19.1.9 ProSe Direct Communication/Pre-configured authorisation / UE out of coverage on the frequency used for sidelink communication / Isolated one-to-one ProSe direct communication / Success/Direct link keepalive/Release upon User request / MO

36.523-13GPPEvolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Packet Core (EPC)Part 1: Protocol conformance specificationRelease 16TSUser Equipment (UE) conformance specification

19.1.9.1 Test Purpose (TP)

(1)

with { UE being authorized for performing ProSe Direct Communication being provisioned with Radio parameters for when the UE is "not served by E-UTRAN" associated with a geographical area, and, UE out of coverage on the frequency used for sidelink communication and within the pre-set geographical area }

ensure that {

when { UE wants to establish one-to-one ProSe direct communication with a remote UE with the link layer identifier for the target UE pre-configured }

then { UE sends a DIRECT_COMMUNICATION_REQUEST message }

}

(2)

with { UE being authorized for performing ProSe Direct Communication being provisioned with Radio parameters for when the UE is "not served by E-UTRAN" associated with a geographical area, and, UE out of coverage on the frequency used for sidelink communication and within the pre-set geographical area, and, the UE having sent a DIRECT_COMMUNICATION_REQUEST message }

ensure that {

when { UE receives a DIRECT SECURITY MODE COMMAND from the remote UE requesting the establishment of Security association for the requested direct link }

then { UE sends a DIRECT_SECURITY_MODE_COMPLETE message ciphered and integrity protected with the new security context, and, from this moment on protects all signalling messages and user data with the new security context }

}

(3)

with { UE being authorized for performing ProSe Direct Communication being provisioned with Radio parameters for when the UE is "not served by E-UTRAN" associated with a geographical area, and, UE out of coverage on the frequency used for sidelink communication and within the pre-set geographical area, and, the UE having established one-to-one ProSe direct communication with a remote UE }

ensure that {

when { UE’s keepalive timer T4102 expires }

then { UE performs a Direct link keepalive procedure }

}

(4)

with { UE being authorized for performing ProSe Direct Communication being provisioned with Radio parameters for when the UE is "not served by E-UTRAN" associated with a geographical area, and, UE out of coverage on the frequency used for sidelink communication and within the pre-set geographical area, and, the UE having established one-to-one ProSe direct communication with a remote UE }

ensure that {

when { UE receives request from upper layers to release a direct link with the peer UE }

then { UE releases the secure direct link }

}

19.1.9.2 Conformance requirements

References: The conformance requirements covered in the present TC are specified in: TS 23.303, clause 5.4.5.1, TS 36.331, clause 5.10.4, TS 24.334, clauses 5.1.1, 10.2.3, 10.4.1A, 10.4.2.1, 10.4.2.2, 10.4.2.4, 10.4.3.2, 10.4.3.4, 10.4.4.2, 10.4.4.4, 10.4.5.1, 10.4.5.3, 10.4.6.1, 10.4.6.2. Unless otherwise stated these are Rel-13 requirements.

[TS 23.303, clause 5.4.5.1]

One-to-one ProSe Direct Communication is realised by establishing a secure layer-2 link over PC5 between two UEs.

Each UE has a Layer-2 ID for unicast communication that is included in the Source Layer-2 ID field of every frame that it sends on the layer-2 link and in the Destination Layer-2 ID of every frame that it receives on the layer-2 link.

NOTE: Conflicts between Destination Layer-2 ID for unicast and one-to-many communication will be resolved by RAN WG2.

The UE needs to ensure that the Layer-2 ID for unicast communication is at least locally unique. To that effect the UE should be prepared to handle Layer-2 ID conflicts with adjacent UEs using unspecified mechanisms (e.g. self-assign a new Layer-2 ID for unicast communication when a conflict is detected).

The layer-2 link for one-to-one ProSe Direct Communication is identified by the combination of the Layer-2 IDs of the two UEs. This means that the UE can engage in multiple layer-2 links for one-to-one ProSe Direct Communication using the same Layer-2 ID.

