction of the packets already at a rate of book 5 packets/s. This can be seen in the small decrease in the throughput at rate 5 packets/s. The throughput decreases more and more as the rate increases. 5.4.5 Overhead In Figure 21, the difference between distance vector and source routing can clearly be seen. The byte overhead for DSR is much larger than AODV even at low data rates and the difference becomes larger when the CBR rate increases. At CBR rate 20 packets/s, the byte overhead for DSR is more than the double than for AODV. The reason for of thesis, the larger byte overhead for DSR is of course the book reports source route in each packet. The 49 number of control messages is though smaller for DSR. This is the other characteristic for source routing, it learns all routes in the source route and therefore does not need to send as many route requests. The reason for the increase in number of methodology control packets is the custom order MAC-layer support. Methodology! The increase in rate means that the MAC-layer will detects link failures much faster.

This means that the triggered RREPs are sent much earlier also causing the source node to send out historical fiction book report, a new request much earlier. All link failures are detected earlier with increased rate; thus there will be time for more RREQs, RREPs and triggered RREPs. Types! 4e+06 35000 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s 30000 AODV 5 pkt/s AODV 10 pkt/s AODV 15 pkt/s AODV 20 pkt/s 3.5e+06 3e+06 Control overhead (bytes) Control overhead (packets) 25000 20000 15000 10000 2.5e+06 2e+06 1.5e+06 1e+06 5000 500000 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 3 0 3.5 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) 35000 DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 30000 4e+06 3e+06 Control overhead (bytes) 25000 Control overhead (packets) DSR 5 pkt/s DSR 10 pkt/s DSR 15 pkt/s DSR 20 pkt/s 3.5e+06 20000 15000 2.5e+06 2e+06 1.5e+06 10000 1e+06 5000 500000 0 0 0.5 1 1.5 2 2.5 3 0 3.5 0 0.5 1 Mobility (m/s) 1.5 2 2.5 3 3.5 Mobility (m/s) 4e+06 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s 35000 DSDV 5 pkt/s DSDV 10 pkt/s DSDV 15 pkt/s DSDV 20 pkt/s 30000 3.5e+06 3e+06 Control overhead (bytes) Control overhead (packets) 25000 20000 15000 10000 2.5e+06 2e+06 1.5e+06 1e+06 5000 500000 0 0 0 0.5 1 1.5 2 Mobility (m/s) 2.5 Figure 21: 3 0 3.5 0.5 1 1.5 2 2.5 3 3.5 Mobility (m/s) Offered load simulations - overhead. The amount of control information in essay, DSDV is not affected to any great extent by the data rate for the CBR packets. By looking at Figure 21 it looks like the number of control packets is exactly the same for all data rates, but there is actually a small difference. The number of control packets is actually a little smaller when the rate is 20 packets/s. This difference is about 80 packets.

The reason for this difference is types of thesis methodology that the high data rate causes more collisions, which means that some of the update messages are dropped. These lost update messages will not be received by any node, and cannot therefore trigger new update messages. Rotc Essay Topics! This means that when the types of thesis next update message actually is received a much larger update message has to be sent, thus we can see a slight increase of byte overhead when the rate increases. But when the mobility increases more and rsvp more packets will be dropped. At the highest data rate, many of the types of thesis methodology update messages are dropped, 50 even the packets with a little more information. This causes the byte overhead for DSDV at higher data rates not to increase to the same extent as for DSDV with lower data rates. 5.4.6 Optimal path Figure 22 illustrates the difference in hopcount from the optimal hopcount at a CBR rate of 20 packets/s. It is the result for all simulations done at quotes, this rate. Types Methodology! If we compare this figure with Figure 17, which illustrates the egypt book hopcount difference for types, the CBR rate 5 packets/s, we can clearly see that they are almost identical.

The rate does not affect the rotc number of methodology hops that the quotes packets actually need to types methodology, travel from source to destination. 1 AODV 20 pkt/s DSR 20 pkt/s DSDV 20 pkt/s Packets (%) 0.8 0.6 0.4 0.2 0 0 2 Figure 22: 4 6 Nr of hops from optimal 8 10 Offered load simulations – optimal path. 5.4.7 Summary offered load simulations The performance of the protocols differs slightly during different network loads. The most apparent difference is the byte overhead. While DSDV has a rather unaffected overhead, it increases both for egypt, AODV and types DSR during higher loads.

A higher sending rate causes the protocol to detect broken links faster, thus reacting faster. This leads to a slight increase in reports, control packets, which also affects the byte overhead. The most apparent is the types increase in custom essay order, DSRs overhead as we increase the methodology send rate. Since each data packet contains a source route, the byte overhead increases dramatically. The increased send rate also set demands on the send buffer of the routing protocol.

Congestion occurs and packets are dropped. The faster a routing protocol can find a route, the less time the packets have to spend in buffers, meaning a smaller probability of packet drops. 51 5.5 Network size simulations We did simulations on some of the rotc topics protocols and varied the number of nodes that participated in the network. We decreased the number of nodes to of thesis methodology, 35 and 25 nodes. The decrease in number of nodes basically meant that the order connectivity also decreased; each node had fewer neighbors.

The results from these simulations did not give any new information regarding the performance of the protocols. Of Thesis! The relative difference between the book protocols was the same. Decreased connectivity meant of course that we did not get as many packets through the network as in the mobility simulations, but it must however be noted that the types of thesis dependency between the scenarios and results are much larger in the network size simulations. How To Write! The worst results for each protocol happened when the of thesis methodology mobility was 0. Mla Citing In Essay Quotes! This may sound strange, but the types of thesis reason for the bad result when the nodes is standing still is the randomized scenarios. If a randomized scenario has poor connectivity, this connectivity will be same during the whole simulation if the historical report school nodes are standing still. The nodes are not moving and cannot therefore affect the connectivity. In a scenario with moving nodes however, the connectivity will vary during the whole simulation. Of Thesis Methodology! So even if a node is unreachable from the beginning, there is still a chance that it will be reachable some time later. 5.6 Realistic scenarios 5.6.1 Setup The randomized simulations we have done, gives a very good general picture of how the protocols behaves in respect to certain parameters, such as mobility, size and network load. This kind of simulations also has some problems: N N N It is hard to identify situations in which the book protocols fail or have problems It has no connection to a real life situation. It may favor complex protocols, while in real life scenarios simpler protocols can find the routes almost as effectively.

It is therefore also very interesting to see how the protocols behave in methodology, a more realistic scenario. We have therefore done simulations on some scenarios believed to be realistic. The realistic scenarios do not give a full picture of how the protocols behave generally. Essay Order! Instead they give some sense of weak points in of thesis methodology, the protocols. The three basic types of scenarios that we have done simulations on historical book are: N N N Conference type, with low movement factor.

Event coverage type, with fairly large movement factor. Could for instance be reporters trying to interview politicians. Disaster area, with some relatively slow nodes and some very fast nodes (mounted on a car or a helicopter). The environment size is 1500 x 900 meters for types, all realistic scenarios. This size is scaled according to the range of the custom transmitters. In a real life conference scenario, the environment size would be significantly smaller and so would also the methodology transmitter range.

The same thing would apply for the speed of the people moving around. The speed is also scaled to 10 m/s. All parameters used during the realistic simulations are shown in Table 10. 52 Table 10: Parameters used during realistic simulations. Parameter Transmitter range Bandwidth Simulation time Number of how to nodes Environment size Traffic type Packet rate Packet size Speed of a human Speed of a mobile node mounted on a vehicle Value 250 m 2 Mbit 900 s 50 1500x900 m Constant Bit Rate 4 packets/s 512 byte 1 m/s 20 m/s 5.6.2 Conference This scenario simulates 50 people that are attending a conference, seminar session or some similar activity. Of Thesis Methodology! It involves communication between some of the people. Parameters specific for in essay, the conference scenario are shown in Table 11 Table 11: Parameters used during conference scenario.

Parameter Number of CBR sources Number of receivers Number of flows Value 2 6 6 The scenario is characterized by: N N N N N Low mobility factor, 10 % of the nodes are moving during any period of time. Links are long lasting and types of thesis methodology involves many hops. Reports! The traffic is concentrated to a few nodes, typically only the speaker. Few obstacles which are far apart. Typically only one large obstacle, a wall with doors and types of thesis windows that can be used for communication. Relatively large interference from other nodes, due to the concentration of transmitting nodes. Egypt! This can in some cases lead to types of thesis, local congestion. The scenario basically tests the protocols: N N N Ability to respond to local changes for mla citing, long links. Types Methodology! Ability to cope with large concentration of traffic.

Message overhead with low mobility factor. Figure 23 shows how the scenario was designed and egypt reports created with ad-hockey. Methodology! The scenario is divided into three zones that have their certain characteristics. N N N Zone 1 - Speaker zone: The speaker moves back and forth. This changes the closest neighbor in write a scientific australia, the audience.

Zone 2 - Audience zone: Static audience that is sitting still most of the time. Very seldom does a node go outside to return a certain amount of time later. This will probably result in a link breakage of a longlasting link. Zone 3 - Outsider zone: Outsiders behind a wall that are trying to establish a connection between the speaker and each other. Types Of Thesis! 53 Transmitter range Zone 1 Zone 2 Zone 3 = Node = Obstacle = Movement Figure 23: Conference scenario. Egypt Book Reports! The results for types, this scenario are shown in a scientific report, Table 12 and Table 13.

It must however be noted that we do not distinguish the results for nodes that are in types methodology, zone 2 or zone 3. The calculated mobility factor for this scenario is very low. All protocols except DSDV and the AODV version that only uses hello messages show quite good performance, delivering between 92-99% of the packets with an average throughput between 14.8 – 15.7 Kbit/s. DSDV delivers only write australia 75.6% of the packets with an average throughput of 12.1 Kbit/s and the AODV version with only hello messages delivers 89.3 % of the packets, with a throughput of 14.3 Kbit/s. This shows that an ad-hoc routing protocol must quickly adapt to types, link changes even for long lasting routes as in this case where mobility is very low. Table 12: Mobility factor Received Throughput Sent Average delay Dropped Received packets Packet overhead Byte overhead Average hopcount DSDV 0.0439350 75.6% 12.1 Kbit/s 21510 0.052 s 5250 16260 44054 6406036 5.32 Conference simulation results. DSR - 1 0.0439350 97.1% 15.55 Kbit/s 21510 0.210 s 614 20896 3129 3689865 5.73 DSR - 2 0.0439350 98.0% 15.7 Kbit/s 21510 0.23 s 422 21088 4109 4093220 5.79 54 AODV - 1 0.0439350 89.3% 14.30 Kbit/s 21510 0.26 s 2298 19212 43881 1660020 6.62 AODV - 2 0.0439350 92.3% 14.79 Kbit/s 21510 0.29 s 1644 19866 14537 610884 6.53 AODV - 3 0.0439350 94.0% 15.00 Kbit/s 21510 0.39 s 1376 20134 54677 2112716 6.45 Both versions of DSR have the book reports lowest packet overhead in this scenario, while all versions of AODV show the lowest byte overhead. The large byte overhead for DSR has to do with the fairly large amount of types methodology traffic and that the routes have an egypt book, average hopcount that is as large as 5-6 hops.

As can be seen in Table 13. Of Thesis! DSDV fails to deliver 3599 packets because of route failures. This is due to mla citing quotes, the slow response time when links go down and of thesis the time it takes to find new routes. Book! A lot of packets will be sent using a route that the protocol thinks is valid, while in fact the route is broken and the packets are dropped. Also a lot of of thesis methodology packets are dropped in the interface queue. AODV using only hello messages show the quotes same tendency, dropping 1364 packets because of the same reasons. It is however fewer packets than for DSDV. This has to do with the types time between the HELLO messages. Rotc! The less time between the messages, the faster can the protocol react to broken links and of thesis methodology avoid dropping the packets. In general, most of the packets are dropped in the sendbuffer. Retransmission of these dropped packets could of course be handled by mla citing quotes upper layer protocols, such as TCP.

Table 13: Cause for types of thesis methodology, drop Sendbuffer Route failures ARP Interface queue End of simulation DSDV 3599 74 1567 10 Packet drops in conference scenario. DSR – 1 519 30 34 18 13 DSR – 2 303 98 4 0 17 AODV –1 894 1348 22 4 30 AODV – 2 1364 201 21 10 48 AODV -3 1096 202 14 0 64 5.6.3 Event coverage This scenario simulates a group of 50 highly mobile people that are changing position quite frequently. It could for rsvp, instance represent a group of reporters that are covering a political event, music concert or a sport contest. In real life it would be nearly impossible to types, establish a wired network between the fiction high reporters, but they must be in constant communication with each other, enabling a fast reaction. Of Thesis Methodology! Parameters that are specific for the event coverage scenario are shown in Table 14. Table 14: Parameters used during event coverage scenario. Egypt! Parameter Number of CBR sources Number of of thesis receivers Number of flows Value 9 45 45 The scenario is characterized by: N N N N N Rather high mobility factor. Essay! Typically 50 % of the types nodes are constantly changing their position during any time of custom essay order period.

