An idle listening-aware energy efficient scheme for the DCF of 802.11n

Abstract

802.11 wireless local area network (WLAN) technology is now common in power sensitive devices like smart phones and personal digital assistants (PDAs). However, the energy efficiency of such devices will be very low, especially for next generation WLAN technology. The reasons for this include the existence of a large number of active stations, short data time and ultra high physical layer (PHY) data rate, which are the characteristics of next generation WLAN technology. This poor energy efficiency will be due to the fact that the device will consume a lot of idle-listening energy during the Distributed InterFrame Space (DIFS) and back-off time, and that the energy consumed for idle listening is similar to the energy consumed while receiving data. In this article, we propose an intelligent scheme for reducing the energy consumed in idle listening. Our analysis and simulation programs show that our scheme can lengthen the battery endurance due to the shortening in idle-listening time effectively especially when the number of active stations is large. An important characteristic of our scheme is that it is fully compatible with legacy Distributed Coordinated Function (DCF), and there will be no throughput reduction if this power saving scheme is applied to the DCF of 802.11. We also propose an accurate power consumption model in the MAC layer which to the best of our knowledge has not been presented in any earlier research.