Multihop connectivity in wireless ad hoc networks [Elektronische Ressource] / von Habib-ur Rehman
162 Pages
English
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Multihop connectivity in wireless ad hoc networks [Elektronische Ressource] / von Habib-ur Rehman

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162 Pages
English

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Technische Universität Braunschweig Carl-Friedrich-Gauß-Fakultät Institut für Betriebssysteme und Rechnerverbund Multihop Connectivity in Wireless Ad hoc Networks Von der Carl-Friedrich Gauß-Fakultät der Technischen Universität Carolo-Wilhelmina zu Braunschweig zur Erlangung des Grades eines Doktor-Ingenieurs (Dr.-Ing.) genehmigte Dissertation von Habib-ur Rehman geboren am 22.05.1978 in Faisalabad Eingereicht am: 28.01.2009 Mündliche Prüfung am: 27.03.2009 Referent: Prof. Dr.-Ing Lars Wolf Korreferent: Dr. Utz Roedig (209) Multihop Connectivity in Wireless Ad hoc Networks Submitted to the Carl Friedrich Gauss Faculty, Technical University Braunschweig, in partial fulfillment of the requirements for the degree of Doktor-Ingenieurs (Dr.-Ing) Abstract Wireless ad hoc networks have numerous real life applications as they can be instantaneously established, require no infrastructure, and are autonomic and self-organizing. Multihop connectivity is the ability of the multiple-hops-away nodes—nodes which are not directly connected—to communicate with each other. Since wireless ad hoc networks are infrastructure-less, the participating nodes themselves are supposed to establish the service of multihop connectivity by forwarding the messages on behalf of each other. Routing and Relaying are the two approaches to provide multihop connectivity in wireless ad hoc networks.

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Published 01 January 2009
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Technische Universität Braunschweig
Carl-Friedrich-Gauß-Fakultät
Institut für Betriebssysteme und Rechnerverbund




Multihop Connectivity in Wireless Ad hoc Networks



Von der Carl-Friedrich Gauß-Fakultät
der Technischen Universität
Carolo-Wilhelmina zu Braunschweig
zur Erlangung des Grades
eines Doktor-Ingenieurs (Dr.-Ing.)
genehmigte Dissertation




von Habib-ur Rehman
geboren am 22.05.1978
in Faisalabad






Eingereicht am: 28.01.2009
Mündliche Prüfung am: 27.03.2009
Referent: Prof. Dr.-Ing Lars Wolf
Korreferent: Dr. Utz Roedig


(2009)

Multihop Connectivity in Wireless Ad hoc Networks
Submitted to the Carl Friedrich Gauss Faculty, Technical
University Braunschweig, in partial fulfillment of the
requirements for the degree of Doktor-Ingenieurs (Dr.-Ing)

Abstract
Wireless ad hoc networks have numerous real life applications as they can be
instantaneously established, require no infrastructure, and are autonomic and
selforganizing. Multihop connectivity is the ability of the multiple-hops-away nodes—nodes
which are not directly connected—to communicate with each other. Since wireless ad
hoc networks are infrastructure-less, the participating nodes themselves are supposed to
establish the service of multihop connectivity by forwarding the messages on behalf of
each other. Routing and Relaying are the two approaches to provide multihop
connectivity in wireless ad hoc networks. In Relaying, MAC layer is the point in the
protocol stack at which the switching or forwarding decision takes place, while Routing
schemes perform this decision at a later stage i.e. at Network layer. Routing is a widely
researched and practiced solution to the problem of multihop connectivity, whereas
Relaying has not been adequately explored in wireless ad hoc networks. This thesis
argues that due to the specific nature of the wireless ad hoc networks and the MAC
protocols for these networks, Relaying is technically a more suitable option in these
networks and has higher prospects. This argument is supported by designing a multihop
version of the IEEE 802.11 MAC protocol and comparing its performance with the
AODV routing protocol. The analysis shows that a multihop 802.11 MAC can be
implemented in a much simpler manner and it can achieve performance comparable with
that of AODV. In reactive or on-demand routing—the class of routing protocols widely
acclaimed for its lower overhead—the accessibility prediction scheme is introduced
which reduces the routing overhead by avoiding routing actions which are
possible-tofail. Furthermore, this thesis evaluates the effect of utilizing obsolete routing
information—a common approach to optimize the reactive routing protocols. Based on
the analysis, it is argued that this act is inconsistent with the nature of the reactive routing
and can have limited but unpredictable benefits, mainly when no additional overhead is
incurred.



