The Research Of Channel Allocation Based On802.11p In VANET

With the continuous development of the automotive industry,at present,there is awireless communication technology applied to the traffic environment attracting more andmore attention.That is Vehicual Ad-hoc Network(VANET).VANET contains thecharacteristics of wireless Ad-hoc and sensor networks, which makes communicationbetween cars(Vehicle-to-Vehicle,V2V) or communication between vehicles and roadsideinfrastructure(Vehicle-to-Roadside,V2R).In the traditional single channel MAC protocol,allnodes share a common channel for transmission,in the vehicle environment,there are manyvehicle nodes and roadside infrastructure,so that single channel allocation will make thenetwork throughput limited.Therefore,multi-channel distribution method is used inVENET,each node can use more than one channel,the vehicle can transfer data in differentchannels respectively,which can improve the network throughput.However,since the high-speed moving of vehicle,the vehicle state of connection and the signal changes rapidly.Theeffect of communication is not ideal,the channel assignment is particularly difficult.Therefore a more reasonable channel assignment strategy is needed for the high speedmobile environment and even some special place.This paper based on the existing vehicle network communication protocol andmulti-channel distribution strategy,carries on research to the key problems of vehiclecommunication.First of all,traffic in cities is large,when many vehicles need tocommunicate,the collision in communication easily occur.Secondly,since the traditionalmulti-channel distribution strategy divide the time into control slots and transmission slotsequally,when the numbers of vehicles is few,there will be a waste of channel,when thenumbers of vehicles is big,the channels is not enough for more vehicles.Thus,This paperpropose a distributed channel assignment strategy that divided the CCH interval intoreservation period and safety period,and divided the reservation period into several slots forvehicles.Each vehicle reserve the channel in its own slot to reduce the messagecollision.And when the numbers of vehicles is big,SCH interval is not enough for thetransmission of message,through make a reasonable method to make the vehiclecommunicate in the reservation period without affecting other vehicles’ reservation and thecommunication of safety message,in order to improve the channel utilization. Through the implementation of the protocol in the network simulator veins,the resultshows that the method can greatly improve the channel utilization and reduce theoccurrence of communication collision.