On Energy Efficiency of IEEE 802.16m Interframe Scheduling for Scalable Video Multicast

IEEE 802.16m resource scheduling remains a challenging issue for video multicast. Given the OFDMA frame structure, the IEEE 802.16m scheduling task is comprised of: (1) intraframe scheduling; and (2) interframe scheduling. In the literature, while many studies concentrated on the development of intraframe scheduling mechanisms, few studies looked at the potential of interframe scheduling mechanisms. This paper is the first attempt to investigate the energy efficiency potential of interframe scheduling algorithms to support scalable-video multicast services over IEEE 802.16m networks. Under the premise that the bandwidth requirements of scalable-video subscribers must be satisfied, we first prove that the interframe scheduling problem of minimizing video-subscriber energy consumption is NP-hard. To tackle the NP-hard problem, we propose a multiple bin-packing algorithm, MBPA, for energy-efficient scheduling. The proposed MBPA has full compatibility with the existing intraframe scheduling mechanisms and with the IEEE 802.16m sleep-mode operations. By applying the divide-and-conquer strategy, MBPA effectively eliminates unnecessary wake-up periods and unnecessary state transitions (between wake-up and sleep states), and thus achieves high energy-efficiency. Through theoretical analysis, we show that MBPA is a p-approximation algorithm, where p is a finite value no less than one. Finally, the simulation results show the effectiveness of the proposed MBPA in energy efficiency, user satisfaction, and computational complexity.