7.4 Circuit Switched (CS) Fallback
37.571-23GPPPart 2: Protocol conformanceRelease 16TSUser Equipment (UE) conformance specification for UE positioning
7.4.1 MO-LR Procedure
7.4.1.1 CS fallback: Network does not support EPC-MO-LR
7.4.1.1.1 Test Purpose (TP)
(1)
with { UE in E-UTRA RRC_IDLE state having received an ATTACH ACCEPT message indicating location
services via EPC not supported and location services via CS domain supported }
ensure that {
when { UE initiates MO-LR procedure }
then { UE transmits an EXTENDED SERVICE REQUEST message }
}
7.4.1.1.2 Conformance requirements
References: The conformance requirements covered in the present TC are specified in: TS 23.272, clause 8.3.1.
[TS 23.272, clause 8.3.1]
MO-LR procedure in the CS fallback in EPS is performed as specified in TS 23.271 [8].
When the MO-LR procedure is triggered by the UE’s application, UE will check the LCS Support Indication provided by the Attach and TAU procedures as specified in TS 23.401 [2]:
– If the LCS Support Indication indicates EPC-MO-LR is supported, and if the UE supports EPC-MO-LR, the UE stays in LTE and initiates the EPC-MO-LR procedure.
– If EPC-MO-LR is not supported by either the network or the UE and if the LCS Support Indication indicates CS-MO-LR is supported, and the UE supports CS-MO-LR, the UE assumes CS-MO-LR is provided. Also, if EPC-MO-LR is not supported by either the network or the UE and if network does not provide information on whether CS-MO-LR is supported, then UE assumes CS-MO-LR may be provided. In these cases, if the previous combined EPS/IMSI Attach or Combined TA/LA Update is accepted with no "SMS only" indication, then the UE initiates CS Fallback to perform CS-MO-LR.
NOTE: Based on UE implementation, UE may avoid initiating CS-MO-LR when an IMS VoIP session is active.
– Otherwise, the UE shall not attempt the EPC-MO-LR procedure, i.e. neither EPC-MO-LR nor CS-MO-LR with CS Fallback.
If the UE decided to initiate the CS Fallback for the LCS based on LCS Support Indication check, then, the following is applied:
– When UE is in active mode, UE and the network follows the procedure in clause 6.2 "Mobile Originating Call in Active-Mode". After UE changes its RAT from E-UTRAN to UTRAN/GERAN, it performs CS-MO-LR procedures as specified in TS 23.271 [8].
– When UE is in active mode but there’s no need for PS-Handover, then UE and the network follows the procedure in clause 6.3 "Mobile Originating Call in Active Mode – No PS HO Support in GERAN". After UE changes its RAT from E-UTRAN to UTRAN/GERAN, it performs CS-MO-LR procedure as specified in TS 23.271 [8].
– When UE is in idle mode, UE follows the procedure in clause 6.4 "Mobile Originating Call in Idle Mode". After UE changes its RAT from E-UTRAN to UTRAN/GERAN, it performs CS-MO-LR procedure as specified in TS 23.271 [8].
7.4.1.1.3 Test description
7.4.1.1.3.1 Pre-test conditions
System Simulator:
– Cell 1 (E-UTRA) and Cell 5 (UTRA)
– System information combination 4 as defined in TS 36.508 [8] clause 4.4.3.1 is applied to cell 1.
Table 7.4.1.1.3.1-1: Cell power levels
|
Parameter |
Unit |
Cell1 |
Cell 5 |
Remark |
|
Cell-specific RS EPRE |
dBm/15kHz |
-75 |
– |
The power levels are such that the UE camps on cell 1. |
|
CPICH_Ec |
dBm/3.84 MHz |
– |
-70 |
UE:
– The UE is configured to initiate combined EPS/IMSI attach.
Preamble:
– The UE is in state Registered, Idle Mode (state 2) on cell 1 according to TS 36.508 [8] During the registration procedure, the LAI of cell 5 is allocated to the UE.
