Improved GPSR Algorithm Based On Trust Management In VANET Environment

Vehicular Ad Hoc Network(VANET)is a distributed multi-hop wireless ad hoc network,which improves safety of road traffic through communication between vehicles and between vehicles and roadside units.Greedy Perimeter Stateless Routing(GPSR)protocol,which is the most suitable for VANET scenarios among location-based routing protocols,has attracted extensive attention of researchers.However,this protocol does not take into account the routing decision of next hop selection,and at the same time,the open network environment poses a great threat to security.Therefore,this paper comprehensively considers the optimal routing decision and security of the routing protocol in the VANET environment,and improves the GPSR protocol.The main research contents are as follows:(1)A comprehensive metric model is proposed to solve the problems of unstable links and redundant paths between nodes caused by insufficient consideration in GPSR protocol routing decisions.When GPSR protocol selects the next hop node in greedy forwarding,it only considers the distance between the relay node and the destination node,ignoring other factors that affect the routing decision.Therefore,this paper proposes the P-GPSR protocol,which comprehensively considers the distance,direction,density and link stability between nodes when the node makes the routing decision of the next hop selection.The next hop node is selected by the comprehensive metric value of the node,and routing decisions are made to avoid path redundancy and consider link stability.(2)Aiming at the problem that malicious nodes seriously threaten network security,this paper proposes a T-GPSR protocol,which uses a trust management model in the VANET environment to improve the GPSR protocol.In this trust model,the source node calculates the comprehensive trust value of the node to be selected by obtaining the direct trust value and the indirect trust value of the neighbor nodes.The nodes whose comprehensive trust value is lower than the trust threshold are deleted from the candidate node set as malicious nodes to reduce the impact of malicious nodes on network security.At the same time,nodes with different trust intervals are selected conditionally to avoid the situation that a node is over-selected.In addition,the initialization of the trust value of the new node is also added,so that the new node has more opportunities to participate in packet forwarding.(3)In order to further improve the routing performance,the integrated metric model and trust management model are combined,and an improved GPSR protocol PT-GPSR based on trust management is proposed.The problems caused by insufficient consideration of routing decisions are solved by the two indicators of comprehensive metric value and comprehensive trust value,and the influence of malicious nodes on network security is also reduced,and the network performance is finally improved.Based on the NS3(Network Simulator version 3)network simulator and the SUMO(Simulation of Urban Mobility)traffic simulator,a simulation experiment platform is constructed,and the GPSR protocol,P-GPSR protocol,T-GPSR and PTGPSR protocol are carried out in two environments.Simulation.The experimental results show that,under the same conditions,the PT-GPSR protocol with integrated metric model and trust management model is least affected by malicious nodes,and performs better in packet delivery rate and average end-to-end delay.