Cross-Layer Design of Optimal Contention Period for Mobile WiMAX Systems

In IEEE 802.16e mobile WiMAX system, since mobile stations (MSs) send bandwidth request (BR) messages to base station (BS) during contention period when they need uplink channel to transmit data in the case of multicast polling or broadcast polling, the uplink performance is affected by the size of the contention period in the uplink subframe. The access delay will be increased if the size of the contention period is too small and the resource will be wasted on the contrary. Therefore, we propose a cross-layer analytical model for designing the optimal size of the contention period. The model is simulated using OPNET modeler, and the results show that our proposed model can improve the uplink data transmission efficiency.