22.5.3 NB-IoT / NW initiated detach Re-attach required / UE initiated detach Abnormal case EMM common procedure collision / UE initiated detach Abnormal case Local detach after 5 attempts due to no network response

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

22.5.3.1 Test Purpose (TP)

(1)

with { UE in EMM-REGISTERED state }

ensure that {
when { SS sends DETACH REQUEST message with the Detach type IE "re-attach required" }

then { UE detaches and re-attaches using the EPS security context established before the detach }

}

(2)

with { UE in EMM-DEREGISTERED-INITIATED state due to normal detach }

ensure that {

when { the UE receives AUTHENTICATION REQUEST, SECURITY MODE COMMAND or IDENTITY REQUEST message from the network }

then { the UE responds to the message }

}

(3)

with { UE in EMM-DEREGISTERED-INITIATED state due to normal detach }

ensure that {

when { the UE receives GUTI REALLOCATION COMMAND from the network }

then { the UE ignores the message and continues the detach procedure }

}

(4)

with { UE in EMM-DEREGISTERED-INITIATED state due to normal detach }

ensure that {

when { the UE receives no response to the UE initiated DETACH REQUEST }

then { the UE re-transmits the DETACH REQUEST up to 4 times on the expiry of timer T3421 }

}

(5)

with { UE in EMM-DEREGISTERED-INITIATED state due to normal detach }

ensure that {

when { the UE receives no response to the UE initiated DETACH REQUEST }

then { the UE aborts the detach procedure and perform local detach on the 5th expiry of timer T3421 }

}

22.5.3.2 Conformance requirements

References: The conformance requirements covered in the current TC are specified in: TS 24.301 clauses 4.7, 5.5.2.2.4, 5.5.2.3.2. Unless otherwise stated these are Rel-13 requirements.

[TS 24.301, clause 4.7]

A UE in NB-S1 mode (see 3GPP TS 36.331 [22]) shall calculate the value of the applicable NAS timers:

– indicated in table 10.2.1 plus 240s; and

– indicated in table 10.3.1 plus 180s.

The timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not re-calculate the use of the multiplier until the NAS procedure is completed, restarted or aborted.

[TS 24.301, clause 5.5.2.2.4]

The following abnormal cases can be identified:

…

c) T3421 timeout

On the first four expiries of the timer, the UE shall retransmit the DETACH REQUEST message and shall reset and restart timer T3421. On the fifth expiry of timer T3421, the detach procedure shall be aborted and the UE proceeds as follows:

…

– if "EPS detach" was requested for reasons other than disabling of EPS services, the UE shall enter the EMM-DEREGISTERED state;

…

…

e) Detach and EMM common procedure collision

Detach containing cause "switch off":

– If the UE receives a message used in an EMM common procedure before the detach procedure has been completed, this message shall be ignored and the detach procedure shall continue.

Detach containing other causes than "switch off" and containing detach type "IMSI detach":

– If the UE receives a message used in an EMM common procedure before the detach procedure has been completed, both the EMM common procedure and the detach procedure shall continue.

Detach containing other causes than "switch off" and containing other detach types than "IMSI detach":

– If the UE receives a GUTI REALLOCATION COMMAND, an EMM STATUS or an EMM INFORMATION message before the detach procedure is completed, this message shall be ignored and the detach procedure shall continue.

– If the UE receives an AUTHENTICATION REQUEST, SECURITY MODE COMMAND or IDENTITY REQUEST message before the detach procedure has been completed, the UE shall respond to it as described in subclause 5.4.2, 5.4.3 and 5.4.4 respectively and the detach procedure shall continue.

[TS 24.301, clause 5.5.2.3.2]

When receiving the DETACH REQUEST message and the detach type indicates "re-attach required", the UE shall deactivate the EPS bearer context(s), if any, including the default EPS bearer context locally without peer-to-peer signalling between the UE and the MME. The UE shall stop the timer T3346, if it is running. The UE shall also stop timer(s) T3396, if it is running. The UE shall send a DETACH ACCEPT message to the network and enter the state EMM-DEREGISTERED. Furthermore, the UE shall, after the completion of the detach procedure, and the release of the existing NAS signalling connection, initiate an attach or combined attach procedure. The UE should also re-establish any previously established PDN connection(s).

NOTE 1: When the detach type indicates "re-attach required", user interaction is necessary in some cases when the UE cannot re-activate the EPS bearer(s), if any, automatically.

A UE which receives a DETACH REQUEST message with detach type indicating "re-attach required" or "re-attach not required" and no EMM cause IE, is detached only for EPS services.