[TS 24.334, clause 5.1.1]

The service authorisation for ProSe direct discovery and ProSe direct communication determines whether the UE is authorised to use ProSe direct discovery and ProSe direct communication, in a particular PLMN or when not served by E-UTRAN. In this release of the specification, ProSe direct communication is supported only for Public Safety ProSe-enabled UE. The service authorisation is either:

1) pre-configured in the UE. The pre-configured service authorisation may be stored in the ME, or in the USIM as specified in 3GPP TS 31.102 [17], or in both the ME and the USIM. If both the ME and the USIM contain the same parameters, the values stored in the USIM shall take precedence. The UE shall not use the pre-configured service authorisation if the contents of the USIM indicate that the UE is not authorised to use them (see 3GPP TS 31.102 [17]); or

[TS 24.334, clause 10.4.1A]

The UE shall be authorised for one-to-one ProSe direct communication and obtain the ProSe direct communication policy parameters based on the service authorisation procedure as specified in clause 5 before initiating or participating in any PC5 Signalling Protocol procedures for one-to-one ProSe direct communication.

The UE shall select the radio resources for one-to-one ProSe direct communication as described for one-to-many ProSe direct communication in subclauses 10.2.1, 10.2.2 and 10.2.3.

[TS 36.331, clause 5.10.4]

A UE capable of sidelink communication that is configured by upper layers to transmit non-relay related sidelink communication and has related data to be transmitted or a UE capable of relay related sidelink communication that is configured by upper layers to transmit relay related sidelink communications and satisfies the conditions for relay related sidelink communication specified in this section shall:

2> else (i.e. out of coverage on sidelink carrier):

3> if priorityList is included for the entries of preconfigComm in SL-Preconfiguration defined in 9.3:

3> else:

4> configure lower layers to transmit the sidelink control information and the corresponding data using the pool of resources that were preconfigured i.e. indicated by the first entry in preconfigComm in SL-Preconfiguration defined in 9.3 and in accordance with the timing of the selected SyncRef UE, or if the UE does not have a selected SyncRef UE, based on the UEs own timing;

[TS 24.334, clause 10.2.3]

When the UE is not served by E-UTRAN, the UE shall select the radio parameters to be used for ProSe direct communication as follows:

– if the UE can determine itself located in a geographical area, and the UE is provisioned with radio parameters for the geographical area, the UE shall select the radio parameters associated with that geographical area; or

– in all other cases, the UE shall not initiate ProSe direct communication.

NOTE 1: It is out of scope of the present specification to define how the UE can locate itself in a specific Geographical Area. When the UE is in coverage of a 3GPP RAT it can for example use information derived from the serving PLMN. When the UE is not in coverage of a 3GPP RAT it can use other techniques as determined by local regulations.

Before initiating ProSe direct communication, the UE shall check with lower layers whether the selected radio parameters can be used in the current location without causing interference to other cells as specified in 3GPP TS 36.331 [12], and:

– if the lower layers indicate that the usage would not cause any interference, the UE shall initiate ProSe direct communication; or

[TS 24.334, clause 10.4.2.1]

If the direct link setup is for isolated one-to-one ProSe direct communication, i.e. when none of the two UEs is a ProSe UE-to-network relay, both UEs are required to have fetched in advance the public key of the KMS (Key Management Server), and a set of credentials associated with the UE’s identity (as defined in IETF RFC 6507 [39] and IETF RFC 6508 [40]), as specified by 3GPP TS 33.303 [6].

[TS 24.334, clause 10.4.2.2]

The initiating UE shall meet the following pre-conditions before initiating this procedure:

– a request from upper layers to establish a direct link with the target UE is received and there is no existing link between the initiating UE and that target UE;

– the link layer identifier for the initiating UE (i.e., Layer 2 ID used for unicast communication) is available (e.g. pre-configured or self-assigned);

– the link layer identifier for the target UE (i.e., Layer 2 ID used for unicast communication) is available to the initiating UE (e.g., pre-configured or obtained via ProSe direct discovery); and

– the initiating UE is either authorised for ProSe direct communication in the serving PLMN, or has a valid authorization for ProSe direct communication when not served by E-UTRAN.

