Nearly optimal power saving policies for mobile stations in wireless networks

In wireless communications, sleep mode is commonly used to prolong the battery life time of mobile devices; when there is no data to transmit or receive, a mobile device can switch to sleep mode periodically. Apparently, there is a trade-off between power saving and response delay, and the performance of a power saving mechanism depends on the user traffic characteristics and how well the sleep interval updating policy can capture termination of idle periods. In essence, sleep mode scheduling is a typical inspection problem in reliability engineering. Many solutions have been proposed in the literature, among which the K&O and M&S scheduling policies are most widely applied. In order to develop a traffic dependent power saving policy, this paper models a single user traffic by an ON/OFF process with general OFF duration distribution and compares the power saving mechanism of IEEE802.16e with K&O policy and M&S policy under a wide variety of traffic patterns. The experimental results show that K&O policy always outperforms the power saving policy of IEEE802.16e; moreover, it is much easier to implement.