13.1.3 Call setup from E-UTRAN RRC_CONNECTED / CS fallback to UTRAN with redirection / MT call

36.523-13GPPEvolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Packet Core (EPC)Part 1: Protocol conformance specificationRelease 17TSUser Equipment (UE) conformance specification

13.1.3.1 Test Purpose (TP)

(1)

with { UE in E-UTRA RRC_CONNECTED state }

ensure that {

when { UE receives a DLInformationTransfer message containing a CS SERVICE NOTIFICATION message }

then { UE transmits an ULInformationTransfer message containing an EXTENDED SERVICE REQUEST message with Service Type IE set to "mobile terminating CS fallback or 1xCS fallback” }

}

(2)

with { UE having transmitted an ULInformationTranfer message containing an EXTENDED SERVICE REQUEST message with Service Type IE set to "mobile terminating CS fallback or 1xCS fallback” }

ensure that {
when { SS transmits an RRCConnectionRelease message with redirection to a UTRA cell in same location area and operating in NMO I }

then { UE tunes to UTRA cell and initiates a CS domain PAGING RESPONSE procedure and a parallel PS domain RA Update procedure }

}

(3)

void

(4)

with { UE having transmitted an ULInformationTranfer message containing an EXTENDED SERVICE REQUEST message with Service Type IE set to "mobile terminating CS fallback or 1xCS fallback” and tuned to UTRA cell and initiated a RA Update procedure and having pending UL data to send}

ensure that {
when { UE completes the RA Update procedure }

then { UE transmits a SERVICE REQUEST to set up PS bearers on UTRA cell }

}

(5)

with { UE having transmitted an ULInformationTranfer message containing an EXTENDED SERVICE REQUEST message with Service Type IE set to "mobile terminating CS fallback or 1xCS fallback” and tuned to UTRA cell and initiated a RA Update procedure and having pending UL data to send}

ensure that {
when { PS bearers have been set up on UTRA cell }

then { UE transmits pending UL data }

}

13.1.3.2 Conformance requirements

References: The conformance requirements covered in the current TC are those listed in TC 8.1.3.6, plus those specified in: TS 23.272, clause 7.4, and TS 24.301, clause 5.6.2.3.

[TS 23.272, clause 7.4]

Figure 7.4-1: CS Page in E-UTRAN, Call in GERAN/UTRAN without PS HO

1a. The MSC receives an incoming voice call and responds by sending a Paging Request (IMSI or TMSI, optional Caller Line Identification and Connection Management information, priority indication) to the MME over a SGs interface. The MSC only sends a CS Page for an UE that provides location update information using the SGs interface. In active mode the MME has an established S1 connection and if the MME did not return the "SMS-only" indication to the UE during Attach or Combined TA/LA Update procedures, the MME reuses the existing connection to relay the CS Service Notification to the UE.

If the MME returned the "SMS-only" indication to the UE during Attach or Combined TA/LA Update procedures, the MME shall not send the CS Page to the UE and sends CS Paging Reject towards MSC to stop CS Paging procedure, and this CSFB procedure stops.

The eNB forwards the paging message to the UE. The message contains CN Domain indicator and, if received from the MSC, the Caller Line Identification.

The MME immediately sends the SGs Service Request message to the MSC containing an indication that the UE was in connected mode. The MSC uses this connected mode indication to start the Call Forwarding on No Reply timer for that UE and the MSC should send an indication of user alerting to the calling party. Receipt of the SGs Service Request message stops the MSC retransmitting the SGs interface Paging message.

NOTE 1: The pre‑configured policy may be used by UE to avoid being disturbed without Caller Line Identification display and the detailed handling is to be decided by CT WG1 and CT WG6.

NOTE 2: This procedure can also take place immediately after MSC receives MAP_PRN from HSS, if pre-paging is deployed. Caller Line Identification is also provided in the case of pre-paging.

