13.2.5 PC5 unicast / link identifier update

38.523-13GPP5GSPart 1: ProtocolRelease 17TSUser Equipment (UE) conformance specification

13.2.5.1 Test Purpose (TP)

(1)

with { UE having established a DIRECT LINK with Layer 2 ID-1 to a peer UE }

ensure that {

when { UE receives a DIRECT LINK IDENTIFIER UPDATE REQUEST message with same Layer 2 ID-1 }

then { UE transmits a DIRECT LINK IDENTIFIER UPDATE REJECT message }

}

(2)

with { UE having established a DIRECT LINK with old Layer 2 ID-1 to a peer UE. UE receives a DIRECT LINK IDENTIFIER UPDATE REQUEST message and responds with a DIRECT LINK IDENTIFIER UPDATE ACCEPT message with new Layer 2 ID-2 }

ensure that {

when { UE receives a V2X packet from the peer UE }

then { the Layer 2 ID associated with the V2X packet is the old Layer 2 ID-1 }

}

(3)

with { UE having established a DIRECT LINK with old Layer 2 ID-1 to a peer UE. UE receives a DIRECT LINK IDENTIFIER UPDATE REQUEST message and responds with a DIRECT LINK IDENTIFIER UPDATE ACCEPT message with new Layer 2 ID-2 }

ensure that {

when { UE receives a DIRECT LINK IDENTIFIER UPDATE ACK message from the peer UE }

then { UE transmits a V2X packet and the Layer 2 ID associated with the V2X packet is the new Layer 2 ID-2 }

}

13.2.5.2 Conformance requirements

References: The conformance requirements covered in the present TC are specified in: TS 24.587, subclause 6.1.2.5.3, 6.1.2.5.4 and 6.1.2.5.6. Unless otherwise stated these are Rel-16 requirements.

[TS 24.587, subclause 6.1.2.5.3]

Upon receipt of a DIRECT LINK IDENTIFIER UPDATE REQUEST message, if the target UE determines:

a) the PC5 unicast link associated with this request message is still valid; and

b) the timer T5010 for the PC5 unicast link identified by this request message is not running,

then the target UE accepts this request, and responds with a DIRECT LINK IDENTIFIER UPDATE ACCEPT message.

The target UE shall create the DIRECT LINK IDENTIFIER UPDATE ACCEPT message. In this message, the target UE:

a) shall include the target UE’s new layer-2 ID assigned by itself;

b) shall include the new LSB of KNRP-sess ID;

c) shall include the initiating UE’s new MSB of KNRP-sess ID;

d) shall include the initiating UE’s new layer-2 ID;

e) shall include the target UE’s new application layer ID if received from upper layer;

f) shall include the initiating UE’s new IP address/prefix if received from the initiating UE and IP communication is used;

g) shall include the initiating UE’s new application layer ID if received from the initiating UE; and

h) shall include the target UE’s new IP address/prefix if IP communication is used and changed.

After the DIRECT LINK IDENTIFIER UPDATE ACCEPT message is generated, the target UE shall pass this message to the lower layers for transmission along with the initiating UE’s old layer-2 ID for unicast communication and the target UE’s old layer-2 ID for unicast communication, and start timer T5010. The UE shall not send a new DIRECT LINK IDENTIFIER UPDATE ACCEPT message to the same initiating UE while timer T5010 is running.

Before target UE receives the traffic using the new layer-2 IDs, the target UE shall continue to receive the traffic with the old layer-2 IDs (i.e. initiating UE’s old layer-2 ID and target UE’s old layer-2 ID) from initiating UE.

Before target UE receives the DIRECT LINK IDENTIFIER UPDATE ACK message from initiating UE, the target UE shall keep sending traffic to the initiating UE using the old layer-2 IDs (i.e. initiating UE’s old layer-2 ID for unicast communication and target UE’s old layer-2 ID for unicast communication).

