In mobile communication systems, accurate and efficient coordination and interoperability require the base station to be fully aware of the capabilities of the UE. Typically, the eNB initiates a query, and the UE reports whether it supports certain features or functionalities. By doing this, the base station can make appropriate configurations and perform correct resource allocation.
When the UE initially connects to the network, the core network triggers eNB to retrieve the UE's capabilities. The process is as follows:
1. The MME (Mobility Management Entity) initiates the Initial Context Setup Request via S1AP interface to establish the initial context for the UE.
2. If the Initial Context Setup Request does not contain any UE capability information, eNB will initiate an RRC (Radio Resource Control) UE Capability Enquiry to UE.
3. Upon receiving the enquiry, UE responds with its capabilities through the RRC UE Capability Information, which is then sent back to eNB.
4. After receiving the RRC UE Capability Information from UE, eNB sends UE Capability Info Indication to MME, which then stores the UE's capabilities.
As long as the UE under the control of MME, MME will store the UE's capabilities for future reconnections, streamlining network operations.
