Fatma Hrizi, Jerome Haerri and Christian Bonnet

EURECOM, Mobile communications department

Cooperative protocols for Cooperative protocols for wireless vehicular wireless vehicular

communicationcommunication

Vehicular networks: The ChallengesVehicular networks: The Challenges Applications

Safety Efficiency Entertainment, Internet access

Key concept Provide appropriate information to the driver/vehicle

Large amount of data to exchange Local scope information: Awareness (GPS data) Global scope information: Emergency, traffic and road information…

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2

Safety applications requirements Short delay and high reliability

Awareness: Broadcast – need to reach all neighboring nodes Periodic – need to update position information

Shared medium limitation Congestion at medium access Collision at reception

Cooperation in vehicular networks Cooperation in vehicular networks (1/2)(1/2)

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Load on channel

Need to regulate the channel load

Channel capacity exceeded!

Cooperation in vehicular networks Cooperation in vehicular networks (2/2)(2/2)

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Congestion control policy of a node benefits others

Need for cooperative and common congestion control policy One hop transmission

Transmission rate control Transmission power control

Multi-hop transmission Select best relay

Best relay to be selected

If B does not retransmit => reduce channel load

at A

A

B

AB

Reduce channel load at

B

Does not impact channel load at A

No need for B retransmission

C

Talk outlineTalk outline

Cooperative congestion control strategiesMulti-hop communication

Bi-Zone Broadcast protocol (BZB)One-hop communication

Transmission rate control

Conclusion and perspectives

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Disseminate broadcast information reliably and in brief delay

Distance-based contention scheme Select the best relay according to the distance: the furthest Minimize the waiting time of distant node

Multi-hop communication: BZBMulti-hop communication: BZB

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Dth

Tx Range

Impact of RSU in dissemination

A

B

C

D

tA sends B sends

C cancels D cancels

BD

C

Dth: Distance threshold

BZB: Performance EvaluationBZB: Performance Evaluation

500 nodes500 nodes50 50 nodesnodes

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SDP: Simple distance based protocol

One-hop communication: Transmission One-hop communication: Transmission rate controlrate control Approach:

Tune rate to avoid congestion Rely on position information prediction

Transmit only when Mobility not predictable: Sudden mobility change Topology not predictable: Announce its presence

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tTmax

TransmissionApplication requirement!

Tmax

TransmissionI moved from predicted position!

Predicted position

Realposition

Intersection collision warning

Tmax: Maximum Tx period

Transmission!

Transmission rate control: Transmission rate control: ArchitectureArchitecture

Kalman Filter Simplistic assumptions: linear problem with Guassian noise

Neural Network Learning phase

Kalman Filter Neural Network Genetic algorithm Particle Filter

GPS data

V2X data

Map data

Decision

Mobility Prediction system

CooperativeDecision maker

Predicted data

Real Position data

Error

Transmit position?

ApplicationRequirements

Network density

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Genetic algorithm Processing time No guarantee for convergence

Particle Filter Degeneracy problem

Conclusion and perspectivesConclusion and perspectives So far..

Congestion-aware approach for multi-hop and one-hop communicationsBZB protocolTransmission rate control

Some issues have not yet been fully investigatedMobility prediction schemesChannel-aware mechanisms for congestion control strategies Cooperation between multiple applications and protocols

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Multiple applicationsSatisfy different applications requirements

Multiple protocolsConsider the various congestion control policies and resources limitation

Conclusion and perspectivesConclusion and perspectives

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Intersection collision warning

(ICW)!

Lane change warning (LCW)!

(1)

(2)Which decision I

take?

Applications

ICW LCW … Appn

Facilities

Networking & Transport

CP1 CP2 CPn

Access Technologies

…Which congestion control scheme I

use?ICW: Intersection collision warningLCW: Lane change warningCP: Congestion control policy

Thank you for your attentionThank you for your attention

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Contact : Fatma Hrizi

Mobile Communications Department EURECOM 2229 Route des Crêtes - BP 193 F-06904 Sophia Antipolis Cedex FRANCE Tel: +33-493.00.82 68 Fax: +33-493.00.82 00

Email : fatma.hrizi@eurecom.fr

Multi-hop communication: BZBMulti-hop communication: BZB

V2V disseminationContention-based scheme

Minimise the waiting time of distant node

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Dth

Tx Range

dthdwhereTTrandom

dthdwhereTrandomewaitingtim

upperlower

upper

),(

),0(

V2V/V2I dissemination: Impact of infrastructure in message disseminationRSUs are equipped with high antennas ensuring more

coverage and are wiredly connected to the TOCMore priority to RSU considering density

Multi-hop communication: I-BZBMulti-hop communication: I-BZB

RSUannotIf

RSUanIfNK

TTrandomKewaitingtim

neigh

upperlower

1

/1

),(

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