A Fair Centralized Scheduling Algorithm Based on Traffic Demand for IEEE 802.16 Mesh Networks

The IEEE 802.16/WiMAX mesh network, which is dynamically self-organized and self-configured, is a promising solution for wireless broadband access in metropolitan scale with a cost-effective deployment. As in most wireless multi-hop networks, traffic scheduler in MAC is one of most important factor for the performance of 802.16 mesh networks. Two scheduling modes, centralized scheduling and distributed scheduling, are supported by MAC in 802.16 mesh networks. In centralized scheduling, fixed-length time slots are proportionally assigned to SSs by Mesh BS running a scheduling algorithm. Several centralized scheduling algorithms have been proposed to improve the system performance. One of them, named as LTD in this paper, is designed on the basis of traffic demand. In LTD, lower traffic demand is always assigned time slots before the higher traffic demand, which result in average transmission delay decrease, but the transmission delay of higher traffic demand will increase sharply because of lower allocating priority. A new centralized scheduling algorithm based on the ratio of wait time and traffic demand is proposed in this paper. In the proposed algorithm, not only the lower traffic demand can be assigned time slots first by MBS to decrease the average delay time, the transmission delay of the higher traffic demand is also carefully considered. Simulation results show that our proposed algorithm can not only get lower average delay similar as LTD, but also keep the delay of higher traffic demand lower.