S1-AP reset or ENodeB behavior once receiving the release context with Detach reason ?

Question

What is the behavior for the LTE eNodeB if the enodeB received release context (with detach reason) or S1AP reset, what happened with the Radio Resource toward UE ?

Answer 1

Here there are two questions have been asked.
1. Detach of an UE
2. Reset.

I would like to explain each one separately.

--> When MME finishes NAS level messages related to detach procedure. It sends S1-AP "UE Context Release Command" message witch appropriate cause. Once enodeB receives this message for an UE. it shall release S1 resources and Uu resources for that UE and confirm to MME with reply S1-AP message i.e "UE Context Release Complete". If you see Cause receives in "UE Context Release Command" has sub level NAS cause. As per my knowledge, regardless of this cause value, enodeB would clear the S1 and Uu resources for that particular UE.

--> Now for your query, when eNodeB receives S1-AP "RESET" message. MME may all to reset all the ue contexts from the eNodeB or a subset. Based on the failure occurred at MME. If it is for all S1 reset, then enodeB shall release S1 and Uu resources(which is nothing but radio resoures) for all the available UEs else list of UEs sent by MME. eNodeB shall also acknowledge MME by sending ACK message.

Note: Radio resource shall be released for an UE or set of UEs in both the cases.