13.1.11 Call setup from E-UTRA RRC_IDLE / CS fallback to GSM with PSHO / EDTM not supported / MT call

36.523-13GPPEvolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Packet Core (EPC)Part 1: Protocol conformance specificationRelease 16TSUser Equipment (UE) conformance specification

13.1.11.1 Test Purpose (TP)

(1)

with { UE in E-UTRA RRC_IDLE state }

ensure that {

when { UE receives a Paging message with CN domain indicator set to “CS” }

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 a MobilityFromEUTRACommand message with handover to a GERAN cell in a different location area and operating in NMO I }

then { UE handovers to GERAN cell }

}

(3)

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 handovered to GERAN cell and initiated a RA Update procedure }

ensure that {

when { UE has handovered to GERAN cell }

then { UE sets up MT CS call on GSM cell }

}

13.1.11.2 Conformance requirements

References: The conformance requirements covered in the present TC are specified in: TS 23.272, clauses 6.4 and 6.3, and, TS 36.331, clause 5.4.3.3.

[TS 23.272, clause 7.2]

The procedure for Mobile Terminating Call in idle mode is illustrated in figure 7.2-1, in the normal case. Clause 6.6 describes the procedure when the procedure is rejected by the MME.

Figure 7.2-1: Mobile Terminating Call in idle mode

1. G‑MSC receives IAM.

2. G‑MSC retrieves routing information of the terminating UE by Send Routing Info procedures as specified in TS 23.018 [5].

3. G‑MSC sends IAM to the MSC on the terminating side as specified in TS 23.018 [5].

4. The MME receives a Paging Request (IMSI, VLR TMSI, Location Information) message from the MSC over a SGs interface. If the TMSI is received from the MSC, it is used by the MME to find the S‑TMSI which is used as the paging address on the radio interface. If the IMSI is received from the MSC, the IMSI shall be used as the paging address on the radio interface. If location information is reliably known by MME (i.e. MME stores the list of TAs), the MME shall page the UE in all the TAs. If the MME does not have a stored TA list for the UE, the MME should use the location information received from the MSC to page the UE.

NOTE 1: This procedure takes place before step 3, immediately after MSC receives MAP_PRN from HSS, if pre-paging is deployed.

If the MME receives a Paging Request message for an UE which is considered as detach for EPS services, the MME sends the Paging reject message to the MSC with an appropriate cause value. This rejection triggers the MSC to page the UE over A or Iu-cs interface.

NOTE 2: In case of a CS fallback capable UE in NMO II or III, there is a case where, for example, the MME releases the SGs association due to the UE idle mode mobility while the VLR still maintains the SGs association.

5. If the MME did not return an "SMS-only" indication to the UE during Attach or Combined TA/LA Update procedures, the MME sends a Paging (as specified in TS 23.401 [2]) message to each eNodeB. The Paging message includes a suitable UE Identity (i.e. S‑TMSI or IMSI) and a CN Domain Indicator that indicates which domain (CS or PS) initiated the paging message. In this case it shall be set to "CS" by the MME.

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 paging to the eNodeBs and sends Paging Reject towards MSC to stop CS Paging procedure and this CSFB procedure stops.

6. The radio resource part of the paging procedure takes place. The message contains a suitable UE Identity (i.e. S‑TMSI or IMSI) and a CN Domain indicator.

7a. The UE establishes an RRC connection and sends an Extended Service Request (CS Fallback Indicator) to MME. The UE indicates its S-TMSI in the RRC signalling. The Extended Service Request message is encapsulated in RRC and S1‑AP messages. The CS Fallback Indicator indicates to the MME that CS Fallback for this UE is required. The MME sends the SGs Service Request message to the MSC containing an indication that the UE was in idle mode (and hence, for example, that the UE has not received any Calling Line Identification information). Receipt of the SGs Service Request message stops the MSC retransmitting the SGs interface Paging message.

NOTE 3: In order to avoid the calling party experiencing a potentially long period of silence, the MSC may use the SGs Service Request message containing the idle mode indication as a trigger to inform the calling party that the call is progressing.

