ABSTRACT
The opportunistic network is one of the most interesting evolution of Mobile Ad-hoc Network (MANET).In an opportunistic network,information about the context in which users communicate is notavailable as there is no dedicated complete path from a source to a destination. This makes the design of an efficient routing protocol for an opportunistic network difficult. The research is aimed at the development of an improved integrated routing protocol in opportunistic networks. Simulation was carried out using the opportunistic network environment (ONE) simulator.This report presents the modeled opportunistic network using the epidemic, the prophet and the integrated routing protocol. Four pre-emptive congestion control strategies (use of acknowledgement, buffer size advertisement, data centric method and the avoidance of duplication) were developed and incorporated into the integrated routing protocol. The integrated routing protocol outperformed the epidemic and the prophet routing protocols by 5.4% and 4.3%, respectively with respect to the delivery probability. Results showed that the duplication avoidance improved the integrated routing protocol because it reduced the packet loss and improved the delivery probability when tested on a 10-node test model and on the benchmark Helsinki simulation area. Duplication avoidance reduced the packet loss by 58% and improved the delivery probability by 4% at the end of the simulation time of 43200 seconds when compared with the delivery probability and packet loss of the original integrated routing protocol on Helsinki which are 0.1048 and 670, respectively. The use of acknowledgement, buffer size advertisement, data centric method reduced the packet loss by 2.5%, 57% and 57%, respectively but did not improve on the delivery probability significantly. The final delivery probabilities ofthe use of acknowledgement, buffer size advertisement, data centric method are 0.105, 0.103 and 0.105, respectively. These results showed that duplication avoidance is the preferred congestion control strategy for the integrated routing considered in this research.
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TABLE OF CONTENTS
DECLARATION……………………………………………………………………………………………………… iv
CERTIFICATION …………………………………………………………………………………………………… iv
DEDICATION………………………………………………………………………………………………………….. v
ACKNOWLEDGEMENT ………………………………………………………………………………………… vi
ABSTRACT ……………………………………………………………………………………………………………. vii
LIST OF FIGURESxi
LIST OF TABLESxiii
LIST OF ABBREVIATIONS …………………………………………………………………………………. xiv
CHAPTER ONE: INTRODUCTION
1.1 Background ………………………………………………………………………………………………………….. 1
1.2 Problem Statement ………………………………………………………………………………………………… 3
1.3 Aim and Objectives ……………………………………………………………………………………………….. 3
1.4 Methodology ………………………………………………………………………………………………………… 4
1.5 Significant Contribution …………………………………………………………………………………………. 5
1.6 Thesis Organization……………………………………………………………………………………………….. 5
CHAPTER TWO:LITERATURE REVIEW
2.1 Introduction6
2.2 Review of Fundamental Concepts ………………………………………………………………………………………… 6
2.2.1 Opportunistic networks ………………………………………………………………………………………………… 6
2.2.2 Opportunistic network node definition …………………………………………………………………………… 9
2.2.3 Opportunistic networks and mobile Ad-hoc network ……………………………………………………… 10
2.2.4 Routing in opportunistic networks ……………………………………………………………………………….. 12
(i) Dissemination-based Routing …………………………………………………………………………………………………….. 13
(ii) Context-based Routing……………………………………………………………………………………………………………… 13
(iii) Routing Based on Fixed Infrastructure ……………………………………………………………………………………… 14
(iv) Routing Based on Mobile Infrastructure …………………………………………………………………………………….. 14
2.2.4.1 The Epidemic Routing protocol ……………………………………………………………………………………………. 14
2.2.4.2 The Prophet Routing Protocol ……………………………………………………………………………………………… 15
2.2.4.3 Integrated Routing Protocol ………………………………………………………………………………………………… 16
2.2.4.4 Integrated routing protocol probabilities ………………………………………………………………………………. 17
2.2.4.5 Routing strategies of the integrated routing …………………………………………………………………………… 18
2.2.5 Congestion in opportunistic networks …………………………………………………………………………… 19
