Universal power saving mechanism for random traffic intensity in IEEE 802.16e wireless metropolitan area networks

To extend the battery life of an mobile station (MS) roaming in wireless metropolitan area networks (WMAN), the support of power saving mechanism is needed. However, the features of fast growing of sleeping window and fixed listening window in power saving class of type I (PSC-I), which is designed for handling non-real-time and bursty traffic, may consume much more power when the traffic intensity is time-varying. As a solution, we propose a universal power saving mechanism, namely UPSM, which adopts a constant sleeping window to reduce the negotiation overhead and alleviate the possible degradations of sleep ratio, energy saving, and mean packet delay caused from irregular packet inter-arrival gaps. Moreover, we utilize a score based metric for evaluations and also provide the mathematical analyses for figuring out appropriate settings. As confirmed by the performance evaluation, the proposed UPSM with specific constant sleeping window can easily achieve better power saving capability than PSC-I under any kind of traffic intensity.