Every now and then the types of thesis methodology nodes tend to book, cluster. Links involve a few hops and relatively short-lasting. Traffic is spread all over the place. Many obstacles. Types Of Thesis! Nodes can usually only communicate with a few nodes. This will lead to a low interference from the other nodes, except for the moments of clustering. 55 The scenario tests the custom essay protocols: N N Ability to respond to fast link changes and fluctuating traffic. Message overhead with constant topology updates. Figure 24 shows how the types methodology scenario was designed. 50 % of the nodes are moving randomly with a constant speed of 1 m/s. High School! Every now and then a temporary cluster contain approximately 10 nodes will form.

These clusters remain static for methodology, a certain amount of time. Rsvp Write! Temporary clusters = Node = Obstacle Figure 24: = Movement Event coverage scenario. Types Methodology! The results for rotc essay topics, the event coverage scenario are shown in Table 15 and Table 16. As Table 15 shows, the methodology two protocols that has the lowest fraction of packets received are DSDV and rsvp how to the AODV version that entirely relies on feedback from types of thesis link-layer. These protocols only have a fraction of packets received that lies around 91-92 %. For all other protocols/versions this value is at least 94 %. The mobility factor for the scenario is 0.72, which is quite low even though considering we have about mla citing, 50 % of the nodes in types methodology, movement. The nodes are however only moving with a speed of historical book high 1 m/s. DSDV has the highest overhead of all the methodology protocols, counted in essay order, both number of control packets and of thesis methodology bytes. DSR both with and without eavesdropping have a very low overhead. It must however be noted that the rotc essay traffic load in types of thesis methodology, this scenario is very low and most of the egypt book communication is taking place in a very small area, thus leading to a very low average hopcount of of thesis approximately 1.5 for mla citing in essay, all protocols. In this scenario, AODV with only hello message shows better results than AODV with only link-layer support and the reason is that the hello messages makes it possible to keep track of neighbors. Most of the types methodology communication is taking place within clusters, so to how to write report, know the neighbors will probably mean that we will not have to types, make as many requests.

The topology of the network is changing quite frequently. This causes a protocol like DSDV to have a very large overhead. The communication however, take mostly place within the clusters. This makes the job for the on-demand-based protocols much easier. The hopcount from source to destination is very small so the protocols will find a route very quickly. The protocols which are entirely on-demand will have a slightly 56 higher delay and the protocols that uses some sort of periodic messages (DSDV and the ADOV version that use hello messages) will have lower delay.

Table 15: Mobility factor Received Throughput Sent Average delay Dropped Received packets Packet overhead Byte overhead Average hopcount DSDV 0.721611 91.4% 14.75 Kbit/s 4500 0.075 s 385 4115 42415 10578764 1.46 hops Event coverage simulation results. DSR – 1 0.721611 97.5% 15.68 Kbit/s 4500 0.138 s 111 4389 1056 141196 1.53 hops DSR – 2 0.721611 97.7% 15.71 Kbit/s 4500 0.140 s 102 4398 1354 158420 1.57 hops AODV – 1 0.721611 94.5% 15.33 Kbit/s 4500 0.024 s 245 4255 31342 1137752 1.55 hops AODV – 2 0.721611 92.2% 14.89 Kbit/s 4500 0.214 s 352 4148 2722 117904 1.75 hops AODV – 3 0.721611 95.1% 15.36 Kbit/s 4500 0.015 s 219 4281 31443 1142180 1,55 hops Table 16 shows that most of the packets are dropped due to route failures and in those cases where there exists a sendbuffer, congestion/time-out in the sendbuffer. Egypt! AODV that only uses link-layer support (AODV 2) has most of the dropped packets due to of thesis methodology, failed ARP requests and DSDV drops most of rsvp how to write its packets at the interface queue. Table 16: Cause for drop Sendbuffer Route failures ARP Interface queue End of simulation DSDV Packet drops in event coverage scenario. DSR - 2 81 19 1 AODV - 1 100 83 61 1 102 48 235 DSR – 1 81 21 9 9 AODV - 2 131 32 178 10 1 AODV - 3 100 15 104 5.6.4 Disaster area This scenario represents some sort of of thesis methodology disaster area in custom essay order, a region that lacks any sort of types of thesis methodology telecommunication infrastructure. It could for instance represent a natural disaster or a large rescue operation. Every rescue team member could have a personal communicator with ad-hoc network capability. These personal communicators are capable of communicating with each other and historical report high with relay nodes that are mounted on a vehicle, like a helicopter, car or boat.

The parameters that are specific for the disaster area scenario are shown in Table 17. Table 17: Parameters used during disaster area scenario. Types Of Thesis! Parameter Number of CBR sources Number of receivers Number of flows 57 Value 38 87 87 The scenario is characterized by: N N N N N N A node movement, where approximately 95 % of the nodes are moving slightly, while the remaining 5 % are changing their position very often. Network partitioning now and then. Long and short lasting links that only are a few hops.

Traffic that is how to spread all over the nodes. Of Thesis! Many obstacles. Low interference from the other nodes. Fiction Book Report! The scenario tests the protocol: N N Ability to work with both slow and types of thesis methodology fast changing network topologies. Ability to cope with network partitioning. Figure 25 shows how the scenario was designed. There are two highly mobile nodes moving at the speed 20 m/s back and forth. There are also three separate subnetworks that can connect to each other through the relays mounted on mla citing quotes the highly mobile nodes. Within each subnetwork, the methodology movement is randomized at speed 1 m/s.

Subnetwork 2 Subnetwork 1 Vehicle 1 = Node Subnetwork 3 = Obstacle Figure 25: Vehicle 2 = Movement Disaster area scenario. Order! The results for of thesis methodology, the disaster area scenario are shown in school, Table 18 and Table 19. The calculated mobility factor for this scenario is quite high. Many of the nodes are moving slightly (people), and types some nodes are moving very fast (vehicles). The protocols that show the best results in this scenario are the purely reactive approaches, that is AODV using both hello messages and MAC support and DSR with eavesdropping. They have a delivery ratio between 54–58 % of the packets with an average throughput of reports 14.1 – 14.8 Kbit/s. DSDV has the worst performance, delivering only 29,5% of the packets with an average throughput of 12.42 Kbit/s. A delivery ratio of only 58 % for the best protocol may sound like a terrible ratio, but because of network partitioning, it is types hard for any protocol to successfully deliver more packets than that. 58 DSDV show the lowest delay, but this is egypt book due to the low delivery ratio. All versions of AODV keep an of thesis, average delay between 0.89 – 1.05 seconds, while the DSR versions lie between 1.19 – 1.25 seconds. Both DSR versions keep a low packet overhead compared to the other protocols.

The byte overhead is however twice as large for DSR compared to AODV. How To A Scientific Report Australia! As expected, DSDV uses the shortest paths with an average of of thesis 3.42 hops. Book Reports! The other protocols has an average hopcount of 5.0-5.2 hops. Of Thesis Methodology! Table 18: Mobility factor Received Throughput Sent Average delay Dropped Received packets Packet overhead Byte overhead Average hopcount DSDV 1.154619 29.5% 12.42 Kbit/s 29616 0.196 s 20867 8749 41402 6497476 3.42 hops Disaster area simulation results. DSR – 1 1.154619 58.0% 14.79 Kbit/s 29616 1.252 s 12440 17176 27048 4880992 5.01 hops DSR – 2 1.154619 54.50% 14.43 Kbit/s 29616 1.187s 13464 16152 30692 5137148 5.16 hops AODV – 1 1.154619 48.0% 13.07 Kbit/s 29616 0.888 s 15382 14234 61557 2426164 5.23 hops AODV – 2 1.154619 52.2% 13.49 Kbit/s 29616 1.052 s 14161 15455 50686 2426164 5.24 hops AODV – 3 1.154619 54.0% 14.09 Kbit/s 29616 0.988 s 13635 15981 77311 3096228 5.26 hops DSDV drops a lot of packets because of essay route failures. In this scenario, DSDV also drops a large amount of packets in the interface queue.

One large cause for drops in the other protocols, lies in the sendbuffer. If routes are not found within time, packets in the buffer are dropped because of timeouts or congestion. Another large cause for packet drops is route failures. Types Methodology! This scenario is very interesting and should be investigated further, especially for the AODV protocol. We discovered when running the simulations that AODV tend to form short lived routing loops. Since the author claim that this protocol should be loop free at rsvp how to write, all times, one possible cause for this might be invalid use of the sequence numbers or the fact that sequence numbers are unsynchronized during network partitioning. Very few packets were dropped because of this (less than 5). Another interesting thing with this scenario is that all main nodes send traffic both ways to types of thesis, each other.

This causes AODV to respond to requests with temporary routes set up by other requests. Since it is unclear from the draft whether the temporary routes should be regarded as a normal route in the routing table or not, we decided to try both in this scenario. By only allowing RREPs to write report, use the types methodology temporary routes, and by rotc not allowing a node to respond to a RREQ with a temporary route, the routing loops could be avoided. However, the types performance of the protocol decreased. We therefore used simulations where we considered the temporary routes as a normal route.

Table 19: Cause for egypt reports, drop Sendbuffer Route failures ARP Interface queue End of simulation DSDV 15853 479 4528 7 DSR – 1 10033 1990 35 3 1 Packet drops in disaster area. DSR - 2 10277 2960 64 159 9 59 AODV – 1 9836 5047 292 34 2 AODV - 2 10693 3046 241 20 1 AODV - 3 10941 2470 64 44 116 5.6.5 Summary realistic scenarios The realistic scenarios show how the types of thesis protocols behave in certain situations. For this purpose, three scenarios were designed and simulated with different versions of the protocols DSDV, DSR and AODV. DSR show the book reports best performance results overall. If source routing is undesirable, another good candidate is AODV with only types of thesis MAC layer support.

It has a slightly higher packet overhead, but an overall good delivery ratio. 5.7 Observations The protocols that we have worked with most are AODV and egypt book reports DSR, thus we have observed some important differences for these protocols, that in types, some way affect the performance of the protocols. 5.7.1 Ability to find routes AODV To illustrate AODVs ability to find routes, we use a simple scenario (see Figure 26). How To! The scenario consists of four nodes A, B, C and D connected to each other. A C D B Figure 26: Simple example scenario. Node A needs a route to node D. No data has been sent earlier, thus the only routes known to the AODV protocol are the different neighbors in the scenario. This is of thesis because AODV uses hello messages to keep track of the neighbors of write a node. A RREQ is generated by types of thesis methodology node A and broadcasted to custom essay, its neighbors. The RREQ propagates through the network until it reaches node C. Since node C has a route to node D it can comply with the RREQ and generate a RREP.

During the propagation of the types methodology RREQ, a reverse path is set up to node A. Custom Essay! The RREP is unicasted back to A. It uses the temporarily backward route set up by the RREQ. During the types methodology propagation of the rotc topics reply, a forward route is types set up to node D by all intermediate nodes, resulting in the routing table shown in Table 20, thus all temporary routes are updated to in essay quotes, active routes. Types Of Thesis Methodology! Table 20: Node A Destination Nexthop B B D B Routing tables for AODV after a route discovery process. Topics! Node B Destination A C D Nexthop A C C Node C Destination B D A Nexthop B D B Node D Destination C Nexthop C After the types of thesis methodology route discovery process, only B and C have routes to all other nodes in mla citing in essay, the scenario. Node A does not know that there is a route to node C, nor does node D know of the route to methodology, A and B. Rsvp How To! Thus AODV has to go through the types methodology route discovery process several times to essay, discover all the routes. This leads to more control traffic and higher delays.

On the other hand, it saves memory by not having to keep information about routes that might not be used. 60 DSR The ability to find routes differs slightly between the DSR and AODV protocol. Of Thesis! DSR can make use of the source route carried in each packet header to book reports, discover routes to nodes by methodology which the in essay quotes packet has traveled through. If new routes are found, DSR can take advantage of this without having to of thesis, go through a new route discovery phase, thus reducing the essay number of control packets and decreasing the delay. The memory usage of a node is instead increased by having to types methodology, store more routes.

We consider the how to same scenario as for the AODV protocol (Figure 26). Node A needs a route to node D. No data has been sent earlier, thus DSR has no knowledge of any routes. Since no routes are known, the RREQ propagates until it reaches node D. Of Thesis! During the rsvp how to propagation of the RREQ, every node in types methodology, its path learn a route back to all the nodes by which the RREQ has passed through. The RREP is unicasted back to A, using the routes learned during the propagation of the RREQ. As the RREP propagates, each node also learns the routes to all nodes for which the mla citing quotes RREP has passed through, resulting in the routing tables shown in Table 21. After the route discovery phase, each node has a route to every other node in this example. Table 21: Node A Destinatio n B C D Path B B-C B-C-D Routing caches for DSR, after a route discovery process. Node B Destinatio n A C D Path A C C-D Node C Destinatio n A B D Path B-A B D Node D Destinatio n A B C Path C-B-A C-B C 5.7.2 Temporary backward routes When a RREQ propagates in search for a route in AODV, a temporary backward route is set up towards the requesting node.

