8.1.14 Signalling connection release indication procedure

25.3313GPPProtocol specificationRadio Resource Control (RRC)Release 17TS

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

Figure 8.1.14-1: Signalling connection release indication procedure, normal case

8.1.14.1 General

The signalling connection release indication procedure is used by the UE to indicate to the UTRAN that one of its signalling connections has been released or it is used by the UE to request UTRAN to initiate a state transition to a battery efficient RRC state. The procedure may in turn initiate the RRC connection release procedure.

8.1.14.2 Initiation

The UE shall, on receiving a request to release (abort) the signalling connection from upper layers for a specific CN domain:

1> if a signalling connection in the variable ESTABLISHED_SIGNALLING_CONNECTIONS for the specific CN domain identified with the IE "CN domain identity" exists:

2> initiate the signalling connection release indication procedure.

1> otherwise:

2> abort any ongoing establishment of signalling connection for that specific CN domain as specified in 8.1.3.5a.

Upon initiation of the signalling connection release indication procedure in CELL_PCH or URA_PCH state, the UE shall:

1> if variable READY_FOR_COMMON_EDCH is set to TRUE:

2> move to CELL_FACH state by performing the actions as described in subclause 8.5.47, and continue with the signalling connection release indication procedure as below.

1> else:

2> if variable HSPA_RNTI_STORED_PCH is set to TRUE:

3> move to CELL_FACH state by performing the actions as described in subclause 8.5.56, and continue with the signalling connection release indication procedure as below.

2> else:

3> if variable H_RNTI and variable C_RNTI are set:

4> continue with the signalling connection release indication procedure as below.

3> else:

4> perform a cell update procedure, according to subclause 8.3.1, using the cause "uplink data transmission";

4> when the cell update procedure completed successfully:

5> continue with the signalling connection release indication procedure as below.

The UE shall:

1> set the IE "CN Domain Identity" to the value indicated by the upper layers. The value of the IE indicates the CN domain whose associated signalling connection the upper layers are indicating to be released;

1> if the UE includes the IE "Signalling Connection Release Indication Cause" and does not set it to "UE Requested PS Data session end";

2> set the IE "Signalling Connection Release Indication Cause" to "any other cause";

1> transmit a SIGNALLING CONNECTION RELEASE INDICATION message on DCCH using AM RLC;

1> if the SIGNALLING CONNECTION RELEASE INDICATION message did not include the IE "Signalling Connection Release Indication Cause" set to "UE Requested PS Data session end".

2> remove the signalling connection with the identity indicated by upper layers from the variable ESTABLISHED_SIGNALLING_CONNECTIONS.

When the successful delivery of the SIGNALLING CONNECTION RELEASE INDICATION message has been confirmed by RLC the procedure ends.

In addition, if the timer T323 value is stored in the IE "UE Timers and constants in connected mode" in the variable TIMERS_AND_CONSTANTS, and if there is no CS domain connection indicated in the variable ESTABLISHED_SIGNALLING_CONNECTIONS, the UE may:

1> if the upper layers indicate that there is no more PS data for a prolonged period:

2> if timer T323 is not running:

3> if the UE is in CELL_DCH state; or

3> if the UE is in CELL_FACH state and the variable HS_DSCH_DRX_CELL_FACH_2CYCLE_STATUS is set to FALSE; or

3> if the UE is in CELL_FACH state and the variable HS_DSCH_DRX_CELL_FACH_2CYCLE_STATUS is set to TRUE and HS-DSCH second DRX cycle_FACH is shorter than the shorter CN domain specific DRX cycle length for the PS domain and CS domain; or

3> if the UE is in CELL_FACH state and the variable HS_DSCH_DRX_CELL_FACH_2CYCLE_STATUS is set to TRUE and HS-DSCH second DRX cycle_FACH is equal to or longer than the shorter CN domain specific DRX cycle length for the PS domain and CS domain, and V316 < 1; or

3> if the UE is in CELL_PCH state or URA_PCH state and the DRX cycle length in use is shorter than the shorter CN domain specific DRX cycle length for the PS domain and CS domain; or

3> if the UE is in CELL_PCH state or URA_PCH state and the DRX cycle length in use is equal to or longer than the shorter CN domain specific DRX cycle length for the PS domain and CS domain, and V316 < 1:

4> if the UE is in CELL_PCH state or URA_PCH state and the DRX cycle length in use is equal to or longer than the shorter CN domain specific DRX cycle length for the PS domain and CS domain:

5> increment V316 by 1.

