Research On Routing Protocol Based On Opportunity Communication In Vehicular Ad-hoc Networks

The nodes in the Vehicular Ad-hoc Networks(VANETs)are the vehicles which move at a rapid speed.The mobility of nodes makes the network topology change frequently,thus,the connection between vehicle nodes are intermittent.As a result,the communication between the vehicle nodes is extremely unstable,and the transmission performance is rapidly deteriorating.In order to provide better services and improve the traffic congestion,it is needed to design an efficient routing protocol for VANETs which has better packet delivery rate and network overhead.This article focused on the routing protocols in VANETs environment,we concluded our contributions as follows:1)This paper analyzed several major routing protocols,and mainly focused on the routing protocol based on the opportunistic network which is called Prophet,including the principle of the Prophet routing protocol and the defects used in the VANETs environment.Furthermore,we simulated the multiple vehicle movement models and compare their advantages and defects.Finally,the experimental results indicated that the SPMB model(Shortest Path Map Based Movement)is more suitable for actual traffic road environment.2)This paper analyzed the network performance and application defects of Prophet protocol in VANETs networks,especially in the urban road scenarios.And an improved routing protocol was proposed — MD_Prophet protocol(Multi-Dimension Probabilistic Routing Protocol based on the Communication of Opportunity)which is based on Prophet.Firstly,three new concepts were defined: the stability of effective time,the connection frequency for nodes based on the time period and the expected delay of meeting.In addition,we analyzed their impacts on the data forwarding quantitatively.Secondly,the prediction algorithm of the delivery probability was improved based on the above mentioned concepts.Finally,in order to improve the data forwarding strategy and optimize the data transmission,multi-dimensional forwarding model was constructed according to the prediction algorithm of the delivery probability and expected delay of meeting.3)MD_Prophet protocol was implemented on the ONE simulation platform.To analyze and compare its network performance,a large number of simulation experiments were performed.Comparing to Prophet protocol,these simulation result showed that the packet delivery of MD_Prophet protocol was enhanced,the network overhead was reduced,and overall performance were improved generally.In addition,we analyzed the performance of the MD_Prophet protocol by changing the number of vehicles,the speed of vehicle,and the buffersize of the vehicle.Specially,for urban traffic scenarios where the vehicle density is high and the speed of vehicles is not too high,MD_Prophet protocol has more advantages than others.