Research On Wireless Communication And Resource Allocation In V2X Communications

With the number of vehicles increasing,the demand for various types of applications,such as high-definition maps,dynamic traffic information and security services,is also gradually showing diverse characteristics.However,considering that the basic communication infrastructures are overloaded,and there are many problems such as too large delay and unstable transmission links when vehicle requesting from remote base station,it is necessary to fully cooperate with the infrastructure and available vehicles to assist in meeting various requirements.As an effective vehicle management strategy,Internet of Vehicles (IoV)alleviates the sharp contradiction between vehicle communications demand and resource allocation with infrastructure shortage in a large extent,and has a broad development prospect.However,considering the limited resources and the repeatability of massive requests,the technology of IoV still faces three major problems.Firstly,due to the large number of vehicles and serious traffic jams,it is inefficient and feasible to manage each vehicle separately,which puts forward high requirements for resource allocation scheme.Second,the vehicles steer too fast,resulting in too short a contact time between the vehicles and the infrastructure to download the entire content.Finally,there is repeatability and redundancy of content requesting among vehicles,which further increases the communication burden on the infrastructure.Therefore,in view of the above three aspects of the problem,this paper respectively carried out the researches.Firstly,we studied the data sharing and frequency spectrum resource management scheme based platoon scenario,then in view of the vehicle and infrastructure cannot support large content assigned completely,we proposed the method of NOMA based coded data caching and dissemination in vehicular networks.Finally,aiming at the problem of vehicle repeatly request the contents,we put forward a method based full-duplex relay aided for efficiently content sharing.The specific research contents are as follows.First of all,considering the serious traffic jams and insufficient spectrum resources,we consider the platoon scenario,and propose the data sharing and frequency spectrum resource management scheme based platoon scenario.Specifically,considering multiple vehicles using the same resources,it will produce cumulative interference.Therefore,we use the cumulative interference among multiple vehicles to construct hypergraph,then we use hypergraph coloring algorithm to manage the interference among the vehicles in the platoon,and propose hypergraph-based resource allocation and interference management,to maximize the the spectrum efficiency in platoon scenario and ensure the communication quality at the same time.Finally,simulation results illustrate rationality and effectiveness of the proposed scheme.Secondly,in view of the limited contact time between the vehicle and the road side unit,and the vehicles cannot receive complete content within the contact time,we consider introducing the distributed coded cache technology,and propose the method of the NOMA based coded data caching and dissemination in vehicular networks scheme.Specifically,we use erasure codes to encode content before transmitting content.After road side units transmit parts of content pieces to vehicles,the vehicles receive the rest of content pieces through V2V communication.Considering that when the traditional orthogonal multiple access technology is used to transmit the content pieces,content pieces need to be transmit to different vehicles successively,which has the problem of low spectral efficiency.We use the non-orthogonal multiple access technology to transmit the content pieces to vehicles in the scenario,so as to improve the efficiency of the deployment of the content pieces.In the V2V communications stage,interference management is carried out among vehicles and spectrum resources are allocated reasonably.We propose a matching theory based resource allocation and user pairing scheme to minimize the total delay of vehicles.Finally,simulation results illustrate the rationality and effectiveness of the proposed scheme.Finally,given that there will be a number of different hot contents,the request vehicles will have different requirements for different hot contents,and the repeated requesting of the same content will increase the pressure of base station backhaul link,we propose a method of full-duplex relay aided for efficiently content sharing.Specifically,we consider the content pieces of different contents to deploy on content caching vehicles,and the content request vehicles can receive enough content pieces from content caching vehicles to decode the original content.However,the cache space of content caching vehicles is limited,resulting the content caching vehicles cannot cache content pieces of all contents,so that how to make content caching vehicles caching content pieces will affect the performance of the whole system.At the same time,if a content caching vehicle leaves the target area,it will cause the loss of its caching content pieces and reduce the robustness of the system.Therefore,it is also very important to consider the repair of the lost or damaged content pieces.In particular,we consider the reasonable design for different contents caching on cache vehicles in the scheme,then we use full-duplex technology to receive content pieces from caching vehicles.At the same time,considering the content pieces will missed due to a cache vehicles leave the condition,we put forward matching theory based content pieces deployment and transmission scheme to minimize the request vehicle transmission cost of obtaining a desired content.Finally,simulation results illustrate the rationality and effectiveness of the proposed scheme.