Slot allocation algorithm in Combined Distributed and Centralized scheduling scheme for IEEE 802.16 based wireless mesh networks

IEEE 802.16 mesh mode defines centralized and distributed scheduling schemes for transmitting external and internal packet respectively. These schemes are independently executed for allocating minislots to each data subframe. Deploying the Combined Distributed and Centralized scheduling (CDC) can be more flexible to allocate minislots. In this paper, we propose a collision free slot allocation algorithm in the CDC scheme that can improve spatial reuse with considering fairness among all nodes in the network. Our algorithm allows internal and external packets to be transmitted simultaneously in some time slots that the transmissions do not lead to collision. Also, special attention is taken on the relay function for routing in both centralized and distributed schemes, which has been rarely considered in previous research. The simulation results confirm the effectiveness of the proposed algorithm in terms of link concurrency ratio, length of scheduling and Channel Utilization Ratio (CUR).