Open Radar

 
Summary:
Dear support team,

From the latest iOS update we saw that the RSSI measurements provided for CLBeacon objects through CoreLocation are not as accurate as they used to be.

By comparing iOS 9.2.1 13D15 (iPad Air A1474) iOS 9.3.1 13E238 (iPhone 5S A1457) and iOS 9.3.2 13F69 (iPhone 6S A1688) we confirmed that from iOS 9.3 the accuracy of the RSSI measurements is much less accurate and stable as it used to be. For a test environment where we are measuring the signal strength for a particular beacon, surrounded with fewer beacons, we can get measurement from -60 to -97dBm for the iPhone 5S and -61 to -93dBm for iPhone 6S, while in the iPad the difference is from -80 to -88dBm for the same test conditions.

Experimenting this gap of 36-37dB in new iOS 9.3.x devices seems to be a firmware issue, since when we had the iPhone 5S with version lower than 9.3 we got a similar behavior than we currently have in the iPad, a smaller gap of 8dB. You can see the video comparison here https://youtu.be/7jT_BPj4IjE

We would like to ask you whether you also notice this behavior and if you are planning to provide a bug fix for this issue in further releases

Steps to Reproduce:
Measure a CLBeacon signal strength (RSSI) keeping the iBeacon and the phone in fixed positions. The issue is more visible when several iBeacons are also in range and the RSSI of one is studied over time.

Expected Results:
Successive measurements should be in the same range with some dB of difference (due to interferences, fluctuations, etc)

Actual Results:
Measurements have spikes of -30dB or more that does not seems to come from the raw measurements but from a wrong filtering/data processing from iOS 9.3 and newer.

Version:
iOS 9.2.1 [13D15],  iOS 9.3.1 [13E238],  iOS 9.3.2 [13F69]

Notes:


Configuration:
iPad Air A1474, iPhone 5S A1457, iPhone 6S A1688