New delay-efficient TDMA-based distributed schedule in wireless mesh networks

Time division multiple access (TDMA)-based medium access control (MAC) protocols can guarantee quality of service (QoS) in wireless environments. However, in an environment where multihop packet transmissions are necessary for real-time communications, each node may experience the well-known queuing delay. This queuing delay increases multihop packet transmission delay, resulting in not meeting the delay bound of real-time applications in multihop wireless networks. This article first introduces two kinds of queuing delays that can occur in multihop wireless networks. Then, this article proposes a new delay-efficient TDMA-based distributed scheduling scheme to eliminate the secondary queuing delay. For the performance analysis of the proposed scheme, the scheduling overhead is first evaluated in terms of power consumption. Next, the multihop packet transmission delay of the proposed scheduling scheme is derived and validated through a simulation, before comparing the result with that of the conventional minimum length scheduling scheme which employs distance-2 graph coloring. According to the simulation and analysis results, for a deterministic packet arrival, the proposed scheme works well irrespective of the packet interarrival rate and outperforms the conventional graph coloring. However, in case of a non-deterministic packet arrival, the multihop packet transmission delay of the proposed scheme is slightly higher than that of the conventional graph coloring because the probability that each node has more than two packets increases at the beginning of the frame. However, the multihop packet transmission delay of the conventional graph coloring is intolerable when the packet interarrival rate is high.