Avoiding the rush hours

Justin Manweiler, Romit Roy Choudhury
2011 Proceedings of the 9th international conference on Mobile systems, applications, and services - MobiSys '11  
WiFi continues to be a prime source of energy consumption in mobile devices. This paper observes 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
more » ... d packets to it. As the AP density increases in the vicinity, the waiting time inflates, resulting in a proportional decrease in battery life. We design SleepWell, a system that achieves energy efficiency by evading network contention. The 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 implement SleepWell on a testbed of 8 Laptops and 9 Android phones, and evaluate it over a wide variety of scenarios and traffic patterns (YouTube, Pandora, FTP, Internet radio, and mixed). Results show a median gain of up to 2x when WiFi links are strong; when links are weak and the network density is high, the gains can be even more. We believe SleepWell is a desirable upgrade to WiFi systems, especially in light of increasing WiFi density. Recently, authors in NAPman [24] showed the possibility of improvements with PSM. The core observation is that multiple clients (associated to the same AP) may wake up after an AP advertisement, and expect to receive their respective burst of packets. However, since
doi:10.1145/1999995.2000020 dblp:conf/mobisys/ManweilerC11 fatcat:y3ahebnfm5fppj44ok57r5e62y