Enhanced Power Saving for IEEE 802.11 WLAN with Dynamic Slot Allocation

In the area of wireless mobile communication, minimizing energy consumption as well as maximizing data throughput in medium access control (MAC) layer is a very important research issue. The Distributed Coordination Function (DCF) of IEEE 802.11 provides the power saving mechanism (PSM) that allows nodes to remain silent in ‘doze mode’ for reducing energy consumption. However, IEEE 802.11 PSM is known to cause unnecessary energy consumption due to the problems of an overhearing, a back-off time delay and possible packet collisions. To overcome these problems, we present a new MAC protocol called ‘Slotted-PSM’ for IEEE 802.11 WLANs. In our proposed scheme, the Beyond-ATIM window is divided into a number of time slots, and any node that participates in communication wakes up in its slot times only and other nodes can enter to doze mode during the slot times. Slotted-PSM can reduce unnecessary energy consumption and idle listening problem in the Beyond-ATIM window.