11.1.8 MO MMTEL voice call setup from NR RRC_CONNECTED / EPS Fallback with handover / Single registration mode with N26 interface / voiceFallbackIndication
38.523-13GPP5GSPart 1: ProtocolRelease 17TSUser Equipment (UE) conformance specification
11.1.8.1 Test Purpose (TP)
(1)
with { UE supporting both S1 mode and N1 mode and operating in single-registration mode, and, the Network has indicated "interworking without N26 interface not supported", and, the UE is in NR RRC_CONNECTED state, then, the User initiates a MMTEL call, the MO IMS voice session establishment has been initiated }
ensure that {
when { UE receives a MobilityFromNRCommand message which includes targetRAT-Type set to eutra and with voiceFallbackIndication, and the UE does not succeed in establishing the connection to the target radio access technology }
then { UE selects another suitable E-UTRA cell with starting a TAU procedure by using “mo-VoiceCall” as the establishment cause value in RRCConnectionRequest, and, UE successfully completes the MO MMTEL call in EPS }
}
11.1.8.2 Conformance requirements
References: The conformance requirements covered in the present test case are specified in: TS 23.502, clauses 4.13.6.1, TS 24.501, clauses 4.8.2.2, 5.5.1.2.2, 5.5.1.2.4, 5.1.4.2 and 6.1.4.1, TS 38.331, clause 5.4.3.5. Unless otherwise stated these are Rel-16 requirements.
[TS 23.502, clause 4.13.6.1]
Figure 4.13.6.1-1 describes the EPS fallback procedure for IMS voice.
When the UE is served by the 5G System, the UE has one or more ongoing PDU Sessions each including one or more QoS Flows. The serving PLMN AMF has sent an indication towards the UE during the Registration procedure that IMS voice over PS session is supported, see clause 5.16.3.10 in TS 23.501 [2] and the UE has registered in the IMS. If N26 is not supported, the serving PLMN AMF sends an indication towards the UE during the Registration procedure that interworking without N26 is supported, see clause 5.17.2.3.1 in TS 23.501 [2].
Figure 4.13.6.1-1: EPS Fallback for IMS voice
1. UE camps on NG-RAN in the 5GS and an MO or MT IMS voice session establishment has been initiated.
2. Network initiated PDU Session modification to setup QoS flow for voice reaches the NG-RAN (see N2 PDU Session Request in clause 4.3.3).
3. NG-RAN is configured to support EPS fallback for IMS voice and decides to trigger fallback to EPS, taking into account UE capabilities, indication from AMF that "Redirection for EPS fallback for voice is possible" (received as part of initial context setup as defined in TS 38.413 [10]), network configuration (e.g. N26 availability configuration) and radio conditions. If NG-RAN decides not to trigger fallback to EPS, then the procedure stops here and following steps are not executed.
NG-RAN may initiate measurement report solicitation from the UE including E-UTRAN as target.
NOTE 1: If AMF has indicated that "Redirection for EPS fallback for voice is not possible", then AN Release via inter-system redirection to EPS is not performed in step 5.
4. NG-RAN responds indicating rejection of the PDU Session modification to setup QoS flow for IMS voice received in step 2 by PDU Session Modification Response message towards the PGW-C+SMF (or H-SMF+P-GW-C via V-SMF, in the case of home routed roaming scenario) via AMF with an indication that mobility due to fallback for IMS voice is ongoing. The PGW-C+SMF maintains the PCC rule(s) associated with the QoS Flow(s) and reports the EPS Fallback event to the PCF if PCF has subscribed to this event.