A RREP might use this backward route. This route is normally set to expire after 3 seconds if it is not used. Types Of Thesis Methodology! It is not clear from the draft if this route may be used by application data as well. Book Reports! Using this route for data affects the behavior of the of thesis protocol in some way and it is not described how the protocol should handle this. One of the problems with this temporary route is with the way it is set up. How To Write! When the RREQ propagates, we do not know who will be using the backward route, so no active neighbors can be put into the active neighbor list. If during this time, a link failure or an expired route entry somewhere breaks the route, the types methodology rest of the mla citing in essay quotes nodes in the route are not informed of this and therefore have redundant routes in types methodology, their tables.

When the how to write a scientific report route is used again, the application data will come to a node in the route that does not have a valid entry for the destination and will therefore be dropped while a triggered RREP tries to inform the nodes in the route that it is broken. This problem will become more apparent in a network with a higher load. Another problem is the short lifetime if temporary routes are installed into the routing table. Lets say node A sets up a temporary route to D. Node A can then respond with the temporary route to another request searching for a route to D. Since the temporary route has a short lifetime, it might expire before the actual data has a chance to types of thesis methodology, use it. This results in unnecessary control overhead and packet drops. To deal with this, the routing agent could chose to only allow RREP to use the temporary route. Also a check of the expire time before responding with a RREP could be used to assure that the route wont timeout shortly after the node has responded with the mla citing information.

A question about of thesis methodology, this was directed to the author of the protocol with the response that this check should not be done, instead the protocol should rely on the sequence numbers to provide the order freshness of a route. We implemented a version of the AODV protocol that used the temporary route for all packets since it showed a slightly better performance result then if not allowing data packets to use the temporary route. The implementation done in Gothenburg used the temporary route only for route replies. So we have a small difference in types of thesis methodology, our implementations. 61 5.7.3 Buffers The use of send buffers in the routing protocol also affects the performance of the routing protocol; especially the size of the buffers and the time a packet is allowed to stay there before it is dropped. The send buffer buffers data packets while the routing protocol requests a route to the destination. In our simulations, AODV used a buffer capable of holding 64 packets and allowing them to stay in the buffer for maximum 8 seconds. A Scientific! Allowing the packets to stay in the buffer for longer period of times will of course increase the amount of successfully routed packets, but also increase the average delay. Also the of thesis choice of queuing discipline will affect the measured performance.

If the how to write report buffer is full, there must be some smart algorithm to decide which packets should be dropped. The routing protocol could decide not to buffer any packets at all and depend on higher layer protocols such as TCP to retransmit lost packets. This would however affect the measured performance in methodology, the simulations and order give unfair results for the protocol. 5.8 Discussion If we compare the work that we have done against the work that was done by of thesis methodology the CMU Monarch project [3], many similarities can be seen. Their conclusion was that both DSR and AODV performs well at custom essay order, all mobility rates and movement speeds.

We have come to the same conclusion, but we feel however that their definition of mobility (pause time) does not represent the dynamic topology to the same extent as our mobility factor that is based on the actual relative movement pattern. The only node speeds that they have tested are 1 m/s and 20 m/s, which are not showing the complete range. Our mobility factor has a speed range from types methodology 0 m/s up to 20 m/s and shows how the protocols behave in write a scientific report australia, the complete range. They have also only shown the result for one DSR version and one AODV version. The DSR version that they show the results for is using eavesdropping, which we regard as being unrealistic, because of the security issuses discussed earlier. The AODV version that they have used is not using hello messages, which changes the behavior of AODV. We have tested different versions and of thesis methodology shown that DSR with eavesdropping has a slightly better performance than DSR without eavesdropping. We have also shown that AODV with MAC-layer support and hello messages has better performance than AODV with only MAC-layer support. Our results also show that it is necessary to use some support from the MAC-layer to achieve a performance that is book reports good even at high mobility factors. Types Methodology! The CMU Monarch project, have used the number of sources as a definition of the load that is offered the network. Their simulations with the different number of sources are almost identical to each other.

The only protocols that showed a significantly difference was TORA, that only delivered 40 % of the packets with the egypt book lowest pause time and highest number of sources. Our definition of of thesis load was based on the rate that the custom essay order sources are sending packets with. Even DSR that had the best results in the CMU paper fails to deliver a large fraction of the packets when the rate is increased. The increase of the rate also very clearly shows how much the overhead for DSR increases compared to for instance AODV. Of Thesis! 5.9 Classification Why is historical fiction report high school there any need for classification of routing protocols? If one routing protocol is superior than the other routing protocols for instance in very high mobile environments, why not always use that routing protocol? If it handles high mobile environments, it should also be good at low mobile environments. In real life, many parameters affect the types behavior of the routing protocol.

It is also important to recognize the need that is required in a particular scenario. In one scenario, there is maybe more need for high throughput than there is for low delay. In another scenario there is how to a scientific report maybe more need for low delay etc. This is becoming more and of thesis methodology more important now, in particular when active networks [29] is becoming an essay, interesting issue in networking. Active networking means that you add user controllable capabilities to the network. The network is no longer viewed a passive mover of bits, but rather as a more general computation engine. This makes it possible for instance to adjust the routing protocol depending on the scenario. You could basically send the routing protocol and methodology let it install itself into rotc essay topics, the nodes. 62 5.9.1 Mobile networks As the simulation results show, the mobility of the network greatly affects the performance of the protocols. It is of thesis crucial that the protocol ability to detect broken routes is fast enough and that they also react to these changes.

DSDV Since DSDV is how to report dependent of types of thesis its periodic updates, its ability to deal with a dynamic topology is very poor. It has a poor ability to fast detect broken links and order takes time to converge. This protocol should really be avoided for use in ad-hoc networks where it is crucial to deal with frequent changing topology. Methodology! This protocol could however be an option for how to, networks that are static during long periods of times. AODV The original AODV protocol using only types of thesis methodology HELLO messages as link breakage detection shows poor results as mobility increases. This protocol needs better link breakage detection. Using lower layers such as MAC to detect transmission errors can achieve this. Custom Essay! If this is types methodology used, the protocol actually shows a very good performance. Custom! This protocol is types of thesis a definite choice for rsvp how to, highly mobile networks. DSR This protocol is highly optimized and types of thesis methodology also shows good results in the simulations.

The protocol could definitely be used in highly mobile networks as well as static networks. 5.9.2 Size of networks When talking about the size of a network, it is not only the number of nodes in the network that is of interest. Write A Scientific! The area that the nodes are spread out over is also interesting. This basically decides the connectivity of the network. A large area with many nodes may mean longer routes then for a smaller area with the same number of nodes.

At the types same time, many nodes close to each other means a higher collision probability. DSDV This protocol does not scale well. Its use of periodic broadcasts limits the protocol to small networks. If the protocol would be used in large networks, the converge time to a steady state would increase when routes go up and down. The reason is that updates must propagate from one end of the network to the other. AODV This protocol scales well, and could be used in write, both small and medium sized networks. The combination of on-demand and of thesis distance vector makes this protocol suitable for large networks as well. The information that each node must store for each wanted destination is rather small compared to for instance DSR that has to store whole source routes. In large networks however, the propagation of requests to egypt reports, all nodes is methodology a waste of resources. A better solution is probably to divide the network into clusters or zones, like for rsvp write, instance ZRP and CBRP have done. DSR This protocol has some limitations when it comes to the size of the network.

A larger network often means longer routes and longer routes means that the source overhead in types methodology, each packet grows. The current implementation limits each packet to carry a source route of maximal 16 hops. This can of course be adjusted, but one should keep in book report high school, mind the large overhead this causes. One could imagine a network with 20 nodes connected in a straight line. Types Of Thesis! Then this implementation would not manage to route to all nodes. We therefore recommend this protocol for small and medium sized networks.

63 5.9.3 Network scenarios Conference For low mobility scenarios, like the conference scenario that we did simulations on, DSR is the best protocol to use if the hopcount is small (fewer than 5 hops). The reasons are high delivery rate, low delay and low message overhead in terms of packets and byte overhead. If the rotc essay topics number of hops increases and get as many as 10 hops, each packet must carry a very large byte overhead, which can be very costly, when the load increases. Another good candidate for this scenario when the number of hopcount increases is one of the AODV versions that use MAC-layer support. Types Of Thesis! AODV has also a very high delivery ratio, but the mla citing quotes number of control packets is somewhat larger.

Event coverage In average mobile scenarios, like the event coverage scenario, where nodes tends to cluster and almost all communication is of thesis methodology within the clusters, DSR is by all means the best protocol. It has a very large delivery ratio and the overhead is very small, even counted in bytes, because of the historical book report school few hops required to types methodology, reach the destination. The AODV versions show a very good result also, but the overhead is larger. So for essay, these type sort of networks DSR it the best protocol. Types Of Thesis! Disaster In networks that become partitioned, DSR with eavesdropping show the best results in this scenario. It has a high delivery ratio, high throughput, a delay around 1.2 seconds and egypt reports low packet overhead.

It also uses only 5 hops in average to reach a destination. Types! This protocol is order therefore recommended in this type of scenario. Eavesdropping might however be undesirable because of security issues. Types Of Thesis! One other candidate for this scenario is AODV with MAC support. It has almost as high delivery ratio as DSR and also a lower delay. The packet overhead is write a scientific twice as high but the byte overhead is smaller. 5.10 Improvements The simulations have shown that DSR with and types methodology without eavesdropping and the AODV versions that use linklayer support has the overall best result in mla citing quotes, almost all simulations. DSR has as mentioned earlier the advantage that it learns more information for each request it sends out. If a request goes from S to D and the reply from D to S, S will learn the route to methodology, all intermediate routes between S and essay topics D. This means that it is not necessary to send out as many requests as for example AODV.

The source routing approach is therefore very good in the route discovery and route maintenance cases. However, source routing is not desirable to methodology, use for data packets. First of all, it adds a lot of overhead. Secondly it is not as traditional as for instance distance vector or link-state that are widely used in fiction report high school, wired networks. Our proposal is therefore to methodology, implement a protocol that is a combination of source routing and distance vector. Source routing should be used in route discovery and route maintenance phases. These phases would also include that the order routing tables where set up accordingly during the propagation of the requests and replies. When the data packets are forwarded a distance vector algorithm should be used. The packets are simply forwarded to the nexthop according to the routing table. This in combination with that the protocol stores several routes for each destination would probably mean a protocol with a performance that is even better than the protocols that have been simulated in this master thesis.

64 6 Implementation study The implementation study that was conducted at Ericsson Mobile Data Design in Gothenburg [28] has implemented the types AODV protocol. The goal was to rotc, deliver a working routing protocol as specified in types methodology, the original AODV draft [19]. 6.1 Design Main Event Queue Route Table Send Hello Send Request Check Neighb Check sender Remove route Neighbors / Senders Lookup Add Delete Update Need route? Add Delete Update time Is member? Host unreachable Lookup failed Message Request buffer Send request Send reply Send hello Receive msg Add Delete Is member? Rreq Rrep Hello Route add Route del User space /dev/route Iotcl() Icmp.c UDP FIB Kernel Table Kernel route.c Other daemons Figure 27: Overview of mla citing in essay quotes AODV daemon. Types! The implementation that has been done should only rotc topics be considered as a prototype to confirm the usefulness of AODV. It is implemented as a daemon in user space. The advantage with this is methodology that debugging and testing is much easier to do.

A final implementation should be made in kernel space with more optimized design. Thus abandon the modular design and optimize the code to go really fast. Figure 27 shows the design of the user space daemon and how it interacts with the kernel code. The different modules will be explained in the following chapters. 6.1.1 Main Main ties together all other modules of the mla citing in essay user space daemon. Of Thesis Methodology! It is also in main that the AODV specific code lies. 65 6.1.2 Event queue Queue for events that are supposed to be performed at certain times. Egypt Book! These events include: N N N N Periodic hello messages Send / retransmit route requests Timeouts of route entries Hello timeout 6.1.3 Route table This module is an interface against the submodules Daemon Table and of thesis Kernel Table. It takes care of these two, so when you want to lookup or change a route from egypt book Main, you only types of thesis methodology have to do one call to this module instead of two to the both submodules.

The entries in Daemon Table module have all the fields that is required for AODV, sequence number, list of active neighbors and so on. The operations supported are Lookup, Add and mla citing quotes Delete. The Kernel Table is not a table in the sense Daemon Table is, instead this submodule just communicates with the kernel, sending messages about adding and deleting entries and receives netlink need-route messages. 6.1.4 Neighbors / senders Keeps track of the neighbors of a node. A neighbor is a host that sends/receives hello messages that is directly received/sent by another node. This demands that the links are bi-directional. At first it was thought that the WaveLAN cards would take care of types methodology this, but it was not the case. The signal strength and the range was different between the order hosts. To be able to guarantee bi-directional link, the concept Sender was added. Types Of Thesis! A host is classified as a sender if it can be heard by at least one other node. Historical Book High School! When sending hello messages a node sends the list of current Senders and if the receiver of the Hello messages is in of thesis methodology, this list, it is a Neighbor and can start act as one 6.1.5 Request buffer This buffer prevents the network of being flooded by multiple request for the same address.

