State transition reduction for sleep scheduling in IEEE 802.16e mobile subscriber stations

IEEE 802.16e devices may enter sleep mode to conserve energy. There has been some work studying how to schedule device’s packet transmissions to maximize the device’s sleep period while meeting associated QoS (quality of service) requirements. This paper proposes two schemes that attempt to save more energy for a given sleep schedule by accelerating or deferring scheduled packet transmissions with the intention to further reduce the frequency of transitions from sleep to active modes (states). Performance evaluation results indicate that the proposed schemes effectively reduce state transitions when compared with existing sleep scheduling schemes. Packet delays may also be improved in case of accelerating packet transmissions. Keywords—WiMAX; sleep scheduling; QoS; state transitions