Paper Title
P-RILI: Power Reducing Idle Listening In Wireless Networks

Idle listening (IL) is the dominant source of energy consumption in WiFi. Most existing protocols, such as the 802.11 power-saving mode (PSM), attempt to reduce the time spent in IL by sleep scheduling. However, through an extensive analysis of real-world traffic, we found more than 60 percent of energy is consumed in IL, even with PSM enabled. To remedy this problem, we propose Energy-Minimizing idle Listening (P-RiLi) that reduces the power consumption in IL, given that the time spent in IL has already been optimized by sleep scheduling. Observing that radio power consumption decreases proportionally to its clock rate, P-RiLi adaptively down clocks the radio during IL, and reverts to full clock rate when an incoming packet is detected or a packet has to be transmitted. P-RiLi incorporates sampling rate invariant detection, ensuring accurate packet detection and address filtering even when the receiver’s sampling clock rate is much lower than the signal bandwidth. Further, it employs an opportunistic down clocking mechanism to optimize the efficiency of switching clock rate, based on a simple interface to existing MAC-layer scheduling protocols. We have implemented P-RiLi on the USRP software radio.