Background BLE scan in DOZE mode on Android devices

Background BLE scan in DOZE mode on Android devices could be divided into two different groups depending on the mechanisms used for scheduling background tasks. Most of the new solutions will not work for old Android versions and all the old solutions will be killed by Android in new versions. We will review two different strategies for scanning in the background — for versions before API 26 (Oreo) and after. Android will not allow starting the service when your app is killed so here we need better solutions. Each solution could be used if you will decide not to fight with Doze mode.