Related PICS/PIXIT Statements:
– Method of triggering a CS-MO-LR request for a location estimate.
7.4.1.1.3.2 Test procedure sequence
Table 7.4.1.1.3.2-1: Main behaviour
|
St |
Procedure |
Message Sequence |
TP |
Verdict |
|
|
U – S |
Message |
||||
|
1 |
Cause the UE to initiate MO-LR procedure. |
– |
– |
– |
– |
|
2 |
The UE transmits an RRCConnectionRequest message on Cell 1. |
–> |
RRCConnectionRequest |
– |
– |
|
3 |
The SS transmits an RRCConnectionSetup message on Cell 1. |
<– |
RRCConnectionSetup |
– |
– |
|
4 |
The UE transmits an RRCConnectionSetupComplete message on Cell 1. This message includes an EXTENDED SERVICE REQUEST message. |
–> |
RRCConnectionSetupComplete |
1 |
P |
|
5 |
The SS transmits an RRCConnectionRelease message for redirection to UTRAN carrier on Cell 5. |
<– |
RRCConnectionRelease |
– |
– |
|
6-14 |
Steps 1 to 6 and steps 10 to 12 of the test procedure in subclause 6.1.2.1 are performed on Cell 5. Note: RRC connection establishment procedure and LCS procedure are performed in UTRAN cell. |
– |
– |
– |
– |
7.4.1.1.3.3 Specific message contents
Table 7.4.1.1.3.3-1: SystemInformationBlockType6 for cell 1 (preamble, table 7.4.1.1.3.2-1)
|
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 { |
FDD |
||
|
carrierFreq[n] |
Same as cell 5 |
||
|
cellReselectionPriority[n] |
3 |
Lower than cell 1 priority (priority = 4) |
|
|
} |
|||
|
carrierFreqListUTRA-TDD SEQUENCE (SIZE (1..maxUTRA-TDD-Carrier)) OF SEQUENCE { |
1 entry |
TDD |
|
|
carrierFreq[n] |
Same as cell 5 |
||
|
cellReselectionPriority[n] |
3 |
Lower than cell 1 priority (priority = 4) |
|
|
} |
|||
|
} |
|||
Table 7.4.1.1.3.3-2: Message ATTACH ACCEPT (preamble, Table 7.4.1.1.3.2-1)
|
Derivation Path: TS 36.508 Table 4.7.2-1 |
|||
|
Information Element |
Value/remark |
Comment |
Condition |
|
Location services indicator in EPC (EPC-LCS) |
0 |
location services via EPC not supported |
|
|
Location services indicator in CS (CS-LCS) |
01 |
location services via CS domain supported |
|
Table 7.4.1.1.3.3-3: EXTENDED SERVICE REQUEST (step 4, table 13.1.2.3.2-1)
|
Derivation path: 36.508 table 4.7.2-14A |
|||
|
Information Element |
Value/Remark |
Comment |
Condition |
|
Service type |
0000 ‘mobile originating CS fallback or 1xCS fallback’ |
||
|
CSFB response |
Not present |
||
|
EPS bearer context status |
Not present or any allowed value |
||
Table 7.4.1.1.3.3-4: Message RRCConnectionRelease (step 5, Table 7.4.1.1.3.2-1)
|
Derivation Path: TS 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 |
|
|
} |
|||
|
} |
|||
|
} |
|||
|
} |
|||
|
} |
|||
|
Condition |
Explanation |
|
UTRA-FDD |
UTRA FDD cell environment |
|
UTRA-TDD |
UTRA TDD cell environment |
Table 7.4.1.1.3.3-5: Message FACILITY (step 6, Table 7.4.1.1.3.2-1)
|
Derivation Path: 24.080 Table 2.3 |
||||
|
Information Element |
Value/remark |
Comment |
Condition |
|
|
Supplementary service protocol discriminator |
1011 |
supplementary services (call independent) |
||
|
Transaction identifier |
||||
|
Facility message type |
0011 1010 |
FACILITY |
||
|
Facility |
Return Result=LCS‑MOLRRes |
Set according to Table 7.4.1.1.3.3-6 |
||
Table 7.4.1.1.3.3-6: LCS-MOLRRes (step 6, Table 7.2.2.2.3.2-1)
