NI session keep timeout when apps running in background

Hi All

I can run the nearby interaction even the apps is in background, while there is a distance information in the accessory side, the apps invoke delegate function "didRemove nearbyObject" with timeout periodically.

is there any way to disable the timeout when it is running in background? Or anything I did wrong so that the session keep timeout while there is distance measurement in accessory side, please anyone help. Thanks in advance