During my investigation concerning the RSSI detection reliability for iBeacons, I discovered that the RSSI frequency differs extremely between foreground and background mode.
My setting: Two beacons setup in a venue (vending machine) broadcasting the same UUID and Major, but different Minors => Region defined using UUID and Major.
Use case 1: Approaching the venue with my smart phone in my pocket (running app in background). Dwelling for 15 seconds in front of venue (distance 1.5 meter).
Use case 2: Approaching the venue with my smart phone in my hand, running the app in foreground. Dwelling for 15 seconds in front of venue (distance 1.5 meter).
Ranging logs for use case 1:
[2016-03-07 16:22:31] lumen.INFO: Range Beacon [2016-03-07 16:22:31] Maj.: 16 0
[2016-03-07 16:22:32] lumen.INFO: Range Beacon [2016-03-07 16:22:32] Maj.: 16 0
[2016-03-07 16:22:33] lumen.INFO: Range Beacon [2016-03-07 16:22:33] Maj.: 16 0
[2016-03-07 16:22:34] lumen.INFO: Range Beacon [2016-03-07 16:22:34] Maj.: 16 0
[2016-03-07 16:22:50] lumen.INFO: Range Beacon [2016-03-07 16:22:50] Maj.: 16 18446744073709551527
[2016-03-07 16:22:51] lumen.INFO: Range Beacon [2016-03-07 16:22:51] Maj.: 30 0
[2016-03-07 16:22:51] lumen.INFO: Range Beacon [2016-03-07 16:22:51] Maj.: 16 0
[2016-03-07 16:22:52] lumen.INFO: Range Beacon [2016-03-07 16:22:52] Maj.: 30 0
[2016-03-07 16:22:52] lumen.INFO: Range Beacon [2016-03-07 16:22:52] Maj.: 16 0
[2016-03-07 16:22:53] lumen.INFO: Range Beacon [2016-03-07 16:22:53] Maj.: 30 0
[2016-03-07 16:22:53] lumen.INFO: Range Beacon [2016-03-07 16:22:53] Maj.: 16 0
[2016-03-07 16:22:54] lumen.INFO: Range Beacon [2016-03-07 16:22:54] Maj.: 30 0
[2016-03-07 16:22:54] lumen.INFO: Range Beacon [2016-03-07 16:22:54] Maj.: 16 0
[2016-03-07 16:22:55] lumen.INFO: Range Beacon [2016-03-07 16:22:55] Maj.: 30 0
[2016-03-07 16:22:55] lumen.INFO: Range Beacon [2016-03-07 16:22:55] Maj.: 16 0
[2016-03-07 16:22:56] lumen.INFO: Range Beacon [2016-03-07 16:22:56] Maj.: 16 0
[2016-03-07 16:22:56] lumen.INFO: Range Beacon [2016-03-07 16:22:56] Maj.: 30 0
[2016-03-07 16:22:57] lumen.INFO: Range Beacon [2016-03-07 16:22:57] Maj.: 30 0
[2016-03-07 16:22:57] lumen.INFO: Range Beacon [2016-03-07 16:22:57] Maj.: 16 0
[2016-03-07 16:22:58] lumen.INFO: Range Beacon [2016-03-07 16:22:58] Maj.: 16 0
[2016-03-07 16:22:58] lumen.INFO: Range Beacon [2016-03-07 16:22:58] Maj.: 30 0
[2016-03-07 16:22:59] lumen.INFO: Range Beacon [2016-03-07 16:22:59] Maj.: 30 0
[2016-03-07 16:22:59] lumen.INFO: Range Beacon [2016-03-07 16:22:59] Maj.: 16 0
Ranging log for use case 2:
[2016-03-07 16:51:04] lumen.INFO: Range Beacon [2016-03-07 16:51:04] Maj.: 30 0
[2016-03-07 16:51:04] lumen.INFO: Range Beacon [2016-03-07 16:51:04] Maj.: 16 18446744073709551521
[2016-03-07 16:51:05] lumen.INFO: Range Beacon [2016-03-07 16:51:05] Maj.: 30 0
[2016-03-07 16:51:05] lumen.INFO: Range Beacon [2016-03-07 16:51:05] Maj.: 16 18446744073709551521
[2016-03-07 16:51:05] lumen.INFO: Range Beacon [2016-03-07 16:51:05] Maj.: 30 0
