RRC has two possible states
- RRC IDLE
- RRC CONNECTED.
A UE in EPS Mobility Management (EMM) – IDLE is RRC IDLE
A UE in EPS Mobility Management (EMM) – CONNECTED is RRC CONNECTED.
- Support for Discontinous Reception (DRX) configured by NAS
- UE has no RRC connection
- UE listens to paging and broadcast system information
- UE has an identity , which uniquely identifies the UE in a tracking area level only not at cell level
- For mobility purpose Cell re-selection is performed (by the UE)
- No RRC context in the eNode B for the UE
- UE has an RRC connection
- Network can transmit and/or receive data from UE with very limited access delay
- UE has context in eNodeB
- Mobility is Network controlled and is triggered by Measurement reporting and executed as handover
- UE performs neighboring cell measurements
- UE specific DRX/DTX for UE power saving and resource preservation exists in RRC Connected mode. These functions are controlled by an eNodeB using RRC protocol
- Channel quality monitoring reported by the UE in MAC layer
- MAC control plane related procedures such as Discontinuous Transmission (DTX), UL synchronization, channel estimate etc. take place in connected mode.