The Research On Delay Minimization Routing Algorithms In Urban CR-VANET

The limitation of spectrum resources is one of the most important factors that restrict the development of VANET(Vehicular Ad Hoc Networks).Because the cognitive radio technology enables unauthorized users to dynamically access the free frequency band,the introduction of cognitive radio technology into VANET(CRVANET)can effectively alleviate the shortage of communication resources in VANET.However,the links in CR-VANET can be easily interrupted by vehicle density,vehicle mobility,and PUs’ activities.Moreover,the link’s interruption will result in the delay.The low latency network is the prerequisite for applications functioning well in CRVANET.In order to minimize end to end delay in urban CR-VANET,the content of the thesis is presented as follows:1)For the rapid movement of vehicles and across cell transmissions in urban single lane expressway,we study and design the delay minimization routing algorithm DMRSCR-VANET in urban single lane scenario.Firstly,we analyze the end to end delay in urban single lane scenario.Secondly,based on the vehicles fast mobility and the area that relays locate in,we divide the end to end transmission into three subscenarios.In each scenario,we design the greedy forwarding based channel selection and relay selection algorithm to ensure the minimum delay.Finally,through extensive experiments,the simulation results show that our algorithm is superior to SABE and KFCR-VANET in end to end delay.2)For the rapid movement of vehicles,the sparsity of traffic density and across cell transmissions in the urban bi-directional roadway,we study and design the delay minimization routing algorithm DMRBRCR-VANET for urban bi-directional roadway scenario.Firstly,we study the end to end delay in urban single lane scenario.Secondly,based on vehicle sparse density and the relationship between vehicle’s direction of motion and packets expected transmission direction,we divide the transmission into four sub-scenarios.In each scenario,we design the greedy forwarding based channel selection and relay selection algorithm to ensure the minimum delay.Finally,through extensive experiments,results show that our algorithm is superior to SABE and KFCRVANET in end to end delay.3)For the rapid movement of vehicles,the sparsity of traffic density and across cell transmissions in the urban intersection,we study and design the delay minimization routing algorithm DMRICR-VANET for urban intersection scenario.Firstly,we study the end to end delay in urban intersection scenario.Secondly,based on vehicles’ connectivity and PU activities,we design a metric to select the optimum direction.Then we propose jointly channel selection and relay selection algorithm for delay minimization.Finally,through extensive experiments,results show that our algorithm is superior to CAIR and DDDR-VANET in end to end delay.