The initiating UE initiates the direct link setup procedure by generating a DIRECT_COMMUNICATION_REQUEST message with:

– the User Info set to:

– the initiating UE’s User Info received from upper layers if the target UE is not a ProSe UE-to-network relay UE;

– an IP Address Config IE set to one of the following values:

– "DHCPv4 Server" if only IPv4 address allocation mechanism is supported by the initiating UE, i.e., acting as a DHCPv4 Server;

– "IPv6 Router" if only IPv6 address allocation mechanism is supported by the initiating UE, i.e., acting as an IPv6 Router;

– "DHCPv4 Server & IPv6 Router" if both IPv4 and IPv6 address allocation mechanisms are supported by the initiating UE; or

– "address allocation not supported" if neither IPv4 nor IPv6 address allocation mechanism is supported by the initiating UE;

– a Link Local IPv6 Address IE formed locally based on IETF RFC 4862 [15] if the IP Address Config IE is set to "address allocation not supported" and the link is setup for isolated one-to-one communication;

NOTE 1: the UE can reuse a Link Local IPv6 IP address for multiple isolated one-to-one communication links.

– a Maximum Inactivity Period IE to indicate the maximum inactivity period of the requesting UE over this direct link;

NOTE 2: The value of Maximum Inactivity Period IE can be calculated based on UE’s local settings, such as keepalive timer T4102 (see 10.4.3), retransmission timer T4101 (see 10.4.3), and maximum number of allowed retransmissions for DIRECT_COMMUNICATION_KEEPALIVE message.

– a Nonce_1 IE set to the 128-bit nonce value generated by the initiating UE for the purpose of session key establishment over this direct link;

– a UE Security Capabilities IE set to indicate the list of algorithms that the initiating UE supports for the security establishment of this direct link;

– an MSB of KD-sess ID IE set to the most significant 8 bits of the KD-sess ID; and

– Optionally, a KD ID IE set to the known ID of KD which was previously established if the initiating UE has an existing KD with the target UE.

If the direct link setup is for isolated one-to-one ProSe direct communication, the DIRECT_COMMUNICATION_REQUEST message shall also include the following parameters:

– the Signature IE set to the ECCSI signature calculated with the following information elements, as specified in 3GPP TS 33.303 [6]:

– User Info; and

– Nonce_1.

After the DIRECT_COMMUNICATION_REQUEST message is generated, the initiating UE shall pass this message to the lower layers for transmission along with the initiating UE’s Layer 2 ID (for unicast communication) and the target UE’s Layer 2 ID (for unicast communication), and start timer T4100. The UE shall not send a new DIRECT_COMMUNICATION_REQUEST message to the same target UE while timer T4100 is running.

Figure 10.4.2.2.1: Direct link setup procedure

[TS 24.334, clause 10.4.5.1]

Security association for a direct link between two ProSe-Enabled UEs is established during the direct link setup procedure or direct link rekeying procedure with the exchange of message contents related to direct security mode establishment. After successful completion of the direct security mode control procedure, the selected security algorithms and keys are used to integrity protect and cipher all PC5 Signalling messages exchanged between the UEs; and are also used to cipher all data plane traffic exchanged between the UEs.

[TS 24.334, clause 10.4.5.3]

Upon receipt of the DIRECT_SECURITY_MODE_COMMAND message, the peer UE shall check whether the security mode command can be accepted or not. This is done by performing the integrity check of the message and by checking that the received UE security capabilities have not been altered compared to the latest values that the peer UE sent to the commanding UE in the DIRECT_COMMUNICATION_REQUEST or DIRECT_REKEYING_REQUEST message.

In order to check the integrity, the peer UE needs to create the security context as described in 3GPP TS 33.303 [6]. If the MSB of KD ID were included in the DIRECT_SECURITY_MODE_COMMAND message then the peer UE shall take one of the following two actions:

– If performing isolated one-to-one ProSe direct communication, the peer UE shall first check the signature included in the SIGN IE of the DIRECT SECURITY MODE COMMAND and then obtain the new KD from the Encrypted Payload IE; or

If MSB of KD ID was not included in the DIRECT_SECURITY_MODE_COMMAND, then the peer UE shall use either the existing KD indicated by the KD ID included in the DIRECT_COMMUNICATION_REQUEST or the currently used one.

