Android iBeacon client - How to save battery

Question

I've been given the task to create an iBeacon client for Android. The purpose of the client is to transmit the ID of the closest beacon over WIFI/3g/4g to a server when another client requests the users position.

Now, I wonder, what is the best way of doing this, with respect to battery consumption?

There are (as far as I can see) two approaches:

1). Whenever the ID of the closest beacon changes, upload the new ID directly to the server.

2). Store the ID of the closest beacon locally on the client's phone. Only upload it to the server when the server requests the client to do so.

Nr 1). means that WIFI has to be activated every time the user approaches a new iBeacon. On the other hand, 2). requires the phone to listen to a port in order to handle requests from the server.

EDIT: I read about the Radio State Machine here: http://developer.android.com/training/efficient-downloads/efficient-network-access.html

If I keep a ServerSocket running in the background, will this keep my phone in Radio Low Power? It seems to me, that option 1) will put the phone into full radio power every time a beacon ID is transmitted, but after that, the phone will fall back into Low Power/Sleep mode, which will save me battery. 2) on the other hand will prevent the phone from reaching Sleep mode, since I have to keep a persistent connection to the server.

Answer 1

I would go with option one because it is simpler and less brittle. If you are really worried about battery, just place limits on how often it can talk to the server(e.g. 10x per hour) so it does not get crazy.

Other things may use battery even more, so test first and make sure this really requires optimization. For example, run this in the background for 10 hours and see how much it drains a fully charged battery vs. When the app is not reporting to the server. If it is only a few percent, then it is probably efficient enough.