19.1.10 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 / MT

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

19.1.10.1 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 receives a request for the establishment of one-to-one ProSe direct communication from a remote UE }

then { UE request the establishment of Security association for the requested for a direct link by sending DIRECT SECURITY MODE COMMAND message unciphered and integrity protected with the new security context }

}

(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 requested establishment of Security association for the requested for a direct link }

ensure that {

when { UE receives a DIRECT_SECURITY_MODE_COMPLETE message from the remote UE }

then { UE sends a DIRECT_COMMUNICATION_ACCEPT message and considers the establishment of one-to-one ProSe direct communication completed }

}

(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 receives a DIRECT_COMMUNICATION_KEEPALIVE message including a Maximum Inactivity Period IE as part of a Direct link keepalive procedure }

then { UE responds with a DIRECT_COMMUNICATION_KEEPALIVE_ACK message }

}

(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, and, having set timer T4108 as result of a Direct link keepalive procedure }

ensure that {

when { UE gets involved in a communication with the remote UE }

then { UE restarts timer T4108, and, when timer T4108 expires without any communication the UE either initiate its own keepalive procedure to check the link or releases the secure direct link with the release reason #3 "Direct connection is not available any more" }

}

(5)

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 }

}

19.1.10.2 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, 10.4.2.3, 10.4.3.2, 10.4.3.3, 10.4.3.4, 10.4.3.5.2, 10.4.4.2, 10.4.4.4, 10.4.5.1, 10.4.5.2, 10.4.5.4, 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 10.4.2.3]

Upon receiving a DIRECT_COMMUNICATION_REQUEST message, the target UE shall store the pair of Layer 2 IDs (for unicast communication) used in the transport of this message provided by the lower layers and associate them with a direct link context.

The target UE then checks the User Info IE included in the DIRECT_COMMUNICATION_REQUEST message and determines whether this request can be accepted or not. Then, the target UE examines the IP Address Config IE to see whether there is at least one common IP address configuration option supported by both the initiating UE and the target UE. If the above check is successful, the target UE shall invoke the direct security mode control procedure as specified in subclause 10.4.5 to establish a security association between the target UE and the initiating UE. Only after the completion of link authentication procedure and a successful establishment of the security association, the target UE shall send a DIRECT_COMMUNICATION_ACCEPT message to the initiating UE.

The target UE shall include an IP Address Config IE set to one of the following values:

– "DHCPv4 Server" if only IPv4 address allocation mechanism is supported by the target UE and the target UE is able to act as DHCP server;

– "IPv6 Router" if only IPv6 address allocation mechanism is supported by the target UE and the target UE is able to act as IPv6 Router;

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

– "address allocation not supported" if neither IPv4 nor IPv6 address allocation is supported by the target UE.

If the IP Address Config IE is set to "address allocation not supported" and the received DIRECT_COMMUNICATION_REQUEST message included a Link Local IPv6 Address IE, the target UE shall include a Link Local IPv6 Address IE set to the link-local IPv6 address formed locally.

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

[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 10.4.5.2]

A commanding UE may initiate the direct security mode control procedure in response to receiving a DIRECT_COMMUNICATION_REQUEST or a DIRECT_REKEYING_REQUEST message.

To initiate this procedure, the commanding UE shall either identify an existing KD based on the KD ID included in the DIRECT_COMMUNICATION_REQUEST or DIRECT_REKEYING_REQUEST message, or derive a new KD if it either does not share a known KD with the peer UE or wishes to derive a new KD, as specified in 3GPP TS 33.303 [6]. In the latter case, the commanding UE shall generate the MSB of KD ID to ensure that the resultant KD ID will be unique in the commanding UE. Then, it shall generate a LSB of KD-sess ID such that the KD-sess ID formed by combining with the MSB of KD-sess ID (received in the DIRECT_COMMUNICATION_REQUEST or DIRECT_REKEYING_REQUEST that triggered the direct security mode procedure) is unique within the commanding UE.

Following this, the commanding UE shall generate a 128-bit Nonce_2 value. With KD, Nonce_2 and Nonce_1 received in the DIRECT_COMMUNICATION_REQUEST or DIRECT_REKEYING_REQUEST message, the commanding UE shall derive KD- sess as specified in 3GPP TS 33.303 [6].

Then, the UE shall construct a DIRECT_SECURITY_MODE_COMMAND message with the following:

– Nonce_2 IE set to Nonce_2;

– the LSB of KD-sess ID IE set to indicate the least significant 8-bits of KD-sess ID;

– the UE Security Capabilities IE set to the UE Security Capabilities received in the DIRECT_COMMUNICATION_REQUEST message or DIRECT_REKEYING_REQUEST; and

– the Chosen Algorithms IE set to the algorithms to be used for ciphering and integrity protection.

