CODEWITHSUNDEEP
androidbluetoothbluetooth-lowenergyandroid-bluetoothaltbeacon
akhalsa
akhalsa

Reputation: 2313

Alt Beacon Android unstable

I am building an android application based on the Alt Beacon. I should preface this with the fact that my test device is a Digiland (P-O-S) tablet running android 4.4.

I am using the Radius Networks USB beacon and their Alt Beacon library found here: https://github.com/AltBeacon/android-beacon-library

In both my own application and in the reference application provided with the library I am seeing significant instability / extremely slow detection times for the beacon. For example, you can see the reference application's log below. The tablet is sitting no more than 1/2 meter away from the beacon the whole time.

Has anyone seen this behavior before? Am I doing something wrong? The broadcast rate on the beacon appears to be set to 10Hz and the power seems to be set to maximum. Should I get a different device and try it on that? I saw some other posts suggested turning off the wifi which I did, and this log is from a trial with the wifi off.

One thing I should note is that I have increased the scan frequency with the following block of code in the application subclass:

beaconManager.setBackgroundBetweenScanPeriod(9000l);
beaconManager.setBackgroundScanPeriod(1000l);
beaconManager.setForegroundBetweenScanPeriod(9000l);
beaconManager.setForegroundScanPeriod(1000l);
try{
    beaconManager.updateScanPeriods();
}catch (RemoteException e){
    e.printStackTrace();
}

I am not sure if this is done improperly, but when I remove it, I still see the same behavior described in the log below, just over a somewhat longer period of time.

Any advice people have would be much appreciated since I feel like I am spinning my wheels on this!

07-01 15:23:59.005  10771-10771/org.altbeacon.beaconreference D/ReferenceApplication﹕ setting up background monitoring for beacons and power saving
07-01 15:23:59.655  10771-10816/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:23:59.655  10771-10816/org.altbeacon.beaconreference D/ReferenceApplication﹕ auto launching MainActivity
07-01 15:24:20.154  10771-11297/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:24:39.174  10771-11486/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:25:00.132  10771-11647/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:25:09.472  10771-11730/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:25:30.123  10771-11871/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:25:39.173  10771-11954/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:26:00.065  10771-12070/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:26:29.099  10771-12083/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:26:29.100  10771-12083/org.altbeacon.beaconreference D/ReferenceApplication﹕ Sending notification.
07-01 15:26:40.112  10771-12096/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:27:19.120  10771-12127/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:27:19.120  10771-12127/org.altbeacon.beaconreference D/ReferenceApplication﹕ Sending notification.
07-01 15:27:40.041  10771-12208/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:27:59.110  10771-12786/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:28:30.144  10771-13052/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:28:39.202  10771-13131/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:28:50.133  10771-13226/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:29:09.125  10771-13375/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:29:30.119  10771-13452/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:29:49.144  10771-13473/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:30:00.060  10771-13510/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:30:19.134  10771-13552/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:30:19.135  10771-13552/org.altbeacon.beaconreference D/ReferenceApplication﹕ Sending notification.
07-01 15:30:30.096  10771-13560/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:31:09.124  10771-13575/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:31:09.125  10771-13575/org.altbeacon.beaconreference D/ReferenceApplication﹕ Sending notification.
07-01 15:31:20.110  10771-13576/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:31:29.101  10771-13578/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.
07-01 15:31:29.101  10771-13578/org.altbeacon.beaconreference D/ReferenceApplication﹕ Sending notification.
07-01 15:32:40.101  10771-13647/org.altbeacon.beaconreference D/ReferenceApplication﹕ did exit region
07-01 15:32:59.131  10771-13651/org.altbeacon.beaconreference D/ReferenceApplication﹕ did enter region.

One more interesting thing to note is that when I do a filter for onScanResult in the logs I see this:

