Energy-Efficient Sleep-Mode Operations for Broadband Wireless Access Systems

Broadband wireless access systems usually provide flexible sleep-mode operations for mobile stations to conserve energy during idle or active modes. For example, the IEEE 802.16e offers several sleep-mode classes that can be applied to mobile subscriber stations (MSSs) to reduce their power consumptions for different applications. Unfortunately, previous studies did not fully utilize sleep-mode features, and the power consumption of an MSS with multiple network connections is not optimized. In this work, two scheduling algorithms for sleep-mode operations based on the IEEE 802.16e are proposed. These schemes guarantee the quality of services (QoSs) of the network connections for an MSS and also minimize the power consumption of the MSS. Simulation results demonstrate that the proposed schemes outperform the traditional approaches.