If the DIRECT_SECURITY_MODE_COMMAND message is used for isolated one-to-one ProSe direct communication, then the commanding UE shall include the following additional parameters in the DIRECT_SECURITY_MODE_COMMAND message in order to create a new KD:

– the User Info IE set to the User Info received from upper layers;

– the MSB of KD ID IE set to the MSB of KD ID of the new KD; and

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

– User Info;

– Nonce_1; and

– the Encrypted Payload IE set to the SAKKE payload generated as specified in 3GPP TS 33.303 [6].

The commanding UE shall select the integrity protection and ciphering algorithms that will be used and include these choices in the Chosen algorithms IE in the DIRECT SECURITY MODE COMMAND message. The UE shall include the received UE security capabilities that was present in the DIRECT_COMMUNICATION_REQUEST or a DIRECT_REKEYING_REQUEST message that triggered the DIRECT SECURITY MODE COMMAND message.

The commanding UE shall send the DIRECT SECURITY MODE COMMAND message unciphered, but shall integrity protect the message with the new security context. After sending the DIRECT_SECURITY_MODE_COMMAND message, the commanding UE shall start timer T4111 (see figure 10.4.5.2.1).

Figure 10.4.5.2.1: Direct Security mode control procedure

[TS 24.334, clause 10.4.5.4]

Upon receipt of the DIRECT_SECURITY_MODE_COMPLETE message, the commanding UE shall stop timer T4111. If an LSB of KD ID IE was included in the message, the commanding UE uses this and the MSB of KD ID it previously sent to form the KD ID of the new KD. From this time onwards the commanding UE shall protect all signalling messages and user data with the new security context.

[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 (see subclause 10.4.2) has indicated "DHCPv4 Server" in the IP Address Config IE, then the initiating UE in the direct link setup procedure (see subclause 10.4.2) shall initiate the IPv4 address configuration with DHCPv4 procedure acting as a DHCP client;

– if the target UE in the direct link setup procedure has indicated "IPv6 Router" in the IP Address Config IE , then the initiating UE in the direct link setup procedure shall initiate the IPv6 address configuration with IPv6 stateless address auto-configuration acting as an IPv6 host;

– if the target UE in the direct link setup procedure has indicated "DHCPv4 Server & IPv6 Router" in the IP Address Config IE, then the initiating UE in the direct link setup procedure shall choose either IP version and initiate the address configuration procedure, acting as a client or host;

– 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 10.4.3.3]

Upon receiving a DIRECT_COMMUNICATION_KEEPALIVE message, the peer UE shall respond with a DIRECT_COMMUNICATION_KEEPALIVE_ACK message including the Keepalive Counter IE set to the same value as that received in the DIRECT_COMMUNICATION_KEEPALIVE message.

If a Maximum Inactivity Period IE is included in the DIRECT_COMMUNICATION_KEEPALIVE message, the peer UE shall stop the inactivity timer T4108 if it is running, and restart the timer T4108 with the value provided in the IE, If any communication activity occurs in this direct link before the timer T4108 expires, the UE shall stop the timer T4108 and reset it with the initial value.

[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 10.4.3.5.2]

If the inactivity timer T4108 expires, if the peer UE is a ProSe UE-to-network relay UE, it shall initiate the direct link release procedure specified in 10.4.4 with the release reason #3 "Direct connection is not available any more". Otherwise, the peer UE may:

A) initiate is own keepalive procedure to check the link; or

B) initiate the direct link release procedure specified in 10.4.4 with the release reason #3 "Direct connection is not available any more".

Whether the UE chooses A or B is left to UE implementation.

[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.

19.1.10.3 Test description

19.1.10.3.1 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 an 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 19.1.10.3.1-1, 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 19.1.10.3.1-1: 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].

19.1.10.3.2 Test procedure sequence

Table 19.1.10.3.2-1: 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

SS-UE1 sends a DIRECT_COMMUNICATION_REQUEST message, IP Address Config IE set to "address allocation not supported".

<–

DIRECT_COMMUNICATION_REQUEST

4

Check: Does the UE send a DIRECT_SECURITY_MODE_COMMAND message unciphered but integrity protected with the new security context?

–>

DIRECT_SECURITY_MODE_COMMAND

1

P

5

SS-UE1 sends a DIRECT_SECURITY_MODE_COMPLETE message ciphered and integrity protected with the new security context.

<–

DIRECT_SECURITY_MODE_COMPLETE

6

Check: Does the UE send a DIRECT_COMMUNICATION_ACCEPT message?

–>

DIRECT_COMMUNICATION_ACCEPT

2

P

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.

7

SS-UE1 sends a DIRECT_COMMUNICATION_KEEPALIVE message with a Keepalive Counter IE that contains the value of the keepalive counter for this link=0, and a Maximum Inactivity Period IE.

<–

DIRECT_COMMUNICATION_KEEPALIVE

8

Does the UE send a DIRECT_COMMUNICATION_KEEPALIVE_ACK message including the Keepalive Counter IE set to the same value as that received in the DIRECT_COMMUNICATION_KEEPALIVE message?

