Performance Evaluation of Power Management for Best Effort Applications in IEEE 802.16 Networks

Reduced energy consumption is a crucial aspect of mobile Broadband Wireless Access (BWA) networks, which are expected to be populated by battery-operated devices, like mobile phones and palmtops. For this reason the IEEE 802.16e, which is one of the front-runner competitors in this field, specifies a set of power saving mechanisms to be employed by the Base Station (BS) and Mobile Stations (MSs) to reduce the amount of time the latter spend with the wireless interface on. These mechanisms are classified into three class types, which are designed for different types of applications. In this paper we focus on class type I, which fits the typical requirements of best-effort traffic. With class type I, an MS with power saving enabled alternates between sleep and listening periods. The duration of the sleep periods increases by a factor 2 each time listening period ends, up to a maximum sleep window size. Since the standard does not provide guidelines for setting the above parameters, which are negotiated between the BS and MSs when setting up a power saving class, we evaluate via simulation their impact on the performance, in terms of both application-specific metric, i.e. delay or throughput depending on the type of traffic, and the amount of energy saved.