User-Driven Idle Energy Save for 802.11x Mobile Devices

Modern mobile devices are equipped with multiple network interfaces, with WiFi to be the preferred choice when it can be associated with an Access Point. Our study using real traces and experiments with 802.11 devices uncovers long idle times, while WiFi is scanning for networks and is listening for incoming traffic. During idle, WiFi consumes a significant amount of energy, which is exacerbated with the 802.11n/ac high speed features (MIMO, channel-bonding). State of the art power saving solutions, including the IEEE 802.11 PSM and SMPS features are user-agnostic, infrastructure-driven and oblivious to the power hungry 802.11n/ac features. As a result they may not save energy in practical settings. To this end, this work presents WiFi idle energy save (WiFi-ies). WiFi-ies leverages user context and behavior information to identify idle times where energy can be saved. We verify WiFi-ies energy savings using trace-driven simulations and prototype implementations on Android smartphones.