On VANET Routing Algorithm Based On Mobile Model With Avoidance Analysis

ii Because of the limited vehicle network node communication range of the VANET,the reliability and stability of information transfer can be easily affected by some environmental factors.In real day life,there exist many scenarios that some vehicles will avoid emergency vehicles,and thus the running track of special vehicle breaks the original driving pattern,and then,affect the performance of vehicle network routing.In this thesis,in order to deal with the problems that driving track will change under avoidance environment,a mobile vehicle model that includes avoidance behavior is introduced;Based on the characteristics of avoidance environment,an adaptive routing algorithm strategy to avoidance environmental is presented,start with improving the reliability of data transmission.Aiming to reduce the delay,the operational functions of proposed routing algorithm strategy is implemented by FPGA.Detail words are listed as follows:Firstly,according to the driving characteristics of vehicles in avoidance scene,based on IDM_LC mobile model,a novel mobile model IDM_A is put forward,and expand to the VANET-Highway scenario that is implemented by NS-3,in advance,constructs single track three-lane road scene,embedded IDMA mobile model to simulate the avoidance behavior.In those two models,simulate and analyze the vehicles driving speed in different traffic density,and in addition,we analyze the connectivity influence of changing the traffic track.Simulation results show that: as the emergency vehicles join in,the vehicle connectivity will become better.Secondly,considering the defects of GPSR routing protocol in urban environment,this paper refers to the thought that transmit VHRP routing protocol in group,and proposed one greedy forwarding that restrict linear path by grouping the velocity direction,take use of traffic information to help vehicles that in crossroads to select the improvement strategy of transmission direction-GPSR_A routing algorithm can be applied to an avoidance scene.In the NS-3,this paper further expands constructed avoidance scene,and builds urban roads scene that contains more than one intersection,we write the GPSR_A,GPSR,GPCR routing protocol-related code,and analyzed these three routing protocol performance from the three aspects of delivery rates,the number of nodes required for transmission and the transmission delay.The results showed that: GPSR_A routing protocol has obviously advantages in terms of the data delivery rate and the number of nodes required for transmission,in addition,its transmission delay also has a relatively good performance.Finally,as GPSR_A algorithm includes angle calculation,it is more time-consuming than other calculations.For the problem of its increased delay,proposed an angle offset improved algorithm that based on CORDIC rotation algorithm to improve the speed,and uses FPGA realized the hardware implementation.According to the required computation time,analyzed and compared the improved algorithm and CORDIC algorithm.Experimental results show that: the proposed improved algorithm can meet the needs of GPSR_A routing algorithm,and the computation time is much less than the traditional angle algorithm.