A generalized analytical model for contention-based access in IEEE 802.16 wireless networks

The base station in IEEE 802.16, or WiMAX, networks allocates contention-based time slots for the mobile stations to transmit their requests for additional bandwidth. Using a technique called subchannelization, multiple concurrent transmissions by mobile stations can be admitted by the base station during the same contention period. For transmission during this period, each station employs a contention-resolution mechanism. In this paper, we develop an analytical model for the bandwidth request and resolution mechanism during this contention period when subchannelization is employed. The model is shown to accurately model the contention period when subchannelization is enabled. Performance metrics, such as throughput, average waiting time, and contention period capacity, show that adding more subchannels to the contention time slots increases throughput and reduces average waiting time. Several simulation results are carried out to validate the model.