Performance analysis of bandwidth request mechanism in ITU-R vehicular pathloss model

In this paper, we investigate the performance of contention bandwidth request (BR) mechanisms for WiMAX two-hop relay network under ITU-R vehicular pathloss model. The first hop and second hop corresponds to air interface from mobile station (MS) to relay station (RS) and from RS to base station (BS), respectively. To overcome fixed bandwidth allocation at RS, the proposed system carries out contention BR mechanism. Under these circumstances, the contributions made in this paper are two-fold. First, unique failure models are developed for two hops of a link and the stations (MS and RS) adaptively set their contention window based on the developed model. Such technique effectively reduces collision due to contention with reduced access delay during contention bandwidth request. Finally, the two-hop BR along with the failure model is realized with four combinations of message and code BR mechanism. Simulations validate the effectiveness of the joint BR mechanisms under ITU-R vehicular environment.