2.2.6 Buffer management ……………………………………………………………………………………………………. 20
2.2.7 Pre-emptive data eviction ……………………………………………………………………………………………. 21
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2.2.8 Evaluating the Performance of DTN Routing Protocols ……………………………………………………. 23
2.2.9 The ONE Simulator ……………………………………………………………………………………………………… 24
2.3 Review of Similar Works …………………………………………………………………………………………………… 26
CHAPTER THREE: MATERIALS AND METHODS
3.1 Introduction ……………………………………………………………………………………………………………………… 35
3.2 Model Test Case ……………………………………………………………………………………………………………… 35
3.3 Installation and Configuration ……………………………………………………………………………………………. 36
3.4 Simulation ……………………………………………………………………………………………………………………….. 36
3.5 Visualization ……………………………………………………………………………………………………………………. 47
3.6 Simulation of the Improved Integrated Routing Protocol with Congestion Control. ………………….. 47
3.6.1 Buffer eviction using acknowledgement ……………………………………………………………………….. 47
3.6 2 Buffer size advertisement ……………………………………………………………………………………………. 48
3.6.3 Data-centric node congestion avoidance ………………………………………………………………………. 49
3.6.4 Duplication avoidance …………………………………………………………………………………………………. 50
3.7 Validation of the congestion control strategies ……………………………………………………………………… 51
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1 Introduction …………………………………………………………………………………………………………………….. 57
4.1 The Performance Evaluation of the Congestion Control Strategies …………………………………………. 57
4.3 General Discussion …………………………………………………………………………………………………………… 66
CHAPTER FIVE: CONCLUSION AND RECOMMENDATIONS
5.1 Introduction ……………………………………………………………………………………………………………………… 68
5.2 Conclusions ……………………………………………………………………………………………………………………… 68
5.3 Limitations ………………………………………………………………………………………………………………………. 69
5.4 Recommendations for Further Work …………………………………………………………………………………… 69
REFERENCES ………………………………………………………………………………………………………… 70
Appendix A1 ……………………………………………………………………………………………………………….
The Program Class for Epidemic Router ……………………………………………………………………… 73
Appendix A2
Epidemic Routing Settings ………………………………………………………………………………………… 74
Appendix B1
Program for Prophet Routing ……………………………………………………………………………………… 76
Appendix B2
Prophet Settings ……………………………………………………………………………………………………….. 82
Appendix C1
Setting for Integrated Routing on 10-node test case ………………………………………………………. 84
Appendix D1
CHAPTER ONE
INTRODUCTION
1.1 Background
Traditionally, communication between two or more devices in a network uses infrastructure-based wired networks. In some instances, however, such communication is limited as it becomes difficult to expand the network due to cost, environment, etc. This, coupled with the need for mobility and independence of network infrastructure, brought the need for wireless networks (Dinakar et al., 2013).
A wireless network uses access points and base stations (for mobility) to ensure communication among users and between users and the network. Each base station and access point usually has a maximum number of defined users it can ideally handle. These traditional wireless networks, however, have the following constraints (Dinakar et al., 2013) :
(i) Centralized administration is usually required.
(ii) Power requirements to serve all the base stations and access points.
(iii) Usually capital intensive to deploy and scale up.
(iv) Difficult to maintain.
The opportunistic network is an autonomous connection of users that communicate over a relatively bandwidth constrained wireless network. According to Kaur & Kaur (2009) and Verma & Srivastava (2012), it has the following basic features:
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(i) It has wirelessly connected nodes which can be fixed or mobile (a node is an electronic device that is attached to a network and is capable of sending, receiving or forwarding information over communication channel).
(ii) A complete path between two nodes aspiring to communicate does not exist.
(iii) It does not have a fixed communication range.
(iv) Its routes are dynamically built as any node can opportunistically be used as the next hop provided it is likely to bring the message closer to the final destination.
(v) Network topology is also flexible as it can change at any time.