If the MME receives paging request message with priority indication, e.g. eMLPP priority, from the MSC, then the MME processes this message and also the subsequent CS fallback procedure preferentially compared to other normal procedures.

1b. UE sends an Extended Service Request (CS Fallback Indicator, Reject or Accept) message to the MME. Extended Service Request message is encapsulated in RRC and S1‑AP messages. CS Fallback Indicator indicates MME to perform CS Fallback. The UE may decide to reject CSFB based on Caller Line Identification.

1c. Upon receiving the Extended Service Request (CSFB, Reject), the MME sends Paging Reject towards MSC to stop CS Paging procedure and this CSFB procedure stops.

1d. The MME sends an S1‑AP UE Context Modification Request message to eNodeB that includes a CS Fallback Indicator. This message indicates to the eNB that the UE should be moved to UTRAN/GERAN.

If MME received priority indication in Step 1a, the MME sends S1-AP UE Context Modification Request message to the eNodeB with priority indication, i.e. "CSFB High Priority", as specified in TS 36.413 [35].

1e. The eNB shall reply with S1-AP UE Context Modification Response message.

2. The eNodeB may optionally solicit a measurement report from the UE to determine the target GERAN cell to which the redirection procedure will be performed.

The network performs one of steps 3a or 3b or 3c.

3a. If the UE and network support inter-RAT cell change order to GERAN and the target cell is GERAN:

The eNodeB can trigger an inter‑RAT cell change order (optionally with NACC) to a GERAN neighbour cell by sending an RRC message to the UE. The inter-RAT cell change order may contain a CS Fallback Indicator which indicates to UE that the cell change order is triggered due to a CS fallback request. If the inter-RAT cell change order contains a CS Fallback Indicator and the UE fails to establish connection to the target RAT, then the UE considers that CS fallback has failed. Service Request procedure is considered to be successfully completed when cell change order procedure is completed successfully.

3b. If the UE or the network does not support inter-RAT PS handover from E-UTRAN to GERAN/UTRAN nor inter-RAT cell change order to GERAN:

The eNodeB can trigger RRC connection release with redirection to GERAN or UTRAN instead of PS HO or NACC.

3c. If the UE and network support "RRC connection release with redirection and Multi Cell System Information to GERAN/UTRAN":

The eNodeB can trigger RRC connection release with redirection to GERAN or UTRAN and include one or more physical cell identities and their associated System Information.

NOTE 3: Service Request procedure supervision timer shall be sufficiently long considering the optional measurement reporting at step 2.NOTE 4: Service Request procedure supervision timer shall be sufficiently long considering the optional measurement reporting at step 2.

4. The eNodeB sends an S1 UE Context Release Request message to the MME. If the target cell is GERAN and either the target cell or the UE does not support DTM the message includes an indication that the UE is not available for PS service.

5. The MME releases the UE Context in the eNodeB as well as all eNodeB related information in the S-GW as specified in TS 23.401 [2].

In case the Cause indicates that RRC was released due to abnormal conditions, e.g. radio link failure, the MME suspends the EPS bearers (Step 8).

The UE performs one of steps 6a or 6b or 6c and THEN performs step 6d.

6a. (Step 6a is performed if step 3a, Cell Change Order to GERAN, was performed)

The UE moves to the new cell in GERAN. The UE uses the NACC information and/or receives the broadcast System Information and when it has the necessary information to access the GERAN cell, establishes a radio signalling connection.

6b. (Step 6b is performed if step 3b, RRC release with redirection, was performed)

The UE moves to the target RAT, identifies a suitable cell preferably of the same PLMN as received in LAI IE of combined EPS/IMSI Attach/TAU Accept message,, receives the broadcast System Information and when it has the necessary information to access GERAN/UTRAN, establishes a radio signalling connection.

