Performance of an efficient sleep mode operation for IEEE 802.16m

Abstract

Power saving is one of the important issues for battery-powered mobile station in mobile WiMAX. Both IEEE 802.16e and IEEE 802.16m standards define sleep mode operations for power saving of mobile stations. In IEEE 802.16e, sleep mode alternates the listening window of fixed length and the sleep window where the sleep window can be doubled. The mobile station sends or receives packets during the active mode. In IEEE 802.16m, sleep cycle consists of extendable listening window and sleep window where sleep cycle can be doubled and the sleep window is the remaining part of sleep cycle. The mobile station sends or receives the data during the extendable listening window without going back to the active mode. The extendable listening window is implemented by T_AMS timer which plays the role of sleep mode request/response messages in the IEEE 802.16e. In this paper, we propose an efficient sleep mode operation for IEEE 802.16m advanced mobile WiMAX. The proposed scheme takes advantages of sleep modes in both IEEE 802.16e and IEEE 802.16m. This scheme has binary exponential sleep windows which guarantee the minimum length for effective power saving. The mobile station uses the T_AMS timer in IEEE 802.16m so that the mobile station sends or receives data packets during the extendable listening window in the sleep mode. We mathematically analyze the proposed scheme by an embedded Markov chain to obtain the average message delay and the average power consumption of a mobile station. The analytical results match with the simulation results very well. The analytical results show that the power consumption of our scheme is better than those of the legacy sleep modes in the IEEE 802.16e and the IEEE 802.16m under the same delay bound.