[2016-03-07 16:51:05] lumen.INFO: Range Beacon [2016-03-07 16:51:05] Maj.: 16 18446744073709551524
[2016-03-07 16:51:05] lumen.INFO: Range Beacon [2016-03-07 16:51:05] Maj.: 30 0
[2016-03-07 16:51:05] lumen.INFO: Range Beacon [2016-03-07 16:51:05] Maj.: 16 18446744073709551524
[2016-03-07 16:51:06] lumen.INFO: Range Beacon [2016-03-07 16:51:06] Maj.: 30 18446744073709551518
[2016-03-07 16:51:06] lumen.INFO: Range Beacon [2016-03-07 16:51:06] Maj.: 16 18446744073709551528
[2016-03-07 16:51:07] lumen.INFO: Range Beacon [2016-03-07 16:51:07] Maj.: 30 18446744073709551520
[2016-03-07 16:51:07] lumen.INFO: Range Beacon [2016-03-07 16:51:07] Maj.: 16 18446744073709551533
[2016-03-07 16:51:08] lumen.INFO: Range Beacon [2016-03-07 16:51:08] Maj.: 30 18446744073709551525
[2016-03-07 16:51:08] lumen.INFO: Range Beacon [2016-03-07 16:51:08] Maj.: 16 18446744073709551538
[2016-03-07 16:51:09] lumen.INFO: Range Beacon [2016-03-07 16:51:09] Maj.: 30 18446744073709551525
[2016-03-07 16:51:09] lumen.INFO: Range Beacon [2016-03-07 16:51:09] Maj.: 16 18446744073709551538
[2016-03-07 16:51:10] lumen.INFO: Range Beacon [2016-03-07 16:51:10] Maj.: 30 18446744073709551521
[2016-03-07 16:51:10] lumen.INFO: Range Beacon [2016-03-07 16:51:10] Maj.: 16 18446744073709551536
[2016-03-07 16:51:11] lumen.INFO: Range Beacon [2016-03-07 16:51:11] Maj.: 30 18446744073709551522
[2016-03-07 16:51:11] lumen.INFO: Range Beacon [2016-03-07 16:51:11] Maj.: 16 18446744073709551535
[2016-03-07 16:51:12] lumen.INFO: Range Beacon [2016-03-07 16:51:12] Maj.: 30 18446744073709551523
[2016-03-07 16:51:12] lumen.INFO: Range Beacon [2016-03-07 16:51:12] Maj.: 16 18446744073709551536
[2016-03-07 16:51:13] lumen.INFO: Range Beacon [2016-03-07 16:51:13] Maj.: 30 18446744073709551522
[2016-03-07 16:51:13] lumen.INFO: Range Beacon [2016-03-07 16:51:13] Maj.: 16 18446744073709551534
[2016-03-07 16:51:14] lumen.INFO: Range Beacon [2016-03-07 16:51:14] Maj.: 30 18446744073709551522
[2016-03-07 16:51:14] lumen.INFO: Range Beacon [2016-03-07 16:51:14] Maj.: 16 18446744073709551534
[2016-03-07 16:51:15] lumen.INFO: Range Beacon [2016-03-07 16:51:15] Maj.: 30 18446744073709551522
[2016-03-07 16:51:15] lumen.INFO: Range Beacon [2016-03-07 16:51:15] Maj.: 16 18446744073709551535
[2016-03-07 16:51:16] lumen.INFO: Range Beacon [2016-03-07 16:51:16] Maj.: 30 18446744073709551522
[2016-03-07 16:51:16] lumen.INFO: Range Beacon [2016-03-07 16:51:16] Maj.: 16 18446744073709551537
[2016-03-07 16:51:17] lumen.INFO: Range Beacon [2016-03-07 16:51:17] Maj.: 30 18446744073709551522
[2016-03-07 16:51:17] lumen.INFO: Range Beacon [2016-03-07 16:51:17] Maj.: 16 18446744073709551535
[2016-03-07 16:51:18] lumen.INFO: Range Beacon [2016-03-07 16:51:18] Maj.: 30 18446744073709551521
[2016-03-07 16:51:18] lumen.INFO: Range Beacon [2016-03-07 16:51:18] Maj.: 16 18446744073709551535
[2016-03-07 16:51:19] lumen.INFO: Range Beacon [2016-03-07 16:51:19] Maj.: 30 18446744073709551521
