Analysis and Enhancement of Bandwidth Request Strategies in IEEE 802.16 Networks

IEEE 802.16 based broadband wireless access network is considered as one of the most promising wireless access technologies. It employs a request/grant scheme in bandwidth allocation where each subscriber station (SS) can send bandwidth requests (BRs) to the base station (BS) before bandwidth can be granted to SSs. The 802.16 standard defines two types of BR strategies, namely incremental requests and aggregate requests. In this paper, we first present an analytic model to analyze their performance and show that both types of BRs have rooms for improvement when facing two common types of traffic patterns, called the uphill traffic pattern and the periodic/bursty traffic pattern, in terms of overhead and data waiting time in the queue. Then, we propose two enhancement strategies, called the aggressive strategy and the conservative strategy, that exploit the property of the two traffic patterns to improve the performance. The simulation results show that the two enhancement strategies can effectively reduce the overhead and data waiting time, at the price of somewhat less bandwidth utilization in the case of conservative strategy.