Hybrid Frame Structure for improving network throughput in WiMAX Mesh networks

IEEE 802.16d standard defines WiMAX Mesh mode, which uses Centralized Scheduling (CS), Distributed Scheduling (DS), and co-existence of CS/DS data subframes to allocate resources for data transmissions. The CS and CS/DS schemes are suitable for Internet traffic, but the lack of spatial reuse in over-pessimistic use of CS causes scalability problems and bandwidth limitations. In this paper a Hybrid Frame Structure (HFS), which fine tunes the nodes in the network according to their hop counts, using both CS and DS methods to overcome this problem is proposed. By exploiting the spatial reuse property of DS, HFS achieves significant network throughput increase and acceptable latencies, without changing any control message contents defined in the standard. The proposed method is implemented and evaluated using our publicly available NETLAB WiMAX Mesh Simulator (NEMMS).