7b. MME sends S1‑AP: Initial UE Context Setup (UE capabilities, CS Fallback Indicator, LAI and other parameters specified in TS 23.401 [2]) to indicate the eNodeB to move the UE to UTRAN/GERAN. The registered PLMN for CS domain is identified by the PLMN ID included in the LAI, which is allocated by the MME.

7c. The eNodeB shall reply with S1-AP: Initial UE Context Setup Response message.

8a. If the eNodeB knows that both the UE and the network support PS handover: The information flow may continue as described in clause 7.3 "Mobile Terminating call in Active Mode – PS HO supported" from step 2, in clause 7.3, and onwards.

. If the eNodeB knows that either the UE or the network does not support PS handover: The information flow shall continue as described in clause 7.4 "Mobile Terminating call in Active Mode – No PS HO support" from step 2, in clause 7.4, and onwards.

NOTE 4: Even in case both the UE and the network support PS HO, the eNodeB may choose to use a different inter-RAT mobility procedure.

[TS 23.272, clause 7.3]

This flow may be executed when the eNodeB knows that both the UE and the network support PS HO in the normal case. Clause 6.6 describes the procedure when the procedure is rejected by the MME.

Figure 7.3-1: CS Page in E-UTRAN, Call in GERAN/UTRAN

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, CS call indicator) 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 Page 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 Service Notification to the UE and shall send Paging Reject towards MSC to stop CS Paging procedure, and this CSFB procedure stops.

The eNodeB 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 CT1 and CT6.

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

NOTE 3: In order to avoid the calling party experiencing a potentially long period of silence, the MSC may use the SGs Service Request message as a trigger to inform the calling party that the call is progressing.

1b. UE sends an Extended Service Request (CS Fallback Indicator, Reject or Accept) message to the MME. The Extended Service Request message is encapsulated in RRC and S1‑AP messages. CS Fallback Indicator indicates to the 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. MME sends an S1‑AP UE Context Modification Request (CS Fallback Indicator, LAI) message to eNodeB. This message: indicates to the eNodeB that the UE should be moved to UTRAN/GERAN. The registered PLMN for CS domain is identified by the PLMN ID included in the LAI, which is allocated by the MME.

1e. The eNodeB 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/UTRAN cell to which PS handover will be performed.

3a. The eNodeB triggers PS handover to a GERAN/UTRAN neighbour cell by sending a Handover Required message to MME. The eNodeB selects the target PS handover cell considering the PLMN ID and possibly the LAC for CS domain provided by the MME in step 1d. In the following an inter-RAT handover from E‑UTRAN to UTRAN or GERAN as specified in TS 23.401 [2] begins. The eNodeB indicates in the Source RNC to Target RNC Transparent container that PS handover was triggered due to CSFB. The eNodeB also indicates whether CSFB was triggered for emergency purpose. As part of this handover, the UE receives a HO from E‑UTRAN Command and tries to connect to a cell in the target RAT. The HO from E-UTRAN Command may contain a CS Fallback Indicator which indicates to UE that the handover was triggered due to a CS fallback request. If the HO from E-UTRAN Command 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.

The UE establishes the signalling connection as described in step 4b.

NOTE 4: During the PS HO the SGSN does not create a Gs association with the MSC/VLR.

3b. If the target RAT is GERAN and the UE has entered Dedicated Mode, the UE starts the Suspend procedure (see TS 44.018 [4]) unless both the UE and the Target cell support DTM in which case TBF re-establishment may be performed.

3c. A Gn/Gp-SGSN that receives the Suspend message from the UE follows the Suspend procedure specified in TS 23.060 [3], clause 16.2.1.1.1.

An S4-SGSN that receives the Suspend message from the UE follows the Suspend procedure specified in TS 23.060 [3]. The S4-SGSN deactivates GBR bearers towards S-GW and P-GW(s) by initiating MS-and SGSN Initiated Bearer Deactivation procedure as specified in TS 23.060 [3], and starts the preservation and suspension of non-GBR bearers by sending Suspend Notification message to the S-GW. The S-GW releases all RNC related information (address and TEIDs) for the UE if Direct Tunnel is established, and sends Suspend Notification message to the P-GW(s). The SGSN stores in the UE context that 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.