The peer UE shall then derive the KD-sess based on the KD-sess ID in the same way as the commanding UE. Finally the peer UE shall use the algorithms indicated in the Chosen Algorithms IE.

If the DIRECT_SECURITY_MODE_COMMAND message can be accepted, the peer UE shall send a DIRECT_SECURITY_MODE_COMPLETE message ciphered and integrity protected with the new security context. The DIRECT_SECURITY_MODE_COMPLETE message shall include the 16 least significant bits of the KD ID if the initiating UE included the MSB of KD ID in the DIRECT_SECURITY_MODE_COMMAND message.

From this time onward the peer UE shall protect all signalling messages and user data with the new security context.

[TS 24.334, clause 10.4.2.4]

Upon receipt of the DIRECT_COMMUNICATION_ACCEPT message, the initiating UE shall stop timer T4100. From this time onward the initiating UE shall use the established link for all one-to-one communication (including additional PC5 Signalling messages) to the target UE.

[TS 24.334, clause 10.4.6.1]

The IP address configuration procedure is performed after the establishment of the direct link to enable IP connectivity between the UEs at each end of the direct link.

[TS 24.334, clause 10.4.6.2]

When neither of the two UEs on the direct link acts as a ProSe UE-to-network relay, the two UEs shall select the IP version (IPv4 or IPv6) to be used based on the following rules:

– if the target UE in the direct link setup procedure has indicated "address allocation not supported" in the IP Address Config IE and the initiating UE has indicated "DHCPv4 Server", "IPv6 Router" or "DHCPv4 Server & IPv6 Router" in the IP Address Config IE, then the target UE shall:

a) initiate the IPv4 address configuration with DHCPv4 procedure acting as a DHCP client, if the initiating UE has indicated "DHCPv4 Server";

b) initiate the IPv6 address configuration with IPv6 stateless address auto-configuration acting as an IPv6 host if the initiating UE has indicated "IPv6 Router"; and

c) choose either IP version and initiate the corresponding IP address configuration procedure as a client or host, if the other UE has indicated "DHCPv4 Server & IPv6 Router"; and

– if both of the UEs has indicated "address allocation not supported" in the IP Address Config IE, then the UEs shall use IPv6 link-local addresses formed locally as defined in RFC 4862 [15].

[TS 24.334, clause 10.4.3.2]

The requesting UE manages a keepalive timer T4102 and a keepalive counter for this procedure. The keepalive timer T4102 is used to trigger the periodic initiation of the procedure. It is started or restarted whenever the UE receives a PC5 Signalling message or PC5 user plane data from the peer UE over this link. The keepalive counter is set to an initial value of zero after link establishment.

The requesting UE may initiate the procedure if:

– a request from upper layers to check the viability of the direct link is received; or

– the keepalive timer T4102 for this link expires.

The requesting UE initiates the procedure by stopping timer T4102 if it is still running and generating a DIRECT_COMMUNICATION_KEEPALIVE message with a Keepalive Counter IE that contains the value of the keepalive counter for this link. Optionally, the initiating UE may include a Maximum Inactivity Period IE to indicate the maximum inactivity period of the requesting UE over this direct link. When a remote UE sends DIRECT_COMMUNICATION_KEEPALIVE message to the ProSe UE-to-network relay UE, this IE shall be included.

After the DIRECT_COMMUNICATION_KEEPALIVE message is generated, the requesting UE shall pass this message to the lower layers for transmission along with the requesting UE’s Layer 2 ID (for unicast communication) and the peer UE’s Layer 2 ID (for unicast communication), and start retransmission timer T4101.

Figure 10.4.3.2.1: Direct link keepalive procedure

[TS 24.334, clause 10.4.3.4]

Upon receiving a DIRECT_COMMUNICATION_KEEPALIVE_ACK message, the requesting UE shall stop retransmission timer T4101, start keepalive timer T4102 and increment the keepalive counter for this link.