This buffer stores already processed requests. 6.1.6 Message Handles the different types of messages that the daemon can send and receive. These messages are: N N N Hello Route Request Route Reply. 6.2 Setup The computers used for this implementation study was: N N 2 stationary computers with Lucent WaveLAN ISA cards. 3 laptops with Lucent WaveLAN PCMCIA cards.

The implementation started first with the 2 stationary computers running FreeBSD7. The choice of FreeBSD was primarily made because FreeBSD offers the essay best documentation of its kernel source. It was later discovered when the laptops arrived that FreeBSD was incompatible with the Lucent WaveLAN PCMIA cards in types, the laptops. Linux8 however has support for both variants of the LucentWaveLAN cards and Linux was therefore chosen as development operating system. It is book not very hard to port the code to types of thesis, FreeBSD in the future if so desired. Book! 7 8 FreeBSD 2.2.6 Linux Red Hat 5.1 66 6.3 Testing The purpose of testing the implementation is to verify that the implementation works correctly and to see if the performance is of thesis suitable for real life applications. 6.3.1 Correctness To verify that the implementation of AODV behaved correctly, computers were placed in different scenarios to how to, test the different parts of the types of thesis protocol. The following tests where made: N N N N N N N Bi-directional links and neighbors: Tests that two nodes can send hello messages to each other and report australia registry the counterpart as a neighbor. Unidirectional links and neighbors: It tests the same as above, but with the difference that we only have an uni-directional link, so only types methodology one of the nodes can hear the other and how to write a scientific australia registry him as a neighbor. Neighbor link down: Tests that neighbors moving away from each other causes the link between them to go down. Zero hop route requests: Tests that a request to a neighbor that also is the requested destination generates a reply that is correctly received.

This is not the normal operation of the of thesis protocol, but could happen if two nodes are in range but have not accepted each other as neighbors. Single hop route request: Tests the situation where node S searches the route to D and we have one node B in between. S broadcasts a request that is caught by B, which knows the route to D and sends a reply back to S. Multihop route request: Almost the same situation as the rsvp write single hop route request. The difference is that we have two nodes between the of thesis methodology requesting source and the destination. The route request must therefore be forwarded one hop before a reply can be generated.

Triggered route reply: Tests that the triggered route reply is generated whenever a route goes down. 6.3.2 Performance No actual performance tests were done. The results for so few nodes would be misleading. Book! Instead tests with real applications like Netscape and Telnet were done. The problems that occurred with these tests were related to the on-demand nature of AODV. Telnet for instance returns host-unreachable when trying to telnet to a computer on the first attempt. The second attempt however is successful. The reason is types of thesis that when Telnet makes its first attempt, no route to the destination exists.

This will result in how to write a scientific, an error message from the kernel to Telnet, at the same time as a new request is sent to the neighbors. This request will eventually find a route to the destination and types of thesis it is how to australia installed in the routing table. When Telnet makes a second attempt connect to the same host, a route will already exist in the routing table and telnet will successfully reach the destination host. The solution to this problem is simply to take care of the error messages that the kernel sends to types of thesis methodology, the application. Book Reports! The error message should be buffered and if a route is types of thesis not found in a certain amount of time, the error message should be sent to the application, but if a route is actually found the error message can be discarded. Rsvp! 6.4 Problems / Limitations Problems that occurred during the implementation include: N N N FreeBSD incompatibilities: As mentioned before, lack of functional drivers to of thesis, FreeBSD forced the implementation study to be done under Linux. Historical Fiction High! Address: The current prototype requires that each node participating in the network have a predefined unique IP-address. There is of thesis a great need for a dynamic assigned IP-address architecture, which assigns nodes IP-addresses as they enter the mla citing quotes network. IPv6 holds such functionality. Types Of Thesis! This prototype is however done for IPv4 so no consideration has been done to implement such functionality. Three-way handshake: To guarantee bi-directional links, a three way handshake was necessary for the hello messages before two nodes can be certain of the other nodes existence.

The handshake uses piggybacking. It concatenates a list of all nodes it receives hello messages from to the hello messages it sends. When a node receives a hello message and finds its own address in the concatenated list it will add the sending node to its own list of neighbors which it has bi-directional links to. Three hello 67 N messages instead of one wastes bandwidth, but could also in book, a worst case scenario mean that it could take as long as two full hello intervals before two nodes in range of each other accepts the bi-directional links. Temporary routes: When a request is broadcasted from a node, it will propagate through the network and at methodology, the same time install a temporary route back to the source.

The problem with this temporary route is first of all that the how to request is unaware of if the route ever will be used and secondly who will use it. This means that it does not know the types of thesis active neighbors that are using this entry and can therefore not inform these neighbors if a link should go down on this route. The solution that was implemented differs somewhat of write a scientific report australia what was done in types methodology, the simulation study. The solution is to mla citing quotes, store the temporary routes separately and only install them in the routing table when the methodology route reply is propagating back through the custom network. Types Methodology! 6.5 Improvements Possible features that could be added to this prototype: N N N N Link layer hellos: The addition of link layer feedback from 802.11 would significantly increase the performance as the simulation study has shown. Redundant routes: Store all routes to a destination, not only the one we are currently using. If a route goes down due to a link failure, the next stored route would be tried before a new request is to be sent. How To A Scientific Report Australia! This saves a lot of of thesis overhead a and egypt reports makes the delay somewhat smaller. Dynamic IP-addresses: As mention under limitations, dynamic address assignment is a requirement for of thesis, these kind of mla citing quotes networks.

Multicast: Multicast groups within a ad-hoc network could be added. The latest AODV draft has support for this. 6.6 Implementation conclusions The implementation of the AODV protocol has shown that it is types possible to get these protocols to work in real-life. It must however be noted that real-life in this case only consisted of five computers. The AODV prototype has also given some insight into the problems that arise when trying to run real applications on an ad-hoc network. Applications like Netscape and Telnet get host unreachable in the first attempt. The second attempt finds the route successfully. This has to do with the book school on-demand feature of the AODV protocol.

68 7 Conclusions 7.1 Results The simulations have shown that there certainly is a need for of thesis, a special ad-hoc routing protocol when the mobility increases. It is however necessary to have some sort of feedback from the link-layer protocol like IEEE MAC 802.11 when links go up and down or for neighbor discovery. To only be dependent on periodic messages at the IP-level will result in a very high degree of packet losses even when mobility increases a little. The simulations have also shown that more conventional types of protocols like DSDV have a drastic decrease in performance when mobility increases and are therefore not suitable for mobile ad-hoc networks. AODV and DSR have overall exhibited a good performance also when mobility is high.

DSR is however based on source routing, which means that the byte overhead in each packet can affect the total byte overhead in the network quite drastically when the offered load to the network and the size of the network increases. In these situations, a hop-by-hop based routing protocol like AODV is write more desirable. One advantage with the methodology source routing approach is however that in its route discovery operation it learns more routes. Fiction School! Source routing is however not desirable in types, ordinary forwarding of how to a scientific report data packets because of the large byte overhead. A combination of AODV and DSR could therefore be a solution with even better performance than AODV and methodology DSR. Another key aspect when evaluating these protocols is to test them in realistic scenarios. We have tested them in three types of scenarios. DSR had the best performance, but the large byte overhead caused by the source route in each packet makes AODV a good alternate candidate.

It has almost as good performance. Essay! The implementation study conducted at ERV in Gothenburg has shown that it is possible to get a real ad-hoc network up and running. The main problems that did occur were related to the testing of the types of thesis protocol with real applications. When a route was needed by the application and the route did not exist in the routing table, the kernel informed the applications of write a connection error before giving the routing protocol enough time to find a route. Types Of Thesis Methodology! 7.2 Further studies Ad-hoc networking is a rather hot concept in mla citing in essay quotes, computer communications.

This means that there is much research going on and many issues that remains to be solved. Due to limited time, we have only focused on the routing protocols. However there are many issues that could be subject to further studies. First of all, the simulator environment could be improved. These are just some of the types of thesis methodology improvements that could be made: N N More routing protocols, for historical book high, instance TORA, ZRP and CBRP. Types Of Thesis! Measurement of computing complexity.

Secondly, there are many issues related to ad-hoc networks that could be subject to further studies: N N N Simulations which take unidirectional links into consideration. Some sort of analysis of whether many small control messages are more costly to egypt book reports, send in terms of resources than fewer large control messages. Security: A very important issue that has to be considered is the security in an ad-hoc network. Routing protocols are prime targets for impersonation attacks. Methodology! Because ad-hoc networks are formed without centralized control, security must be handled in a distributed fashion.

This will probably mean that IP- 69 N N N N N N Sec [14] authentication headers will be deployed, as well as the necessary key management to distribute keys to the members of the ad-hoc network. Rotc Essay Topics! Quality of Service (QoS): What needs are there for Quality of Service in an ad-hoc network? This is related to what the networks actually will be used for. Types Of Thesis Methodology! Hand-over of real-time traffic between nodes. Egypt! How should real-time traffic smoothly be handed over to another node when a route goes down? Should flooding be used before a route is found? Multicast: We have only types of thesis looked at custom essay order, unicast routing. Multicast routing is types of thesis methodology also an interesting issue that has to be considered.

Connecting ad-hoc networks to the Internet through access points: How do you connect an ad-hoc network to fiction book, the Internet? It is not possible to just add the access point as default in types, the routing tables. This would mean that nodes without a route to a certain destination would be routed to historical fiction report, the Internet. Mobile IP: Integration of types of thesis mobile IP into rsvp how to, ad-hoc networks. Types Of Thesis! Addressing of hosts: How should the hosts in an ad-hoc network be addressed? What happens if one adhoc network is partitioned in to two separate networks or two ad-hoc networks are merged into one new larger ad-hoc network? IP Index Router IP Router (IP) Index Index Figure 28: Router (RID) IP IP Different router identification approaches. From left to book school, right: 3a, 3b, 3c. There are basically three types of identifiers to consider (Figure 28): 1) Interface identifiers: Interfaces are present on both routers and hosts.

In the Internet addressing architecture, interfaces are identified by IP addresses. 2) Host identifiers: Can either be a permanent identifier or a temporary identifier. 3) Router identifiers: Is unspecified and generally depends on the routing policy. Types Of Thesis Methodology! There are three approaches to MANET router identification and rotc addressing currently being considered: a) Single IP address (AODV): Identifies a MANET node (both the router and the host) with a single IP address. Of Thesis Methodology! This approach leaves several issues open: N How to support sets or subnets of hosts attached to how to, a MANET router?

N How to support the use of multiple wireless interfaces? b) Single IP address with interface indexes (DSR): Identifies a MANET router with a single IP address and each interface with a single-byte interface index. This makes it possible to enable simultaneous support for multiple wireless technologies, with the types of thesis methodology IP address acting as router identifier. The problem with this scheme is write that it is of thesis methodology not IP in the classical sense where interfaces are identified by IP addresses. The use of a non-standard addressing architecture will likely complicate interoperability. Essay Topics! c) Router identifier and IP interface addresses (IMEP): Identifies a MANET router with a router Identifier (RID) and identifies each interface with an IP address. This approach can support sets or subsets of attached hosts and simultaneous use of of thesis multiple wireless technologies.

Approach a) and b) seem tailored to how to, support a mobile host that acts like a router. Approach c) is intended to support a mobile router platform to which one or more host-like devices may be permanently or temporally affiliated. These approaches say nothing about how IP addresses are assigned to types, interfaces (on hosts or routers), or what the RID is and how it is assigned. This is a separate problem, although one which is related to routing. 70 8 References [1] Dimitri Bertsekas and in essay quotes Robert Gallager, “Data Networks - 2nd ed”. Of Thesis! Prentice Hall, New Jersey, ISBN 013-200916-1. [2] Bommaiah, McAuley and fiction Talpade. AMRoute, “Adhoc Multicast Routing Protocol”, Internet draft, drafttalpade-manet-amroute-00.txt, August 1998. Work in methodology, progress. [3] Josh Broch, David A. Maltz, David B. Johnson, Yih-Chun Hu and book high school Jorjeta Jetcheva, “A performance Comparison of of thesis methodology Multi-hop Wireless Ad Hoc Network Routing Protocols”. Mobicom'98, Dallas Texas, 25–30 October, 1998. How To Write Report! [4] Josh Broch, David B. Of Thesis! Johnsson, David A. Maltz, “The Dynamic Source Routing Protocol for fiction report high, Mobile Ad Hoc Networks”. Internet Draft, draft-ietf-manet-dsr-00.txt, March 1998. Work in progress. Methodology! [5] Scott Corson and essay order Joseph Macker, “ Mobile Ad Hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations”.

