Demo: Avoiding the rush hours, wifi energy management via traffic isolation

WiFi continues to be a prime source of energy consumption in mobile devices. We observe that, despite a rich body of research in WiFi energy management, there is room for improvement. Our key finding is that WiFi energy optimizations have conventionally been designed with a single AP in mind. However, network contention among different APs can dramatically increase a client's energy consumption. Each client may have to keep awake for long durations before its own AP gets a chance to send packets to it. As the AP density increases in the vicinity, the waiting time inflates, resulting in a proportional decrease in battery life. We present a demonstration of SleepWell, a system to appear in the MobiSys 2011 main conference. SleepWell achieves energy efficiency by evading network contention. APs regulate the sleeping window of their clients in a way that different APs are active/inactive during non-overlapping time windows. The solution is analogous to the common wisdom of going late to office and coming back late, thereby avoiding the rush hours. We believe SleepWell is a desirable upgrade to WiFi systems, especially in light of increasing WiFi density.