[TS 24.334, clause 10.4.4.2]

The releasing UE shall initiate the procedure if:

– a request from upper layers to release a direct link with the peer UE which uses a known Layer 2 ID (for unicast communication) is received and there is an existing link between those two UEs; or

The releasing UE initiates the direct link release procedure by generating a DIRECT_COMMUNICATION_RELEASE message with a Release Reason IE indicating one of the following cause values:

#1 Direct Communication to peer UE no longer needed;

After the DIRECT_COMMUNICATION_RELEASE message is generated, the releasing UE shall pass this message to the lower layers for transmission along with the releasing UE’s Layer 2 ID (for unicast communication) and the peer UE’s Layer 2 ID (for unicast communication). The releasing UE shall release the direct link locally if the release reason is #3 "Direct connection is not available any more". Otherwise, the releasing UE shall start timer T4103.

Figure 10.4.4.2.1: Direct link release procedure

[TS 24.334, clause 10.4.4.4]

Upon receipt of the DIRECT_COMMUNICATION_RELEASE_ACCEPT message, the releasing UE shall stop timer T4103. From this time onward the releasing UE shall no longer send or receive any messages via this link.

19.1.9.3 Test description

19.1.9.3.1 Pre-test conditions

System Simulator:

SS-UE

– SS-UE1.

– As defined in TS 36.508 [18], configured for and operating as ProSe Direct Communication transmitting and receiving device.

GNSS simulator (optional).

NOTE: For operation in off-network environment, it shall be ensured that after the UE is powered up it considers the geographical area as being one of the geographical areas set in the USIM for operation when UE is "not served by E-UTRAN". This can be done by usage of a GNSS simulator, or some suitable MMI action.

UE:

– ProSe related configuration

– The UE is authorised to perform ProSe Direct Communication; The UE is equipped with a USIM containing values shown in Table 19.1.9.3.1-1, and, relevant to each of the supported services values as specified in TS 36.508 [18], section 4.9.3.1 (e.g. Direct Communication Radio Parameters and geographical area when UE is "not served by E-UTRAN", ProSe Layer-2 Group ID, etc.).

Table 19.1.9.3.1-1: USIM Configuration

USIM field

Value

EFUST

Service n°101 (ProSe) supported.

EFPST

Service n°3 (ProSe Direct Communication radio parameters) supported.

Service n°6 (ProSe policy parameters) supported.

Service n°7 (ProSe group counter) supported.

EFAD

b3=1: the ME is authorized to use the parameters stored in the USIM or in the ME for ProSe services for Public Safety usage.

EFPROSE_RADIO_COM

b2=1 indicates that the UE is authorised to perform one-to-one ProSe direct communication when not served by E-UTRAN.

– For operation in off-network environment, it shall be ensured that after the UE is powered up it considers the geographical area as being one of the geographical areas set in the USIM for operation when UE is "not served by E-UTRAN". If this is not done by using n GNSS simulator then the UE needs to be preconfigured via a suitable MMI action.

Preamble:

– The UE is in state Switched OFF (state 1) according to TS 36.508 [18].

19.1.9.3.2 Test procedure sequence

Table 19.1.9.3.2-1: Main behaviour

St

Procedure

Message Sequence

TP

Verdict

U – S

Message

1

Power up the UE.

2

Wait for 15 sec to allow the UE to establish that it is out of coverage and initiate scanning the frequency pre-set for ProSe communication for any activities.

3

Make the UE initiate one-to-one ProSe direct communication with the remote UE preconfigured in the USIM (ProSe Layer-2 Group ID).

4

Check: Does the UE send a DIRECT_COMMUNICATION_REQUEST message, IP Address Config IE set to "address allocation not supported"?

–>

DIRECT_COMMUNICATION_REQUEST

1

P

5

SS-UE1 sends a DIRECT_SECURITY_MODE_COMMAND message.

<–

DIRECT_SECURITY_MODE_COMMAND

6

Check: Does the UE send a DIRECT_SECURITY_MODE_COMPLETE message ciphered and integrity protected with the new security context?

–>

DIRECT_SECURITY_MODE_COMPLETE

2

P

7

SS-UE1 sends a DIRECT_COMMUNICATION_ACCEPT message.

