Would a Bluetooth LE Jedi know any trick how to get a reliable BLE scanning mode on cheap Android 4.4 devices ?
Everything works fine from Android 5 to 6, and most of the Android 4.4 phones... However, on some cheap phones with 4.4 we encounter random issues, some phones do not detect anything, or sometimes just a few beacons among others, depending on environment, daytime, weather, or whatever... It's obviously due to a poor software or hardware on this side, but is there any trick to make it more stable programmatically ? (for example enabling / disabling Bluetooth regularly)
EDIT
To describe a typical behavior:
First, note that it is the exact same behavior with all scanning Apps I could test (Estimote, Kontakt.io, AltBeacon, etc. etc.) - so this is much probably not a matter of App implementation.
It occurs only below Android 5 (4.4.2, 4.4.3, 4.4.4) and on cheap devices, never on phones like a Samsung S5 for example.
The behavior: let's assume we have 5 beacons very close (less than 2 meters, all working fine). - Once rebooted the phone finds 5 beacons for 1 or 2 minutes. - Then it finds nothing for 5 minutes. - After a refresh it finds 2 beacons. - Another refresh of the scan: only 1 found. Then none... etc.
I could not find any logic, for now it looks erratic. Enabling / disabling Wifi / Bluetooth, Bluetooth+Wifi, Wifi then Bluetooth, etc. make sometimes the scan find one more beacon, sometimes not... there is probably not much difference if I just wait without changing those params.
The only way to get back a reliable scan is to reboot the device... then it works only for 1 or 2 minutes again...
It occurs on some very different devices (a Wiko Sunset, a Samsung XCover, an Orange Roya).
On more recent devices (Nexus 6, Samsung S5, Samsung A4...), 100% of the beacons are detected, for hours, and never lost.
So, as the complete reboot is actually the best solution to get all beacons detected I was wondering if there is a way to "refresh" the device's Bluetooth module without rebooting it... Or if we just have to become a philosopher about this ;-)
if you are develop your application using node.js then there are many api's avaliable which may work for you.But in case of android it is totally depend on your android version
来源：https://stackoverflow.com/questions/35503904/android-4-4-ble-scanning-lack-of-stability