OPTIMAL CONTENTION WINDOW ASSIGNMENT FOR BEST EFFORT SERVICES IN IEEE 802.16 SYSTEMS

摘要

In IEEE 802.16-based networks, the transmission of best effort (BE) traffics is basically controlled by the contention-window size. Subscriber stations (SSs) contend for bandwidth request to allocate uplink bandwidth for BE traffics. The truncated binary exponential backoff algorithm is used to schedule for bandwidth-request retransmissions in IEEE 802.16-2004 standard. In this paper, we propose a contention-window size assignment scheme for the base station. The contention-window size is updated dynamically according to the arrival rate of BE traffics and the number of SSs which encountered transmission collision for bandwidth-request. Simulation results show that the proposed scheme indeed can improve throughput and delay in the transmission of bandwidth-request. Moreover, the proposed scheme offers optimal throughput for BE traffics.