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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
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A Mobile Infrastructure Based VANET Routing Protocol in the Urban Environment School of Electronics Engineering and Computer Science, PKU, Beijing, China IEEE CMC 2010 JieLuo XinxingGu 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
Related Work • GPSR • GPSR selects the node that is the closest to the destination among the neighboring nodes D GPSRwill choose B, because B is closer to D than A. A B S Greedy Perimeter Stateless Routing for Wireless Networks. MobiCOM 2000
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
Urban VANETs Analysis • Traffic lights have great influence on the vehicle movement 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 Transmission range between cars and between cars and bus R1 R1 Transmission range between buses R2
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 wouldbe 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
MIBR Design A B
MIBR Design A B
MIBR Design A B
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 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