I want to do some power management research regarding the wifi interface of android phone. But I have found the wifi in android is really efficient. I used at&t nexus s phone. Due to my measurement by the power monitor, there is no tail power(timeout). As long as there is no data transfer, the wifi will go idle. And the transtion power(from idle to transfer mode) is nearly zero and there is no latency from idle to transfer mode. This is quite different from 3G interface. And even I use the API like WifiManager.disconnected to disconnect the wifi from the access point, the power saving from the idle mode is only about 20mW. And the transtion back(reconnect) latency is very high(about 10 second). So it looks like that nowadays the wifi interface is really power-efficient and there is no room to do much system-level power management. Am I right? :>
Yes.Anyway I have found that the wifi in nexus s is very efficient. It's nearly energy proportional with the receiving and sending speed. This is very different from 3G. In terms of 3G, there is an obvious transferring state and the power doesn't change a lot in the state even when the speed changes. Hope this information helps:>