13.1.8 Call setup from E-UTRA RRC_CONNECTED/ CS fallback to GSM with redirection / MO 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
13.1.8.1 Test Purpose (TP)
(1)
with { UE in E-UTRA RRC_CONNECTED state }
ensure that {
when { UE is triggered by upper layers to perform a circuit switched voice call }
then { UE transmits an ULInformationTransfer message containing an EXTENDED SERVICE REQUEST message with Service Type IE set to "mobile originating 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 originating CS fallback or 1xCS fallback” }
ensure that {
when { SS transmits an RRCConnectionRelease message with redirection to a GERAN cell in a same location area and operating in NMO I }
then { UE tunes to GERAN cell and completes MO circuit switched voice call setup procedure on GERAN }
}
13.1.8.2 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 6.3, and TS 24.301, clause 5.6.1.1.
[TS 23.272, clause 6.3]
Figure 6.3-1: CS Call Request in E-UTRAN, Call in GERAN/UTRAN without PS HO
1a. The UE sends an Extended Service Request (CS Fallback Indicator) 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 only transmits this request if it is attached to CS domain (with a combined EPS/IMSI Attach) and can not initiate an IMS voice session (because e.g. the UE is not IMS registered or IMS voice services are not supported by the serving IP‑CAN, home PLMN or UE).
1b. The MME sends an S1‑AP Request message to eNB that includes a CS Fallback Indicator. This message indicates to the eNB that the UE should be moved to UTRAN/GERAN.
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.
3a. If the UE and network support inter-RAT cell change order to GERAN and the target cell is GERAN: The eNodeB triggers 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 handover from E-UTRAN to GERAN/UTRAN nor inter-RAT cell change order to GERAN: The eNodeB triggers RRC connection release with redirection to GERAN/UTRAN instead of PS HO or NACC.
NOTE 2: 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 (Cause) message to the MME. Cause indicates that the UE is not available for the PS service.
5. S1 UE Context in the eNodeB is released as specified in TS 23.401 [2].
6. The UE moves to the new cell in GERAN/UTRAN and establishes a radio signalling connection.
If the UE obtains LA information of the new cell (e.g. based on the system information) and the LA of the new cell is different from the one stored in the UE, it performs a Location Area Update or a Combined RA/LA Update procedure in case the target system operates in Network Mode of Operation (NMO) I. Alternatively, 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.
If the UE moves to an UTRAN cell and ISR is not active or the RA of the cell is different to the one the UE is registered in, the UE performs a Routing Area Update. This can be performed as part of the combined RA/LA Update procedure when the LA of the new cell is different from the one stored in the UE and the target system operates in NMO I.
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, which contains the MM and PDP contexts of the UE.
8. If PS services are suspended, the MME starts the preservation of non-GBR bearers and the deactivation of GBR bearers.
9. The UE continues with the MO call setup procedure.
10a. In case the MSC serving the 2G/3G cell is different from the MSC that served the UE while camped on E‑UTRAN and if the Location Area Update / Combined RA/LA Update was not performed in step 6, the MSC shall reject the call setup service request, if implicit location update is not performed.
10b. A UE detecting that the MSC rejected the service request shall perform the Location Area Update according to existing GERAN or UTRAN procedures.
10c. After completion of the Location Area Update the UE continues with a MO call setup procedure.
11. After the CS voice call is terminated and if the UE is in GERAN and PS services are suspended, then (as specified in TS 23.060 [3]) the UE shall resume PS services by sending a Routing Area Update Request message to the SGSN. The Update Type depends on the mode of operation of the GERAN network, e.g. in mode I a Combined RA/LA Update is used and in mode II or III Routing Area Update is used.
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], i.e. if the UE is not registered in the current RA/LA, the UE performs combined RA/LA update procedure when the target system operates in NMO I, or separate LA update and RA update procedures when the target system operates in NMO II/III. Also for NMO I if the UE performed only RA update due to the CS call the UE performs a combined RA/LA update (see TS 23.060 [3], clause 6.3.1) which creates the Gs association.
[TS 24.301, clause 5.6.1.1]
The purpose of the service request procedure is to transfer the EMM mode from EMM-IDLE to EMM-CONNECTED mode and establish the radio and S1 bearers when uplink user data or signalling is to be sent. Another purpose of this procedure is to invoke MO/MT CS fallback procedures.
This procedure is used when:
– the network has downlink signalling pending;
– the UE has uplink signalling pending;
– the UE or the network has user data pending and the UE is in EMM-IDLE mode;
– the UE in EMM-IDLE or EMM-CONNECTED mode has requested to perform mobile originating/terminating CS fallback;
– the network has downlink cdma2000® signalling pending; or
– the UE has uplink cdma2000® signalling pending.
The service request procedure is initiated by the UE, however, for the downlink transfer of signalling, cdma2000® signalling or user data in EMM-IDLE mode, the trigger is given by the network by means of the paging procedure (see subclause 5.6.2).
