RPB-MD: A Novel Robust Message Dissemination Method for VANETs

Congyi Liu and Chunxiao ChiganMichigan Technological University

GLOBECOM 2008

Outline Introduction RPB-MD:

Relative Position Based Message Dissemination Performance Evaluation Conclusion

Introduction VANETs providing multi-hop wireless communic

ation among vehicles, promises a broad applications.

Robust message disseminations are desirable for most of safety-critical VANET applications.

Related Work To disseminate messages by delaying different

times to avoid peak load This scheme requires location service and does not

consider the issue of partitions, which may affect the delivery ratio significantly.

Carry and forward Would result in high overhead (especially under the

dense vehicular traffic), and high computation complexity because of the process of partition crossing.

Related Work (cont.) Considered the direction of vehicle movement to

disseminate messages. Can not ensure robust message dissemination.

Goal In this paper, we address the issue of robustly

disseminating messages to all intended vehicles in the zone-of-relevance.

Zone-of-relevance defines the area where the message is of interest to the drivers.

The design of such mechanisms aims at high message delivery ratio with acceptable latency and overhead.

Assumptions We can get the precise relative distance between two

neighbors (i.e. Based on received signal strength indication, RSSI.)

The reference direction ,which is used as a basis for the comparison of vehicles’ directions, can also be achieved in the highway scenario.

Assume that two directional antennas are equipped for every vehicle to communicate with each other within 180o

RPB Forwarding Strategy - Overview

A

C

B D F

E

A

C

F

Message Head

Message Head

Message HeadActive State

Active State

Active StateIntermediate State

Intermediate State

Inactive StateActive StateIntermediate State

Intermediate StateActive State

Intermediate StateActive StateInactive StateMessage Holder

Message Holder

Message Holder Message Holder

Message Holder

Implicit ACKExplicit ACK

The Next Candidate Message Head

The Next Candidate Message Head

A

C

B

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11

e

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11

e

67.002.03002508.0 iW

6.012.03001508.0 iW

msmsTi 65.1)67.01(5

msmsTi 2)6.01(5

Hold the message further with probability

iP iPλ

Message Head abnormal modes handling – case1

A

C

BA

C

B

Message Head abnormal modes handling – case2 (t1)

A

C

BAD

)1(50150100080

36002

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E

)1(50200100080

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emsTi

D

Message Head abnormal modes handling – case3 (t2)

A

C

BAD

C

Message Holder abnormal modes handling – case1(T’)

A

C

BAD

msmsTi 7.1630010050

B

msmsTi 3.3330020050

Message Holder abnormal modes handling – case2 (t3)

A

C

BAD

msmsTi 7.1630010050

B

msmsTi 3.3330020050

Addressing Model

r

Update of the total relative distance

Update of total relative distance

A A B

Simulation Parameter

Parameter Value

802.11 DCF data rate 2Mbps

Communication Range 250m

Number of lanes 2/direction

Vehicle density 5-100 cars/(km。 lane)

Average speed 90km/h

Waiting time T0 50ms

Waiting time T’ 1s

Waiting time t1 2s

Waiting time t2 2.5s

Waiting time t3 3s

Simulation model 12km

Distance from S to D 6.5km

message size 512bytes

Simulator ns-2 (version 3.31)

Comparison: Epidemic routing M. Nekovee, and B.B. Bogason, “Reliable and Efficient

Information Dissemination in Intermittently Connected Vehicular Adhoc Networks,” Proceedings of IEEE Vehicular Technology Conference, pp.2486–2490, April 2007.

A. Vahdat, and D. Becker, “Epidemic Routing for Partially Connected Ad Hoc Networks,” Technical Report CS-200006, 2000. http://issg.cs.duke.edu/epidemic/epidemic.pdf

Conclusion This paper proposed a novel relative position base

d message dissemination scheme for VANETs.

The scheme can ensure robust message dissemination and desirable performance under all VANET traffic densities.