android dev: problem with mobile internet connection after phone wake up

Question

Hello, I've encountered a problem with mobile internet connection after phone wake up from sleep mode. There is an application which updates some data periodically. AlarmManager triggers my BroadcastReceiver which starts service. service acquires PARTIAL_WAKE_LOCK and some http requests are sent. Unfortunately when update interval is quite big (5h) service could not send/download anything. Problem doesn't appear when I'm using WIFI connection instead of mobile and WIFI sleep policy is set to never. Everything is OK on mobile connection when update interval is short (less than half an hour). I'm also sure 5h event is received by my BroadcastReceiver because I've checked it.

How such events should be handled. I've tried to check whether connection is established by ConnectivityManager and retry 5 times if not but still same problem appears.

Thanks for any answer in advance

Answer 1

The Android system turns of WiFi a few minutes when the device is suspended (i.e. screen turned off). When the device turns on again (by acquiring the wake-lock), it will take a few seconds until network connection is re-established (this is also true for 3G data connections, which are also torn-down while device is sleeping).

My suggestion:
- Wait for ConnectivityManager's broadcast that the network is up again. Practice proves that waiting 2-3 seconds after the broadcast is received helps things to settle before starting to send and receive data.
- A bit easier: After grabbing the wake-lock, wait a longer timeout and then try to connect.