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Introduction: a 4G View

Part 1Mobile Ad Hoc NetworkingWuhan University

What is an Ad Hoc Network?

A mobile ad hoc network (MANET) is

n Communication networkn Wireless signalingn Multi-hopn Mobile

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MANET Applications

Tactical networksDisaster reliefRescue tasksAccess extensionWireless sensor networks

Bit of History – A DARPA View

Packet Radio Network (PRNet)Survivable Radio Network (SURAN)Global Mobile (GloMo) ProgramTactical Internet (TI)Extending Littoral Battle-Space

Advanced Concept Technology Demonstration (ELB ACTD)

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Wireless Comm. Characteristics

Higher interference + lower reliabilityn From other sources & self interference

Lower bandwidthShared mediumHighly dynamic network structureLimited computing & energy resourcesLimited service coverageWeak Security

Categorization of Wireless Networks

Network architectureCommunication coverage areaAccess technologyApplication domain

By …

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By Network Architecture

Infrastructure-basedn Cellular networksn Wireless local area networksn Satellite phones

Infrastructureless (ad hoc)n Focus of this course

By Coverage AreaWireless Wide-Area Networks (Wireless WAN)n Cellular networks and satellite networksWireless Metropolitan-Area Networks

(Wireless MAN)n Fixed wireless, e.g. Nokia Rooftop Routers & IEEE

802.16

Wireless Local-Area Networks (Wireless LAN)n IEEE 802.11 & HIPERLAN/2Wireless Personal-Area Networks (Wireless

PAN)n Bluetooth & ZigBee

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By Coverage Area (Cont’d)

Wireless Body-Area Networks (Wireless BAN)

WANMANLANPANBAN

~1m ~10m ~100m ~1km ~10km

By Access Technology

FDMATDMAGSMCDMAWi-Fi (802.11)Infrared

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By Network Applications

Enterprise networksHome networksTactical networksSensor networksPervasive computingWearable networksn Body-area networks (BAN)

Automated vehicle networks

Evolution of Wireless Networks

MC-CDMAOFDM

CDMA2000W-CDMATD-SCDMA

GPRSEDGE

TDMA/FDDCDMA/FDD

FDMA/FDD

Access technology

Converged voice, data and MM; all IP

Voice, high-speed data (144 kbps ~ 2Mbps)

Mostly voice, high-speed data (10 ~ 384 kbps)

Mostly voice, low-speed data (10 ~ 70 kbps)

VoiceMedia type

AMPSNMTTACS

Analog

1980s

1G

CDMA2000W-CDMATD-SCDMA

GPRSEDGE

GSMDCS1900IS-54/95/136CDMAOne

Example systems

DigitalDigitalDigitalDigitalSignal type

2010s2000sLate 1990s1990sTime frame

4G3G2.5G2GGeneration

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Foci of 4G

Network integrationAll-IP networkingUltra-high speed and MultimediaUbiquitous computingSupport for ad hoc networkingLocation intelligence

Characteristics of MANETs

WirelessInfrastructurelessMulti-hopDynamic structure

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Design Issues and Challenges

No existing infrastructureMobile usersPHY layer limitationsn Bandwidth, quality, reliability and variance

Energy conservationSecurity and cooperationScalabilityQuality of Service (QoS)

Medium Access Control

Share wireless channelHalf duplex signalingn Self interference

CSMACollision avoidanceHidden terminal problem

A B C

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Routing

Most active areaPrimary objectives: correct and efficientn Simplicity and ease of implementationn Rapid route convergencen Distributed and light-weightn Bandwidth, computing power and energyn Scalablen Secure and reliablen QoS support

Classification of Routing Protocols

Proactiven DSDV, CGSR, WRP, OLSR, FSR

Reactiven AODV, DSR, TORA, ABR

Hybridn ZRP

HierarchicalLocation-based

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MulticastingUnicastingn To unique destination

Broadcastingn To all nodes in the network

Multicastingn To subset of nodesn Tree-basedn Mesh-based

Geocastingn To nodes in specified geographic region

TCP IssuesAssumption in Internetn Packet loss = network congestionn Reduce traffic flow by slowing down

transmissionDifferent interpretation of packet loss

in wireless networksn Link layer error or network disconnectionNew treatmentn Cellular networksn Ad hoc networks

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Energy Conservation

Save energy without compromising network performancePHY – Reducing transmission powerMAC – putting air interface into sleep

modeEnergy efficient routing protocolsDuty cycle sharing among clusters

Network Security

Forms of attacksn Passive eavesdroppingn Denial of service (DoS)n Signaling attacksn Flow disruptionn Resource depletionn Data integrity attacksn Stolen device attacks

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Cooperation

Selfish behavior among nodesn “Since energy is scarce, why would I

bother to forward other people’s packets?”

Economics modelsn Game theory

Quality of Service

QoS modeln Throughput/capacityn Delayn Delay jittern Packet loss rate

QoS routingQoS signalingQoS MAC

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Performance EvaluationAnalysisComputer Simulationn E.g. OPNET, ns2, GloMoSim, QualNetn Mobility models & networking modules

Testbed measurementn APE – Uppsala University, Swedenn Project MART – Helsinki University, Finlandn MONARCH – Carnegie Mellon University, USAn MOMENT – UC Santa Barbara, USAn DAWN – Trinity College in Dublin, Ireland

Future Research

Routing protocol optimizationQoS supportSimulationSecurityStandardization and interoperability

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Ubiquitous ComputingThe most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it.

— The late Mark WeiserFather of Ubiquitous Computing

Evaluation

Three-hour final examn September 23, 2006