5. NG-RAN initiates either handover (see clause 4.11.1.2.1), or AN Release via inter-system redirection to EPS (see clause 4.2.6 and clause 4.11.1.3.2), taking into account UE capabilities. The PGW-C+SMF reports change of the RAT type if subscribed by PCF as specified in clause 4.11.1.2.1, or clause 4.11.1.3.2.6. When the UE is connected to EPS, either 6a or 6b is executed
6a. In the case of 5GS to EPS handover, see clause 4.11.1.2.1, and in the case of inter-system redirection to EPS with N26 interface, see clause 4.11.1.3.2. In either case the UE initiates TAU procedure; or
6b. In the case of inter-system redirection to EPS without N26 interface, see clause 4.11.2.2. If the UE supports Request Type flag "handover" for PDN connectivity request during the attach procedure as described in clause 5.3.2.1 of TS 23.401 [13] and has received the indication that interworking without N26 is supported, then the UE initiates Attach with PDN connectivity request with request type "handover".
In inter-system redirection, the UE uses the emergency indication in the RRC message as specified in clause 6.2.2 of TS 36.331 [16] and E-UTRAN provides the emergency indication to MME during Tracking Area Update or Attach procedure. For the handover procedure see clause 4.11.1.2.1, step 1.
7. After completion of the mobility procedure to EPS or as part of the 5GS to EPS handover procedure (see clause 4.11.1.2.1), the SMF/PGW re-initiates the setup of the dedicated bearer(s) for the maintained PCC rule(s) in step 4 including of the dedicated bearer for IMS voice, mapping the 5G QoS to EPC QoS parameters. The PGW-C+SMF behaves as specified in clause 4.9.1.3.1. The PGW-C+SMF reports about Successful Resource Allocation and Access Network Information if subscribed by PCF.
The IMS signalling related to IMS voice call establishment continues after step 1 as specified in the TS 23.228 [55].
At least for the duration of the voice call in EPS the E-UTRAN is configured to not trigger any handover to 5GS.
[TS 24.501, clause 4.8.2.2]
See subclause 5.1.4.2 for coordination between 5GMM and EMM and subclause 6.1.4.1 for coordination between 5GSM and ESM.
[TS 24.501, clause 5.5.1.2.2]
If the UE supports S1 mode, the UE shall:
– set the S1 mode bit to "S1 mode supported" in the 5GMM capability IE of the REGISTRATION REQUEST message;
– include the S1 UE network capability IE in the REGISTRATION REQUEST message; and
– if the UE supports sending an ATTACH REQUEST message containing a PDN CONNECTIVITY REQUEST message with request type set to "handover" to transfer a PDU session from N1 mode to S1 mode, set the HO attach bit to "attach request message containing PDN connectivity request with request type set to handover to transfer PDU session from N1 mode to S1 mode supported" in the 5GMM capability IE of the REGISTRATION REQUEST message.
[TS 24.501, clause 5.5.1.2.4]
If the UE included S1 mode supported indication in the REGISTRATION REQUEST message, the AMF supporting interworking with EPS shall set the IWK N26 bit to either:
a) "interworking without N26 interface not supported" if the AMF supports N26 interface ; or
b) "interworking without N26 interface supported" if the AMF does not support N26 interface
in the 5GS network feature support IE in the REGISTRATION ACCEPT message.
The UE supporting S1 mode shall operate in the mode for interworking with EPS as follows:
a) if the IWK N26 bit in the 5GS network feature support IE is set to "interworking without N26 interface not supported", the UE shall operate in single-registration mode;
b) if the IWK N26 bit in the 5GS network feature support IE is set to "interworking without N26 interface supported" and the UE supports dual-registration mode, the UE may operate in dual-registration mode; or
NOTE 3: The registration mode used by the UE is implementation dependent.
c) if the IWK N26 bit in the 5GS network feature support IE is set to "interworking without N26 interface supported" and the UE only supports single-registration mode, the UE shall operate in single-registration mode.
The UE shall treat the received interworking without N26 interface indicator for interworking with EPS as valid in the entire PLMN and its equivalent PLMN(s).
The network informs the UE about the support of specific features, such as IMS voice over PS session, emergency services or emergency services fallback, in the 5GS network feature support information element. In a UE with IMS voice over PS session capability, the IMS voice over PS session indicator, the Emergency services support indicator, and the Emergency services fallback indicator shall be provided to the upper layers. The upper layers take the IMS voice over PS session indicator into account when selecting the access domain for voice sessions or calls. When initiating an emergency call, the upper layers also take the IMS voice over PS session indicator, the Emergency services support indicator, and the Emergency services fallback indicator into account for the access domain selection.
