Multi-service scheduling mechanism with QoS guarantee for centralized scheduling of WiMax mesh mode

IEEE 802.16 mesh mode is connection-less, and can not provide quality of service (QoS) according to different requirements of different data flows as Point-to-Multipoint (PMP) mode. In view of this problem, a new centralized scheduling mechanism to guarantee QoS of multiple services in IEEE 802.16 mesh network was proposed. In this mechanism, connections are classified into four classes, i.e., Unsolicited Grant Service (UGS), real-time Polling Service (rtPS), non-realtime Polling Service (nrtPS) and Best Effort (BE), which is similar to PMP mode. To reduce control overhead, Subscriber Stations (SS) request the base station (BS) to assign aggregate end-to-end bandwidth for each of its service classes. BS allocates slots to every service class of all SSs, and the SSs allocate the granted slots further for each service class among its connections. The proposed scheduling algorithms in both BS and SSs first ensure minimum bandwidth request and then allocate the residual slots fairly according to the maximum bandwidth request. Simulation using ns-2 reveals the proposed solution can ensure QoS requirements of all the connections in centralized scheduling of mesh mode.