An optimal power-saving class II for VoIP traffic and its performance evaluations in IEEE 802.16e

A power-saving mode (PSM) is a commonly used method for reserving the energy of a mobile station (MS) in wireless networks. Recently, a new attempt has been made to apply a PSM to real-time traffic such as Voice over IP (VoIP) traffic. This paper investigates the methodology on the use of PSM for a VoIP connection in the context of IEEE 802.16e standard. Based on the network delay model, we develop an algorithm for finding the most energy-efficient length of sleep interval while satisfying the given delay constraint of the end-to-end VoIP connection. The performance of the proposed algorithm is numerically evaluated with respect to the packet buffering delay in the base station (BS) and the energy consumption of an MS. The results provide a guideline for deciding the sleep interval length for VoIP connections and show the trade-off between the energy consumption of an MS and the packet buffering delay in the BS.