|
Derivation Path: 24.080 clause 4.4.2 |
||||
|
Information Element |
Value/remark |
Comment |
Condition |
|
|
LCS-MOLRRes::= SEQUENCE { |
||||
|
locationEstimate |
‘90D6B9D6B860B800300220430144’O |
Ellipsoid point with altitude and uncertainty Ellipsoid = 9 Spare = 0 Degrees of latitude = D6B9D6 Degrees of longitude = B860B8 Altitude =0030 Uncertainty semi-major= 02 Uncertainty semi-minor =20 Orientation of major axis =43 Uncertainty Altitude= 01 Confidence=44 |
||
|
} |
||||
7.4.1.2 CS fallback: UE does not support EPC-MO-LR
7.4.1.2.1 Test Purpose (TP)
(1)
with { UE in E-UTRA RRC_IDLE state having received an ATTACH ACCEPT message indicating location
services via EPC supported and location services via CS domain supported }
ensure that {
when { UE initiates MO-LR procedure }
then { UE transmits an EXTENDED SERVICE REQUEST message }
}
7.4.1.2.2 Conformance requirements
References: The conformance requirements covered in the present TC are specified in: TS 23.272, clause 8.3.1.
[TS 23.272, clause 8.3.1]
MO-LR procedure in the CS fallback in EPS is performed as specified in TS 23.271 [8].
When the MO-LR procedure is triggered by the UE’s application, UE will check the LCS Support Indication provided by the Attach and TAU procedures as specified in TS 23.401 [2]:
– If the LCS Support Indication indicates EPC-MO-LR is supported, and if the UE supports EPC-MO-LR, the UE stays in LTE and initiates the EPC-MO-LR procedure.
– If EPC-MO-LR is not supported by either the network or the UE and if the LCS Support Indication indicates CS-MO-LR is supported, and the UE supports CS-MO-LR, the UE assumes CS-MO-LR is provided. Also, if EPC-MO-LR is not supported by either the network or the UE and if network does not provide information on whether CS-MO-LR is supported, then UE assumes CS-MO-LR may be provided. In these cases, if the previous combined EPS/IMSI Attach or Combined TA/LA Update is accepted with no "SMS only" indication, then the UE initiates CS Fallback to perform CS-MO-LR.
NOTE: Based on UE implementation, UE may avoid initiating CS-MO-LR when an IMS VoIP session is active.
– Otherwise, the UE shall not attempt the EPC-MO-LR procedure, i.e. neither EPC-MO-LR nor CS-MO-LR with CS Fallback.
If the UE decided to initiate the CS Fallback for the LCS based on LCS Support Indication check, then, the following is applied:
– When UE is in active mode, UE and the network follows the procedure in clause 6.2 "Mobile Originating Call in Active-Mode". After UE changes its RAT from E-UTRAN to UTRAN/GERAN, it performs CS-MO-LR procedures as specified in TS 23.271 [8].
– When UE is in active mode but there’s no need for PS-Handover, then UE and the network follows the procedure in clause 6.3 "Mobile Originating Call in Active Mode – No PS HO Support in GERAN". After UE changes its RAT from E-UTRAN to UTRAN/GERAN, it performs CS-MO-LR procedure as specified in TS 23.271 [8].
– When UE is in idle mode, UE follows the procedure in clause 6.4 "Mobile Originating Call in Idle Mode". After UE changes its RAT from E-UTRAN to UTRAN/GERAN, it performs CS-MO-LR procedure as specified in TS 23.271 [8].