6c. (Step 6c is performed if step 3c, RRC connection release with redirection and Multi Cell System Information, was performed)

The UE moves to the target RAT and identifies a suitable cell preferably of the same PLMN as received in LAI IE of combined EPS/IMSI Attach/TAU Accept message. The UE uses the NACC information and/or receives the broadcast System Information and when it has the necessary information to access GERAN/UTRAN, the UE establishes the radio signalling connection.

6d. If the LA of the new cell is different from the one stored in the UE, the UE shall initiate a Location Area Update or a Combined RA/LA Update as specified in TS 23.060 [3] for the different Network Modes of Operation (NMO). The UE shall set the "CSMT" flag in the LAU Request. The "CSMT" flag is used to avoid missing MT call in roaming retry case. In NMO I, the UE in GERAN may perform LA update over the RR connection instead of combined RA/LA update over the packet access as defined in TS 24.008 [21], clause 4.7.5.2.5, unless enhanced CS establishment in DTM is supported. Further the UE performs any Routing Area Update procedure as specified in TS 23.060 [3].

In NMO I a CSFB UE should perform LAU (and if it does so, shall set the "CSMT" flag) and RAU procedures instead of a Combined RA/LA Update procedure to speed up the CSFB procedure.

When the MSC receives a LA Update Request, it shall check for pending terminating CS calls and, if the "CSMT" flag is set, maintain the CS signalling connection after the Location Area Update procedure for pending terminating CS calls.

7. If the target RAT is GERAN and DTM is not supported, the UE starts the Suspend procedure specified in TS 23.060 [3], clause 16.2.1.1.2. This triggers the SGSN to send a Suspend Request message to the MME. The MME returns a Suspend Response to the SGSN even though GUTI cannot be derived from the P-TMSI and RAI pair.

8. If the S1-AP UE Context Release Request message, received from the eNodeB in step 4, indicates that the UE is not available for the PS services in the target cell, the MME deactivates GBR bearers towards S-GW and P-GW(s) by initiating MME-initiated Dedicated Bearer Deactivation procedure as specified in TS 23.401 [2], and starts the preservation and suspension of non-GBR bearers by sending Suspend Notification message to the S-GW. The S-GW releases all eNodeB related information (address and TEIDs) for the UE, and sends Suspend Notification message to the P-GW(s). The MME stores in the UE context that the UE is in suspended status. All the preserved non-GBR bearers are marked as suspended status in the S-GW and P-GW(s). The P-GW should discard packets if received for the suspended UE.

NOTE 4: Step 8 can not be triggered by the Suspend procedure since the full GUTI can not be derived from the P‑TMSI and RAI included in the Suspend Request message.

9. If the UE does not initiate a LAU procedure, the UE responds to the paging by sending a Paging Response message as specified in TS 44.018 [4] or TS 25.331 [7]. When received at the BSS/RNS, the Paging Response is forwarded to the MSC.

NOTE 6: The MSC should be prepared to receive a Paging Response after a relatively long time from when the CS Paging Request was sent (step 1a).

9a. If UE is registered in the MSC serving the 2G/3G cell and the UE is allowed in the LA the MSC shall establish the CS call.

9b. If the UE is not registered in the MSC that receives the Paging Response or the UE is not allowed in the LA, the MSC shall reject the Paging Response by releasing the A/Iu-cs connection. The BSS/RNS in turn releases the signalling connection for CS domain.

9c. The signalling connection release shall trigger the UE to obtain the LAI, which causes the initiation of a Location Area Update or a Combined RA/LA procedure as specified in TS 23.060 [3] for the different Network Modes of Operation (NMO).

The Location Area Update triggers the Roaming Retry for CS Fallback procedure as defined in clause 7.5.

After performing the LAU procedure the MSC shall establish the CS call if the UE is allowed in the LA.

[TS 24.301, clause 5.6.2.3]

The network may initiate the paging procedure for non-EPS services when the UE is IMSI attached for non-EPS services (see example in figure 5.6.2.3.1).