<–

DIRECT_COMMUNICATION_ACCEPT

EXCEPTION: After the communication is established, an IP address configuration procedure is performed depending on what the UE has indicated in the IP Address Config IE (if it is not "address allocation not supported") in the DIRECT_COMMUNICATION_REQUEST message, and, the SS-UE1 itself indicating "address allocation not supported" in the DIRECT_COMMUNICATION_ACCEPT message.

8

Start timer T4102=px_ProSe_T4102_keepalive_value.

NOTE: The SS shall not send any direct communication data (neither PC5 Signalling message nor PC5 user plane data) until the event in step 9 takes place to ensure that the UE does not re-start timer T4102.

9

Timer T4102 expires

10

Check: Does the UE send a DIRECT_COMMUNICATION_KEEPALIVE message with a Keepalive Counter IE that contains the value of the keepalive counter for this link=0?

–>

DIRECT_COMMUNICATION_KEEPALIVE

3

P

11

SS-UE1 sends a DIRECT_COMMUNICATION_KEEPALIVE_ACK message.

<–

DIRECT_COMMUNICATION_KEEPALIVE_ACK

12

Make the UE release the one-to-one ProSe direct communication with the remote UE.

13

Check: Does the UE send a DIRECT_COMMUNICATION_RELEASE message with a Release Reason IE indicating ‘Direct Communication to peer UE no longer needed’?

–>

DIRECT_COMMUNICATION_RELEASE

4

P

14

SS-UE1 sends a DIRECT_COMMUNICATION_RELEASE_ACCEPT message.

<–

DIRECT_COMMUNICATION_RELEASE_ACCEPT

19.1.9.3.3 Specific message contents

Table 19.1.9.3.3-1: DIRECT_COMMUNICATION_ACCEPT (step 7 Table 19.1.9.3.2-1)

Derivation path: 36.508 [18], Table 4.7F.3-0A.

Information Element

Value/remark

Comment

Condition

IP Address Config

‘0011’B

address allocation not supported

Link Local IPv6 Address

If the UE indicated ‘address allocation not supported’ in the IP Address Config IE in the DIRECT_COMMUNICATION_REQUEST message then a link-local IPv6 address formed locally

128-bit IPv6 address

Table 19.1.9.3.3-2: DIRECT_SECURITY_MODE_COMMAND (step 5, Table 19.1.9.3.2-1)

Derivation path: 36.508 [18], Table 4.7F.3-0G.

Information Element

Value/remark

Comment

Condition

UE Security Capabilities

Set to the UE Security Capabilities received in the DIRECT_COMMUNICATION_REQUEST message

Chosen Algorithms

One of the non-null algorithms provided in UE Security Capabilities (i.e. different to EIA0 (null integrity protection algorithm)/EEA0 (null ciphering algorithm))

MSB of KD ID

The MSB of KD ID of the new KD

KD Freshness

Not included

GPI

Not included

User Info {

Type of User Info

IMSI

Odd/even indication

Reflecting the number of digits in the IMSI

Identity digits

A value different to the IMSI of the UE

}

Table 19.1.9.3.3-3: DIRECT_SECURITY_MODE_COMPLETE (step 6, Table 19.1.9.3.2-1)

Derivation path: 36.508 [18], Table 4.7F.3-0H.

Information Element

Value/remark

Comment

Condition

LSB of KD ID

Not included

Table 19.1.9.3.3-4: DIRECT_COMMUNICATION_KEEPALIVE (step 10, Table 19.1.9.3.2-1)

Derivation path: 36.508 [18], Table 4.7F.3-0B.

Information Element

Value/remark

Comment

Condition

Keepalive Counter

0

Maximum Inactivity Period

Any allowed value

Table 19.1.9.3.3-5: DIRECT_COMMUNICATION_RELEASE (step 13, Table 19.1.9.3.2-1)

Derivation path: 36.508 [18], Table 4.7F.3-0D.

Information Element

Value/remark

Comment

Condition

Release Reason

‘0001’B

Direct communication to the peer UE no longer needed