[TS 24.501, clause 5.1.4.2]
At inter-system change from N1 mode to S1 mode when there is at least one active PDU session for which interworking with EPS is supported as specified in subclause 6.1.4.1, the UE shall enter substates EMM-REGISTERED.NORMAL-SERVICE and 5GMM-REGISTERED.NO-CELL-AVAILABLE and initiate a tracking area updating procedure (see 3GPP TS 24.301 [15]).
[TS 24.501, clause 6.1.4.1]
Upon inter-system change from N1 mode to S1 mode, the UE shall create the default EPS bearer context and the dedicated EPS bearer context(s) based on the parameters of the mapped EPS bearer contexts or the associations between QoS flow and mapped EPS bearer in the PDU session, if available. The EPS bearer identity assigned for the QoS flow of the default QoS rule becomes the EPS bearer identity of the default bearer in the corresponding PDN connection. If there is no EPS bearer identity assigned to the QoS flow of the default QoS rule, the UE shall release locally the PDU session. If there is no EPS bearer identity assigned to the QoS flow(s) which is not associated with the default QoS rule, the UE shall locally delete the QoS rules and the QoS flow level QoS parameters associated with the QoS flow(s). The UE uses the parameters from each PDU session for which interworking with EPS is supported to create corresponding default EPS bearer context and optionally dedicated EPS bearer context(s) as follows:
a) the PDU session type of the PDU session shall be mapped to the PDN type of the default EPS bearer context as follows:
1) the PDN type shall be set to "non-IP" if the PDU session type is "Ethernet" or "Unstructured";
2) the PDN type shall be set to "IPv4" if the PDU session type is "IPv4";
3) the PDN type shall be set to "IPv6" if the PDU session type is "IPv6"; and
4) the PDN type shall be set to "IPv4v6" if the PDU session type is "IPv4v6";
b) the PDU address of the PDU session shall be mapped to the PDN address of the default EPS bearer context as follows:
1) the PDN address of the default EPS bearer context is set to the PDU address of the PDU session, if the PDU session type is "IPv4", "IPv6" or "IPv4v6"; and
2) the PDN address of the default EPS bearer context is set to zero, if the PDU session type is "Ethernet" or "Unstructured";
c) the DNN of the PDU session shall be mapped to the APN of the default EPS bearer context;
d) the APN-AMBR and extended APN-AMBR received in the parameters of the default EPS bearer context of the mapped EPS bearer contexts shall be mapped to the APN-AMBR and extended APN-AMBR of the default EPS bearer context;
e) for each PDU session in state PDU SESSION ACTIVE, PDU SESSION MODIFICATION PENDING or PDU SESSION INACTIVE PENDING the UE shall set the state of the mapped EPS bearer context(s) to BEARER CONTEXT ACTIVE; and
f) for any other PDU session the UE shall set the state of the mapped EPS bearer context(s) to BEARER CONTEXT INACTIVE.
Additionally, for each mapped EPS bearer context or the association between QoS flow and mapped EPS bearer in the PDU session:
a) the EPS bearer identity shall be set to the EPS bearer identity received in the mapped EPS bearer context, or the EPS bearer identity associated with the QoS flow;
b) the EPS QoS parameters shall be set to the mapped EPS QoS parameters of the EPS bearer received in the mapped EPS bearer context, or the EPS QoS parameters associated with the QoS flow;
c) the extended EPS QoS parameters shall be set to the mapped extended EPS QoS parameters of the EPS bearer received in the mapped EPS bearer context, or the extended EPS QoS parameters associated with the QoS flow; and
d) the traffic flow template shall be set to the mapped traffic flow template of the EPS bearer received in the mapped EPS bearer context, or the stored traffic flow template associated with the QoS flow, if available.