[2016-03-07 16:51:19] lumen.INFO: Range Beacon [2016-03-07 16:51:19] Maj.: 16 18446744073709551535
[2016-03-07 16:51:20] lumen.INFO: Range Beacon [2016-03-07 16:51:20] Maj.: 30 18446744073709551521
[2016-03-07 16:51:20] lumen.INFO: Range Beacon [2016-03-07 16:51:20] Maj.: 16 18446744073709551534
[2016-03-07 16:51:21] lumen.INFO: Range Beacon [2016-03-07 16:51:21] Maj.: 30 18446744073709551522
[2016-03-07 16:51:21] lumen.INFO: Range Beacon [2016-03-07 16:51:21] Maj.: 16 18446744073709551534
[2016-03-07 16:51:22] lumen.INFO: Range Beacon [2016-03-07 16:51:22] Maj.: 30 18446744073709551519
[2016-03-07 16:51:22] lumen.INFO: Range Beacon [2016-03-07 16:51:22] Maj.: 16 18446744073709551533
[2016-03-07 16:51:23] lumen.INFO: Range Beacon [2016-03-07 16:51:23] Maj.: 30 18446744073709551520
[2016-03-07 16:51:23] lumen.INFO: Range Beacon [2016-03-07 16:51:23] Maj.: 16 18446744073709551531
[2016-03-07 16:51:24] lumen.INFO: Range Beacon [2016-03-07 16:51:24] Maj.: 30 0
[2016-03-07 16:51:24] lumen.INFO: Range Beacon [2016-03-07 16:51:24] Maj.: 16 18446744073709551518
[2016-03-07 16:51:25] lumen.INFO: Range Beacon [2016-03-07 16:51:25] Maj.: 30 0
[2016-03-07 16:51:25] lumen.INFO: Range Beacon [2016-03-07 16:51:25] Maj.: 16 18446744073709551518
[2016-03-07 16:51:26] lumen.INFO: Range Beacon [2016-03-07 16:51:26] Maj.: 30 0
[2016-03-07 16:51:26] lumen.INFO: Range Beacon [2016-03-07 16:51:26] Maj.: 16 18446744073709551517
[2016-03-07 16:51:27] lumen.INFO: Range Beacon [2016-03-07 16:51:27] Maj.: 30 0
[2016-03-07 16:51:27] lumen.INFO: Range Beacon [2016-03-07 16:51:27] Maj.: 16 0
[2016-03-07 16:51:28] lumen.INFO: Range Beacon [2016-03-07 16:51:28] Maj.: 30 0
[2016-03-07 16:51:28] lumen.INFO: Range Beacon [2016-03-07 16:51:28] Maj.: 16 18446744073709551520
[2016-03-07 16:51:29] lumen.INFO: Range Beacon [2016-03-07 16:51:29] Maj.: 30 0
[2016-03-07 16:51:29] lumen.INFO: Range Beacon [2016-03-07 16:51:29] Maj.: 16 0
[2016-03-07 16:51:30] lumen.INFO: Range Beacon [2016-03-07 16:51:30] Maj.: 30 0
[2016-03-07 16:51:30] lumen.INFO: Range Beacon [2016-03-07 16:51:30] Maj.: 16 0
[2016-03-07 16:51:31] lumen.INFO: Range Beacon [2016-03-07 16:51:31] Maj.: 30 0
[2016-03-07 16:51:31] lumen.INFO: Range Beacon [2016-03-07 16:51:31] Maj.: 16 0
[2016-03-07 16:51:32] lumen.INFO: Range Beacon [2016-03-07 16:51:32] Maj.: 30 0
[2016-03-07 16:51:32] lumen.INFO: Range Beacon [2016-03-07 16:51:32] Maj.: 16 0
[2016-03-07 16:51:33] lumen.INFO: Range Beacon [2016-03-07 16:51:33] Maj.: 16 0
[2016-03-07 16:51:34] lumen.INFO: Range Beacon [2016-03-07 16:51:34] Maj.: 16 0
[2016-03-07 16:51:35] lumen.INFO: Range Beacon [2016-03-07 16:51:35] Maj.: 16 0
[2016-03-07 16:51:36] lumen.INFO: Range Beacon [2016-03-07 16:51:36] Maj.: 16 0
[2016-03-07 16:51:37] lumen.INFO: Range Beacon [2016-03-07 16:51:37] Maj.: 16 0
Does anyone know why the detection frequency of the RSSI value does differ that much between the two use cases? Is ranging in the background that much worse?
Thx.