Internet-Draft, draft-ietf-manet-issues-01.txt, March 1998. Types Of Thesis Methodology! Work in rotc essay, progress. [6] M.Scott Corson, S. Papademetriou, Philip Papadopolous, Vincent D. Types Of Thesis Methodology! Park and Amir Qayyum, “An Internet MANET Encapsulation Protocol (IMEP) Specification”. Internet draft, draft-ietf-manet-imepspec01.txt, August 1998. Work in progress. [7] Kevin Fall and Kannan Varadhan, “ns notes and how to a scientific documentation”. Of Thesis Methodology! The VINT project, UC Berkeley, LBL, USC/ISI, and Xerox PARC, May 1998. Rsvp Write! Work in progress. [8] Zygmunt J. Types Of Thesis! Haas and Marc R. Egypt! Pearlman, “The Zone Routing Protocol (ZRP) for methodology, Ad Hoc Networks”, Internet draft, draft-ietf-manet-zone-zrp-01.txt, August 1998.

Work in progress. [9] IEEE Computer Society LAN MAN Standards Committee, “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications”, IEEE Std 802.11-1997. The Institute of Electrical and historical book report Electronics Engineers, New York. [10] Philippe Jacquet, Paul Muhlethaler and Amir Qayyum, “Optimized Link State Routing Protocol”. Internet draft, draft-ietf-manet-olsr-00.txt, November 1998. Work in progress. [11] Mingliang Jiang, Jinyang Li and Yong Chiang Tay, “Cluster Based Routing Protocol (CBRP) Functional specification”. Types Of Thesis Methodology! Internet draft, draft-ietf-manet-cbrp-spec-00.txt, August 1998. Work in progress. [12] David B. Johnson and David A.Maltz, “Dynamic source routing in ad hoc wireless networks”. In Mobile Computing, edited by Tomasz Imielinski and Hank Korth, chapter 5, pages 153-181. Kluwer Academic Publishers. [13] David B. Johnson and David A. Maltz, “Protocols for adaptive wireless and mobile computing”. In IEEE Personal Communications, 3(1), February 1996. [14] Stephen Kent and Randall Atkinson, “Security Architecture for the Internet Protocol”, Internet draft, draft-ietf-ipsec-arch-sec-07.txt, July 1998.

Work in book reports, progress. [15] Mobile Ad-hoc Networks (MANET). URL: (1998-11-29). Work in progress. 71 [16] Vincent D. Park and M. Scott Corson, “Temporally-Ordered Routing Algorithm (TORA) Version 1: Functional specification”. Internet draft, draft-ietf-manet-tora-spec-01.txt, August 1998. Work in progress. [17] Vincent D. Park and M. Scott Corson, “A performance comparison of the methodology Temporally-Ordered Routing Algorithm and Ideal Link-state routing”. In Proceedings of IEEE Symposium on Computers and Communication ’98, June 1998. [18] Charles E. Rotc! Perkins, “Mobility support, Mobile IP and types Wireless Channel Support for ns-2”, presentation slides. URL: charliep/mobins2/, (1998-11-29). How To A Scientific Report! Work in progress. [19] Charles E. Perkins, “Ad Hoc On Demand Distance Vector (AODV) Routing”. Types! Internet draft, draft-ietfmanet-aodv-01.txt, August 1998.

Work in rotc essay, progress. [20] Charles E. Perkins, “Ad Hoc On Demand Distance Vector (AODV) Routing”. Internet draft, draft-ietfmanet-aodv-02.txt, November 1998. Work in progress. [21] Charles E. Perkins, “Mobile Ad Hoc Networking Terminology”. Internet draft, draft-ietf-manet-term00.txt, October 1997. Work in progress. Types! [22] Charles E. Mla Citing In Essay! Perkins and Pravin Bhagwat, “Highly dynamic Destination-Sequenced Distance-Vector routing (DSDV) for mobile computers”. In Proceedings of the SIGCOM '94 Conference on Communications Architecture, protocols and Applications, pages234-244, August 1994. A revised version of the paper is available from Types! (1998-11-29) [23] Larry L. Peterson and Bruce S. Davie, “Computer Networks - A Systems Approach”. San Francisco, Morgan Kaufmann Publishers Inc. ISBN 1-55860-368-9. [24] Plummer, D., An Ethernet Address Resolution Protocol - or - Converting Network Protocol Addresses to 48.bit Ethernet Address for Transmission on Ethernet Hardware, RFC-826, MIT, November 1982. Book Reports! [25] Theodore S. Rappaport, “Wireless Communications: Principles and Practice”. New Jersey, Prentice Hall. ISBN 0-13-375536-3. [26] Raghupathy Sivakumar, Prasun Sinha and Vaduvur Bharghavan, “Core Extraction Distributed Ad hoc Routing (CEDAR) Specification”, Internet draft, draft-ietf-manet-cedar-spec-00.txt, October 1998.

Work in progress. [27] Martha Steenstrup, “Routing in communication networks”. New Jersey, Prentice Hall. ISBN 0-13010752-2. [28] Jerry Svedlund and Johan Kopman, “Routing protocols in types of thesis, wireless ad-hoc networks - An implementation study”. Uppsala: Uppsala University. Master thesis. [29] D. L. Mla Citing! Tennenhouse and D. Wetherall, “Towards an active network architecture”. In Multimedia Computing and methodology Networking 96, San Jose, CA, Jan 1996. [30] The CMU Monarch Project. “The CMU Monarch Projects Wireless and Mobility Extensions to book reports, ns”. Of Thesis! URL: (1998-11-29).

Work in progress. Egypt! 72 Appendix A -Terminology This appendix contains some terminology [21] that is related to ad-hoc networks. A.1 General terms Bandwidth: Total link capacity of a link to carry information (typically bits). Channel: The physical medium is divided into logical channel, allowing possibly shared uses of the types of thesis methodology medium. Topics! Channels may be made available by subdividing the medium into distinct time slots, distinct spectral bands, or decorrelated coding sequences. Convergence: The process of approaching a state of of thesis methodology equilibrium in which all nodes in the network agree on a consistent state about the rotc topics topology of the types network.

Flooding: The process of delivering data or control messages to every node within the any data network. Essay! Host: Any node that is not a router. Interface: A nodes attachment to types, a link. Link: A communication facility or medium over which nodes can communicate at the link layer. Loop free: A path taken by a packet never transits the same intermediate node twice before arrival at the destination. MAC-layer address: An address (sometimes called the link address) associated with the custom essay order link interface of a node on a physical link. Next hop: A neighbor, which has been designated to forward packets along the types of thesis way to a particular destination. Neighbor: A node that is within transmitter range from another node on the same channel. Node: A device that implements IP.

Node ID: Unique identifier that identifies a particular node. Router: A node that forwards IP packets not explicitly addressed to itself. In case of ad-hoc networks, all nodes are at least unicast routers. Routing table: The table where the routing protocols keep routing information for egypt reports, various destinations. This information can include nexthop and the number of hops to the destination. Types! Scalability: A protocol is scalable if it is write applicable to large as well as small populations. Source route: A route from the source to the destination made available by the source. Of Thesis! Throughput: The amount of data from rsvp write a source to a destination processed by the protocol for which throughput is to be measured for instance, IP, TCP, or the MAC protocol. 73 A.2 Ad-hoc related terms Ad-hoc: For this special or temporary purpose or a special case without generic support. AODV: Ad-Hoc On-Demand Distance Vector.

Routing protocol for wireless ad-hoc networks. Asymmetric: A link with transmission characteristics that are different of the transmitter and receiver. For instance, the range of one transmitter may be much higher than the range of types of thesis another transmitter on the same medium. The transmission between the two hosts will therefore not work equally well in both directions. Historical Fiction Book Report! See also symmetric. Types Of Thesis Methodology! Beacon: Control message issued by how to write report australia a node informing other nodes in its neighborhood of its continuing presence. Bi-directional: see symmetric. CBRP: Cluster Based Routing Protocol. Routing protocol for wireless ad-hoc networks.

Cluster: A group of nodes typically in range of each other, where one of the nodes is elected as the cluster head. The cluster head ID identifies the cluster. Each node in the network knows its corresponding cluster head(s) and therefore knows which cluster(s) it belongs to. DSDV: Dynamic Sequenced Distance Vector. Types Of Thesis Methodology! Routing protocol for wireless Ad Hoc networks. DSR: Dynamic Source Routing. Routing protocol for wireless Ad Hoc networks. Proactive: Tries to in essay quotes, maintain the routing map for the whole network all the time.

See also reactive. Reactive: Calculates route only upon receiving a specific request. Types Of Thesis Methodology! See also proactive RREQ: Routing Request. A message used by AODV for egypt, the purpose of types of thesis discovering new routes to a destination node. Write A Scientific Report Australia! RREP: Route Reply. A message used by methodology AODV to reply to route requests. Symmetric: Transmission between two hosts works equally well in both directions.

See also asymmetric. TORA: Temporally Ordered Routing Algorithm. Routing protocol for wireless ad-hoc networks. Unidirectional: see asymmetric. ZRP: Zone Routing Protocol. Routing protocol for wireless ad-hoc networks. 74 Appendix B - AODV implementation for ns This appendix contains a little more details about the implementation of AODV that we did for ns. The implementation of AODV is in essay quotes done according to the draft [19] released in August 1998. B.1 Message formats AODV have four different messages that it uses for of thesis methodology, route discovery and mla citing quotes route maintenance.

All messages are sent using UDP. B.1.1 Route Request – RREQ The format of the of thesis route request message is shown in Figure 29. Custom Essay! 0 1 2 31 01234567890123456789012345678901 Type[8] Reserved[16] Hop count[8] Broadcast ID[32] Destination IP address[32] Destination Sequence Number[32] Source IP address[32] Source Sequence Number[32] Figure 29: N N N N N N N N Route request format. Type: Type of types methodology message. Reserved: Reserved for future use. Currently sent as 0 and ignored on reception. Hop count: Number of hops from the source IP address to the node handling the request. Broadcast ID: A sequence number identifying the particular request uniquely when taken in conjunction with the source nodes IP address.

Destination IP address: IP address of the destination for which a route is required. In Essay! Destination sequence number: The last sequence number received in the past by the source for any route towards the types of thesis destination. Source IP address: IP address of the custom order node that originated the request. Source sequence number: Current sequence number for route information generated by the source of the of thesis methodology route request. 75 B.1.2 Route Reply - RREP The format of the historical fiction book report high route reply message is shown in Figure 30. 0 1 2 31 01234567890123456789012345678901 Type[8] L Reserved[16] Hop count[8] Destination IP address[32] Destination Sequence Number[32] Lifetime[32] Figure 30: N N N N N N N Route reply format. Type: Type of message. L: If the L-bit is set the message is a hello message and contains a list of the nodes neighbors. Reserved: Reserved for future use. Currently sent as 0 and ignored on reception. Hop count: Number of types of thesis hops from the source IP address to the destination IP address.

Destination IP address: IP address of the historical fiction report high school destination for methodology, which a route is supplied. Destination sequence number: The destination sequence number associated to the route. Fiction Book! Lifetime: Time for which nodes receiving the Reply consider the types of thesis methodology route to in essay quotes, be valid. B.1.3 Hello Hello messages are a special case of Route reply messages. The difference is methodology that a hello message always supplies the route to how to write a scientific report australia, itself. This means that the hop count field is set to 0, the destination address set to the nodes IP address and the destination sequence number set to the nodes latest sequence number.

B.1.4 Link failure Link failure messages are also special Route reply messages, but in types methodology, this case the custom essay destination reflects the route that has broken. The broken route is assigned an infinite hop count and a sequence number that is increased with one. 76 B.2 Design Figure 31 shows how AODV was designed when implemented for ns. AODV OTcl C++ AODV_Agent Hdr_AODV Request Buffer Figure 31: AODV_RTable AODVConstants AODV design of implementation for simulator. AODV The tcl script that starts the AODV routing agent and creates all mobile nodes that are using AODV as routing protocol. AODV_Agent Implements all AODV specific parts.

Handles RREQ, RREP, Hello and Triggered RREP. It also has a send buffer that buffers packets while a route is searched for. The timers that handles timeouts on route entries and the send buffer are also implemented here. Hdr_AODV Defines the message format for all messages that AODV uses. Request Buffer Implements the methodology request buffer that prevents a node to process the same RREQ multiple times. AODV_RTable The routing table that AODV uses. The routing table also implements the active neighbor list for each route entry. AODVConstants All AODV constants are defined here, which makes it easy to modify for instance the high hello interval. 77 B.3 Important routines B.3.1 Sending RREQ RREQ will only be sent by types of thesis the source nodes (no intermediate nodes sends RREQs), if there does not exist any route for the destination. Custom Order! 1. 2. 3. 4. 5. Types Of Thesis! 6. 7. 8. 9. 10. 11.

12. B.3.2 if ( no route exists ) else Receiving RREQ When a node receives a RREQ, it must first of all decide if it already has processed the RREQ. The RREQ is discarded if it has been processed. Otherwise the source address and the broadcast ID from essay topics RREQ will be buffered to prevent it from being processed again. 1. Methodology! 2. 3. 4. 5. Essay! if ( (source addr, broadcast ID) in request buffer ) else The next step is to create or update the route entry in the routing table. This route can be used by types of thesis methodology the RREP when a route is found.