After inter-system change from N1 mode to S1 mode, the UE shall associate the PDU session identity, the S-NSSAI, and the session-AMBR with the default EPS bearer context, and for each EPS bearer context mapped from one or more QoS flows, associate the QoS rule(s) for the QoS flow(s) and the QoS flow description(s) for the QoS flow(s) with the EPS bearer context.
After inter-system change from N1 mode to S1 mode, the UE and the SMF shall maintain the PDU session type of the PDU session until the PDN connection corresponding to the PDU session is released if the UE supports non-IP PDN type and the PDU session type is "Ethernet" or "Unstructured".
After inter-system change from N1 mode to S1 mode, the UE and the SMF shall maintain the always-on PDU session indication.
After inter-system change from N1 mode to S1 mode, the UE and the SMF shall maintain the maximum number of supported packet filters until the PDN connection corresponding to the PDU session is released.
[TS 38.331, clause 5.4.3.5]
The UE shall:
1> if the UE does not succeed in establishing the connection to the target radio access technology:
2> if the UE supports Radio Link Failure Report for Inter-RAT MRO:
3> store handover failure information in VarRLF-Report according to 5.3.10.5;
2> if voiceFallbackIndication is included in the MobilityFromNRCommand message:
3> attempt to select an E-UTRA cell:
4> if a suitable E-UTRA cell is selected:
5> perform the actions upon going to RRC_IDLE as specified in 5.3.11, with release cause ‘RRC connection failure’;
11.1.8.3 Test Description
11.1.8.3.1 Pre-test conditions
System Simulator:
– 3 cells
– NR Cell 1 as defined in TS 38.508-1 [4] Table 4.4.2-3. System information combination NR-6 as defined in TS 38.508-1 [4], sub-clause 4.4.3.1.2.
– E-UTRA Cell 1 and Cell 2 as defined in TS 36.508 [7] Table 4.4.2-2. System information combination 31 as defined in TS 36.508 [7], sub-clause 4.4.3.1.1.
– N26 interface is configured.
– Power levels are constant and as defined in Tables 11.1.8.3.1-1/2.
Table 11.1.8.3.1-1: Time instances of cell power level and parameter changes for conducted test environment
|
Parameter name |
Unit |
NR Cell 1 |
E-UTRA Cell 1 |
E-UTRA Cell 2 |
Remark |
|
|
T0 |
SS/PBCH SSS EPRE |
dBm/SCS |
-88 |
– |
– |
|
|
RS EPRE |
dBm/15kHz |
– |
"Off" |
-91 |
Table 11.1.8.3.1-2: Time instances of cell power level and parameter changes for OTA test environment
|
Parameter name |
Unit |
NR Cell 1 |
E-UTRA Cell 1 |
E-UTRA Cell 2 |
Remark |
|
|
T0 |
SS/PBCH SSS EPRE |
dBm/SCS |
-82 |
– |
– |
|
|
RS EPRE |
dBm/15kHz |
– |
"Off" |
-91 |
UE:
– The UE is configured to use IMS preconditions
Preamble:
– With E-UTRA Cell 1 "Serving cell", E-UTRA Cell 2 "Non-suitable "Off" cell" and NR Cell 1 "Non-suitable "Off" cell" in accordance with TS 38.508-1 [4], Table 6.2.2.1-3, the UE is brought to state RRC_IDLE using generic procedure parameters Connectivity (E -UTRA/EPC) and Unrestricted nr PDN (On) in accordance with the procedure described in TS 38.508-1 [4], clause 4.5.2. 4G GUTI and eKSI are assigned and security context established.
– The UE is switched-off.
– With E-UTRA Cell 1 "Non-suitable "Off" cell", E-UTRA Cell 2 "Non-suitable "Off" cell" and NR Cell 1 "Serving cell" in accordance with TS 38.508-1 [4], Table 6.2.2.1-3, the UE is brought to state 1N-A, RRC_IDLE Connectivity (NR) with at least one IMS PDU session on NR Cell 1, in accordance with the procedure described in TS 38.508-1 [4], Table 4.5.2.2-2. 5G-GUTI and ngKSI are assigned.