4a. 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 procedure as follows:

– If the network is operating in NMO-I (Network Modes of Operation), the UE should initiate a separate Location Area Update before initiating the RAU procedure instead of a Combined RA/LA Update procedure (to speed up the CSFB procedure); or

– if the network is operating in NMO-II or NMO-III the UE shall initiate a Location Area Update procedure before initiating the RAU procedure required for PS handover.

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. Further the UE performs any Routing Area Update procedure as specified in TS 23.060 [3].

The UE may initiate a Location Area Update procedure immediately when the UE is handed over to the target cell i.e. before the UE receives e.g. LAI or NMO information as part of the RAN Mobility Information.

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.

4b. If the UE does not initiate a LAU procedure, it shall respond with a Paging Response message to the MSC as follows:

– If the Target RAT is UTRAN or GERAN Iu mode: The UE establishes a radio signalling connection and responds to the paging by sending an RRC Paging Response as specified in TS 25.331 [7]. The CN Domain Indicator is set to "CS" in the Initial Direct Transfer message.

– If the Target RAT is GERAN A/Gb mode: The UE establishes a radio signalling connection and responds to paging by using the procedures specified in TS 44.018 [4] (i.e. UE requests and is assigned a dedicated channel where it sends a SABM containing a Paging Response to the BSS and the BSS responds by sending a UA). Upon receiving the SABM (containing a Paging Response message) the BSS sends a COMPLETE LAYER 3 INFORMATION message (containing a Paging Response message) to the MSC which indicates CS resources have been allocated in the GERAN cell. If both the UE and the target cell support enhanced CS establishment in DTM (indicated by GERAN system information included within the HO from E‑UTRAN Command) an RR connection may be established while in packet transfer mode without release of the packet resources, see TS 43.055 [24]. After the establishment of the main signalling link as described in TS 44.018 [4] the UE enters either Dual Transfer Mode or Dedicated Mode and the CS call establishment procedure completes.

NOTE 5: The BSS should be prepared to receive a Paging Response even when the corresponding Paging Request has not been sent by this BSS.

5a. After performing the LAU procedure or after receiving the Paging Response the MSC shall establish the CS call if the UE is allowed in the LA.

5b. 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 message by releasing the A/Iu-CS. The BSC/RNC in turn releases the signalling connection for UTRAN or GERAN CS domain. 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.

5c. After performing the LAU procedure the MSC shall establish the CS call if the UE is allowed in the LA.

6. The UE performs any remaining steps of the inter-RAT handover from E-UTRAN to UTRAN or GERAN as specified in TS 23.401 [2]

With the exception of steps 1a and 1c, above, Call Forwarding (see TS 23.082 [31]) is performed on the basis of the TS 24.008 [21] signalling received on the GERAN/UTRAN cell.

If the UE remains on UTRAN/GERAN after the CS voice call is terminated the UE performs normal mobility management procedures as defined in TS 23.060 [3] and TS 24.008 [21].

[TS 36.331, clause 5.4.3.3]

The UE shall be able to receive a MobilityFromEUTRACommand message and perform a cell change order to GERAN, even if no prior UE measurements have been performed on the target cell.

The UE shall:

1> stop timer T310, if running;

1> if the MobilityFromEUTRACommand message includes the purpose set to ‘handover‘:

2> if the targetRAT-Type is set to ‘utra‘ or ‘geran‘:

3> consider inter-RAT mobility as initiated towards the RAT indicated by the targetRAT-Type included in the MobilityFromEUTRACommand message;

3> forward the nas-SecurityParamFromEUTRA to the upper layers;

3> access the target cell indicated in the inter-RAT message in accordance with the specifications of the target RAT;

3> if the targetRAT-Type is set to ‘geran‘:

4> use the contents of systemInformation, if provided for PS Handover, as the system information to begin access on the target GERAN cell;

13.1.11.3 Test description

13.1.11.3.1 Pre-test conditions

System Simulator:

– Cell 1 serving cell

– Cell 24 suitable neighbour cell

– Cell 1and Cell 24 are in the differentLA

– The parameters settings and power levels for Cell 1 and Cell 24 are selected according to [18], [5] so that camping on Cell 1 is guaranteed and no cell re-selection to Cell 24 can take place (GERAN priority is lower than serving and S Cell 1 > Thresh Cell 1,low).