1. 2. 3. Rsvp How To! 4. 5. 6. 7. 8. if ( no route to source addr ) elseif ( source seqno in RREQ source seqno in route entry ) elseif ((source seqno in of thesis methodology, RREQ = source seqno in route entry) AND ( hop count in RREQ hop count in egypt reports, route entry )) Then, the methodology node must check if it knows the route to the wanted destination. If the node knows the route it will unicast a RREP to the source. Otherwise it will forward the RREQ. 1. 2. 3. 4. 5. 6. Rsvp! 7. 8. Of Thesis! 9. 10. if ( you are destination of RREQ ) elseif (( have route to destination ) AND (destination seqno in route entry = destination seqno in mla citing in essay, RREQ)) else 78 B.3.3 Forwarding RREQ When a node receiving a RREQ that it has not processed yet does not have a route, it will forward the RREQ. 1. 2. Types Of Thesis Methodology! 3. 4. 5. create a RREQ packet: copy all fields from received RREQ into new packet increment hop count field locally broadcast new RREQ packet discard received RREQ B.3.4 Forwarding RREP When a node receives a RREP that is write a scientific report australia not addressed for the node, it will set up the forward route by types of thesis updating the routing table and forward the RREP back to the requesting source. This part is however not explicit specified in the AODV draft. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

13. if ( route to requested destination does not exist ) elseif(destination seqno in RREP destination seqno in route entry) elseif ((destination seqno in mla citing in essay quotes, RREP = destination seqno in route entry ) AND ( hop count in RREP hop count in entry )) if (route to types of thesis methodology, requesting source exists) B.3.5 Receiving RREP When the originating source receives the RREP it will update the routing table. 1. 2. A Scientific Report Australia! 3. 4. 5. 5. 6. 7. 8. 9. 10. Of Thesis! 11. if (route to destination does not exist) elseif (destination seqno in RREP destination seqno in route entry) elseif (( destination seqno in RREP = destination seqno in route entry ) AND (hop count in RREP hop count in entry )) else 79 B.3.6 Hello handling Each node periodically broadcasts a hello message to rsvp how to, all neighbors. When a node receives a hello message it knows that the sending node is a neighbor and will update the routing table. 1. Types Methodology! 2. 3. 4. Mla Citing In Essay Quotes! 5. 6. 7. 8. 9. B.3.7 if (route entry for HELLO source exists) else Forwarding packets AODV uses a active neighbor list to keep track of types of thesis methodology which neighbors that are using a particular route. These lists are used when sending triggered route replies. The neighbor lists are updated every time a packet is forwarded. 1. How To! 2. 3. 4. Of Thesis Methodology! 5. 6. B.3.8 if (route entry to write a scientific, destination exists) Sending Triggered RREP Link breakages are detected by either the of thesis methodology link layer which notifies the routing agent or by using hello messages. If a node has not received hello messages from a node for a certain amount of time it will assume that the link is down. Every time a link is fiction detected as down, AODV will send a Triggered RREP to inform the affected sources. 1. 2. Types Of Thesis Methodology! 3. 4. B.3.9 for write a scientific, (each address in the active neighbor list for a route entry) Receiving Triggered RREP Every time a Triggered RREP is received informing about a broken link, the affected route entry must be deleted and neighbors using this entry must be informed.

1. Methodology! 2. 3. 4. if (have active neighbors for broken route) delete route entry for broken route 80 Appendix C -Simulator screenshots This appendix shows some screenshots of Network animator and Ad-hockey. Network animator is the visualization tool for ns and historical book report Ad-hockey is the visualization for the mobility extension developed by the CMU Monarch project. Types Of Thesis! C.1 Network animator Figure 32 shows a screenshot of Network animator. The scenario contains 19 nodes in book report high, a wired network. Some of the types of thesis nodes are sending packets, which also can be seen in the figure. With this tool it is report very easy to trace packets as they propagate through the network. The circles represent the types of thesis nodes and the lines between the circles are the physical wired links that connect the nodes with each other. Figure 32: Screenshot – Network animator. 81 C.2 Ad-hockey The screenshots of Ad-hockey that can be seen in Figure 33, Figure 34 and Figure 35 shows the playback trace of the realistic scenarios that with did simulations on.

The big white rectangle in essay topics, the middle is the movement area. The different colored circles are the nodes. The colors of the nodes represent what action the nodes are performing at the moment. It could for instance be that the types of thesis node is sending, forwarding or receiving a packet. The lines between the nodes do not represent wired links. The lines are actually packets that propagate from node to node. Egypt Book! The detached rectangles and lines that also can be seen within the types methodology movement area are obstacles. Figure 33: Screenshot – Ad-hockey – Conference scenario. 82 Figure 34: Screenshot – Ad-hockey – Event coverage scenario. How To Report! Figure 35: Screenshot – Ad-hockey – Disaster area. 83 . TERM Spring #039;00 PROFESSOR Hesham TAGS Computer network, . routing protocol, ad-hoc network.

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Nietzsche’s Critique of Morality essay. Friedrich Nietzsche was a renowned German philosopher who lived in the late 19 th century. Of Thesis Methodology. His extensive studies, arguments and counterarguments on morality and ethics are a source of inspiration and the subject of extensive studies. However, he has attracted an equal measure of controversy and criticism. He was born in egypt book reports the city of Leipzig and types methodology, raised under strict Lutheran Church principles. However, views presented in his studies suggest that he was in opposition to rotc topics the Occident which is types of thesis methodology regarded as the core of Christian and Platonic origin and teachings. Therefore, it is with a palpable degree of irony that his philosophies negate the stout principles which guided him during his childhood. This research paper shall explore Nietzsche’s critique of Christian morality and establish whether his claim is justifiable.

Overview: Nietzsche’s Approach to Morality. Nietzsche, in his studies on morality, emphasized the difference between philosophical laborers and true philosophers. Philosophical laborers are bent on rewriting history in an attempt to justify their beliefs or moral concepts. Nietzsche depicted such people as liars and manipulators who were driven by selfish, self-fulfilling objectives. Egypt Reports. They created an authoritative, seemingly-real past in order to support their abstract ideas. Conversely, genuine philosophers exhaust all past events and methodology, facts in a subjective, broad-minded and creative manner in order to predict mankind’s future. Thus, they attempt to uncover the truth and historical book high school, create a new, virtuous perspective beneficial to all mankind.

Nietzsche regarded Plato as a genuine philosopher. However, he felt that over the centuries, Plato’s philosophies had been manipulated in order to suit philosophical laborers’ presumptions and their fear of the universe’s randomness and futility. Therefore, genuine philosophers were charged with the responsibility of reconstructing Platonian principles and the creation of a new platform for evaluating morality. Under this new and creative platform, an individual must develop personal moralities. This is types of thesis evidenced by report, his rejection of Platonic-Christian dogmatism, more so amongst the youth. Types Methodology. Nietzsche insisted that mainstream Christian churches held a dogmatic approach towards the truth; a perspective that was subjectively nihilistic (Nietzsche, 2003, 114). Therefore, Nietzsche sought to rotc topics establish that reality is never in a constant state of of thesis methodology, flux; rather, it is dynamic and always in a transient state. Slave Morality versus Master Morality.

Nietzsche’s critique of historical fiction book high, Western/Christian principles on types, morality is manifested in his description of the master-slave morality concept which he referred to as ‘ressentiment.’ He imagined that at how to report australia the onset of civilization, proto-humans (people who existed in types of thesis the early ages) had a beastly consciousness. Thus, their actions were based on how to write, random internal drives and basic, desire-ridden impulses. With the advent of civilization and the passage of types of thesis, time, people were divided into two major strata: the master race and the slave race. Whereas the master race was the minority, they were intellectually gifted. Historical Fiction Report High. Hence, they managed to subdue the slave race. Over a lengthy period of dominance, the slave race underwent radical intellectual changes because they were redirected by their masters from acting merely on the basis of their natural instincts.

The master race was very oppressive. Therefore, the slave race developed a deep hatred and a culture of resentment towards them. Of Thesis. Arguably, over time, they developed a ‘bad’ conscience. How To A Scientific Report Australia. The need to types of thesis methodology find someone or something to blame for this ‘bad’ conscience led to the emergence of a social-construction figure that slaves could identify as the root of all evil: the demon. Topics. Consequently, out of fear of of thesis methodology, this evil figure, there emerged a need for a supreme, protective being: God. Thus, Nietzsche argues that God, the holiest, divine and supreme Christian being, is an imaginary social construct and the product of a need for historical fiction, protection originally due to the slaves’ deep ‘ressentiment’ for their masters. Hence, Nietzsche feels that Christianity is the types ‘greatest curse’ and is a fruit of one’s ‘innermost corruption’ and ‘instinct for revenge.’ To him, it is mankind’s ‘immortal blemish’ (Kennedy, 2010, 4-5). Nietzsche is in essay objection to the herd morality concept because it places value to what he feels is pointless and futile. Thus, its pursuance is for the benefit of ‘lower’ men (comparable to slaves) and not ‘higher’ men (masters). He argues that if values practiced by particular individuals are deemed as favorable and successful, then this will lead others towards adopting similar values. Eventually, this shall create a herd-like populace.

Therefore, it is not a principle which man should embrace. Nietzsche’s concept of the herd morality is of thesis methodology a refinement of his slave morality theory. In fact, various notions in the slave morality perspective have been refined and represented in a more coherent manner. First, the custom order deep fear possessed by slaves is represented as humility. Secondly, impotence is regarded as the heart’s power of types methodology, goodness. Thirdly, cowardice and submission are referred to as patience and obedience respectively. Moreover, the inability to take revenge is presented as the willingness to forgive. Finally, the desire to seek revenge is presented as one’s desire for how to write a scientific, justice. Therefore, Nietzsche creates a contrast between principles of morality. For instance, there is a contrast between happiness and suffering, self-love in types methodology opposition to altruism, equality versus social injustices and the contentment of the soul versus satisfaction of the body’s desires.

Nietzsche regarded morality and its inherent values as pointless and historical fiction report high school, of no consequence. In fact, they are impediments to the attainment of glory and greatness. In order to achieve this, one must undergo great suffering, injustices, danger and self-sacrifice. It is in stark contrast to the interests manifested by the majority and thus negates herd morality. Whereas an individual’s well-being ensures that people are submissive and of thesis methodology, modest, greatness demands an utter neglect of these principles. Nietzsche criticizes this principle and refers to it as both shrewd and absurd. Whereas it provides a basis via which people who do not have a strong will can control their instinctive drives and emotions, it is restrictive towards the development of great individuals. As the heard morality took center stage, it lost its ascetic ideal due to the fact that it drives an individual towards happiness and contentment in how to write report this world rather than suffering in types of thesis methodology this world and achieving redemption and greatness in the next. Hence, this morality concept has led to rsvp how to write the deterioration and compromise in of thesis methodology the heights that man could have soared to in the past. Therefore, Christianity has fostered a mediocre, uninspired population.

Nietzsche’s Critique of Christian Morality. Nietzsche regarded ‘ressentiment’ as toxic to the attainment of greatness, heroism and pride. Its inclusion in the Occident as the founding pillar of Christianity implies that Christians embrace ‘weaker’ values which are extolled as desirable virtues. ‘Ressentiment’ drove early-age populations towards a need to obtain power and seek revenge. However, this was achieved through evaluation of egypt reports, principles and underlying values instead of attaining greatness. Types Of Thesis. Nietzsche aptly illustrates that Jews, in an attempt to get rid of the master-slave relationship, rejected the report high conventional ‘aristocratic value equation (good=aristocratic=powerful=beautiful=happy=loved by the gods)’ in favor of the adoption of values that depict suffering, poverty, submission and powerlessness as desirable aspects. These ‘lowly’ people would achieve salvation in their next life. However, ‘the rich noble and powerful’ were depicted as ‘eternally wicked, cruel, lustful, insatiate, godless, cursed and damned’ (Nietszche, 2003, 17).

Therefore, by a misrepresentation of these values, Jews managed to overthrow their masters, take their long awaited revenge and eternally seize power. Hence, according to types of thesis methodology Nietzsche, Jesus Christ was not an essay ultimate figure representing forgiveness, humbleness and of thesis, love but a climax of the campaign against oppression. On the other hand, he referred to reports nobleness as ‘a positive basic concept’ which ‘affirmed itself gratefully and triumphantly.’ This signified his disdain for Christian moral concepts which advocate for submissiveness, humility and leading a lowly life. He refers to himself and others like him as ‘we noble ones; we good, beautiful, happy ones’ implying that they are the indisputable masters and that Christian morals were merely a revolt against the master’s yoke (Nietzsche, 2003, 19-20). An analysis of Nietzsche’s work reveals that there are specific Christian traits that he is totally in opposition to. These are the representation of Christian concepts as unconditionally valid, the formulation of morality principles based on ‘ressentiment,’ the notion of ‘free will’ which depicts individuals as independent from of thesis their actions, and the ‘ascetic ideal.’ Thus, Nietzsche proposes that philosophers should come up with new values that aptly describe Plato’s underlying values. However, this proposition has been heavily criticized, more so due to the fact that he does not propose these values.

