Study On Ultra-reliable And Low Latency Routing Technology For V2V

With the increasing number of vehicles,the driving safety of vehicles has become more and more important.Internet of Vehicles(IoV)helps to build an intelligent transportation system,which can effectively improve the safety of vehicle driving.Ultra-reliable and low latency communication(URLLC)are important indicators to measure the communication performance of IoV.Therefore,it is of great significance to realize the ultra-reliable and low latency transmission for IoV.Routing technology is typically used to find the transmission path from the source point to the destination point for packets,and it is an important technology to realize URLLC.However,current implementation of URLLC for IoV is mainly focused on the physical layer,and routing technology to realize URLLC has not formed a technical specification.To solve this problem,this dissertation designes a routing algorithm for V2 V communication to realize the URLLC between vehicles.The main contents of this study are as follows:First,combining the function and communication scenario of each part in IoV,the estimation models of latency and reliability are established.Then,key factors that affecting the latency and reliability of the routing algorithm are analyzed.According to this,the thought of constructing weights and back-off mechanism is proposed to optimize the latency and reliability performance.And utility functions for latency and reliability are established.After that,from the perspective of constructing weights,a routing algorithm based on dynamic weights is designed.Subjective and objective weighting method are used to solve weight coefficients,but the judgment matrix could not be determined.Aiming at this problem,a low-latency solution for weight coefficients is proposed.Finally,according to the thought of fallback mechanism,a model of fallback mechanism based on waiting and replicas is established to improve the reliability of the routing algorithm based on dynamic weights.Simulation results show that,compared with the greedy algorithm in GPSR and Dijkstra algorithm in GSR,the routing algorithm based on dynamic weights decreases the transmission latency by 47.9%.In addition,the latency performance is more significant when the vehicle density is high,and the transmission latency has been decreased by 54.6% at best.In addition,through the use of the back-off mechanism,the packet arrival ratio of the routing algorithm based on dynamic weights has increased by25.8% and the low-latency performance is maintained.The contribution of this dissertation mainly includes the following three aspects:(1)The thought of constructing weights and fallback mechanism is proposed as the whole scheme of URLLC routing algorithm for IoV.Based on this scheme,the routing algorithm based on dynamic weights and its fallback mechanism are designed,which jointly optimize latency and reliability to achieve a balance between latency and reliability performance.(2)Aiming at low latency,in view of the problem of the routing strategy,three communication parameters that affect V2 V communication are determined in the routing algorithm based on dynamic weights.And a weight function is established as the basis for routing selection.Then,when solving the weight coefficients,in order to solve the problem that the subjective and objective weighting method cannot determine the judgment matrix,a low-latency solution for weight coefficients is proposed.According to this,the optimal solution of the importance factor in the judgment matrix is obtained.(3)Aiming at high reliability,a fallback scheme based on waiting,replicas and two-hop backhaul is designed for reliability problem caused by reducing the latency using weight-constructing method.And a model of fallback mechanism is established for the routing algorithm based on dynamic weights.