Feeder Link Monitoring and Notification in Satellite Communications

Hello,

I have a question. How does the satellite side become aware of the situation when the feeder link connection weakens or breaks in satellites (bent pipe or regenerative payload)? For example, is the signal strength of the feeder link connection measured? Is there a countdown or timer on the slot to reconnect?

How is this notified to the user side? Is there a special signaling that indicates that the feeder link connection is broken?

I couldn’t find any information when I looked at the 3GPP and ITU standardization.

Thanks.