Analysis and Enhancement of BWR Mechanism in MAC 802.16 for WIMAX Networks

Abstract

WiMAX [Worldwide Interoperability for Microwave Access] is the latest contender as a last mile solution for providing broadband wireless Internet access and is an IEEE 802.16 standard. In IEEE 802.16 MAC protocol, Bandwidth 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. This paper mainly deals with Performance Analysis and Improvement of Uplink Throughput in MAC 802.16 by the Application of a New Mechanism of Circularity. The implementation incorporates a generic simulation of the contention resolution mechanism at the BS. An analysis of the total uplink access delay and also uplink throughput is performed. A new paradigm of circularity is employed by selectively dropping appropriate control packets in order to obviate the bandwidth request collisions, which yields the minimum access delay and thereby effective utilization of available bandwidth towards the uplink throughput. 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.