Prediction-based routing for real time communications in wireless multi-hop networks

Real time communication (RTC) has critical quality of service (QoS) requirements, which is much more challenging in wireless multi-hop networks. Traditional measurement-based routing schemes often ignore the interference from the coming RTC traffic itself (i.e. self-traffic), so they can not get an accurate quality estimation of the path to serve the coming RTC traffic. In this paper, we propose a novel prediction-based routing metric, PPTT (Path Predicted Transmission Time), to estimate end-to-end delay of RTC traffics. PPTT is traffic-aware by taking explicit consideration of both self-traffic and neighboring traffics interfering with the RTC flow, and thus offers an accurate prediction of transmission delay. By selecting route with minimal PPTT, the quality of service for the coming RTC flow will be improved, in terms of end-to-end delay and goodput. To evaluate the performance, we implement PPTT scheme and study its performance in a wireless multi-hop test bed consisting of 32 nodes equipped with IEEE 802.11 a/b/g combo cards, and we also conduct extensive simulations with different random topologies in network simulator NS2 for a more comprehensive comparison. Experiment results show that this routing metric outperforms other non prediction-based routing metric such as ETX (Expected Transmission Count) and WCETT (Weighted Cumulative Expected Transmission Time) in terms of delay and goodput in wireless multi-hop networks.