Connectivity Analysis In Cognitive Vehicular Networks

Intelligent Transport System(ITS)has received extensive attention in order to ensure road safety,improve transportation efficiency and resource utilization.Vehicular Ad Hoc Network(VANET)is an indispensable and critical part of the ITS.VANET takes full account of mobility management and integrates V2 X and 5G communication technologies,which greatly improves the quality of service(Qo S)of the network.However,with the increasing number of wireless applications and in-vehicle services,the communication demand in the VANET increases dramatically,and the scarcity of spectrum resources is aggravated.To improve the utilization of spectrum resources,cognitive radio(CR)technology has been introduced into the VANET,forming the Cognitive Vehicular Network(CVN).There are two main reasons why cognitive radio technology can be applied to VANET: Firstly,with the rapid development of various communication technologies,the available spectrum resources are increasingly scarce.With the use of cognitive radio technology,the idle spectrum can be used dynamically without special band division.Secondly,because vehicles on the road tend to be highly mobile and the network environment on the road is highly dynamic,the available authorization spectrum can be sensed in a more reasonable way without relying on large-scale infrastructure.However,the dynamic characteristics of the available spectrum and network topology in the CVN have brought great challenges to the connectivity analysis.The factors involved include the cognitive ability of vehicles,the cooperation of different inter-vehicle communication modes,vehicle transmission capacity,vehicle density and the transmission power of primary users.These factors have mutual influence on the connectivity performance of the CVN.Therefore,this paper first models and analyzes the connectivity in single-hop and multihop clustering scenarios in the CVN.In the single-hop scenario,the log-normal shadowing model is introduced to analyze,and the connectivity probability expression of the whole network is derived based on the vehicle cognitive probability and communication probability.For the multi-hop clustering scenarios,this paper divides them into two sub-processes for detailed analysis,which are inter-cluster integration process and intra-cluster communication process,and deduces their respective connectivity probability expressions.The simulation results and comparative analysis show that the network connectivity performance in multihop clustering scenario is significantly better than that in single-hop scenario.Then,on the basis of the above analysis,this paper further considers the connectivity performance of the CVN under the influence of the primary users.The network model considering the behavior of the primary user is established,and the expressions of outage probability and non-outage probability are deduced.Finally,the final expression of the connectivity probability is deduced by combining the vehicle cognitive probability with the inter-vehicle communication probability.The simulation results show that the distance between the primary user and the cognitive vehicle and the transmission power of the primary user have a significant impact on the network connectivity performance.