Acknowledgements

I am extremely thankful to Prof. Lars Wolf for his supervision and guidance during
my PhD studies and his invaluable contribution in my training as a researcher. Although,
most of the time he has not mentioned all the things explicitly to me, while working with
him I had the opportunity to observe that how much organized a researcher should be,
and had learnt that there are times when you need to be patient and take your actions after
thorough evaluation of the circumstances.
I must mention the external examiner Dr. Utz Roedig for his evaluation of the thesis
and his valuable comments and questions which have improved my understanding of my
own work.
Certainly, without the patience and cooperation of the colleagues at the IBR, it would
have never been so easy. I will always remember how much I have disturbed Frank
Steinberg, our network administrator, with my uncontrolled simulations; the ever-ready
questions and suggestions of Oliver Wellnitz during the presentations; communication
with our secretaries in my poor Deutsch; and the support of other colleagues here or
there.
I am very grateful to the Higher Education Commission (HEC) of Pakistan and the
German Academic Exchange Service (DAAD) for their financial support of my PhD
studies. The guidance of Ms. Monika Osman and her colleagues at the DAAD in daily
matters during my stay in Germany has helped me to peacefully focus on my research.
I believe that it would be unfair if I will not mention that the stay in Germany has
helped a lot in my mental and social bringing up. After all, life is not about just doing
research and writing the thesis. Although, I have not tried much to improve my Deutsch
or to speak in Deutsch, the opportunity to observe the German society and system was
extremely vital. I am proud to say that “Ich war in Deutschland und dort habe ich
promoviert.”
Finally, I want to dedicate this thesis to my parents, sisters and brothers. I know they
have missed me a lot when I was away and always have wished for my success and
progress. And I know how much proud and happy they are on this achievement. I love
you guys.




Contents
Chapter 1 Introduction .....................................................................................................1
1.1 The Challenge of Multihop Connectivity............................................................3
1.2 This Thesis ..........................................................................................................4
1.3 Overview .............................................................................................................5

Chapter 2 Wireless Ad hoc Networks and the Problem of Multihop
Connectivity ....................................................................................................7
2.1 Wireless Ad hoc Networks..................................................................................7
2.1.1 Characteristics .............................................................................................8
2.1.2 Classification and Scope .............................................................................9
2.2 Standards and Technologies..............................................................................11
2.2.1 IEEE 802.11 Wireless Local Area Networks Standards ...........................11
2.2.2 High Performance Radio Local Area Network (HiperLAN) ....................12
2.2.3 IEEE 802.15 Working Group for Wireless Personal Area
Networks ...................................................................................................12
2.3 Multihop Connectivity in Wireless Ad hoc Networks ......................................14
2.4 onnectivity Solutions ......................................................................16
2.4.1 Multihop Connectivity using Forwarding .................................................17
2.4.2 Routing in Wireless Ad hoc Networks......................................................21
2.4.3 Relaying in Wi ....................................................23
2.5 Ad hoc On-Demand Distance Vector (AODV) Routing Protocol ....................25
2.5.1 Sequence Number......................................................................................25
2.5.2 Routing Table ............................................................................................25
2.5.3 Route Discovery ........................................................................................26
2.5.4 Route Maintenance....................................................................................28
2.6 IEEE 802.11 WLAN MAC Protocol.................................................................30
2.6.1 IEEE WLAN Components ........................................................................31
2.6.2 Frame Types and Formats .........................................................................31
2.6.3 MAC Architecture and Operations............................................................34
2.7 Multihop Extensions for the IEEE 802.11 MAC Protocol................................36
2.7.1 Data Driven Cut-through Multiple Access (DCMA)36
2.7.2 IEEE 802.11 Ad Hoc Bridge.....................................................................38
2.7.3 A Bridging Method for Mobile Ad hoc Networks ....................................39
2.7.4 Conclusion.................................................................................................40
2.8 Chapter Summary..............................................................................................41

