Originally Posted by afv011
WiFi has 3 sleep policies: sleep after a certain inactivity time (usually 15 minutes), do not sleep if charging, never sleep. CM7 defaults to the 1st. You can easily change the behaviour to any of the 3 policies, just to go "Settings", "Wireless networks", "WiFi settings" then press "Menu" and select "Advanced", then "Sleep policy"
In CM7, that setting is described as, "Specify when to switch from Wi-Fi to mobile data," so perhaps it doesn't work in the absence of a mobile data network? Mine is defaulted to "When screen turns off," with the other options being "Never when plugged in" and "Never."
In any case, deep sleep would also turn off WiFi until the device wakes, wouldn't it?