7 Protocol states

25.3313GPPProtocol specificationRadio Resource Control (RRC)Release 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

7.1 Overview of RRC States and State Transitions including GSM and E-UTRA

Figure 7.1-1 shows the RRC states in UTRA RRC Connected Mode, including transitions between UTRA RRC connected mode and GSM connected mode for CS domain services, and between UTRA RRC connected mode and GSM/GPRS packet modes or E-UTRA RRC connected mode for PS domain services. It also shows the transitions between Idle Mode and UTRA RRC Connected Mode and furthermore the transitions within UTRA RRC connected mode.

Figure 7.1-1: RRC States and State Transitions including GSM and E-UTRA

NOTE^: 1: The indicated division within Idle Mode is only included for clarification and shall not be interpreted as states.

NOTE: Transitions between GSM/GPRS and E-UTRA are not shown.

The RRC connection is defined as a point-to-point bi-directional connection between RRC peer entities in the UE and the UTRAN characterised by the allocation of a U-RNTI. A UE has either zero or one RRC connection.

If NAS informs AS about a new selected PLMN, registered PLMN or equivalent PLMN list while being in connected mode, the UE shall perform the actions according to subclause 8.5.24.

NOTE: The state transitions are specified in clause 8.

7.2 Processes in UE modes/states

NOTE: This subclause specifies what processes shall be active in the UE in the different RRC modes/states. The related procedures and the conditions on which they are triggered are specified either in clause 8 or elsewhere in the relevant process definition.

7.2.1 UE Idle mode

UE processes that are active in UE Idle mode are specified in [4].

The UE shall perform a periodic search for higher priority PLMNs as specified in [25], unless the UE is receiving MBMS services via p-t-m radio bearers.

The UE shall store available measurement results as specified in [4], when logged measurement is configured.

The UE shall perform ANR measurements and logging as specified in [4], when logged ANR measurement is configured.

A UE that is capable of receiving MBMS services on cells operating in MBSFN mode as specified in subclause 8.1.1.6.3 is operating in idle mode and acts on RRC messages and system information received from this cell operating in MBSFN mode independently from messages received from cells not operating in MBSFN mode. This implies that procedures executed based on messages and system information received from a cell operating in MBSFN mode shall not interact with messages and system information received from a cell not operating in MBSFN mode unless explicitely specified otherwise.

NOTE 1: This implies that the UE is operating an independent stack for the reception of MBMS services on cells operating in MBSFN mode as specified in subclause 8.1.1.6.3.

NOTE 2: For 1.28 Mcps TDD, if the cell is operating in MBSFN mode, system information and MCCH messages are transmitted on the MBSFN Special Timeslot [30].

7.2.2 UTRA RRC Connected mode

In this specification unless otherwise mentioned "connected mode" shall refer to "UTRA RRC connected mode".

7.2.2.1 URA_PCH or CELL_PCH state

In the URA_PCH or CELL_PCH state the UE shall perform the following actions:

NOTE: For 3.84 Mcps TDD and 7.68 Mcps TDD, neither DCCH nor DTCH are available in these states.
For FDD and 1.28 Mcps TDD, DCCH and DTCH reception on HS-DSCH may be configured in CELL_PCH state, if the UE supports HS-DSCH reception in CELL_PCH and URA_PCH state. Otherwise, neither DCCH nor DTCH are available in CELL_PCH state. In URA_PCH, neither DCCH nor DTCH are available.

1> if the UE is "in service area":

2> maintain up-to-date system information as broadcast by the serving cell as specified in the subclause 8.1.1;

2> perform cell reselection process as specified in [4];

2> perform a periodic search for higher priority PLMNs as specified in [25], unless the UE is receiving MBMS services via p-t-m radio bearers;

NOTE: If the DRX cycle length is 80ms, then a search for higher priority PLMNs may not identify all the available PLMNs due to the paging occasion on the current serving cell coinciding with the MIB of the cell of interest.

2> for 3.84 Mcps TDD and 7.68 Mcps TDD; or

2> for FDD and 1.28 Mcps TDD, if the UE does not support HS-DSCH reception in CELL_PCH and URA_PCH state; or

2> if the IE "HS-DSCH paging system information" is not included in System Information Block type 5 or System Information Block type 5bis; or

2> for 1.28 Mcps TDD, if variable H_RNTI or variable C_RNTI is not set, and the IE "PICH info" is included in IE "Secondary CCPCH system information" in System Information Block type 5 or System Information Block type 6:

3> monitor the paging occasions and PICH monitoring occasions determined according to subclauses 8.6.3.1a, 8.6.3.2 and 8.5.42 and receive paging information on the PCH mapped on the S-CCPCH selected by the UE according to the procedure in subclause 8.5.19;

2> else:

3> monitor the paging occasions and PICH monitoring occasions determined according to subclauses 8.6.3.1a, 8.6.3.2 and 8.5.39 and receive PCCH on the HS-DSCH mapped on the HS-PDSCH, or DCCH and DTCH on the HS-DSCH mapped on the HS-PDSCH and the associated HS-SCCH selected by the UE according to the procedure in subclause 8.5.40 for FDD and 8.5.40a for 1.28 Mcps TDD.