Since there is no direct connection between the source and the destination coupled with the fact that routes are built dynamically, designing an efficient routing protocol for opportunistic networks is a very critical issue. Information about the context in which users communicate is also a key piece of knowledge required to design an efficient routing protocol. In opportunistic networks, this information is not available, thus further making it difficult to design such routing protocols. Context information is the users‟ working address and institution, working environment and users behavior, probability of meeting another user or visiting a particular place. It is important to identify suitable forwarders based on context information about the destination (Verma & Srivastava, 2012).
The two main routing techniques for opportunistic networks as presented in literatures (Kaur & Kaur, 2009; Orozco, et al.; Verma & Srivastava, 2012) are:
i. The „Prophet‟ (context-aware) routing.
ii. The „Epidemic‟ (context-oblivious) routing.
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„Prophet‟ is able to learn automatically from the past communications opportunities determined by user‟s mobility pattern and use them in the future. This self-learning feature is absent in „Epidemic‟ as it floods the message all over the network, thereby causing congestion and creating high overhead. Epidemic is the only solution when context information about the users is not available (Lindgren, et al., 2003). Verma & Srivastava,(2012) showed that „epidemic‟ is better (in terms of message delay and delivery probability) in absence of context information while „prophet‟ gives better result with context information available. The integrated routing protocol for opportunistic network was developed by Verma & Srivastava (2012) in order to sum up the merits of the two protocols mentioned above. The integrated routing technique uses context data as soon as it is available and falls back to dissemination-based routing when context information is not available.
1.2Problem Statement
Information about the context in which users communicate is not available in an opportunistic network as there is no dedicated complete path from a source to a destination. This makes the design of an efficient routing protocol for an opportunistic network difficult(Verma & Srivastava, 2012). Utilizing the characteristics of opportunistic network to design a buffer management strategy is still an open issue (Pan et al., 2013).This research is aimed at improving the existing integrated routing protocol by incorporating buffer management into it as a means of controlling congestion using pre-emptive eviction of data.
1.3Aim and Objectives
The aim of this research is to develop an improved integrated routing protocol with congestion control using pre-emptive eviction of data.
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The objectives are as follows:
(i) Development of the improved integrated routing protocol with congestion control via buffer management.
(ii) Simulation and comparison of performance of the improved integrated routing protocol with that of the conventional integrated routing protocol.
(iii) Validation of the developed model with a real-life scenario (Helsinki Region).
1.4 Methodology
The methodology adopted in carrying out this research is as follows:
i. Modeling of the Test Case Scenario.
ii. Development of the epidemic routing protocol and its simulation using the opportunistic network environment (ONE) simulator.
iii. Development of the prophet routing protocol and its simulation using ONE simulator.
iv. Development of the integrated routing protocol as a hybrid of the prophet and the epidemic routing protocol and its simulation using ONE simulator.
v. Simulation of the improved integrated routing protocol with congestion control using buffer management.
vi. Comparison of performance of the conventional integrated routing protocol with that of the improved integrated routing protocol.
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vii. Validation of the improved integrated routing protocol using a real-life scenario (Helsinki region).
1.5 Significant Contribution
Many researchershave worked on designing a routing protocol for the opportunistic networks. Also, some researches have tried to address the problem of congestion in opportunistic networks.The significant contributions of this research work are as follows:
i. Development of an improved integrated routing protocol for the opportunistic network with Duplication-Avoidance based Congestion Control strategy
ii. Achieved a 58% reduction in the packet loss and 4% improvement in the delivery probability when tested on the benchmark Helsinki simulation area,
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1.6 Thesis Organization
The general introduction has been presented in chapter one. The rest of the chapters are structured as follows: Detailed review of fundamental concept on the opportunistic networks, ONE simulator and areview of similar research works is presented in chapter two. In chapter Three, modeling of thetest case scenario, configuration, installation as well as simulation are presented. The results, its analysis and discussion are presented in chapter four. Conclusion and recommendations are discussed in chapter five. Quoted references and appendices are also provided at the end of this thesis.
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