Heuristic Contention Based Bandwidth Request for IEEE 802.16 Networks

In this paper, we suggest and investigate CDMA based contention resolution with base station assisted backoff (C-BAB) for orthogonal frequency division multiple access (OFDMA) based WiMAX networks. Previous research on contention resolution considered CDMA with mobile assisted TBEB(C-MAB) suffers low contention efficiency and high access delay due to the type of accessing mechanism in WiMAX network. Also it has limitations in estimating the contention window based on current channel status. With C-BAB, the BS estimates the optimum contention window by accounting average contention window with instantaneous probability of failure. The performance of WiMAX network in terms of contention efficiency and access delay is studied by varying number of stations and the number of ranging slots allocated for bandwidth request. The contention efficiency and access delay of C-BAB show an improvement of 23.87% and 33.20%, respectively, than C- MAB.