Time slot assignment algorithms for reducing upstream latency in IEEE 802.16j networks

In IEEE 802.16j wireless multihop networks, transmission latency from relay nodes to a gateway node is one of the important performance metrics. The transmission latency is mainly affected by a scheduling delay at every relay node, which is determined by algorithms for assigning time slots to wireless links between relay nodes. In this paper, we propose 2 kinds of time slot assignment algorithms for upstream wireless links in IEEE 802.16j multihop networks. One of the proposed algorithms assigns time slots considering the hop count from a gateway node, and the other takes the path from the relay node to the gateway node into account. We evaluated the performance of the proposed algorithms through simulation experiments and confirmed that our algorithms can decrease the upstream latency by up to 15% compared with the existing method, without increasing the average transmission latency of the entire network.