Performance Analysis And Optimization Of Cognitive Radio Cooperative Vehicle Network

With the increasing scarcity of spectrum resources,the concept of cognitive radio(CR)gradually enters people's field of vision.Cognitive radio has the ability of perceiving "spectrum hole"(spectral resources that have been allocated to a user but not used for a certain period of time)and making reasonable use,which is an effective means to alleviate the shortage of spectrum resources and has applications in all fields.Vehicles are one of the most important tools for people to travel.How to make smarter trips and how to make them more convenient and convenient for people is an urgent problem to be solved.Therefore,the vehicle ad hoc networks(VANET)has gradually become the focus of attention.Collaborative vehicle network can not only provide safety information but also provide entertainment information,which is an important part of intelligent transportation.In order to study the reachable throughput and resource allocation problem of the vehicle network,this paper applies cognitive technology to the vehicle network.In order to obtain the throughput that can be achieved when multiple vehicles of interest(VOI)want to download data,first,cognitive radio technology is applied to a collaborative vehicle network,by establishing a Markov model,the three states of a VOI vehicle node are analyzed.According to the relationship between the equilibrium conditions and the transition probability in the steady state,the probability that a vehicle node is in the download state under steady state is deduced,and then the expression of the throughput that a vehicle node can reach in the defined period is obtained.Therefore,it provides a certain reference and theoretical basis for the deployment of base stations in reality.When solving the problem of multiple vehicle users competing for multiple channels at the same time,in order to ensure user fairness while further improving the throughput of the system,the vehicle users adopt the proportional fair scheduling algorithm to allocate resources while incorporating cognitive technologies into consideration.The scheduled user has the ability to perceive the "spectral hole",that is,the cognitive user uses the idle time slot of the primary user to transmit his own data to achieve the purpose of improving the system throughput.At the same time,the problem of cognitive user reconstruction is also considered.For the channel available time is less than the transmission time,two reconstruction schemes are proposed.Bycomparing and analyzing the delays in the two cases,the reconstruction decision basis is given.