Figure 5.6.2.3.1: Paging procedure for CS fallback to A/Gb or Iu mode

To initiate the procedure when no NAS signalling connection exists, the EMM entity in the network requests the lower layer to start paging (see 3GPP TS 36.300 [20], 3GPP TS 36.413 [23]). The paging message includes a CN domain indicator set to "CS" in order to indicate that this is paging for CS fallback.

NOTE: The timer T3413 is not started in the network when the paging procedure is initiated for CS fallback.

To notify the UE about an incoming mobile terminating CS service when a NAS signalling connection exists, the EMM entity in the network shall send a CS SERVICE NOTIFICATION message. This message may also include CS service related parameters (e.g. Calling Line Identification, SS or LCS related parameters).

Upon reception of a paging indication, the UE shall respond with an EXTENDED SERVICE REQUEST. If the paging is received in EMM-IDLE mode, the UE shall respond immediately. If the paging is received as NAS CS NOTIFICATION message in EMM-CONNECTED mode, the UE may request upper layers input i.e. to accept or reject CS fallback before responding with an EXTENDED SERVICE REQUEST. The response is indicated in the CSFB response information element in the EXTENDED SERVICE REQUEST message in both EMM-IDLE and EMM-CONNECTED modes.

13.1.3.3 Test description

13.1.3.3.1 Pre-test conditions

System Simulator:

– 2 cells, one E-UTRA and one UTRA cell and same Location areas but different Routing areas:

– Cell 1 E-UTRA serving cell

– Cell 5 suitable neighbour UTRA cell

– The parameters settings and power levels for Cell 1 and Cell 5 are selected according to [18], [5] and Table 13.1.3.3.2-1 so that camping on Cell 1 is guaranteed and no cell re-selection to Cell 5 can take place (utra priority is lower than serving and S Cell 1 > Thresh Cell 1,low).

– System information combination 4 as defined in TS 36.508 [18] clause 4.4.3.1 is used in E-UTRA cells.

UE:

None.

Preamble:

– The UE is in state Loopback activated (state 4) on cell 1 according to [18] using UE test loop mode B with IP_PDU_delay set according to PIXIT parameter px_TestLoopModeB_Delay.

13.1.3.3.2 Test procedure sequence

Table 13.1.3.3.2-1 shows the cell power levels after the preamble.

Table 13.1.3.3.2-1: Cell power levels

Parameter

Unit

Cell 1

Cell 5

Remark

Cell-specific RS EPRE

dBm/15kHz

-75

–

The power levels are such that camping on Cell 1 is guaranteed.

CPICH_Ec (UTRA FDD)

dBm/3.84 MHz

–

-70

PCCPCH_Ec (UTRA LCR TDD)

dBm/1.28 MHz

–

-72

Table 13.1.3.3.2-2: Main behaviour

St

Procedure

Message Sequence

TP

Verdict

U – S

Message

1

The SS transmits one IP packet to the UE on the DRB associated with the default EPS bearer context on Cell 1.

<–

IP packet

–

–

2

The SS transmits a DLInformationTransfer message on Cell 1 containing a CS SERVICE NOTIFICATION message.

<–

DLInformationTransfer

NAS: CS SERVICE NOTIFICATION

–

–

–

EXCEPTION: Step 3a1 describes behaviour that depends on the UE capability; the "lower case letter" identifies a step sequence that takes place if a capability is supported.

–

–

–

–

3a1

IF the UE needs to request upper layer input before accepting the CS fallback, the incoming CS call is accepted at the UE through MMI or AT command.

–

–

–

–

4

Check: Does the UE transmit an ULInformationTranfer message containing an EXTENDED SERVICE REQUEST with Service Type IE set to "mobile terminating CS fallback or 1xCS fallback” on Cell 1?

–>

ULInformationTransfer

NAS: EXTENDED SERVICE REQUEST

1

P

5

The SS transmits an RRCConnectionRelease message on Cell 1 with IE redirectionInformation including UTRA-CarrierFreq of Cell 5.