[24.587, subclause 6.1.2.5.4]

Upon receipt of the DIRECT LINK IDENTIFIER UPDATE ACCEPT message, the initiating UE shall stop timer T5009 and respond with a DIRECT LINK IDENTIFIER UPDATE ACK message. In this message, the initiating UE:

a) shall include the target UE’s new layer-2 ID;

b) shall include the target UE’s new LSB of KNRP-sess ID;

c) shall include the target UE’s new application layer ID, if received; and

d) shall include the target UE’s new IP address/prefix, if received.

After the DIRECT LINK IDENTIFIER UPDATE ACK message is generated, the initiating UE shall pass this message to the lower layers for transmission along with the initiating UE’s old layer-2 ID for unicast communication and the target UE’s old layer-2 ID for unicast communication and shall stop timer T5011 if running and start a timer T5011 as configured if at least one of V2X service identifiers for the PC5 unicast link satisfying the privacy requirements as specified in clause 5.2.3.

Upon sending the DIRECT LINK IDENTIFIER UPDATE ACK message, the initiating UE shall update the associated PC5 unicast link context with the new identifiers and pass the new layer-2 IDs (i.e. initiating UE’s new layer-2 ID for unicast communication and target UE’s new layer-2 ID for unicast communication if changed) along with the PC5 link identifier down to the lower layer. Then the initiating UE shall use the new layer-2 IDs (i.e. initiating UE’s new layer-2 ID for unicast communication and target UE’s new layer-2 ID for unicast communication if changed) to transmit the PC5 signalling message and PC5 user plane data.

The initiating UE shall continue to receive traffic with the old layer-2 IDs (i.e. initiating UE’s old layer-2 ID for unicast communication and target UE’s old layer-2 ID for unicast communication) from the target UE until it receives traffic with the new layer-2 IDs (i.e. initiating UE’s new layer-2 ID and target UE’s new layer-2 ID if changed) from the target UE.

[24.587, subclause 6.1.2.5.6]

If the DIRECT LINK IDENTIFIER UPDATE REQUEST message cannot be accepted, the target UE shall send a DIRECT LINK IDENTIFIER UPDATE REJECT message. The DIRECT LINK IDENTIFIER UPDATE REJECT message contains a PC5 signalling protocol cause IE set to one of the following cause values:

#3 conflict of layer-2 ID for unicast communication is detected; or

#111 protocol error, unspecified.

For a received DIRECT LINK IDENTIFIER UPDATE REQUEST message from a layer-2 ID (for unicast communication), if the target UE already has an existing link using this layer-2 ID or is currently processing a DIRECT LINK IDENTIFIER UPDATE REQUEST message from the same layer-2 ID, but with user info different from the user info IE included in this new incoming message, the target UE shall send a DIRECT LINK IDENTIFIER UPDATE REJECT message with PC5 signalling protocol cause value #3 "conflict of layer-2 ID for unicast communication is detected".

NOTE: After receiving the DIRECT LINK IDENTIFIER UPDATE REJECT message, whether the initiating UE initiates the PC5 unicast link release procedure or initiates another PC5 unicast link identifier update procedure with a new layer-2 ID depends on UE implementation.

For other reasons causing the failure of link identifier update, the target UE shall send a DIRECT LINK IDENTIFIER UPDATE REJECT message with PC5 signalling protocol cause value #111 "protocol error, unspecified".

Upon receipt of the DIRECT LINK IDENTIFIER UPDATE REJECT message, the initiating UE shall stop timer T5009 and abort this PC5 unicast link identifier update procedure.

13.2.5.3 Test description

13.2.5.3.1 Pre-test conditions

System Simulator:

– NR-SS-UE

– NR-SS-UE1 operating as NR sidelink communication device on the resources (i.e. the frequency included in pre-configuration) that UE is expected to use for transmission and reception via PC5 interface.

– NR-SS-UE1 uses GNSS as the synchronization reference source.

– GNSS simulator

– The GNSS simulator is started and configured for Scenario #1.

UE:

– UE is authorised to perform NR sidelink communication.

– The UE uses GNSS as the synchronization reference source.

