5 Procedure Description

29.3883GPPRelease 17Stage 3TSV2X Control Function to Home Subscriber Server (HSS) aspects (V4)

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

5.1 Introduction

This clause describes the Diameter-based V4 interface related procedures and information elements exchanged between the V2X Control Function and the HSS.

In the tables that describe the Information Elements transported by each Diameter command, each Information Element is marked as (M) Mandatory, (C) Conditional or (O) Optional in the "Cat." column. For the correct handling of the Information Element according to the category type, see the description detailed in clause 6 of the 3GPP TS 29.228 [9].

5.2 V2X Subscriber Information Retrieval

5.2.1 General

This procedure shall be used between the V2X Control Function and the HSS for authorization of the UE for V2X services. The procedure shall be invoked by the V2X Control Function and is used:

– to request V2X related subscription data.

This procedure is mapped to the commands ProSe-Subscriber-Information-Request/Answer (PIR/PIA) in the Diameter application specified in clause 6. Table 5.2.1-1 and table 5.2.1-2 detail the involved information elements.

Table 5.2.1-1: V2X Subscriber Information Retrieval Request

Information Element Name

Mapping to Diameter AVP

Cat.

Description

IMSI

User-Name (See IETF RFC 6733 [3])

This information element shall contain the user IMSI, formatted according to 3GPP TS 23.003 [8], clause 2.2.

Supported Features

(See 3GPP TS 29.229 [6])

Supported-Features

If present, this information element shall contain the list of features supported by the origin host.

Table 5.2.1-2: V2X Subscriber Information Retrieval Answer

Information Element Name	Mapping to Diameter AVP	Cat.	Description
Result (See 6)	Result-Code / Experimental-Result	M	This IE shall contain the result of the operation. The Result-Code AVP shall be used to indicate success / errors as defined in the Diameter base protocol. The Experimental-Result AVP shall be used for V4 errors. This is a grouped AVP which shall contain the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP. The following errors are applicable: – User Unknown – Unknown V2X Subscription – V2X Not Allowed
V2X Subscription Data (See 6.3.2)	V2X-Subscription-Data	C	This information element shall contain the V2X Subscription Data that gives the user permission to use V2X.
MSISDN (See 3GPP TS 29.329 [11])	MSISDN	C	This information element shall contain the user MSISDN, formatted according to 3GPP TS 29.329 [11]. It shall be present if available.
Visited PLMN Id (See 3GPP TS 29.272 [10])	Visited-PLMN-Id	C	This IE shall contain the MCC and the MNC of the PLMN where the UE is registered, see 3GPP TS 23.003 [8]. It shall be present if the UE is roaming in a PLMN different from the Home PLMN.
Supported Features (See 3GPP TS 29.229 [6])	Supported-Features	O	If present, this information element shall contain the list of features supported by the origin host.
Reset-IDs (See 3GPP TS 29.272 [10])	Reset-ID	O	The Reset-ID uniquely identifies a fallible resource in the HSS’s realm on which the user (IMSI) depends. In the event of a restart of the fallible resource a Reset message containing the Reset-ID will exactly identify the impacted subscribers.

5.2.2 Detailed Behaviour of the V2X Control Function

The V2X Control Function shall make use of this procedure to request V2X related subscription data.

If the V2X Control Function retrieved the V2X related subscription data, the V2X Control Function shall perform the authorisation for V2X as described in the 3GPP TS 23.285 [2].

5.2.3 Detailed Behaviour of the HSS

When receiving a V2X Subscriber Information Retrieval Request the HSS shall check if the IMSI for whom data is requested exists in the HSS. If not, an Experimental-Result of DIAMETER_ERROR_USER_UNKNOWN shall be returned.

If the IMSI exists but there is not any V2X subscription data for the IMSI, the HSS shall return an Experimental-Result of DIAMETER_ERROR_UNKNOWN_V2X_SUBSCRIPTION.

If the UE is not allowed to use V2X in the visited PLMN, the HSS shall return an Experimental-Result of DIAMETER_ERROR_V2X_NOT_ALLOWED. Otherwise, the HSS shall return a Result-Code of DIAMETER_SUCCESS and shall store V2X Control Function identity (the V2X Control Function identity is received within the Origin-Host AVP) and download the V2X subscription data to the V2X Control Function. The HSS shall provide the Visited PLMN ID of where the UE is registered if the UE is roaming in a PLMN different from the Home PLMN.

5.3 Update V2X Subscriber Data

5.3.1 General

The Update V2X Subscriber Data procedure shall be used between the V2X Control Function and the HSS to update the subscriber related data downloaded by means of the V2X Subscriber Information Retrieval operation (see clause 5.2) and stored in the V2X Control Function.

It shall be used to update subscriber related data in the V2X Control Function due to administrative changes of the user data in the HSS, i.e. if the user was given a subscription and the subscription has changed. It shall be used at least to perform the following:

– update of all of V2X subscription data of the subscriber,

– update of a subset of the V2X subscription data of the subscriber,

– deletion of the V2X subscription data of the subscriber.

The procedure will also be triggered when the VPLMN has changed.

This procedure is mapped to the commands Update-ProSe-Subscriber-Data-Request/Answer (UPR/UPA) in the Diameter application specified in clause 6.

