what is the minimum compatible version for android operating system if I want to use fused location provider to get current location ?
I don't think there is a minimum version. Even and if you use SDK:10 it will work. http://web.archive.org/web/20141216140051/https://developer.android.com/reference/com/google/android/gms/location/FusedLocationProviderApi.html
and an example https://web.archive.org/web/20130911205013/http://www.kpbird.com/2013/06/fused-location-provider-example.html