Re:If You're Programming a Cell Phone Like a Server, You're ...
by xav0989 on Thursday September 19, 2013 @09:18PM
(#6415425)
I personally setup Llama to turn the wifi when I'm not connected to a tower that I previously defined as "wifi available". It's nifty because I never have to explicitly turn wifi off then back on during my travels. To add a new wifi zone, I simply add the cell tower to the previous list and let the app do the rest.
Llama by itself uses less battery than leaving the wifi chip on, even in passive scanning mode, as the phone is always looking and checking cell towers.
If you are on Android, my guess is that your phone was set to be connected to Wifi during sleep. You can control it by going to Wifi networks section -> menu -> Advanced -> Keep Wi-Fi on during sleep, then setting it to "Only when plugged in" or "Never".
If you're driving around with the phone set to leave the Wifi on during sleep, it'll be constantly going in and out of range of various Wifi connections. If the Wifi part is set for passive scan, then the processor needs to be kept up as the Wifi chip attempts to collect the BSSID of all the network it see and processor tries to figure out whether these networks have been seen or not. If it's set for active scan, then the Wifi needs to power up the radios to transmit beacons. Pretty bad news in either case, unfortunately.