7.4.1.2.3 Test description
7.4.1.2.3.1 Pre-test conditions
System Simulator:
– Cell 1 (E-UTRA) and Cell 5 (UTRA)
– System information combination 4 as defined in TS 36.508 [8] clause 4.4.3.1 is applied to cell 1.
Table 7.4.1.2.3.1-1: Cell power levels
|
Parameter |
Unit |
Cell1 |
Cell 5 |
Remark |
|
Cell-specific RS EPRE |
dBm/15kHz |
-75 |
– |
The power levels are such that the UE camps on cell 1. |
|
CPICH_Ec |
dBm/3.84 MHz |
– |
-70 |
UE:
– The UE is configured to initiate combined EPS/IMSI attach.
Preamble:
– The UE is in state Registered, Idle Mode (state 2) on cell 1 according to TS 36.508 [8] During the registration procedure, the LAI of cell 5 is allocated to the UE related PICS/PIXIT Statements:
– Method of triggering a CS-MO-LR request for a location estimate.
7.4.1.2.3.2 Test procedure sequence
Table 7.4.1.2.3.2-1: Main behaviour
|
St |
Procedure |
Message Sequence |
TP |
Verdict |
|
|
U – S |
Message |
||||
|
1 |
Cause the UE to initiate MO-LR procedure. |
– |
– |
– |
– |
|
2 |
The UE transmits an RRCConnectionRequest message on Cell 1. |
–> |
RRCConnectionRequest |
– |
– |
|
3 |
The SS transmits an RRCConnectionSetup message on Cell 1. |
<– |
RRCConnectionSetup |
– |
– |
|
4 |
The UE transmits an RRCConnectionSetupComplete message on Cell 1. This message includes an EXTENDED SERVICE REQUEST message. |
–> |
RRCConnectionSetupComplete |
1 |
P |
|
5 |
The SS transmits an RRCConnectionRelease message for redirection to UTRAN carrier on Cell 5. |
<– |
RRCConnectionRelease |
– |
– |
|
6-14 |
Steps 1 to 6 and steps 10 to 12 of the test procedure in subclause 6.1.2.1 are performed on Cell 5. Note: RRC connection establishment procedure and LCS procedure are performed in UTRAN cell. |
– |
– |
– |
– |
7.4.1.2.3.3 Specific message contents
Table 7.4.1.2.3.3-1: SystemInformationBlockType6 for cell 1 (preamble, table 7.4.1.2.3.2-1)
|
Same content as Table 7.4.1.1.3.3-1 |
Table 7.4.1.2.3.3-2: Message ATTACH ACCEPT (preamble, Table 7.4.1.2.3.2-1)
|
Derivation Path: TS 36.508 Table 4.7.2-1 |
|||
|
Information Element |
Value/remark |
Comment |
Condition |
|
Location services indicator in EPC (EPC-LCS) |
1 |
location services via EPC supported |
|
|
Location services indicator in CS (CS-LCS) |
01 |
location services via CS domain supported |
|
Table 7.4.1.2.3.3-3: EXTENDED SERVICE REQUEST (step 4, table 13.1.2.3.2-1)
|
Derivation path: 36.508 table 4.7.2-14A |
|||
|
Information Element |
Value/Remark |
Comment |
Condition |
|
Service type |
0000 ‘mobile originating CS fallback or 1xCS fallback’ |
||
|
CSFB response |
Not present |
||
|
EPS bearer context status |
Not present or any allowed value |
||
Table 7.4.1.2.3.3-4: Message RRCConnectionRelease (step 5, Table 7.4.1.2.3.2-1)
|
Derivation Path: TS 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 |
|
|
} |
|||
|
} |
|||
|
} |
|||
|
} |
|||
|
} |
|||
|
Condition |
Explanation |
|
UTRA-FDD |
UTRA FDD cell environment |
|
UTRA-TDD |
UTRA TDD cell environment |
Table 7.4.1.2.3.3-5: Message FACILITY (step 6, Table 7.4.1.2.3.2-1)
|
same content as Table 7.4.1.1.3.3-5 |