Chapter 3 Simulation Methodology...............................................................................43
® ®3.1 OPNET Modeler ............................................................................................43
3.1.1 Simulation Environment............................................................................43
3.2 The MANET_STATION Node Model .............................................................43
3.2.1 Wireless LAN Configuration ....................................................................44
3.2.2 Ad hoc Routing and AODV Configuration...............................................46
3.2.3 Node Mobility Configuration46
3.2.4 MANET Trafic Configuration...................................................................49
3.3 Simulation Scenarios.........................................................................................49
3.4 Analysis/Evaluation Metrics .............................................................................51

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Chapter 4 Enhancement of the Reactive Routing.......................................................... 55
4.1 Extending the Utilization of Collected Routing Information ........................... 55
4.1.1 Predicting the Accessibility ...................................................................... 55
4.1.2 AODV-AP: AODV with Accessibility Prediction ................................... 57
4.1.3 Application of Accessibility Prediction in AODV 59
4.1.4 Performance Analysis of the AODV-AP.................................................. 60
4.1.5 Conclusion ................................................................................................ 66
4.2 Obsolete Routing Information and Reactive Routing Protocols....................... 66
4.2.1 Initialization of the TTL Field in RREQ Packets ..................................... 67
4.2.2 Route Sharing in AODV........................................................................... 69
4.2.3 Effect of the Inconsistent Operations on the Performance of
AODV....................................................................................................... 71
4.3 Chapter Summary ............................................................................................. 77

Chapter 5 Routing vs. Relaying..................................................................................... 79
5.1 The OSI Reference Model ................................................................................ 80
5.2 The Nature of Wireless Ad hoc Networks........................................................ 82
5.3 Heterogeneity and Interoperability ................................................................... 82
5.4 Dependency of Routing Protocols on the MAC Layer..................................... 83
5.5 The Covert Features of Collision Avoidance MAC Protocols ......................... 84
5.6 The IEEE 802.11 MAC 85
5.7 Conclusion ........................................................................................................ 85

Chapter 6 A Multihop Version of the IEEE 802.11 MAC Protocol.............................. 87
6.1 Multihop 802.11 MAC Protocol....................................................................... 87
6.2 Multihop 802.11 MAC-Protocol Architecture.................................................. 88
6.2.1 End-to-End Addressing............................................................................. 88
6.2.2 The Forwarding Table............................................................................... 89
6.2.3 Sequence Control...................................................................................... 90
6.2.4 The Treatment of Address Fields in the Multihop 802.11
MAC Protocol........................................................................................... 90
6.3 Multihop 802.11 MAC-Protocol Operations .................................................... 92
6.3.1 Learning .................................................................................................... 92
6.3.2 Forwarding................................................................................................ 94
6.3.3 Repair........................................................................................................ 95
6.3.4 Forwarding and Repair Modules .............................................................. 99
6.3.5 Route Discovery in Multihop 802.11 MAC Protocol............................. 104
6.3.6 Other Covert Features............................................................................. 105
6.4 Performance Analysis of the Multihop 802.11 MAC..................................... 106
6.4.1 Data Packet Delivery Ratio..................................................................... 107
6.4.2 MAC Overhead....................................................................................... 110
6.4.3 Throughput.............................................................................................. 115
6.4.4 End-to-End Delay of Data Packets ......................................................... 118
6.4.5 Normalized Throughput.......................................................................... 121
6.5 Chapter Summary ........................................................................................... 124

Chapter 7 Conclusions................................................................................................. 127
7.1 Thesis Summary 127
7.2 Thesis Contribution......................................................................................... 128
7.3 Future Work.................................................................................................... 129
viii
Bibliography....................................................................................................................131

Appendix A Taxonomy of Wireless Networks............................................................137
A.1 Based on the Geographical Area or Size of the Network................................137
A.2 Based on the Infrastructure of the Network ....................................................138
A.3 Based on the Topology or Mobility of the Network .......................................138

Appendix B Routing Protocols for Wireless Ad hoc Networks ..................................141
B.1 Proactive Routing Protocols............................................................................141
B.2 Reactive Routing Protocols .............................................................................145
B.3 Hybrid Routing Protocols................................................................................147

List of Figures .................................................................................................................149

List of Tables...................................................................................................................152


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