Hence, in spite of having a valid criticism of Christianity as an abstract form resultant from ‘ressentiment’ his concepts can never be implemented on report high, a practical basis due to several reasons. First, the Platonic-Christian scheme is all-pervasive within world cultures. Thus, there is no suitable context within which his ideas can be accepted and nurtured. Types Methodology. Nietzsche made a fundamental mistake in assuming that all philosophers can be swayed to accept his theories on morality as logically formulated thus rejecting the underlying Christian ethos as the basis of morality. His perspectives on morality and egypt reports, ethics sought to establish the types of thesis methodology harm accruing to people as a result of adopting the status quo. For instance, he depicted the virtues practiced under Christianity as hampering the emergence of great, noble people who would control the masses.

Nonetheless, having presented a viable and logical perspective, he failed to establish how his concepts could be applied (a presupposed ethos). Secondly, Nietzsche’s approaches in certain meta-ethical discourses are misleading and fail to interpret the teachings in their context. In his pursuance of a rational standpoint on morality, he seeks to establish that God is non-existent and that He is an abstract being born out of human fear and how to write, need for types methodology, protection. For instance, Jesus Christ insisted that His followers must love their neighbors. This teaching cannot be evaluated on a meta-ethical level but should be interpreted in its context depending on a particular situation.

Nietzsche’s perspectives depict the fact that human minds are very creative. In addition, they present a guard against a dogmatic discourse. Critics feel that Nietzsche’s work was an attempt at presenting his own understanding of the world. Custom Essay. This was greatly hampered by his limited experience of types of thesis methodology, morality and its inherent virtues. In Essay. Arguably, Christianity is a highly transferable religion. This is one of the major reasons why it has been passed from one generation to another (Hebrews, Hellenistic monarchists, the Roman Empire and other past kingdoms) for such a long period of time (Kennedy, 2010, 6). Types Methodology. Therefore, Christianity accommodates multiple viewpoints and cultures, a fact that Nietzsche completely ignores perhaps due to the fact that he was raised in a stifling and rsvp, oppressive society which limited his experiences on morality.

Thirdly, there has been a raging debate as to whether Nietzsche’s philosophies were the foundation of Nazism. In his studies, he places profound importance on the concept of humanism. Methodology. His hierarchical approach places humanity at how to write the top and disregards all notions indicative of the existence of God or nature’s superiority. Therefore, no man is bound to worship or revere a divine being; rather, he places authority on the hands of a few elites (masters). He is in favor of a master morality approach in contrast to the Judean-Christian approach manifested in slave morality. Nazism was founded on a need to control based on the self-belief that some people were supreme. However, it is absolutely important to differentiate superiority and supremacy. Nietzsche’s philosophies emphasize that a master race controls the types slave race because of custom, their intelligence (excellence). This concept is depicted by the ubermensch (‘over-man’), a superman who is superior, great and heroic. Although Nietzsche does not aptly describe this heroic figure and most of the desirable attributes are a result of the reader’s imagination, this is a dominant figure in his studies. His contrast of the ‘over-man’ versus the ‘last-man’ presents a clear picture of the heroic superman.

Whereas ‘over-man’ is described as ‘he will be to men what men are to of thesis apes, ‘last man’ is described as a person who is of no service to fellow man and is incapable of fathering children. Hence, ‘over-man’ represents an how to report australia evolutionary leap which justifies his superior status beyond other men. Nonetheless, his philosophies are naïve and types methodology, could be ultimately potent if misinterpreted by people in historical fiction report high positions of power (Kennedy, 2003, 8-10). Nietzsche’s approach presents a concrete platform for types of thesis methodology, the evaluation of the Christian morals and egypt book reports, principles. He convinces the types reader that Christianity is a massive cover-up of the underlying truth. Therefore, one is subjected towards finding new values and a new ethos (basis) as the write foundation of morality. However, Nietzsche’s philosophies fail in types helping the reader establish a new basis. It is quite surprising that Nietzsche did not establish a new, practical ethos as a foundation of rotc essay topics, his beliefs on morality.

Therefore, Nietzsche’s philosophies are neither justifiable nor practical.

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6 Punctuation Tips For A Sexier Resume. #1 Thing Recruiters Want You To Know About Getting A Job AppDynamics. How To Land A Job At Northside Hospital. 3 Tips For Getting A Job At Medidata Solutions. The Secret To Networking When You Don#039;t Have Any Time. 3 Ways Emotionally Intelligent Leaders Make The Most Of Online Collaboration. You want a resume, cover letter, and LinkedIn profile that presents you in the best possible light. Of Thesis Methodology! With all of the school, emphasis on of thesis methodology, loading your documents with keywords, accomplishments, and custom order, metrics that make the case for you being the perfect fit for the position you’re after, have you overlooked proper punctuation? Some might wonder what the methodology, big deal is rotc topics about punctuation. Surely if you start your sentences with a capital letter and methodology, end them with a period, that’s all you need to worry about, right? Unfortunately not.

The text in career documents is often so packed with information that seemingly inconsequential punctuation missteps can distort your meaning, or worse: cause the how to write a scientific report australia, reviewer to pause in confusion. Types Of Thesis Methodology! That pause is bad news for you: it may make the reviewer see you as a less-than-attractive candidate, questioning your ability to quotes communicate or pay attention to details, both highly valued skills in today’s workplace. Just as a modern spouse becomes more alluring to types of thesis a partner by doing the dishes and laundry, using proper punctuation makes you downright sexy to a hiring manager. Both efforts make lives easier for the people who are important to essay topics you, so go the extra mile by following these important rules (and do the types of thesis, dishes): In addition to appearing at mla citing the beginning of sentences and in types section headings, capital letters also signify important words. But using too many “important words” in your documents slows the reader down or seems pretentious. For example, I sometimes see text like this in resumes: “Expertise in Human Resources, Training, and rsvp, Recruiting” Try: “Expertise in human resources, training, recruiting” instead. Of Thesis Methodology! Other than proper names like your own name or the names of how to write products, you will rarely need to capitalize words that don’t appear at the beginning of types methodology a line or sentence.

You’ll also want to capitalize your own job title above each position listed on custom essay, your resume. However, if you reference someone else’s job title in your career documents, the types of thesis, general rule is egypt reports that it is of thesis methodology only capitalized when the person#8217;s name follows (Vice President Joe Smith) not when merely referring to the position (as in “reporting to the vice president”). Of course, every rule tends to have its exceptions, and there are a few for capitalization. However, these are good to start with. Use hyphens for compound adjectives that precede a noun, such as “client-focused approach” or “full-time employees.” And if you have two adjectives that modify the historical fiction report high school, same base word, use a hyphen after the first, as in types “mid- and senior-level management.” Do not use a hyphen in a compound adjective if the first word ends in –ly, as in “highly qualified candidate.” Semicolons can either separate two independent clauses when the second clause is not directly related to the first, or they can be useful when you want to book reports list items that already include a comma. For example, “Proficient in software including Microsoft Excel, Word, and PowerPoint; CorelDRAW; and Adobe Photoshop.” Colons are used to join two independent clauses when the of thesis, second clause is directly related to the first. The most common usage in career documents is for rotc essay, lists, as in “Proficient in the following software: MS Excel, Word, and PowerPoint.” There’s fierce debate between those who advocate using serial commas (putting a comma before the final “and” in types a series) and those who don’t. Historical Report School! The best practice for types of thesis, resumes is to use serial commas, as they can really make your career documents easier to understand.

This is especially true when you list series of items where two things may be grouped together (think: sales and marketing). But even sentence construction like “Facilitate mock interviews, identify position and tailor interview questions” may cause the reader to stumble. At first read, it may sound like the egypt reports, candidate is responsible for identifying a position and identifying someone who tailors clothes! So my advice is to avoid ambiguity by always using serial commas in career documents. The current convention is to use one space after a period, not two. Same goes for of thesis methodology, colons. I know, I know. If you grew up learning to type on an IBM Selectric, back in the stone ages like I did, this is a hard habit to break. Rotc Essay! But, if you keep using two spaces, you’ll look as antiquated as the typewriter.

Trust me, knowing these six punctuation tips will make you a real turn on to an employer. Now that you’ve reviewed some of the punctuation rules that you’ll want to be aware of, I’ll share the most important rule of all: however, you choose to use punctuation throughout your career documents, do it consistently! Even more jarring than not following proper punctuation rules is following them only some of the time. Of course, these rules may change depending on the document you may be writing. Or, if you have a profession (like journalists do) that demands adherence to a specific style guide, like AP, Gregg, or Chicago#8230; Hot, I know. ;-) For a more in-depth look at punctuation, I recommend checking out Susan Whitcomb’s book Resume Magic . Of Thesis! It’s a great resource for every aspect of preparing your resume, and has a particularly good section on punctuation. And, if you’d like to see resumes with some real sex appeal, check out my samples on This post was originally published on an earlier date. Essay Order! Kristin S. Johnson is a TORI award-winning, 6-times certified resume writer, job search coach, and methodology, social media consultant. Her approach is egypt cutting-edge, creative, and kind.

As owner of Profession Direction, LLC, she works with professionals and aspiring executives across the types of thesis methodology, country. Disclosure: This post is sponsored by a CAREEREALISM-approved expert. You can learn more about egypt expert posts here .

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Ezra Pound Pound, Ezra (Vol. Of Thesis! 1) - Essay. A major American poet, now living in Italy, Pound will be remembered for a scientific report, his Cantos and for his influence on, and assistance given to, innumerable English-language writers. He has also written prose and has done translations. (See also Contemporary Authors , Vols. 5-8, rev. ed.) Ezra Pound could be a beautiful poet, in methodology dribs and drabs of isolated lyric pieces. His real gift is for pastiche. He has imitated the Greeks, the essay topics Chinese, and finally his own youth. But he has always been obsessed; for a number of years he was clearly insane, and what makes him puzzling—if you really look into him—is his manic oscillation between savagery and tenderness, between real insight and phony scholarship. Any man of good will must be divided about Pound. For myself, surrounded as I am by inexpungible memories of the millions of dead, I cannot think of the purely literary case made out for Pound without horror.

Alfred Kazin, The Youngest Man Who Ever Was (1959), in his Contemporaries (© 1958, 1959, 1960, 1961 by Alfred Kazin; reprinted by of thesis permission of Atlantic-Little, Brown Co.), Atlantic-Little, Brown, 1962, pp. 113-18 . Excitement attends almost all Ezra Pound's prose and historical book report school, poetry—the excitement of the man himself, his urgency and cantankerousness and virtuosity. Also, he has authority . In part this is the irritating authority of the types of thesis methodology self-appointed leader, yet it is indisputable. Topics! One sees it in the reminiscences of types of thesis, his oldest friends, still full of mingled admiration and resentment. 'An uncomfortably tensed, nervously straining, jerky, reddish brown young American,' says Wyndham Lewis, describing Pound's arrival in London in his mid-twenties. 'He had no wish to mix ; he just wanted to impress .' For the historical fiction book school British, as for his own countrymen, he was 'an unassimilable and aggressive stranger.' Still, the authority was there despite the types methodology hostile response; he stood for essay topics, the most rigorous poetic dedication, and the best writers were likely to recognize this fact…. Pound's experiments with translation added enormously to the authority of types, his tone and style. Write Report Australia! From the start translation afforded him the chance to sink himself into the poetry of the past and of other languages and societies. Responsive to tone and methodology, nuance, he could recover the sensibilities of others and find a voice for himself through them. His translations have the same basic virtue as his other poetry: intuitive grasp of the shape and quotes, emotional essence of his subject…. From the types early poems, translations, and adaptations, we can see that the vast excitement of Pound's work is rooted not only in his own personality and abilities but in those artistic and intellectual revolutions which marked the first third of this century.

He is the poet of new beginnings, of released energies, of vast curiosity cutting across cultural barriers. Custom! And tragically, the psychological symptoms of prolonged social crisis, that crisis which culminated in two wars as well as in the Fascist system he has defended, have found expression through him also. He is an epitome of a paradoxical era: a fighter for creative freedom and sanity who found himself, in old age, committed to a mental hospital…. Published in 'installments,' as it were, since 1919, the Cantos has been a gigantic experiment of a new kind, its growth in time essential to its very nature. Each of its larger units extends our range of consciousness concerning the relevance of the central perspective: a universal sensibility gauging the depravity of a usury-ridden world and setting against it the ideals of rational thought, rational economic practices ('rational' in the view of such Social Credit thinkers as Douglas, Gesell, and Pound), and a 'pagan' aestheticism. As each unit is developed, it recapitulates the root-themes in a new context; ordinarily the refocusing is not at first clear to the reader, but the types methodology pattern does emerge. M. L. Mla Citing Quotes! Rosenthal, Ezra Pound: The Poet as Hero (© 1960 by M. L. Rosenthal; reprinted by permission of Oxford University Press, Inc.), in his The Modern Poets: A Critical Introduction, Oxford University Press, 1960, pp. 49-74 . There is … a great deal of of thesis, misunderstanding about Pound, and perhaps even misrepresentation…. The earliest prose, for example the fiction book fine study of Henry James, is perceptive and cogent, and the poetry written during the same period, mostly before World War I, is often carefully wrought and subtle. But even then, in the poetry, one is never wholly certain which of the Pound voices is the real Pound. Pound the lyricist is most frequently in view, and it is in his lyricism that he has had his greatest success.

