Delay-aware TDMA Scheduling for Multi-Hop Wireless Networks

Time Division Multiple Access (TDMA)-based medium access control (MAC) protocols can be used to provide guaranteed quality of service (QoS). Since nodes follow a fixed schedule to transmit data, the schedule plays a major role in determining QoS in terms of delay, throughput etc. In this study, we focus on end-to-end delay and bandwidth utilization as the QoS parameters. We present a TDMA scheduling scheme that minimizes the end-to-end delay of data, while reusing time slots where possible. This is done by ordering the transmissions along a path such that the scheduling delay at intermediate nodes is minimized. The scheme results in end-to-end delay spanning multiple frames. However, because the TDMA frame length is minimized, the end-to-end delay is minimized while increasing the throughput. The proposed scheme uses a heuristic which has a complexity of O(n2), making it suitable for networks with a large number of nodes. We also present a simple distributed version of our heuristic. Simulation results show that our scheme performs better than previous work in literature in terms of end-to-end delay and slot reuse.