Chapter 01

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Copyright © 2006, Dr. Carlos Cordeiro and Prof. Dharma P. Agrawal, All rights reserved. 1 Carlos Cordeiro Philips Research North America Briarcliff Manor, NY Dharma P. Agrawal OBR Research Center for Distributed and Mobile Computing University of Cincinnati, OH

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Transcript of Chapter 01

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Copyright © 2006, Dr. Carlos Cordeiro and Prof. Dharma P. Agrawal, All rights reserved. 1

Carlos CordeiroPhilips Research North AmericaBriarcliff Manor, NY

Dharma P. AgrawalOBR Research Center for Distributed and Mobile ComputingUniversity of Cincinnati, OH

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Table of Contents

Chapters:1. Introduction2. Routing in Ad hoc Networks3. Broadcasting, Multicasting and Geocasting4. Wireless LANs5. Wireless PANs6. Directional Antenna Systems7. TCP over Ad Hoc Networks8. Wireless Sensor Networks9. Data Retrieval in Sensor Networks10.Security11. Integrating MANETs, WLANs and Cellular

Networks

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Chapter 1: Introduction Introduction

The Communication Puzzle Applications of MANETs Challenges

Scalability Quality of Service Client-Server Model Shift Security Interoperation with the Internet Energy Conservation Node (MH) Cooperation Interoperation

Book Organization Conclusions and Future Directions Homework Questions/Simulation Projects References

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A Mobile Ad Hoc Network (MANET)

MH2

MH3

MH2

MH4

MH1

MH5

MH6

MH7Symmetric link

Asymmetric link

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Characteristics of a MANET

An autonomous system of nodes (Mobile Hosts: MHs) connected by wireless links

Same channel used by all nodes Lack of fixed infrastructure Absence of centralized authority Peer-to-peer connectivity Multi-hop forwarding to ensure network connectivity Topology may change dynamically Random Multi-hop Graph Energy-constrained Bandwidth-constrained, variable capacity links

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Important characteristics of a MANETCharacteristi

cDescription

Dynamic Topologies

Nodes are free to move arbitrarily with different speeds; thus, the network topology may change randomly and at unpredictable times.

Energy-constrained Operation

Some or all of the nodes in an ad hoc network may rely on batteries or other exhaustible means for their energy. For these nodes, the most important system design optimization criteria may be energy conservation.

Limited Bandwidth

Wireless links continue to have significantly lower capacity than infrastructured networks. In addition, the realized throughput of wireless communications – after accounting for the effects of multiple access, fading, noise, and interference conditions, etc., is often much less than a radio’s maximum transmission rate.

Security Threats

Mobile wireless networks are generally more prone to physical security threats than fixed-cable nets. The increased possibility of eavesdropping, spoofing, and minimization of denial-of-service type attacks should be carefully considered.

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The envisioned communication puzzle of 4G and beyond

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The scope of various wireless technologies

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Applications of MANETs

Collaborative Work Collaborative computing might be important outside office

environments Crisis-management Applications

Natural disasters with entire communications infrastructure in disarray

Restoring communications quickly is essential Infrastructure could be set up in hours instead of

days/weeks Personal Area Networking

Short-range, localized network of nodes associated with a person

Nodes could be attached to someone’s cell phone, pulse watch, belt, etc.

Bluetooth is an example Eliminates need of wires between devices such as printers,

cell phones, PDAs, laptop computers, headsets, etc. IEEE 802.15 standard working group

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Future Challenges in Ad hoc and Sensor Networks

Scalability Short-range Throughput per node decreases at a rate 1/ , where N is the number of nodes This cannot be fixed except by physical layer improvements, such as directional antennas

Quality of service Need to provide best-effort service only for Voice, live video and file transfer

Client server model shift There is no server, but demand for basic services still exists. Address allocation, name resolution, authentication and service location are just examples of very basic services which are needed

Security Lack of any centralized network management or certification authority Networks are particularly prone to malicious behavior

Interoperation with the Internet Networks require some Internet connection Interface between the two are very different

Energy conservation Lifetime of a single battery and the whole network.

Node cooperation Why anyone should relay other people’s data

Interoperation What happens when two autonomous ad hoc networks move into same area

N

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Book outline Chapter 2: Unicast routing over ad hoc networks Chapter 3: Multicasting, Broadcasting and

geocasting in ad hoc networks Chapters 4 and 5: Most widely used MAC and

physical layers for ad hoc networks Chapter 6: Use of directional antenna for

increasing capacity, connectivity, and covertness of ad hoc networks

Chapter 7: The issue of TCP (Transmission Control Protocol) over ad hoc networks

Chapter 8: Introduction to sensor networks Chapter 9: Data retrieval in sensor networks Chapter 10: Security in ad hoc networks Chapter 11: Integration of heterogeneous wireless

technologies in the context of ad hoc and sensor networks

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Book Organization

Application

Transport

Network

LLC

Physical

MACDataLink

All chapters

Chapters 7, 9 and 11

Chapters 4, 5, 6, and 11

Chapters 4, 5, 6, 8, 9, and 11

Chapters 2, 3, 6, 8, 9, 10, and 11