Abstract: Portable battery operated electronic devices often use a “sleep mode” for energy conservation. A key feature introduced in the IEEE 802 standard ensures power-efficient operation of these battery operated mobile devices. However, the standard fails to define what will trigger a device into the sleep mode while other systems define “waiting time threshold” as a time for which a Mobile Subscriber Station (MSS) waits before entering into sleep mode which has a constant duration. An embodiment of the present invention uses a unique method (1500) and algorithm for optimizing waiting time threshold (1509) according to traffic arrival pattern for uplink (UL) and downlink (DL) data packets. This leads to significant reduction in energy consumption with little increase in average waiting delay and acceptable end-to-end delay for non real time traffic.