Modification of Bandwidth Request Mechanism in MAC 802.16 for Improved Performance

Request (BWR) is the mechanism by which the Subscriber Station (SS) communicates its need for uplink bandwidth allocation to the Base Station (BS). The performance of the system is affected by the collisions of BWR packets in uplink transmission, that have the direct impact on the size of the contention period in uplink sub frame, uplink access delay and uplink throughput. In this paper, we evaluate the performance of this scheme based on the metrics of delay and throughput. Then we enhance its performance by incorporating the principle of circularity. Circularity is a paradigm that allows the identification of certain conditionally selective events or groups of packets. Using this, we introduce selective dropping of BWR packets. This new paradigm improves contention resolution among the bandwidth request packets and thereby reduces the delay and increases the throughput regardless of the density and topological spread of subscriber stations handled by the BS in the network.