11.1.8.3.2 Test procedure sequence
Table 11.1.8.3.2-1: Main behaviour
|
St |
Procedure |
Message Sequence |
TP |
Verdict |
|
|
U – S |
Message |
||||
|
1 |
Void |
– |
– |
– |
– |
|
– |
The following messages are to be observed on NR Cell 1 unless explicitly stated otherwise. |
– |
– |
– |
– |
|
2 |
The SS transmits a Paging message. |
<– |
NR RRC: Paging |
– |
– |
|
3 |
The UE transmits an RRCSetupRequest message. |
–> |
NR RRC: RRCSetupRequest |
– |
– |
|
4-9 |
Steps 3 to 8 of the NR RRC_CONNECTED procedure in TS 38.508-1 [4] Table 4.5.4.2-3 are executed to successfully complete the service request procedure. |
– |
– |
– |
– |
|
10 |
Set the power levels according to “T0” as per Table 11.1.8.3.1-1/2. |
– |
– |
– |
– |
|
11 |
Make the UE attempt an MTSI MO Speech Call. |
||||
|
12-16 |
Steps 1-5 of the MTSI MO speech call for 5GS procedure according to TS 34.229-5 [41] subclause A.9.1 take place. |
– |
– |
– |
– |
|
17 |
The SS transmits a MobilityFromNRCommand message which includes target eutra cell set to E-UTRA Cell 1 according to 38.508-1 [4] Table 4.6.1-8. |
<– |
NR RRC: MobilityFromNRCommand |
– |
– |
|
– |
The following messages are to be observed on E-UTRA Cell 2 unless explicitly stated otherwise. |
– |
– |
– |
– |
|
18 |
Check: Does the UE transmit an RRCConnectionRequest message on E-UTRA cell 2? |
–> |
RRC: RRCConnectionRequest |
1 |
P |
|
19-23 |
UE performs generic procedure as defined in TS 38.508-1 [4], Table 4.9.7.2.2-1 Steps 2-6 for N1 to S1 Inter mode change with condition ‘connected without release’ & ‘mapped 5G security context’. |
– |
– |
– |
– |
|
24-27 |
Generic Test Procedure as defined in Steps 5-8 of TS 36.508-1 [4] Table 4.5A.6.3-1 is performed to establish radio bearer corresponding to IMS PDN. |
– |
– |
– |
– |
|
28 |
The SS configures a new RLC-UM data radio bearer with condition DRB (0,1), associated with the dedicated EPS bearer context. RRCConnectionReconfiguration message contains the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message. EPS bearer context #4 (QCI 1) according to TS 36.508 [7] Table 6.6.2-1: Reference dedicated EPS bearer contexts. Reference dedicated EPS bearer contexts is to establish the dedicated EPS bearer context on IMS PDN. |
<– |
RRC: RRCConnectionReconfiguration NAS: ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST |
– |
– |
|
– |
EXCEPTION: In parallel to the events described in steps 291-3 below, the steps specified in table 11.1.8.3.2-2 will take place. |
– |
– |
– |
– |
|
29 |
The UE transmits an RRCConnectionReconfigurationComplete message. |
–> |
RRC: RRCConnectionReconfigurationComplete |
– |
– |
|
30 |
The UE transmits an ULInformationTransfer message including the ACTIVATE DEDICATED EPS BEARER CONTEXT ACCEPT message. |
–> |
RRC: ULInformationTransfer NAS: ACTIVATE DEDICATED EPS BEARER CONTEXT ACCEPT |
– |
– |
|
31 |
The SS waits 1 second for call duration. |
– |
– |
– |
– |
|
32 |
Release IMS Call as specified in the generic procedure in TS 34.229-1 [35] subclause C.32. |
– |
– |
– |
– |
