Cluster-Based Multi-Channel Communications Protocols in Vehicle Ad Hoc

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Cluster-Based Multi-ChannelCommunications Protocols in

Vehicle Ad Hoc Networks

IEEE Wireless Communications october2006,

vol.13 No. 5

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Outline

INTRODUCTION

SYSTEM ARCHITECTURE

FUNCTIONS AND DESIGNS OF

PROTOCOLS THE CLUSTER CONFIGURATION

PROTOCOL

THE INTRACLUSTER COORDINATION AND

COMMUNICATION PROTOCOL SIMULATION EVALUATIONS

CONCLUSIONS

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INTRODUCTION(1/2)

What is DSRC(Dedicated Short RangeCommunication)?

V2V-based VANETs and V2R-based VANETs.

The data transmitted over the VANETs can beclassified into the real-time traffic and the

non-real-time traffic.

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DSRC

DSRC/802.11pThe standard of 802.11p is based on IEEE 802.11a PHY

layer and IEEE 802.11 MAC layer Seven 10 MHz channels at 5.9GHz

one control channel and six service channels

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Vehicle to

vehicle

Service

channel

Service

channel

Control

channelIntersection

CH 172 CH 174 CH 182CH 180CH 178CH 176 CH 184

5.855

5.925

5.915

5.905

5.895

5.885

5.875

5.865

Frequency (GHz)

Optionally combined

service channels


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V2V-BASED VANETS AND V2R-BASEDVANETS

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THE DATA TRANSMITTED OVER THEVANETS

real-time trafficsuch as safety messages and video/audio

signals

non-real-time trafficsuch as e-maps and road/vehicle-

traffic/weather information

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INTRODUCTION(2/2)

Our proposed scheme mainly consists offollowing three core protocols.Cluster Configuration Protocol

Intracluster Coordination andCommunication Protocol

Intercluster Communication Protocol

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SYSTEM ARCHITECTURE

Four Broadcasting Strategies

1. Probability-based

2. Location-based

3. Neighbor-based

4. Cluster-based

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STRATEGIES

1. Probability-based:A given PDF determines the decision, for

example depending on the number of

copies a node has received.The strategy is often dynamic.

PDF = probability distribution function

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PROBABILITY-BASED0

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Car APDF = 0.8

Car BPDF = 0.5

Forwarding Node choose


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FOUR BROADCASTINGSTRATEGIES

Location-basedThe selection criterion is the amount of

additional area that would be covered by

enabling a node to forward.Some proposal also computes position

prediction as useful input information.

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LOCATION-BASED

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Target


Car B

wants to turn right

Car A


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Neighbor-basedA node is selected depending on its

neighbors status (for instance, the status

concerns how a neighbor is connected tothe network).

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NEIGHBOR-BASED0

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Target


Car B

Car A

Collect the information of neighbors


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Cluster-basedNodes are grouped in clusters represented

by an elected cluster-head. Only cluster-

heads forward packets.Nodes in the same cluster share some

features (e.g., relative speed in VANETs).

Reclustering on-demand or periodically.

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CLUSTER-BASED

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Cluster -Header

Cluster -Header

Gateway -Node



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SYSTEM ARCHITECTURE0

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SYSTEM ARCHITECTURE

Our proposed scheme handles thefollowing three tasksCluster-membership management

Real-time traffic (such as safety messages

delivery)

Non-real-time data communications (suchas

e-maps download, movies download, etc.)

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SYSTEM ARCHITECTURE0

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( FINITE STATE MACHINE,FSM)

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PROTOCOLS

We use the Finite State Machine (FSM)

Each vehicle operates under one andonly one of the following four states at

any given time:

cluster-head (CH)

quasi-cluster-head (QCH)

cluster-member (CM)

quasi-cluster-member (QCM)

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PROTOCOLS0

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22Finite state machine of our proposed scheme. T1 andT2 represent Transceiver 1 and Transceiver 2


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THE INTRACLUSTER COORDINATION

AND COMMUNICATION PROTOCOL

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AND COMMUNICATION PROTOCOL0

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Tt =

N = gap =

v = Lc =

Nlane =


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AND COMMUNICATION PROTOCOL0

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T = repetition period( 200ms)R = channel rate

Tsafety =

Hsafety = packet size

200bytes


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SIMULATION EVALUATIONS

3

2100 180 35m/s 15m2 / s2

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Matlab

25m

5m 150m

400ms

150ms

50ms 200bytes

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The performance of three protocols against non-real-time traffic arrival rate: a) Probability of safety-message-delivery failure; and b) aggregate throughputof non-real-time traffics. The size of the non-real-timetraffic packet is 512 bytes.


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SIMULATION EVALUATIONS0

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29Channel busy rates of the seven different channels. Thesize of the non-real-time traffic packet is 512 bytes and

the packet arrival rate of the non real-time traffic is200packets/sec/vehicle.


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CONCLUSIONS

Reduce data-congestion

Support QoS for real-time delivery of safetymessages

High throughput

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Cluster-Based Multi-Channel Communications Protocols in Vehicle Ad Hoc

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