<–

RRCConnectionRelease

–

–

6

Check: Does the UE transmit an RRC CONNECTION REQUEST message with Establishment cause ‘Registration’ or ‘Terminating Conversational Call‘?

–>

RRC CONNECTION REQUEST

2

P

6A1

The SS transmits an RRC CONNECTION SETUP message.

<–

RRC CONNECTION SETUP

–

–

6A2

The UE transmits an RRC CONNECTION SETUP COMPLETE message.

–>

RRC CONNECTION SETUP COMPLETE

–

–

7-11

Void

–

–

–

–

–

EXCEPTION: In parallel to the events described in steps 12 to 13 A11, the steps specified in Table 13.1.3.3.2-3 shall take place.

–

–

–

–

12

Check: Does the UE transmit a PAGING RESPONSE on Cell 5?

–>

PAGING RESPONSE

2

P

13 A1-13A11

Steps 7 to 17 of the generic test procedure in TS 34.108 subclause 7.2.3.1 are performed on Cell 5.

NOTE: Mobile terminating CS call is set up.

–

–

–

–

14

The SS transmits a SECURITY MODE COMMAND message for the PS domain on Cell 5. See Note.

<–

SECURITY MODE COMMAND

–

–

15

The UE transmits a SECURITY MODE COMPLETE message on Cell 5.

–>

SECURITY MODE COMPLETE

–

–

16

The SS transmits a ROUTING AREA UPDATE ACCEPT message on Cell 5.

<–

ROUTING AREA UPDATE ACCEPT

–

–

17

The UE transmits a ROUTING AREA UPDATE COMPLETE message on Cell 5.

–>

ROUTING AREA UPDATE COMPLETE

–

–

17A

The UE transmits Signalling Connection Release Indication message on Cell 5. See Note 2.

–>

SIGNALLING CONNECTION RELEASE INDICATION

–

–

18

Check: Does the UE transmit a SERVICE REQUEST message on Cell 5?

–>

SERVICE REQUEST

4

P

18A

Void

–

–

–

–

18B

The SS transmits a SECURITY MODE COMMAND message for the PS domain on Cell 5.

<–

SECURITY MODE COMMAND

–

–

18C

The UE transmits a SECURITY MODE COMPLETE message on Cell 5.

–>

SECURITY MODE COMPLETE

–

–

19-20

Steps 11 to 12 of the generic test procedure in TS 34.108 subclause 7.2.4.2 are performed on Cell 5.

NOTE: Mobile originating packet switched session is set up.

–

–

–

–

21

Check: Does the UE loop back the IP packet received in Step 1 on the RAB associated with the PDP context active on Cell 5?

–>

IP packet

5

P

Note 1: A real network will initiate the security mode command procedure for the PS domain immediately after receiving the ROUTING AREA UPDATE REQUEST, but in this test case it was chosen to complete the procedure for CS domain first in order to avoid the possibility of a security mode command procedure running in parallel with another RRC procedure.

Note 2: The UE sends Signalling Connection Release Indication message (as per TS 25.331 cl. 8.1.4.1) for the PS signalling connection release (as per TS 24.008 cl. 4.7.13, after RAU Accept with “no follow-on process”), on the expire of T3340 (as per TS 24.008 cl. 4.7.1.9).

Table 13.1.3.3.2-3: Parallel behaviour

St

Procedure

Message Sequence

TP

Verdict

U – S

Message

0A–0E

Void

–

–

–

1

The UE transmits a ROUTING AREA UPDATE REQUEST message on Cell 5.