Table 11.1.8.3.2-2: Parallel behaviour
|
St |
Procedure |
Message Sequence |
TP |
Verdict |
|
|
U – S |
Message |
||||
|
EXCEPTION: Steps 1a1 to 1a7 describe behaviour that depends on the UE capability; the "lower case letter" identifies a step sequence that take place if a capability is supported |
– |
– |
– |
– |
|
|
1a1-1a2 |
The UE performs IMS re-registration on EUTRAN as per steps 1-2 as defined in TS 34.229-1 [35] C.46. |
– |
– |
– |
– |
|
1a3-1a6A |
Steps 1-5 clause A.9.2 “EPS Fallback for Voice Call / steps after fallback / 5GS” of TS 34.229-5 [41] take place. |
– |
– |
– |
– |
|
1a7 |
Check: Does the UE send an ACK to acknowledge receipt of the 200 OK for INVITE? |
–> |
SIP: ACK |
1 |
P |
11.1.8.3.3 Specific message contents
Table 11.1.8.3.3-1: REGISTRATION REQUEST (preamble)
|
Derivation Path: 38.508-1 [4] Table 4.7.1-6 |
|||
|
Information Element |
Value/remark |
Comment |
Condition |
|
5GMM capability |
|||
|
S1 mode |
‘1’B |
S1 mode supported |
|
|
S1 UE network capability |
Present but contents not checked |
||
Table 11.1.8.3.3-2: REGISTRATION ACCEPT (preamble)
|
Derivation Path: 38.508-1 [4] Table 4.7.1-7 |
|||
|
Information Element |
Value/remark |
Comment |
Condition |
|
5GS network feature support |
|||
|
IMS- VoPS-3GPP |
‘1’B |
IMS voice over PS session supported over 3GPP access |
|
|
IWK N26 |
‘0’B |
Interworking without N26 interface not supported |
|
Table 11.1.8.3-3: Void
Table 11.1.8.3.3-4: MobilityFromNRCommand (step 17, Table 11.1.8.3.2-1)
|
Derivation Path: 38.508-1 [4] Table 4.6.1-8 |
|||
|
Information Element |
Value/remark |
Comment |
Condition |
|
MobilityFromNRCommand::= SEQUENCE { |
|||
|
rrc-TransactionIdentifier |
RRC-TransactionIdentifier |
||
|
criticalExtensions CHOICE { |
|||
|
mobilityFromNRCommand ::= SEQUENCE { |
|||
|
targetRAT-Type |
eutra |
||
|
targetRAT-MessageContainer |
RRCConnectionReconfiguration |
||
|
nas-SecurityParamFromNR |
8 LSB of the downlink NAS COUNT |
||
|
nonCriticalExtension { |
|||
|
voiceFallbackIndication-r16 |
true |
||
|
} |
|||
|
} |
|||
|
} |
|||
|
} |
|||
Table 11.1.8.3.3-5: RRCConnectionReconfiguration (Table 11.1.8.3.3-4)
|
Derivation Path: 36.508-1 Table 4.6.1-8 condition HO-TO-EUTRA(n,0) |
Table 11.1.8.3.3-6: RRCConnectionRequest (step 18, table 11.1.8.3.2-1)
|
Derivation path: 36.508-1 Table 4.6.1-16 |
|||
|
Information Element |
Value/Remark |
Comment |
Condition |
|
RRCConnectionRequest ::= SEQUENCE { |
|||
|
criticalExtensions CHOICE { |
|||
|
rrcConnectionRequest-r8 SEQUENCE { |
|||
|
ue-Identity CHOICE { |
|||
|
s-TMSI |
Any allowed value |
||
|
} |
|||
|
establishmentCause |
mo-VoiceCall-v1280 |
mo-VoiceCall |
|
|
spare |
Present but contents not checked |
||
|
} |
|||
|
} |
|||
|
} |
|||
Table 11.1.8.3.3-7: SystemInformationBlockType2 for E-UTRA Cell 2 (preamble and all steps, Table 11.1.8.3.2-1)
|
Derivation Path: 36.508, Table 4.4.3.3-1 |
|||
|
Information Element |
Value/remark |
Comment |
Condition |
|
SystemInformationBlockType2 ::= SEQUENCE { |
|||
|
voiceServiceCauseIndication-r12 |
true |
||
|
} |
|||