keep receiving packet when the screen is turned off
<p>I am writing a local communication system between Android phones that are connected to the local Wifi Access Point.
In the design of my system, the Android phones should notify the owner once they received an UDP broadcast packet from the Windows server.</p>

<p>The system works just fine when the screen of the phone is turned on. But it is found that, once the screen of Android phone is turned off, the phone just ignored the packet, just like no message is received.</p>

<p>I have tried Google for many time, but still no luck. Actually I really don't know what keyword should I use for doing the searching.</p>

<p>Do any one know how can I do what I want? Thank you very much</p>