4> if the UE is in CELL_FACH state and the variable HS_DSCH_DRX_CELL_FACH_2CYCLE_STATUS is set to TRUE and HS-DSCH second DRX cycle_FACH is equal to or longer than the shorter CN domain specific DRX cycle length for the PS domain and CS domain:

5> increment V316 by 1.

4> set the IE "CN Domain Identity" to PS domain;

4> set the IE "Signalling Connection Release Indication Cause" to "UE Requested PS Data session end";

4> if the UE has a stored configuration in the variable OTHER_STATE_CONFIGURATION with a value of IE "Source RRC state indicator" corresponding to the UE current UE RRC state, and the variable ORDERED_RECONFIGURATION is FALSE:

5> transmit a SIGNALLING CONNECTION RELEASE INDICATION message on DCCH using AM RLC;

5> start the timer T323;

5> when the successful transmission of the SIGNALLING CONNECTION RELEASE INDICATION message has been confirmed by the lower layers:

6> act on sub-clause 8.2.2.3 and move to the RRC state indicated by IE "Target RRC state indicator" in the corresponding configuration in variable OTHER_STATE_CONFIGURATION.

4> else:

5> transmit a SIGNALLING CONNECTION RELEASE INDICATION message on DCCH using AM RLC;

5> start the timer T323.

3> the procedure ends.

The UE shall be inhibited from sending the SIGNALLING CONNECTION RELEASE INDICATION message with the IE "Signalling Connection Release Indication Cause" set to "UE Requested PS Data session end" whilst timer T323 is running.

The UE shall not locally release the PS signalling connection after it has sent the SIGNALLING CONNECTION RELEASE INDICATION message with the IE "Signalling Connection Release Indication Cause" set to "UE Requested PS Data session end".

At transmission or reception of PS data or signalling on SRB3 or upwards, or entering RRC Connected mode, or successful SRNS relocation, the UE shall set V316 to zero.

8.1.14.2a RLC re-establishment or inter-RAT change

If a re-establishment of the transmitting side of the RLC entity on signalling radio bearer RB2 occurs before the successful delivery of the SIGNALLING CONNECTION RELEASE INDICATION message, without the IE "Signalling Connection Release Indication Cause" or with the IE "Signalling Connection Release Indication Cause" set to a value other than "UE Requested PS Data session end", has been confirmed by RLC, the UE shall:

1> retransmit the SIGNALLING CONNECTION RELEASE INDICATION message on the uplink DCCH using AM RLC on signalling radio bearer RB2.

If an Inter-RAT handover from UTRAN procedure occurs before the successful delivery of the SIGNALLING CONNECTION RELEASE INDICATION message without the IE "Signalling Connection Release Indication Cause" or with the IE "Signalling Connection Release Indication Cause" set to a value other than "UE Requested PS Data session end", has been confirmed by RLC, the UE shall:

1> abort the signalling connection while in the new RAT.

8.1.14.3 Reception of SIGNALLING CONNECTION RELEASE INDICATION by the UTRAN

Upon reception of a SIGNALLING CONNECTION RELEASE INDICATION message, if the IE "Signalling Connection Release Indication Cause" is not included or the IE "Signalling Connection Release Indication Cause" is set to "any other cause", the UTRAN requests the release of the signalling connection from upper layers. Upper layers may then initiate the release of the signalling connection.

If the IE "Signalling Connection Release Indication Cause" is set to "UE Requested PS Data session end" in the SIGNALLING CONNECTION RELEASE INDICATION message the UTRAN may initiate a state transition to efficient battery consumption RRC state such as IDLE, CELL_PCH, URA_PCH or CELL_FACH state.

8.1.14.4 Expiry of timer T323

When timer T323 expires:

1> the UE may determine whether any subsequent indications from upper layers that there is no more PS data for a prolonged period in which case it triggers the transmission of a single SIGNALLING CONNECTION RELEASE INDICATION message according with clause 8.1.14.2;

1> the procedure ends.

NOTE: If the UE is in CELL_PCH state or URA_PCH state and the DRX cycle length in use is shorter than the shorter of the CN domain specific DRX cycle lengths for the PS domain and CS domain or the UE is in CELL_FACH state and the variable HS_DSCH_DRX_CELL_FACH_2CYCLE_STATUS is set to TRUE and HS-DSCH second DRX cycle_FACH is shorter than the shorter of the CN domain specific DRX cycle length for the PS domain and CS domain the UE should limit the number of subsequent SIGNALLING CONNECTION RELEASE INDICATION messages with IE "Signalling Connection Release Indication Cause" set to "UE Requested PS Data session end" in order to not adversely impact the battery lifetime or network signalling load.