Research On The Energy Saving Algorithm Of Adjusting Sleep Window In WiMAX Networks

The IEEE802.16e standards define three classes of sleep-mode that can be appliedto mobile subscriber stations (MSSs) for conserving the power of mobile terminals. But,these standards do not fully utilize the traffic features and channel characteristic to savethe energy of mobile terminals. And previous studies on IEEE802.16e barely consideredthe state transitions of the terminal.Firstly，A power saving strategy based on the prediction of both traffic load andchannel quality is proposed in this paper. According to the results of prediction, theenergy can be saved by reducing the frequency of transitions between sleep state andactive state at mobile stations.Furthermore, two methods featuring the coordination of the sleep window ofmobile stations are presented. Both of them can make base stations shut down thetransceiver circuit for reducing integral network energy consumption. However，thereexists obvious differences between them. In the first one, base stations compute thesleep time of each mobile station and set their sleep window based on the minimumallowable delay respectively, and base stations enter into sleep only for a non-emptymaximum common sleep window. But, this algorithm applies only to the Poisson model.In the second algorithm, the base station coordinates the sleep time of all mobilestations based on the delay requirement and the waiting time. This algorithm applies toany traffic model. The simulation studies demonstrate the proposed schemes can save aconsiderable amount of energy with little impact on delay compared with existing sleepscheduling schemes.