Research On GPSR Routing Algorithm In Vehicular Ad Hoc Networks

Vehicular Ad Hoc Network(VANET)is an important part of the intelligent transportation systems.The routing protocol is the key technologies in VANET,largely determining the performance of the communication system in VANET.VANET draws higher demand in the routing protocol because of the fact that the vehicle nodes movies too fast,which makes that the network topology changes frequently and the relationship between the nodes is unstable.On this basis,this paper proposed an improved GPST routing protocol in VANET.Firstly,this paper introduces Vehicular Ad Hoc Network and several representative routing protocols in VANET,including AODV,DREAM and GPSR.Several mobile model such as stochastic mobile model,smooth moving model,urban scene movement model and Manhattan mobile model are described.Then several vehicle node motion models are studied and the Vanet Mobi Sim traffic simulator,which can truly reflect the actual traffic scene,is introduced in detail.Vanet Mobi Sim is used to generate the traffic scene files that can be applied directly to NS2.Then the greedy forwarding algorithm and peripheral forwarding algorithm in GPSR,which are suitable to VANET,is analyzed in detail,and the comparison experiment between GPSR routing protocol and AODV protocol is simulated by NS2.Secondly,this paper analyzes the shortcomings of GPSR routing algorithm in VANET.Then aiming at the instability of the neighbor relationship and the redundancy of the communication path in the routing algorithm,we propose two improvement measures.When the routing algorithm performs greedy forwarding,the cumulative communication duration parameter of the neighbor node is added.When the next hop forwarding node is selected,the neighbor node with the largest cumulative communication duration is selected within a given distance range,which makes the next hop node with both a distance advantage and a stability.When the routing algorithm performs peripheral forwarding,the positional relationships between neighbor nodes are considered.By calculating the angle between the neighbor node and the destination node,the neighbor node which has the most suitable position with the destination node is selected as the next hop forwarding node.Therefore the improved routing path is more reasonable.The improved GPSR routingalgorithm is implemented through TCL programming language and C++programming language.The improved GPSR routing algorithm is embedded in NS2 and simulated with Vanet Mobi Sim traffic simulator.The experimental results show that compared with the original algorithm,the improved GPSR routing algorithm has improved the packet loss rate,end-to-end average delay and throughput performance.Therefore,the improved algorithm is more suitable to VANET.Finally,this paper points out the shortcomings of the improved GPSR routing algorithm and the next work plan,and looks forward to the future development direction of the VANET.