The UE shall invoke the service request procedure when:
a) the UE in EMM-IDLE mode receives a paging request with CN domain indicator set to "PS" from the network;
b) the UE, in EMM-IDLE mode, has pending user data to be sent;
c) the UE, in EMM-IDLE mode, has uplink signalling pending;
d) the UE in EMM-IDLE or EMM-CONNECTED mode is configured to use CS fallback and has a mobile originating CS fallback request from the upper layer;
e) the UE in EMM-IDLE mode is configured to use CS fallback and receives a paging request with CN domain indicator set to "CS", or the UE in EMM-CONNECTED mode is configured to use CS fallback and receives a CS SERVICE NOTIFICATION message;
f) the UE in EMM-IDLE or EMM-CONNECTED mode is configured to use 1xCS fallback and has a mobile originating 1xCS fallback request from the upper layer;
g) the UE in EMM-CONNECTED mode is configured to use 1xCS fallback and accepts cdma2000® signalling messages containing a 1xCS paging request; or
h) the UE, in EMM-IDLE mode, has uplink cdma2000® signalling pending.
[TS 24.008, clause 4.5.1.1, item d)]
d) When the MS is IMSI attached for CS services via EMM combined procedures, as described in 3GPP TS 24.301 [120], and the MS is camping on an E-UTRAN cell, the MM sublayer requests EMM to initiate a service request procedure for CS fallback. The MM connection establishment is delayed until the MS changes to a GERAN or UTRAN cell.
If the MS enters a GERAN or UTRAN cell, then the MS shall initiate the MM connection establishment and send a CM SERVICE REQUEST message. If the MS determines that it is in a different location area than the stored location area, the MS shall first initiate a normal location updating procedure or a combined routing area update procedure, depending on Network Mode of Operation. The MM connection establishment is delayed until successful completion of the normal location updating or combined routing area update procedure. In A/Gb mode, if the MS is a non DTM MS, or a DTM MS in a cell not supporting DTM, the MS may perform location area updating procedure instead of combined routing area update procedure in NMO I.
13.1.8.3 Test description
13.1.8.3.1 Pre-test conditions
System Simulator:
– 2 cells, one E-UTRA and one GERAN cell:
– Cell 1 E-UTRA serving cell
– Cell 24 suitable neighbour GERAN cell
-
- Cell 24 system information indicates that NMO 1 is used
– 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 1 and Cell 24 are in the same LA.
UE:
None.
Preamble:
- The UE is in state Generic RB Established (state 3) according to [18].
13.1.8.3.2 Test procedure sequence
Table 13.1.8.3.2-0: instances of cell power level and parameter changes
|
Parameter |
Unit |
Cell 1 |
Cell 24 |
Remark |
|
|
T1 |
Cell-specific RS EPRE |
dBm/15kHz |
-115 |
– |
The power levels are such that reselection back to cell 1 should not occur |
Table 13.1.8.3.2-1: Main behaviour
|
St |
Procedure |
Message Sequence |
TP |
Verdict |
|
|
U – S |
Message |
||||
|
1 |
Cause the UE to originate CS call. (see Note 1) |
– |
– |
– |
– |
|
2 |
Check: Does the UE transmit an ULInformationTranfer message containing an EXTENDED SERVICE REQUEST with Service Type IE set to "mobile originated CS fallback or 1xCS fallback” on Cell 1? |
–> |
ULInformationTransfer NAS: EXTENDED SERVICE REQUEST |
1 |
P |
|
3 |
The SS transmits an RRCConnectionRelease message on Cell 1 with IE redirectedCarrierInfo including ARFCN of Cell 24. |
<– |
RRCConnectionRelease |
– |
– |
|
3A |
The UE transmits a CHANNEL REQUEST message on Cell24. |
–> |
CHANNEL REQUEST |
– |
– |
|
3B |
The SS changes cell 1 power level according to the row “T1” |
||||
|
4-34 |
Check: Steps 2 to 32 of the generic test procedure described in TS36.508 subclause 6.4.3.8.2 are performed on Cell24 ? |
– |
– |
2 |
P |
|
– |
At the end of this test procedure sequence, the UE is in end state GERAN idle (G1) according to TS 36.508. |
– |
– |
– |
– |
|
Note 1: The trigger in step 1 is the same as in the generic procedure in 36.508 clause 6.4.3.5. |
|||||
13.1.8.3.3 Specific message contents
Table 13.1.8.3.3-1: Void
Table 13.1.8.3.3-2: Void
Table 13.1.8.3.3-3: Void
Table 13.1.8.3.3-4: ULInformationTransfer (step 2, Table 13.1.8.3.2-2)
|
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 Table 13.1.8.3.3-5 |
EXTENDED SERVICE REQUEST |
||
|
} |
||||
|
} |
||||
|
} |
||||
|
} |
||||
|
} |
||||
Table 13.1.8.3.3-5: EXTENDED SERVICE REQUEST (step 2, Table 13.1.8.3.2-2)
|
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 |
|||
Table 13.1.8.3.3-6: RRCConnectionRelease (step 3, Table 13.1.8.3.2-2)
|
Derivation Path: 36.508 Table 4.6.1.1-15 |
|||
|
Information Element |
Value/remark |
Comment |
Condition |
|
RRCConnectionRelease ::= SEQUENCE { |
|||
|
criticalExtensions CHOICE { |
|||
|
c1 CHOICE { |
|||
|
rrcConnectionRelease-r8 SEQUENCE { |
|||
|
redirectedCarrierInfo ::= CHOICE { |
|||
|
Geran |
f11 |
||
|
} |
|||
|
} |
|||
|
} |
|||
Table 13.1.8.3.3-7: Void
Table 13.1.8.3.3-8: ATTACH ACCEPT (Preamble)
|
Derivation Path: 36.508 Table 4.7.2-1 |
||||
|
Information Element |
Value/remark |
Comment |
Condition |
|
|
EPS network feature support |
Not present |
|||