–>

ROUTING AREA UPDATE REQUEST

–

–

2

Void

–

–

3

Void

–

–

4-5

Void

–

–

6

Void

–

–

Table 13.1.3.3.2-4: Void

Table 13.1.3.3.2-5: Void

13.1.3.3.3 Specific message contents

Table 13.1.3.3.3-1: Void

Table 13.1.3.3.3-1A: ACTIVATE TEST MODE (preamble)

Derivation Path: 36.508, Table 4.7A-3, condition UE TEST LOOP MODE B

Information Element

Value/remark

Comment

Condition

UE test loop mode B LB setup

IP PDU delay

Set according to PIXIT parameter px_TestLoopModeB_Delay

Table 13.1.3.3.3-2: SystemInformationBlockType6 for cell 1 (preamble and all steps, Table 13.1.3.3.2-2)

Derivation Path: 36.508 Table 4.4.3.3-5

Information Element

Value/remark

Comment

Condition

SystemInformationBlockType6 ::= SEQUENCE {

carrierFreqListUTRA-FDD SEQUENCE (SIZE (1..maxUTRA-FDD-Carrier)) OF SEQUENCE {

UTRA-FDD

carrierFreq[n]

Same downlink UARFCN as used for cell 5

cellReselectionPriority[n]

3

Lower priority than E-UTRA

}

carrierFreqListUTRA-TDD SEQUENCE (SIZE (1..maxUTRA-TDD-Carrier)) OF SEQUENCE {

UTRA-TDD

carrierFreq[n]

Same downlink UARFCN as used for cell 5

cellReselectionPriority[n]

3

Lower priority than E-UTRA

}

}

Table 13.1.3.3.3-3: DLInformationTransfer (step 2, Table 13.1.3.3.2-2)

Derivation Path: 36.508 Table 4.6.1-3

Information Element

Value/remark

Comment

Condition

DLInformationTransfer ::= SEQUENCE {

criticalExtensions CHOICE {

c1 CHOICE {

dlInformationTransfer-r8 SEQUENCE {

dedicatedInfoType CHOICE {

dedicatedInfoNAS

Set according to 36.508 Table 4.7.2-8A

CS SERVICE NOTIFICATION

}

}

}

}

}

Table 13.1.3.3.3-4: ULInformationTransfer (step 4, Table 13.1.3.3.2-2)

Derivation Path: 36.508 Table 4.6.1-25

Information Element

Value/remark

Comment

Condition

ULInformationTransfer ::= SEQUENCE {

criticalExtensions CHOICE {

c1 CHOICE {

ulInformationTransfer-r8 SEQUENCE {

dedicatedInfoType CHOICE {

dedicatedInfoNAS

Set according to 36.508 Table 4.7.2-14A

EXTENDED SERVICE REQUEST

}

}

}

}

}

Table 13.1.3.3.3-5: Void

Table 13.1.3.3.3-6: RRCConnectionRelease (step 5, Table 13.1.3.3.2-2)

Derivation Path: 36.508 Table 4.6.1-15

Information Element

Value/remark

Comment

Condition

RRCConnectionRelease ::= SEQUENCE {

criticalExtensions CHOICE {

c1 CHOICE {

rrcConnectionRelease-r8 SEQUENCE {

redirectedCarrierInfo ::= CHOICE {

utra-FDD

Downlink UARFCN of cell 5

UTRA-FDD

utra-TDD

Downlink UARFCN of cell 5

UTRA-TDD

}

}

}

Table 13.1.3.3.3-7: RRC CONNECTION REQUEST (step 6, Table 13.1.3.3.2-2)

Derivation Path: 34.108 clause 9.1.1

Information Element

Value/remark

Comment

Condition

Establishment cause

Registration or Terminating Conversational Call

Table 13.1.3.3.3-8: SERVICE REQUEST (step 1, Table 13.1.3.3.2-3)

Derivation Path: 24.008 Table 9.4.20

Information Element

Value/remark

Comment

Condition

Service type

‘001’B

Data

Table 13.1.3.3.3-9: ATTACH ACCEPT (Preamble)

Derivation Path: 36.508 Table 4.7.2-1

Information Element

Value/remark

Comment

Condition

EPS network feature support

Not present