07-01 15:45:49.074  10771-10839/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=24:4B:03:2E:00:D9 RSSI=-91
07-01 15:45:49.117    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=00:07:80:1E:7E:B7, rssi=-56
07-01 15:45:49.120  10771-10784/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=00:07:80:1E:7E:B7 RSSI=-56
07-01 15:45:49.365    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=62:44:C6:64:4D:A5, rssi=-76
07-01 15:45:49.368  10771-10783/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=62:44:C6:64:4D:A5 RSSI=-76
07-01 15:45:59.082    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=62:44:C6:64:4D:A5, rssi=-77
07-01 15:45:59.084  10771-10784/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=62:44:C6:64:4D:A5 RSSI=-77
07-01 15:45:59.130    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=00:07:80:1E:7E:B7, rssi=-59
07-01 15:45:59.133  10771-10783/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=00:07:80:1E:7E:B7 RSSI=-59
07-01 15:45:59.140    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=24:4B:03:2E:00:D9, rssi=-76
07-01 15:45:59.141  10771-10839/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=24:4B:03:2E:00:D9 RSSI=-76
07-01 15:46:09.115    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=00:07:80:1E:7E:B7, rssi=-58
07-01 15:46:09.117  10771-10783/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=00:07:80:1E:7E:B7 RSSI=-58
07-01 15:46:09.124    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=24:4B:03:2E:00:D9, rssi=-86
07-01 15:46:09.126  10771-10839/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=24:4B:03:2E:00:D9 RSSI=-86
07-01 15:46:09.135    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=62:44:C6:64:4D:A5, rssi=-76
07-01 15:46:09.139  10771-10784/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=62:44:C6:64:4D:A5 RSSI=-76
07-01 15:46:19.060    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=24:4B:03:2E:00:D9, rssi=-91
07-01 15:46:19.062  10771-10839/org.altbeacon.beaconreference D/BluetoothAdapter﹕ onScanResult() - Device=24:4B:03:2E:00:D9 RSSI=-91
07-01 15:46:19.092    1425-1495/? D/BtGatt.GattService﹕ onScanResult() - address=00:07:80:1E:7E:B7, rssi=-64

The 00:07:80 device is my beacon, but I have no idea whatsoever when the 24:4B:03 device is. Does anyone know how I can get more data about this device? Is it possible that it is interfering with my actual signal? I have tried using both

Region region = new Region("backgroundRegion",
                Identifier.parse("2F234454-CF6D-4A0F-ADF2-F4911BA9FFA6"), null, null);

and 

Region region = new Region("backgroundRegion",null, null, null);

Unfortunately I get this random fluctuation with both variations.

UPDATE:

I also ran this with the beaconManager.setDebug(true) flag activated. Here is the resulting log

UPDATE 2:

I switched my beacon to only broadcast for iBeacon and the problem seemed to go away for about 10 minutes. Unfortunately the problem quickly returned. Looking through the logs, what I am seeing is quite different now. The logs can be seen here. My assumption is that the problem is with this line: 

07-01 21:46:31.035    2499-2499/com.avtar.truckkeeper D/CycledLeScanner﹕ cancel wakeup alarm: PendingIntent{41f32070: android.os.BinderProxy@41d8f750}

Any thoughts/help would be much appreciated!

Upvotes: 2

Views: 1449

Answers (1)

davidgyoung
davidgyoung

Reputation: 64916

I suspect several things are going on based an analysis of the "resulting log" linked at the bottom of the answer:

  1. The transmitting beacon is configured to transmit both AltBeacon and iBeacon packets.
  2. The Android Beacon Library has not been configured to detect iBeacon packets, only the default AltBeacon packets.
  3. The transmitting beacon is in connectable mode.
  4. The Digiland (P-O-S) tablet can only detect one packet from each distinct Bluetooth LE device per scan cycle when the beacon is in connectable mode. (Several other Android models behave this way including the Nexus 4 and Moto G)
  5. The scan interval has been configured to be super long -- scan for one second every 10 seconds.

All of these things together are creating a perfect storm that is causing these problems:

Because of the flaw described in (4) and the fact that the beacon is in connectable mode as described in (3), this means that only one packet will get picked up per scan cycle. Because the beacon is sending interleaved advertisements as described in (1), that means there is a 50-50 chance that this packet will be an iBeacon packet. If it is an iBeacon packet, because the library has not been configured to detect iBeacons as described in (2), there will be no detections in that cycle. And because the scan cycle is 10 seconds long as described in 5, this will cause intermittent region exits and re-entries. (If no beacon is seen in 10 seconds, the library triggers a region exit.)

Changing any one of these things will probably make the issue go away:

  1. Re-configure your beacon to turn off iBeacon transmissions (or configure the library to detect iBeacon transmissions.)

  2. Make your beacon's connectability timeout shorter -- e.g. after 60 seconds. Once it is no longer connectable, the tablet will be able to get multiple packets in each scan cycle and the problem will go away.

  3. Reduce the length of time of the scan cycle. If you leave the defaults of 1100ms scan time with 0ms between scan time in the foreground, then the library will have 9 cycles to detect the beacon before the 10 second region timeout fires. The 50-50 odds of not detecting the beacon in 9 cycles will then become 0.5^9 = 0.1% chance.

Upvotes: 2

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