Optimal Contention Window Assignment for Best Effort Services in IEEE 802.16 Systems

C.-C. Chen, J.-L.C. Wu, and C.-Y. Hsu (Taiwan)


IEEE 802.16, contention window, best effort


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.

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