This is best exhibited, perhaps, in the early Cantos . It appears intermittently, sometimes in explosive flashes, in the later Cantos , but usually the lyricism is not sustained; in its place one finds anecdotes, cryptic and gnomic utterances, dirty jokes, obscenities of various sorts, and a harsh insistence on the importance to culture of types of thesis, certain political leaders and economists. The majority of Pound's critics find the Cantos his most important literary contribution. Reports! Various efforts have been made to say what they are about. Perhaps the easiest way of getting at their subject matter is to say they are about Pound's reactions to his own reading, of Homer, Ovid, or Remy de Gourmont, of various economists and political leaders, and Pound's own literary recollections, usually memories of London or Paris. As the years went by, Pound became less interested in literature than in economics, although he continued to express literary interests in the Cantos , and his interest in translating from types Greek and Latin remained fairly constant. (p. 7)

Pound is not especially imaginative in creating the substance of his own poems. In Essay Quotes! His gift is verbal, and he is at his best when using another poet's substance for his own purposes. In the Cantos ,… he is types not quite a translator, but he does rely on in essay quotes, the substance of earlier poems. Types Of Thesis! (p. 18) Pound is commonly seen as one who explained, justified, and rationalized the modernist idiom in mla citing quotes poetry.

All this is true. He has also written in that idiom. But at his best, as in occasional passages in the Cantos , he is a lyricist in the company of Herrick, Waller, or Ben Jonson, though certainly of a lesser order. His translations from Chinese poetry have a similar lyric quality. The River Merchant's Wife: A Letter, written in a subdued tone, is as beautiful as any poem in the Pound canon. (p. 19) Rhythms in music and types of thesis, poetry were a fairly constant preoccupation with Pound. Rhythm, he said, determines pitch and melody; pitch depends on the frequency with which sounds strike the ear; variations in mla citing pitch control melody. In poetry, he continued, the frequency of vowel or consonant sounds produces pitch; a changed frequency makes for higher or lower sound, and variation produces the methodology melody of a line. (p. 21) His commitment to mla citing quotes, Imagism and Vorticism was complicated by his interest in Chinese poetry and the Japanese Noh.

Pound also theorized about the relationship between music (in the British Who's Who he identified himself as poet and types of thesis, composer) and rotc, the conversational or prose line…. The city, the automobile, and social life did not deeply engage him. There is a sense then in which Pound is not a modernist poet. Or perhaps one should say he was a modernist only briefly. Pound has a pantheon of writers who helped sustain his vision of the world as it ought to be, and more and more he turned to them. (pp. 25-6)

In the types of thesis Cantos , as the years pass, there is an order increasing dependence on violence and shock, on obscenities and scatological descriptions. Worse, there is an airy indifference when Pound mentions genocide or mass suffering. (p. 42) William Van O'Connor, in his Ezra Pound (University of Minnesota Pamphlets on American Writers, No. 26), University of Minnesota Press, © 1963 (and in Dictionary of American Literary Biography, Scribner's, © 1973) . The classic defence of The Cantos as a unity must always depend upon an unquestioning acceptance of Pound's own critical theory—upon the contention that Pound is exploiting a new, or at least unfamiliar principle of types of thesis, construction—what Pound himself called the book ideogrammic method. Imagist poetry had required the poem to be a hard, clear and complete thing which presents not simply the outward fact, but with that fact creates and communicates an inward experience. Pound's theory proposes the use of these single images in types a syntactical sequence analogous … to how to, Eisenstein's use of the single shot in the montage syntax of the film.

Both developed their theories by analogy with Oriental writing systems, and in both cases the analogy was wrong—which is, of course, of no importance. What is methodology important is that both of mla citing quotes, these two great artists should be reacting in such very similar ways to the new problems of communication created by the twentieth century…. Pound regularly mistook his own total immersion in his material for the total involvement of his reader. Of Thesis Methodology! Only intermittently was he able 'To have gathered from the air a live tradition/or from a fine old eye the unconquered flame'. The rest is vanity. Rotc Essay Topics! Pound bullied his audience, but what is worse, he bullied the tradition too…. By instinct he was a reformer; he wanted to change society, to change people. His poetic theory was an attempt to direct poetry once more into of thesis an exploitation of the egypt book natural and methodology, instinctive patterns of man's experience and behaviour, and his final aim was to educate man into a proper understanding of himself and the world he had inherited. He aimed at a blend of the epic and the correspondence course in general culture…. [Nevertheless], paradoxically, it is to Pound more than anyone else that we owe our contemporary sense of the need for poetry to achieve universality. The very essence of his theory, like that of Eliot's, was that the poet and the poem should, as it were, be loci through which the fullness of how to write, a shared tradition shall manifest itself with new vigour….

The astonishing thing is that a poet who is so often silly as a thinker, and types of thesis methodology, whose emotional equipment is so unstable and unreliable, could ever have achieved the reputation of greatness. Rsvp How To! And yet he is a great poet, and his greatness is not just a matter of his much-vaunted technical excellence—another of the orthodoxies of the Pound enthusiast which needs some questioning…. Furthermore, the of thesis great successes of The Cantos , for fiction book school, instance the types of thesis methodology Pisan sequence, are achieved despite frequent technical failure, to say nothing of the frequent failures of tone and essay, taste which we have to types of thesis, learn to disregard if we are ever to get anywhere with The Cantos . David E. Rotc Topics! Ward, The Emperor's Clothes?, in Essays in Criticism, January, 1968, pp. 68-73 . [The] Cantos convey very clearly the power that has sustained Pound throughout his turbulent career: it lies, still, in the ultimate conviction that the poet is in some way the voice of a supernatural power running through the universe…. It is Pound's conception of a world in memory sustained within the mind of one man that makes the Cantos one of the types great poems in English. Pound calls it … his palimpsest, and indeed there is no better word to describe the effects of these, as of all the earlier Cantos. Pound's poems are a manuscript written over the faintly discernible words of others, a shifting, glittering, glimmering memory of creative achievement that gleams through the write a scientific australia ugliness of existence and makes what Pound … humorously calls a nice quiet paradise over of thesis methodology, the shambles—a paradise within the how to mind, holding together man's cultural achievements, retaining the old scripts, making them legible again. It is, of types of thesis, course, the romantic conception of mind that DeQuincey summed up when he said that the human brain was a natural and mighty palimpsest. How To Write! Deriving from Wordsworth's Prelude and Whitman's Leaves of types, Grass , Pound's Cantos pick up and sustain the cultures of the custom essay order world within the apprehension of an individual mind and pass them on types of thesis, to poets such as [Robert] Lowell. Louis L. Martz, in Yale Review (© 1970 by Yale University; reprinted by permission of the editors), Spring, 1970, pp.

262-63 . Ezra Pound's Cantos are cultural poems. They belong in the tradition of Walt Whitman which survives in the twentieth century in essay the poetry of Hart Crane and William Carlos Williams. Pound differs from a poet like Crane because he does not necessarily see individual reform as the answer to of thesis, external abuses. Crane bolts an iron suspension bridge to our hearts. Custom Order! Pound goes to the external forces themselves; he analyzes social institutions, recommends those he believes will serve as models for the future, and condemns those he believes will generate malignant effects. More than this, Pound writes as a poet-historian. His Cantos lay claim to the validity of historical scholarship.

They claim to be truthful presentations of actual historical events. Ron Baar, Ezra Pound: Poet as Historian (© 1971 by the Duke University Press), in American Literature, January, 1971, pp. 531-43 . [Pound's] spluttering and incandescent failure is worth more than most men's solid achievements. His romantic desire for the earthly beatitude which many artists are continually seeking: his poetry, perhaps, would be a torch lighting up a neglected pathway: as a recent poem declares, a rushlight to lead us back to types, splendour . William Dyson, The Fluctuations of Ezra Pound, in Books and reports, Bookmen, September, 1971, pp. 22-7 . [The] writing of the later Cantos represented for methodology, Pound a radical break with his past, almost a denial of the earlier mode. Erudite to the point of egypt book, pedantry, opaque, and generally incomprehensible except to the most dedicated literary archaeologists, the of thesis later Cantos kept away many who would have come to him quite naturally as a teacher. How To Write A Scientific Report! And so, of course, did the U.S. government, for during that crucial decade of change for methodology, poetry, the 1950s, Ezra Pound was tucked away in St.

Elizabeth's Hospital, a prisoner for fiction, his wartime follies…. Yet it may well have been more than Pound's inaccessibility that diminished his influence with the new generation of types, poets that was then struggling to be born. In a more devious way, it was probably because Ezra Pound, with his secure niche in historical book the literary history of the modern movement, was more academically respectable that his impact [on the Beats and others] was less than [William Carlos] Williams's. Bruce Cook, in types methodology his The Beat Generation (reprinted by permission of Charles Scribner's Sons from The Beat Generation by Bruce Cook; © 1971 Bruce Cook), Scribner's, 1971, p. 119 . Pound always made a great show of learning and a bold claim to authority. His major work, the rsvp Cantos , hints in its very title that it intends to rival the types of thesis methodology Comedy of Dante. It is nearly as polyglot as Joyce's Finnegans Wake . It contains sentences and phrases not only in poetic English and slang both American and Cockney, but in Chinese, ancient Greek, classical Latin, medieval Latin, French, Italian, Provencal, German, and jargons of various origin.

Several of his books bear titles in Latin and other tongues: Lustra, Personae, A Lume Spento …. His interest in Greek and Latin is not merely a pose. It is an rsvp essential part of his development as a poet. Of Thesis! He really loved the classics and believed in order them. But he would not take the trouble to understand them thoroughly…. An earnest reader, if he has no Greek and Latin himself, is pleasantly mystified and feels a vague admiration for a poet with so many languages and of thesis, echoes ringing in historical book report school his mind. Most of his commentators treat Pound's intellectual equipment with deference…. [and] readers seem to believe that Pound is a truly scholarly writer.

How deeply, how accurately, and how sensitively he knows other languages I cannot tell; but although he shows off his Greek and types, his Latin, his Latin is poor and how to, his Greek is contemptible…. He would not admit his deficiencies and types, cure them through humility and industry. Topics! Nor would he shun those areas where a display of ignorance might be damaging. Where others would turn their eyes away from the types methodology sanctuary, or else enter with quiet step and bowed head, Ezra Pound charged in, shouting and singing and hiccuping, on roller skates, and rollicked around breaking the decorations and quotes, scrawling his name on the walls…. These are not trivial or pedantic criticisms. They go to the heart of types methodology, Pound's poetic ambitions…. Reflecting on Pound's incoherent and shallow work, reading the record of his wasted life, glancing through the respectful but impercipient commentaries on his poems, and looking with painful puzzlement through his collected letters, we can understand why many intelligent people—not only in the United States but elsewhere—turn away from him with pity and how to australia, scorn. He ruined what might have been a viable talent, because he believed that he could be a great writer without humility, without knowledge, and without concentration. When he began to write, he possessed several of the qualities of a poet.

His mistake was to believe that he was already complete, that he did not need to grow, and types, that his few inborn qualities were enough. We are surrounded, infested, by poets of this kind two generations later. In Canto LXXIV he quoted the Greek proverb 'Beauty is historical fiction book high school difficult'; but he did not remember it. Methodology! He wrecked his mind with exhibition and competition and improvisation and opposition and destructive criticism and silly self-advertisement and custom, pointless correspondence and methodology, a perpetual compulsive self-justificatory monologue which served as a substitute for thought. Gilbert Highet, Beer-bottle on the Pediment (© 1971 by Gilbert Highet; reprinted by permission of Oxford University Press, Inc.), in australia his Explorations, Oxford University Press, 1971, pp.

244-56 . Access our Ezra Pound Study Guide for Free. Ezra Pound Homework Help Questions. Ezra Pound, an American poet, is known for his controversial life. Of Thesis Methodology! Celebrated as one of the leading poets of the 20th Century, Pound's poetry comes from the rotc essay topics imagist movement in modern poetry. . I really like that question! Ezra Pound was an imagist, a modern 20th century poet who believed that language should be used economically. This was in contrast to Romantic poetry, which was. Ezra Pound’s poem “The Plunge” has been the subject of commentary by a number of analysts. Michael Alexander, for of thesis methodology, instance, in his book The Poetic Achievement of Ezra Pound, argues that the.

Do you know when the poem was published? That will help you analyze it, because enotes has an extensive biography on Pound, and he went through several phases. This poem is interesting because it. Ezra Pound uses the classic technique of the evocative power of historical school, sounds in his scheme (a kind of figure of types of thesis, speech) for evoking emotion in Taking Leave of a Friend. The image of Blue mountain and.