…

If the detach type indicates "IMSI detach" or "re-attach required", then the UE shall ignore the EMM cause IE if received.

22.5.3.3 Test description

22.5.3.3.1 Pre-test conditions

System Simulator:

– Ncell 1, default system information.

UE:

None.

Preamble:

– The UE is in NB-IoT UE Attach, Connected mode (State 2-NB) on Ncell 1 according to TS 36.508 [18].

22.5.3.3.2 Test procedure sequence

Table 22.5.3.3.2-1: Main behaviour

St

Procedure

Message Sequence

TP

Verdict

U – S

Message

1

The SS initiates Detach procedure with the Detach Type IE "re-attach required"

<–

RRC: DLInformationTransfer-NB

NAS: DETACH REQUEST

–

–

2

Check: Does the UE send DETACH ACCEPT message?

–>

RRC: ULInformationTransfer-NB

NAS: DETACH ACCEPT

1

P

3

The SS releases RRC connection.

<–

RRC: RRCConnectionRequest-NB

–

–

–

EXCEPTION: Step 4a1 describes a behaviour which depends on the UE capability

–

–

–

–

4a1

IF NOT pc_Automatic_Re_Attach, the user initiates an attach by MMI or by AT command.

–

–

–

–

5

The Generic procedure ‘NB-IoT UE Attach, Connected mode (State 2-NB)’ as described in TS 36.508 [18], clause 8.1.5.2 takes place.

–

–

–

–

6

Cause UE to initiate normal detach.

–

–

–

–

7

The UE transmits a DETACH REQUEST message.

–>

RRC: ULInformationTransfer-NB

NAS: DETACH REQUEST

–

–

8

SS start Timer=T3421 (15+240=255 sec).

–

–

–

–

9

With T3421 still running the SS sends AUTHENTICATION REQUEST.

<–

RRC: DLInformationTransfer-NB

NAS: AUTHENTICATION REQUEST

–

–

10

Check: Does the UE transmit an AUTHENTICATION RESPONSE message?

–>

RRC: ULInformationTransfer-NB

NAS: AUTHENTICATION RESPONSE

2

P

11

With timer=T3421 (15+240=255 sec) still running the SS shall send SECURITY MODE COMMAND.

<–

RRC: DLInformationTransfer-NB

NAS: SECURITY MODE COMMAND

–

–

12

Check: Does the UE transmit a SECURITY MODE COMPLETE message?

–>

RRC: ULInformationTransfer-NB

NAS: SECURITY MODE COMPLETE

2

P

13

With timer=T3421 (15+240=255 sec) still running the SS shall send IDENTITY REQUEST.

<–

RRC: DLInformationTransfer-NB

NAS: IDENTITY REQUEST

–

–

14

Check: Does the UE transmit an IDENTITY RESPONSE message?

–>

RRC: ULInformationTransfer-NB

NAS: IDENTITY RESPONSE

2

P

15

With timer=T3421 (15+240=255 sec) still running the SS transmits a GUTI REALLOCATION COMMAND message.

<–

RRC: DLInformationTransfer-NB

NAS: GUTI REALLOCATION COMMAND

–

–

16

Check: Does the UE transmit a GUTI REALLOCATION COMPLETE message?

–>

RRC: ULInformationTransfer-NB

NAS: GUTI REALLOCATION COMPLETE

3

F

17

Timer=T3421 (15+240=255 sec) expires

–

–

–

–

–

EXCEPTION: Steps 18-20 are repeated 4 times.

–

–

–

–

18

Check: Does the UE transmits a DETACH REQUEST message?

–>

RRC: ULInformationTransfer-NB

NAS: DETACH REQUEST

3,4

P

19

SS start Timer=T3421 (15+240=255 sec).

–

–

–

–

20

Timer=T3421 expires (15+240=255 sec).

–

–

–

–

–

EXCEPTION: Steps 21a1-21b3 describe behaviour that depends on UE implementation; the "lower case letter" identifies a step sequence that take place depending on whether the UE may attempt to attach automatically.

–

–

–

–

21a1

Start timer Wait for attach=60 sec.

–

–

–

–

21a2

UE transmits an RRCConnectionRequest-NB message, establishmentCause=mo-Signalling.

–>

RRC: RRCConnectionRequest-NB

–

–

21a3

Stop timer Wait for attach.

–

–

–

–

21a4

SS transmits an RRCConnectionSetup-NB message.