– System information combination 5 as defined in TS 36.508 [18] clause 4.4.3.1 is used in E-UTRA cells.

– Cell 24 system information indicates that NMO 1 is used

– DTM is not supported on the Cell 24

UE:

None.

Preamble:

– The UE is in state Registered, Idle Mode (state 2) on Cell 1 according to [18].

13.1.11.3.2 Test procedure sequence

Table 13.1.11.3.2-2: Main behaviour

St

Procedure

Message Sequence

TP

Verdict

U – S

Message

1

The SS transmits a Paging message to the UE on Cell 1 using S-TMSI with CN domain indicator set to “CS”.

<–

Paging

EXCEPTION: Step 2a1 describes behaviour that depends on the UE capability; the "lower case letter" identifies a step sequence that takes place if a capability is supported.

2a1

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.

3

The UE transmits an RRCConnectionRequest message on Cell1.

–>

RRCConnectionRequest

4

The SS transmits an RRCConnectionSetup message on Cell1.

<–

RRCConnectionSetup

5

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

–>

RRCConnectionSetupComplete

NAS: EXTENDED SERVICE REQUEST

1

P

6

The SS transmits a SecurityModeCommand message on Cell 1.

<–

SecurityModeCommand

7

The UE transmits a SecurityModeComplete message on Cell 1.

–>

SecurityModeComplete

8

The SS transmits an RRCConnectionReconfiguration message on Cell 1.

<–

RRCConnectionReconfiguration

9

The UE transmits an RRCConnectionReconfigurationComplete message on Cell 1.

–>

RRCConnectionReconfigurationComplete

10

The SS transmits a MobilityFromEUTRACommand message on Cell 1 with IE handover.

<–

MobilityFromEUTRACommand

11

The UE transmits a PS HANDOVER ACCESS message on Cell 24.

–>

PS HANDOVER ACCESS

2

P

12

The SS transmits a PS PHYSICAL INFORMATION message on Cell 24.

<–

PS PHYSICAL INFORMATION

EXCEPTION: Steps 13a1 to 13b2 describe behaviour that depends on the UE implementation; the "lower case letter" identifies a step sequence that takes place if the UE exercises a particular behaviour

13a1

IF the UE performs LA update THEN check: Does the UE transmit LOCATION UPDATING REQUEST?

–>

LOCATION UPDATING REQUEST

2

P

EXCEPTION: The messages in the next two steps are sent only on Cell 24

13a1Aa1

The UE transmits a Classmark Change message

–>

CLASSMARK CHANGE

EXCEPTION: The next step describes behaviour that depends on UE capability.

13a1Aa2

IF pc_UTRA THEN the UE transmits a Utran Classmark Change message.

–>

UTRAN CLASSMARK CHANGE.

13a2

UE transmits GPRS SUSPENSION REQUEST message with suspension cause set to “LOCATION AREA UPDATE”

–>

GPRS SUSPENSION REQUEST

13a3

The SS transmits MM LOCATION UPDATING ACCEPT

<–

LOCATION UPDATING ACCEPT

13b1

IF the UE does not perform LA update THEN UE transmits GPRS SUSPENSION REQUEST message with suspension cause set to “Mobile terminating CS connection”

–>

GPRS SUSPENSION REQUEST

13b2

Check: Does the UE transmit a PAGING RESPONSE on Cell 24?

–>

PAGING RESPONSE

2

P

14-43

Steps 5 to 34 of the generic test procedure described in TS 36.508 subclause 6.4.3.8.1 is performed on Cell 24.

