A Study On Centralized Scheduling Algorithms In Multi-channel WiMAX Mesh Networks

Along with the increasingly development of economy and society, the demand ofrate and coverage of the wireless network has become increasingly high. WiMAX, atechnology that can provide “the last mile” access, can provide people higher rate andbigger coverage. It is bound to achieve rapid development.In terms of resource allocation, IEEE802.16Standards defines two modes of meshnetwork: centralized scheduling and distributed scheduling, and defines the frameformat and the framework of wireless scheduling. However, this Standard does notexplicitly point out the specific scheduling algorithm. Moreover, the schedulingalgorithm plays a very important role in the resource allocation of a network andinfluences the performance of a network heavily. Therefore, a study on the schedulingalgorithm in mesh networks becomes very meaningful.Currently, researches on802.16scheduling algorithm mainly focus on a singlechannel, few have done on multi-channel system. In a single-channel system, onlytime slots are available for allocation and the design of algorithm is relatively simple.However, in the multi-channel system, the network resources available for allocationcontains time slots and channels. Thus, the design of algorithm is more challenging.This paper focuses on the WiMAX mesh network and studies the problem ofresource allocation. Then, based on the summary of existing achievements, wepropose a new scheduling algorithm. The algorithms running in the base station (BS)distribute channels and time slots for the subscriber stations (SSs) in each schedulingperiod according to the requests of each SS. By building simulation platform onNS2and simulating operation of WiMAX network, we verify the performance of theproposed algorithm. Further, we compare the results with the existing algorithms anddemonstrate that the new algorithm is better than the existing algorithms in thescheduling length, channel utilization and other indicators.