Routine Background Tasks(BLE)

Dear.


I develope an app which ready to connect to device I made in the Background by BLE.


It is almost done. but I found some problem when the App work for a long time(about 5~6 hours).


the App is restarted whan I turn on the Phone.


is there the solution to prevent this behaviour?


the App is searching and sending data to Device in the Background.


Thanks.