Find the nearest beacon

1
votes

I am developing an application, that uses iBeacons. Its main feature is to detect the nearest beacon (distance does not matter, I need simply the nearest one) and present some content according to it.

On IOS it works like a charm, there is no question.

On Android I have strange experiences. I know, it is up to the hardware, bluetooth chip vendor etc. but even if a I tried a lot of things (averaging rssi, queing...), I can't make it stable. The beacons are some 3-5 meters away from each other, there are 8 pieces of them in a ~80 square meters room.

I use Android AltBeacon library. I can not detect the nearest beacon in a stable way: sometimes a Beacon, which is some 5 meters away from the device is 'nearer' by RSSI, than a beacon, which is right next to the device and so on. (beacons use the same TX power and advertising interval, altbeacon scanperiod is 250 msec)

What should I do to make it stable? What, when and how should I average rssi? Or should I do it at all? Or...?

Thank you very much!

1
androidbluetoothibeaconbluetooth-lowenergyaltbeacon

1 Answers

1
votes

The RSSI value will depend on a number of things beside the TX power, among them:

  • Multipath reflections: The 2.4 GHz will reflect from the walls, so if the reflection helps the distant beacon and attenuates the close beacon, then the distant beacon could get at stronger RSSI.
  • The placement of the antenna: Holding the phone the right way can make a big difference.

I can't say why iOS should work better then Android, but it could be that they have an averaging algorithm that works well. From my two points this is not a simple thing to get right.

To learn more about these issues I recommend reading Deploying iBeacon and Common Questions and Answers in Getting Started with iBeacon.