Bluesaver: A Multi-PHY Approach to Smartphone Energy Savings

WiFi effectively has two extremes: low power consumption and high latency, or low latency and high power consumption. WiFi Power Save Mode saves energy by trading added latency for less power consumption. Minimal latency but maximum power, on the other hand, is consumed with WiFi Active Mode. While research has advanced in mitigating these extremes, certain types of network traffic such as constant bitrate streaming make the contrast unavoidable. We introduce Bluesaver, which provides low latency and low energy by maintaining a Bluetooth and WiFi connection simultaneously. Bluesaver is designed at the MAC layer and is able to opportunistically select the most efficient connection for packets while still assuring acceptable latency. We implement Bluesaver on an Android phone and Access Point and show that we can save more than 25% energy over existing solutions and attain the capability of quickly adapting to changes in network traffic.