The Study On Packet Scheduling Algorithms Of WiMAX

The MAC layer and PHY layer specifications are defined in WiMAX standard. Service flows are classified into the UGS, rtPS, nrtPS and BE types according to their QoS requirements, and the QoS requirements are satisfied by the MAC layer mechanisms respectively. In PHY layer, OFDM technique is introduced to guarantee the reliable data transmission in complicated physical environments. Although perfect QoS guarantee are provided for different services, the packet scheduling algorithms to implement the QoS support are not given by the standard. All these issues are left for people to reaserch.The design and implementation of packet scheduling algorithms based on WiMAX's QoS guarantee are discussed in this thesis.In this paper, WiMAX standard is described firstly. Then we give an introduction to the basic knowledge and research on bandwidth management mechanism and existing packet scheduling algorithms. Based on these, the I-DRR(Improved-DRR) algorithm which is improved from Deficit Round Robin algorithm is given and is simulated on simulation tool we have implemented for WiMAX. The simulation results show that compared with DRR, the I-DRR has better performaces on throughput, delay and bandwidth usage ratio and shows better fairness than Priority Queue algorithm.