Date Added: Mar 2012
In IEEE 802.16 e/m mobile broadband wireless systems, Mobile Subscriber Stations (MSSs) are encouraged to enter the sleep mode for energy saving when end users do not have downstream or upstream traffic. To avoid service disruption of an MSS which stays in the sleep mode, IEEE 802.16 e/m specifies a two-way handshake protocol between the Base Station (BS) and an MSS. After performing the handshake process, BS is aware of the sleep status of an MSS, and can thus buffer the downstream traffic which arrives when an MSS is asleep. However, the whole handshaking process takes at least four WiMAX frame durations, and the overhead involved may significantly impair the energy saving efficiency.