– The UE is equipped with a USIM containing default values as per TS 38.508-1 [4] clause 4.8.3.3.3.

Preamble:

– The UE is in state 4-A and Test Loop Function (On) with UE test loop mode E as defined in TS 38.508-1 [4], subclause 4.4A using generic procedure parameter Sidelink (On), Cast Type (Unicast), GNSS Sync (On) using NR-SS-UE initiated unicast mode NR sidelink communication procedure in subclause 4.9.23.

13.2.5.3.2 Test procedure sequence

Table 13.2.5.3.2-1: Main behaviour

St

Procedure

Message Sequence

TP

Verdict

U – S

Message

1

The NR-SS-UE1 transmits a DIRECT LINK IDENTIFIER UPDATE REQUEST message including new Layer 2 ID-2.

<–

PC5-S: DIRECT LINK IDENTIFIER UPDATE REQUEST

–

–

2

The UE transmits a DIRECT LINK IDENTIFIER UPDATE ACCEPT message.

–>

PC5-S: DIRECT LINK IDENTIFIER UPDATE ACCEPT

–

–

3

Trigger the UE to close UE test loop mode E (Receive Mode).

NOTE: Closing of UE test loop mode E may be performed by MMI or AT command (+CCUTLE).

–

–

–

–

4

The NR-SS-UE1 transmits one V2X packet on old Layer 2 ID-1 to the UE.

NOTE: This step verifies TP2 – it is expected that the UE shall receive the packet – if they were received is checked in step 5.

FFS

<–

V2X packet

–

–

5

Trigger the UE to report the counter of successful reception of V2X packet.

NOTE: Requesting the UE to report the counter of successful reception of V2X packet may be performed by MMI or AT command (+CUSPCREQ).

–

–

–

–

6

Check: Does the UE reported counter of successful reception of V2X packet?

–

–

2

P

7

The NR-SS-UE1 transmits a DIRECT LINK IDENTIFIER UPDATE ACK message.

<–

PC5-S: DIRECT LINK IDENTIFIER UPDATE ACK

–

–

8

The NR-SS-UE1 transmits one V2X packet on new Layer 2 ID-2 to the UE.

NOTE: This step verifies TP3 – it is expected that the UE shall receive the packet – if they were received is checked in step 10.

<–

V2X packet

–

–

9

Trigger the UE to report the counter of successful reception of V2X packet.

NOTE: Requesting the UE to report the counter of successful reception of V2X packet may be performed by MMI or AT command (+CUSPCREQ).

–

–

–

–

10

Check: Does the UE reported counter of successful reception of V2X packet?

–

–

3

P

11

Trigger the UE to open UE test loop mode E.

NOTE: Opening of UE test loop mode E may be performed by MMI or AT command (+CCUTLE).

–

–

–

–

12

The NR-SS-UE1 transmits a DIRECT LINK IDENTIFIER UPDATE REQUEST message including Layer 2 ID-2.

<–

PC5-S: DIRECT LINK IDENTIFIER UPDATE REQUEST

–

–

13

Check: Does the UE transmit a DIRECT LINK IDENTIFIER UPDATE REJECT message?

–>

PC5-S: DIRECT LINK IDENTIFIER UPDATE REJECT

1

P

13.2.5.3.3 Specific message contents

Table 13.2.5.3.3-1: DIRECT LINK IDENTIFIER UPDATE REQUEST (step 1 & 10, Table 13.2.5.3.2-1)

Derivation path: TS 38.508-1 [4], Table 4.7.4-23 with condition Rx

Table 13.2.5.3.3-2: DIRECT LINK IDENTIFIER UPDATE ACCEPT (step 2, Table 13.2.5.3.2-1)

Derivation path: TS 38.508-1 [4], Table 4.7.4-24 with condition Tx

Table 13.2.5.3.3-3: DIRECT LINK IDENTIFIER UPDATE REJECT (step 11, Table 13.2.5.3.2-1)

Derivation path: TS 38.508-1 [4], Table 4.7.4-26 with condition Tx