A Fast Efficient Collision Resolution Algorithm in IEEE 802.16

IEEE 802.16 broadband wireless access system adopts TDMA (Time-Division Multiple Access) and contention-based reservation of resource in its uplink MAC layer. Thus there are contentions and collisions between SSs(Subscriber Stations), and the performance is inevitably deteriorated. A fast and efficient backoff algorithm DBC (Dynamical Backoff Control) is proposed to solve the problem. In DBC, by predicting the number of request messages in next uplink frame, BS controls the optimal backoff ranges dynamically. As a result, the successful rate of sending request messages in each frame is increased, the data throughput of MAC layer is promoted, and the mean access delay of SS is reduced. Simulation is conducted in OPNET to compare DBC with binary exponential backoff. Simulation results demonstrate that proposed DBC algorithm makes a great improvement in system performance.