A Mobile Infrastructure Based VANET Routing Protocol in the Urban

Environment

School of Electronics Engineering and Computer Science, PKU, Beijing, China

IEEE CMC 2010

Jie Luo Xinxing Gu Tong Zhao Wei Yan

Outline

Introduction Related Work Urban VANETs Analysis MIBR Design

Routing Forwarding

Performance Evaluation Conclusion

Introduction

Vehicular ad hoc networks have recently received considerable attention

The VANET provides both Roadside-to-Vehicle communication Inter-Vehicle communication (IVC)

Works like a MANET with its own unique characteristics

Introduction

Key Challenge of Urban VANET The existence of frequent network disconnection is one of

the key challenges for routing protocols for urban VANETs

Introduction

Goal Analyze the features of urban VANET Propose a routing protocol MIBR to improve the

connectivity of the network by taking advantage of urban characteristics

Greedy Perimeter Stateless Routing for Wireless Networks. MobiCOM 2000

Related Work

GPSR GPSR selects the node that is the closest to the destination

among the neighboring nodes

S

A

B

D

GPSR will choose B, because B is closer to D than A.

Related Work

RAR A hybrid routing protocol with vehicles and RSU (Road

Side Unit) Roads are divided into sectors by RSU The drawback of this protocol is the requirement and

distribution of static node or RSU

Urban VANETs Analysis

Vehicle movements are constrained by roads in urban environment The routing in urban VANET should be a sequence of road

segments The decision to choose which road segment near the

junction for forwarding is critical

Traffic lights have great influence on the vehicle movement

Urban VANETs Analysis

Vehicles are moving like a cluster

Urban VANETs Analysis

Vehicles have at least two different types in the urban environment Ordinary cars

Less than bus (80% of ordinary cars in Beijing)

Buses More than ordinary cars (20% of buses in Beijing) Larger and more powerful Can carry better wireless equipment with a larger transmission

range than ordinary cars

MIBR Design

Assumptions Each vehicle knows its location through GPS Each vehicle has a digital street map including bus line

information Source node can get the information of destination location

MIBR Design

Assumptions Each bus has two wireless interfaces working on different

channels R1 and R2

Ordinary car has only one interface R1

R1

R2

R1

Transmission range between buses

Transmission range between cars and between cars and bus

MIBR Design

Overview Routing

Selecting an optimal route which consists of a sequence of road segments with the best estimated transmission quality

Forwarding Efficiently forwarding packets hop-by-hop through each road

segment in the selected route

MIBR Design

Routing Calculate hop count number of each road segment by the

density of buses on the road segment MIBR prefers road segment with less hop count number

Dijkstra algorithm would be used to select a shortest route with the minimal expected hop count

The next road segment would be chosen when packet is near a junction

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MIBR Design

Forwarding Bus first strategy

Send the packet to the node on the next road segment when it is near the junction

The decision of next hop near the junction is critical Buses have higher priorities to be the next hop because of the

transmission range between buses is larger

MIBR Design

Forwarding If there are any buses on the next road segment, choose the

one which is the closest to the junction after the next junction. Otherwise, choose the ordinary car

If there are no vehicles on the next road segment, and packet is now on a bus or on an ordinary car, choose a bus which is closest to the next junction. Otherwise, choose the ordinary car

MIBR Design

Forwarding If there are no better suitable forwarding nodes, drop the

packet

Performance Evaluation

Simulation Model Ns-2 simulator Simulated area is based on Southern Beijing with a

1700m*1000m size in real world The vehicle movement trace is generated by

VanetMobiSim

Performance Evaluation

Parameter Value

R1 150m

R2 300m

Bandwidth for both channel 2Mb

Beacon interval 1.0s

Vehicle velocity 0-30m/s

Number of nodes 100-250

The bus percent 20%

Packet size 512bytes

Simulation time 600s

Simulation Parameters Table

Performance Evaluation

The data delivery ratio in different network density

Performance Evaluation

Throughput of networks with 200 nodes

Conclusion

The proposed protocol is a geographical routing using the map topology and the bus line information

The algorithmic complexity of MIBR is low, and the deployment is easy because no static nodes or RSUs are needed in MIBR

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