RRC STATES

RRC STATES

RRC states in LTE are very simple. Its just 2 states as explained in the 3GPP spec 36.331

1. RRC_IDLE
2. RRC_CONNECTED

RRC_IDLE:

1. A UE specific DRX may be configured by upper layers.
2. UE controlled mobility;
    The UE:
     i. Monitors a Paging channel to detect incoming calls, system information change, for ETWS capable UEs, ETWS notification, and for CMAS capable UEs, CMAS notification;
     ii. Performs neighbouring cell measurements and cell (re-)selection;
     iii. Acquires system information
     iv. Performs logging of available measurements together with location and time for logged measurement configured UEs.

RRC_CONNECTED:

Transfer of unicast data to/from UE.

At lower layers, the UE may be configured with a UE specific DRX.
1. For UEs supporting CA, use of one or more SCells, aggregated with the PCell, for increased bandwidth;
2. Network controlled mobility, i.e. handover and cell change order with optional network assistance (NACC) to GERAN;

The UE:
1. Monitors a Paging channel and/ or System Information Block Type 1 contents to detect system
information change, for ETWS capable UEs, ETWS notification, and for CMAS capable UEs, CMAS notification;
2.  Monitors control channels associated with the shared data channel to determine if data is scheduled for it;
3. Provides channel quality and feedback information;
4. Performs neighbouring cell measurements and measurement reporting;
5. Acquires system information.

You can find the RRC state change Diagram across LTE/UMTS/GPRS due to inter RAT handovers here:

Source: 3GPP Spec 36.331