–>

DIRECT_COMMUNICATION_KEEPALIVE_ACK

3

P

9

Wait 1/2 T4108 sec (=the value of the Maximum Inactivity Period IE sent in the DIRECT_COMMUNICATION_KEEPALIVE message).

10

SS-UE1 sends a DIRECT_COMMUNICATION_KEEPALIVE message with a Keepalive Counter IE that contains the value of the keepalive counter for this link=0, and not including the Maximum Inactivity Period IE.

NOTE: Upon receiving the message the UE is expected to restart timer T4108.

<–

DIRECT_COMMUNICATION_KEEPALIVE

11

Does the UE send a DIRECT_COMMUNICATION_KEEPALIVE_ACK message including the Keepalive Counter IE set to the same value as that received in the DIRECT_COMMUNICATION_KEEPALIVE message?

–>

DIRECT_COMMUNICATION_KEEPALIVE_ACK

3

P

12

Start timer T4108=the value set in Maximum Inactivity Period IE send in the DIRECT_COMMUNICATION_KEEPALIVE message in step 6.

NOTE: The SS shall not sent any direct communication data (neither PC5 Signalling message nor PC5 user plane data) until the event in step 14 takes place to ensure that the UE does not re-start timer T4108.

13

Timer T4108 expires.

EXCEPTION: Steps 14a1 to 14b2 describe behaviour that depends on UE implementation; the "lower case letter" identifies a step sequence that depends on how the UE reacts upon timer T4108 expiry.

14a1

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

4

P

14a2

SS-UE1 sends a DIRECT_COMMUNICATION_KEEPALIVE_ACK message.

<–

DIRECT_COMMUNICATION_KEEPALIVE_ACK

14a3

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

14a4

Check: Does the UE send a DIRECT_COMMUNICATION_RELEASE message with a Release Reason IE indicating ‘Direct connection is not available any more’?

–>

DIRECT_COMMUNICATION_RELEASE

5

P

14a5

SS-UE1 sends a DIRECT_COMMUNICATION_RELEASE_ACCEPT message

<–

DIRECT_COMMUNICATION_RELEASE_ACCEPT

14b1

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

14b2

SS-UE1 sends a DIRECT_COMMUNICATION_RELEASE_ACCEPT message.

<–

DIRECT_COMMUNICATION_RELEASE_ACCEPT

19.1.10.3.3 Specific message contents

Table 19.1.10.3.3-1: DIRECT_COMMUNICATION_REQUEST (step 3, Table 19.1.10.3.2-1)

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

Information Element

Value/remark

Comment

Condition

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

}

IP Address Config

‘0011’B

address allocation not supported

Maximum Inactivity Period

‘100 0000’B

64 sec, randomly chosen

Nonce_1

UE Security Capabilities

01111111 01111111

All but null algorithms supported

MSB of KD-sess ID

the 8 most significant bits of the KD-sess ID

KD ID

Not present

Signature

the ECCSI signature calculated with the User Info and Nonce_1 as specified in 3GPP TS 33.303 [51]

Link Local IPv6 Address

a link-local IPv6 address formed locally

Table 19.1.10.3.3-2: DIRECT_SECURITY_MODE_COMMAND (step 4 Table 19.1.10.3.2-1)

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

Information Element

Value/remark

Comment

Condition

MSB of KD ID

Any allowed value

KD Freshness

Not included

GPI

Not included

Signature

The ECCSI signature calculated with the User Info and Nonce_1 as specified in 3GPP TS 33.303 [51]

Encrypted Payload

The SAKKE payload generated as specified in 3GPP TS 33.303 [51].

Table 19.1.10.3.3-3: DIRECT_SECURITY_MODE_COMPLETE (step 5, Table 19.1.10.3.2-1)

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

Information Element

Value/remark

Comment

Condition

LSB of KD ID

16 least significant bits of KD ID

Table 19.1.10.3.3-4: DIRECT_COMMUNICATION_KEEPALIVE (step 7, Table 19.1.10.3.2-1)

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

Information Element

Value/remark

Comment

Condition

Keepalive Counter

0

Maximum Inactivity Period

‘100 0000’B

64 sec, randomly chosen

Table 19.1.10.3.3-5: DIRECT_COMMUNICATION_KEEPALIVE (step 10, Table 19.1.10.3.2-1)

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

Information Element

Value/remark

Comment

Condition

Keepalive Counter

1

Maximum Inactivity Period

Not present

Table 19.1.10.3.3-6: DIRECT_COMMUNICATION_RELEASE (step 14a4, Table 19.1.10.3.2-1)

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

Information Element

Value/remark

Comment

Condition

Release Reason

‘0011’B

Direct connection is not available any more

Table 19.1.10.3.3-7: DIRECT_COMMUNICATION_RELEASE (step 14b1, Table 19.1.10.3.2-1)

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