2> act on RRC messages received on PCCH, BCCH, and DCCH (FDD only);

2> perform measurements process according to measurement control information as specified in subclause 8.4 and in subclause 14.4;

2> maintain up-to-date BMC data if it supports Cell Broadcast Service (CBS) as specified in [37];

2> act on RRC messages received on MCCH if it supports MBMS and has activated an MBMS service as specified in subclause 8.7;

2> run timer T305 for periodical URA update if the UE is in URA_PCH or for periodical cell update if the UE is in CELL_PCH.

2> store available measurements if logged measurement is configured as specified in [4].

2> perform ANR measurements and logging as specified in [4], when logged ANR measurement is configured.

1> if the UE is "out of service area":

2> perform cell selection process as specified in [4];

2> run timer T316;

2> run timer T305 or T307;

2> if the cell selection process fails to find a suitable cell after a complete scan of all RATs and all frequency bands supported by the UE, the UE shall after a minimum of TimerOutOfService time (default value 30 s) of being "out of service area":

3> indicate all available PLMNs to NAS to enable the selection of a new PLMN;

3> if an acceptable cell is found then the UE shall camp on that cell to obtain limited service as defined in [4] and, perform actions according to subclause 8.5.24;

3> else if no acceptable cell is found, the UE shall continue looking for an acceptable cell as defined in [4].

7.2.2.2 CELL_FACH state

In the CELL_FACH state the UE shall perform the following actions:

NOTE: DCCH and, if configured, DTCH are available in this state.

1> if the UE is "in service area":

2> maintain up-to-date system information as broadcast by the serving cell as specified in subclause 8.1.1;

2> perform cell reselection process as specified in [4];

2> perform measurements process according to measurement control information as specified in subclause 8.4 and in subclause 14.4;

2> run timer T305 (periodical cell update);

2> select and configure the RB multiplexing options applicable for the transport channels to be used in this RRC state;

2> store available measurements if logged measurement is configured as specified in [4] when second DRX cycle is used;

2> for 3.84 Mcps and 7.68 Mcps TDD; or

2> for FDD and 1.28 Mcps TDD, if the UE does not support HS-DSCH reception in CELL_FACH state; or

2> if the IE "HS-DSCH common system information" is not included in System Information Block type 5 or System Information Block type 5bis; or

2> for 1.28 Mcps TDD, if the IE "common E-DCH system info" is not included in System Information Block type 5:

3> listen to all FACH transport channels mapped on the S-CCPCH selected by the UE according to the procedure in subclause 8.5.19.

2> else:

3> if variable H_RNTI is set:

4> receive physical channels HS-SCCH(s) using the value of the variable H_RNTI as UE identity and parameters given by the IE(s) "HS-DSCH common system information" according to the procedure in subclause 8.5.36.

3> else:

4> if the variable HS_DSCH_RECEPTION_OF_CCCH_ENABLED is set to TRUE:

5> receive physical channel(s) of type HS-SCCH with selected common H-RNTI using parameters given by the IE(s) "HS-DSCH common system information" according to the procedure in subclause 8.5.37.

2> act on RRC messages received on BCCH, CCCH and DCCH;

2> act on RRC messages received on MCCH if it supports MBMS and has activated an MBMS service as specified in subclause 8.7;

2> act on RRC messages received on, if available, SHCCH (TDD only).

1> if the UE is "out of service area":

2> perform cell selection process as specified in [4];

2> run timers T305 (periodical cell update), and T317 (cell update when re-entering "in service") or T307 (transition to Idle mode), if started;

2> run timers T314 and/or T315, if started;

3> indicate all available PLMNs to NAS to enable the selection of a new PLMN;

3> if an acceptable cell is found then the UE shall camp on that cell to obtain limited service as defined in [4] and perform actions according to subclause 8.5.24;

3> else if no acceptable cell is found, the UE shall continue looking for an acceptable cell as defined in [4].

7.2.2.3 CELL_DCH state

In the CELL_DCH state the UE shall perform the following actions:

NOTE: DCCH and, if configured, DTCH are available in this state.

1> read the system information as specified in subclause 8.1.1 (for UEs in TDD mode);

1> perform measurements process according to measurement control information as specified in subclause 8.4 and in clause 14;

1> select and configure the RB multiplexing options applicable for the transport channels to be used in this RRC state;

1> act on RRC messages received on DCCH;

1> act on RRC messages received on BCCH (applicable only to UEs with certain capabilities and in FDD mode);

1> act on RRC messages received on MCCH if it supports MBMS and has activated an MBMS service as specified in subclause 8.7 (applicable only to UEs supporting MBMS with certain capabilities);

1> act on RRC messages received on BCCH (TDD only) and, if available, SHCCH (TDD only).

NOTE: If any of the above procedures results in different HS-DSCH and E-DCH serving cells, the UE behaviour is unspecified except when Serving E-DCH cell decoupling is configured.