3

P

At the end of this test procedure sequence, the UE is in end state GERAN idle (G1) according to TS 36.508.

13.1.11.3.3 Specific message contents

Table 13.1.11.3.3-1: SystemInformationBlockTyp7 for cell 1 (preamble and all steps, Table 13.1.11.3.2-2)

Derivation Path: 36.331 clause 6.3.1

Information Element

Value/remark

Comment

Condition

SystemInformationBlockType7 ::= SEQUENCE {

carrierFreqsInfoListcarrierFreqsInfoListSEQUENCE (SIZE (1..maxGNFG)) OF SEQUENCE {

carrierFreqs carrierFreqs[n] SEQUENCE {

startingARFCN[n]

Same starting ARFCN used for cell 24

bandIndicator[n]

same band used for GERAN cell24

followingARFCNs[n] CHOICE {

explicitListOfARFCNs[n]

Same ARFCN used for cell24

}

}

commonInfo[n] SEQUENCE {

cellReselectionPriority[n]

3

Lower priority than E-UTRA

}

}

}

Table 13.1.11.3.3-2: Message Paging (step 1, Table 13.1.11.3.2-2)

Derivation Path: 36.508 clause 4.6.1-7

Information Element

Value/remark

Comment

Condition

Paging ::= SEQUENCE {

pagingRecordList SEQUENCE (SIZE (1..maxPageRec)) OF SEQUENCE {

1 entry

ue-Identity[1] CHOICE {

s-TMSI

Set to the value of the S-TMSI of the UE

}

cn-Domain[1]

Cs

}

}

Table 13.1.11.3.3-3: RRCConnectionSetupComplete (step 5, Table 13.1.11.3.2-2)

Derivation Path: 36.508 Table 4.6.1-18

Information Element

Value/remark

Comment

Condition

RRCConnectionSetupComplete ::= SEQUENCE {

rrc-TransactionIdentifier

RRC-TransactionIdentifier-UL

criticalExtensions CHOICE {

c1 CHOICE {

rrcConnectionSetupComplete-r8 SEQUENCE {

selectedPLMN-Identity

Set to the PLMN selected by upper layers

registeredMME

Not present

dedicatedInfoNAS

Set according to 36.508 Table 4.7.2-14A

EXTENDED SERVICE REQUEST

nonCriticalExtension SEQUENCE {}

Not checked

}

}

}

}

Table 13.1.11.3.3-4: RRCConnectionReconfiguration (step 8, Table 13.1.11.3.2-2)

Derivation Path: 36.508 Table 4.6.1-8, condition SRB2-DRB(1, 0)

Table 13.1.11.3.3-5: Message MobilityFromEUTRACommand (step 10, Table 13.1.11.3.2-2)

Derivation Path: 36.508 clause 4.6.1-6

Information Element

Value/remark

Comment

Condition

MobilityFromEUTRACommand ::= SEQUENCE {

criticalExtensions CHOICE {

c1 CHOICE {

mobilityFromEUTRACommand-r8 SEQUENCE {

csFallbackIndicator

True

purpose CHOICE {

handover SEQUENCE {

targetRAT-Type

Geran

targetRAT-MessageContainer

PS HANDOVER COMMAND

nas-SecurityParamFromEUTRA

Not Present

systemInformation

Not present

}

}

}

}

}

}

Table 13.1.11.3.3-6: PS HANDOVER COMMAND (step 10, Table 13.1.11.3.2-2)

Derivation Path: TS 36.508 Table 4.7D.1-1

Table 13.1.11.3.3-7: LOCATION UPDATING ACCEPT (step 13a7, Table 13.1.11.3.2-2)

Derivation Path: TS 36.508 Table 4.7B.2-5

Information Element

Value/remark

Comment

Condition

Mobile identity

Not present

Table 13.1.11.3.3-8: ATTACH ACCEPT (Preamble)

Derivation Path: 36.508 Table 4.7.2-1

Information Element

Value/remark

Comment

Condition

EPS network feature support

Not present