RRC_IDLE
The UE is in the idle state when there is no RRC connection established.
In RRC_IDLE:
- A UE specific DRX cycle may be configured by upper layers.
- UE monitors a paging channel for core network paging using 5G-S-TMSI or IMSI.
- UE performs neighbor cell measurements and cell reselection.
- UE acquires system information (SI).
RRC_INACTIVE
The RRC_INACTIVE state is not present in EN-DC. It only exists in NGEN-DC when the master node is an ng-eNB.
The UE is in an inactive state when there is an RRC connection that has been suspended.
In inactive mode, the UE performs all of the functions that are part of the idle state.
In RRC_INACTIVE:
- A UE specific DRX cycle may be configured by the RRC layer.
- UE Stores the access stratum context.
- A RAN-based notification area is configured by the RRC layer.
- UE performs RAN-based notification area updates periodically.
- UE performs additional updates when moving outside the configured RNA.
- UE monitors a paging channel for RAN based paging using I-RNTI.
A UE in the inactive state can move between nodes within its notification area without needing to inform the network. The network is only notified when the UE moves outside its notification area.