Service class downlink scheduling in WiMAX

Broad band Wireless Access called WiMAX is becoming popular due to its support for QoS, in real time communication. To the best of our knowledge, the WiMAX base station (BS) schedules uplink (UL) and downlink (DL) packets station wise and within a station scheduling is done with respect to priority of services. In this process, while BS transmits packets of different priorities for a subscriber station (SS), it may so happen that a higher priority packet in another SS waits for a longer time to get its transmission opportunity (as in most of the cases round-robin scheduling is used). In this paper, authors have proposed a new BS node scheduling algorithm, where in, the packets for all SS of a particular priority are transmitted sequentially. This proposed scheduling scheme is referred as Service Class Downlink Scheduling (SCDS). With the help of simulation carried out in NS2, we have compared the results for round-robin scheduling algorithm of exiting architecture with SCDS. It has been observed that SCDS provides considerable reduction in real time trafficpsilas average delay and increase in throughput.