<–

RRC: RRCConnectionSetup-NB

–

–

–

EXCEPTION: Steps 21a5a1 and 21a5b1 describe behaviour that depends on UE capabilities; the "lower case letter" identifies a step sequence that take place depending on whether the UE is configured to do Attach Without PDN or not.

–

–

–

–

21a5a1

IF px_DoAttachWithoutPDN THEN

Check: Does the UE transmit an RRCConnectionSetupComplete-NB message to confirm the successful completion of the connection establishment and to initiate the Attach procedure by including the ATTACH REQUEST message? An ESM DUMMY MESSAGE is piggybacked in ATTACH REQUEST.

–>

RRC: RRCConnectionSetupComplete-NB

NAS: ATTACH REQUEST

NAS: ESM DUMMY MESSAGE

5

P

21a5b1

ELSE

Check: Does the UE transmit an RRCConnectionSetupComplete-NB message to confirm the successful completion of the connection establishment and to initiate the Attach procedure by including the ATTACH REQUEST message? A PDN CONNECTIVITY REQUEST message is piggybacked in ATTACH REQUEST.

–>

RRC: RRCConnectionSetupComplete-NB

NAS: ATTACH REQUEST

NAS: PDN CONNECTIVITY REQUEST

5

P

21a6-21a15b1

Steps 5-14b1 from the Generic procedure ‘NB-IoT UE Attach, Connected mode (State 2-NB)’ as described in TS 36.508 [18], clause 8.1.5.2 take place.

–

–

–

–

21a16

The SS transmits an RRCConnectionRelease-NB message to release RRC connection and move to RRC_IDLE.

<–

RRC: RRCConnectionRelease-NB

–

–

21b1

Timer Wait for attach=60 sec expires.

–

–

–

–

21b2

SS sends a Paging message to the UE on the appropriate paging block, and including the UE identity in one entry of the IE pagingRecordLists.

<–

RRC: Paging-NB

–

–

21b3

Check: Does the UE respond to paging by transmitting an RRCConnectionRequest-NB message in the next 30 seconds?

–>

-RRC: RRCConnectionRequest-NB

5

F
22.5.3.3.3 Specific message contents

Table 22.5.3.3.3-1: SystemInformationBlockType1-NB (Preamble and all steps)

Derivation Path: TS 36.508 [18], Table 8.1.4.3.2-3, condition ATTACH_WITHOUT_PDN

Table 22.5.3.3.3-2: DETACH REQUEST (step 1, Table 22.5.3.3.2-1)

Derivation Path: TS 36.508 [18], Table 4.7.2-12

Information Element

Value/remark

Comment

Condition

Detach type

‘001’B

"re-attach required"

Table 22.5.3.3.3-3: Message ATTACH REQUEST (step 5, Table 22.5.3.3.2-1; TS 36.508 [18], steps 4a1 or 4b1, Table 8.1.5.2.3-1, and, step 21a5a1 and 21a5b1, Table 22.5.3.3.2-1)

Derivation path: TS 36.508 [18], Table 4.7.2-4

Information Element

Value/Remark

Comment

Condition

NAS key set identifier

TSC

‘0’B

native security context

NAS key set identifier

The value is the same value to be allocated by SS in the Preamble.

Old GUTI or IMSI

GUTI-1

NOTE: This message is sent integrity protected within a SECURITY NAS PROTECTED MESSAGE.

Table 22.5.3.3.3-4: Message ATTACH ACCEPT (step 5, Table 22.5.3.3.2-1; TS 36.508 [18], steps 13a1 or 13b1 or 13c1, Table 8.1.5.2.3-1)

Derivation path: TS 36.508 [18], Table 4.7.2-1

Information Element

Value/Remark

Comment

Condition

TAI list

Length of tracking area identity list contents

‘00000110’B

6 octets

Number of elements

‘00000’B

1 element

Type of list

‘00’B

"list of TACs belonging to one PLMN, with non-consecutive TAC values"

Partial tracking area identity list

TAI-1

GUTI

GUTI-2

Table 22.5.3.3.3-5: GUTI REALLOCATION COMMAND (step 15, Table 22.5.3.3.2-1)

Derivation Path: TS 36.508 [18], Table 4.7.2-15

Information Element

Value/remark

Comment

Condition

GUTI

GUTI-2

TAI list

Not present

Table 22.5.3.3.3-6: DETACH REQUEST (steps 7 and 18, Table 22.5.3.3.2-1)

Derivation Path: TS 36.508 [18], Table 4.7.2-11

Information Element

Value/remark

Comment

Condition

Detach type

Type of detach

001

EPS detach

Switch off

0

normal detach

GUTI or IMSI

GUTI-2