Table 5.3.1-1 specifies the involved information elements for the request.

Table 5.3.1-2 specifies the involved information elements for the answer.

Table 5.3.1-1: Update V2X Subscriber Data Request

Information element name	Mapping to Diameter AVP	Cat.	Description
IMSI	User-Name (See IETF RFC 6733 [3])	M	This information element shall contain the user IMSI, formatted according to 3GPP TS 23.003 [8], clause 2.2.
Supported Features (See 3GPP TS 29.229 [6])	Supported-Features	O	If present, this information element shall contain the list of features supported by the origin host.
V2X Subscription Data (See 6.3.2)	V2X-Subscription-Data	C	This information element shall contain the V2X Subscription Data that gives the user permission to use V2X service.
Visited PLMN Id (See 3GPP TS 29.272 [10])	Visited-PLMN-Id	C	This IE shall contain the MCC and the MNC of the PLMN where the UE is registered, see 3GPP TS 23.003 [8]. It shall be present if the UE is roaming in a PLMN different from the Home PLMN.
V2X Update Flags (See 6.3.4)	V2X-Update-Flags	M	This Information Element shall contain a bit mask. See clause 6.3.6 for the meaning of the bits.
Reset-IDs (See 3GPP TS 29.272 [10])	Reset-ID	O	The Reset-ID uniquely identifies a fallible resource in the HSS’s realm on which the user (IMSI) depends. In the event of a restart of the fallible resource a Reset message containing the Reset-ID will exactly identify the impacted subscribers.

Table 5.3.1-2: Update V2X Subscriber Data Answer

Information element name

Mapping to Diameter AVP

Cat.

Description

Supported Features

(See 3GPP TS 29.229 [6])

Supported-Features

If present, this information element shall contain the list of features supported by the origin host.

Result

(See 6.4)

Result-Code / Experimental-Result

This IE shall contain the result of the operation.

The Result-Code AVP shall be used to indicate success / errors as defined in the Diameter base protocol.

The Experimental-Result AVP shall be used for V4 errors. This is a grouped AVP which shall contain the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP.

The following errors are applicable in this case:

– User Unknown

– Unknown V2X Subscription

5.3.2 Detailed behaviour of the V2X Control Function

When receiving an Update V2X Subscriber Data request, the V2X Control Function shall check whether the IMSI is known.

If it is not known, a result code of DIAMETER_ERROR_USER_UNKNOWN shall be returned.

If it is known, the V2X Control Function shall update the corresponding data according to the indication as sent in the request, and acknowledge the Update V2X Subscriber Data message by returning an Update V2X Subscriber Data Answer. If the V2X-Update-Flags indicates that the V2X subscription data is to be deleted, the V2X Control Function shall delete the associated V2X UE context if it has been stored before.

If the update of the subscription data succeeds in the V2X Control Function, the Result-Code shall be set to DIAMETER_SUCCESS.

If the V2X Control Function cannot fulfil the received request for other reasons, e.g. due to a database error, it shall set the Result-Code to DIAMETER_UNABLE_TO_COMPLY. In this case, the V2X Control Function shall mark the subscription record "Subscriber data to be restored in the HSS".

5.3.3 Detailed behaviour of the HSS

The HSS shall make use of this procedure to update the relevant subscriber related data in the V2X Control Function to replace a specific part of the user data stored in the V2X Control Function with the data sent.

If the V2X related subscription data is updated or revoked, the HSS sends the updated V2X subscription data to the V2X Control Function. The HSS shall include the V2X-Update-Flags to indicate which part of the data is updated. If all of the V2X subscription data is to be removed, the HSS shall set the "Removal of all V2X Subscription Data" bit of the V2X-Update-Flags, and the HSS shall delete the V2X Control Function Identity if it is stored for this subscriber.

5.4 Notification Procedure

5.4.1 General

This procedure shall be used between the V2X Control Function and the HSS when the HSS needs to be notified about:

– revocation of authorization for V2X service on one PLMN.

– removal of the subscription data from the V2X Control Function either by an MMI interaction or automatically.

This procedure is mapped to the commands ProSe-Notify-Request/Answer (PNR/PNA) in the Diameter application specified in clause 6. Table 5.4.1-1 and table 5.4.1-2 detail the involved information elements.

Table 5.4.1-1: V2X Notify Request

Information Element Name	Mapping to Diameter AVP	Cat.	Description
IMSI	User-Name (See IETF RFC 6733 [3])	C	This information element shall contain the user IMSI, formatted according to 3GPP TS 23.003 [8], clause 2.2. It shall be present if the revocation is for a specific UE.
Supported Features (See 3GPP TS 29.229 [6])	Supported-Features	O	If present, this information element shall contain the list of features supported by the origin host.
PLMN ID (see 3GPP TS 29.272 [10])	Visited-PLMN-Id	C	This information element shall contain the MCC and the MNC of the PLMN where the UE’s authorization for V2X service is revoked, see 3GPP TS 23.285 [2]. It shall be present if the V2X Control Function revokes the authorization for V2X service in a specific PLMN.
V2X Notify Flags (see 6.3.5)	V2X-Notify-Flags	C	This Information Element shall contain a bit mask. See 6.3.7 for the meaning of the bits.

Table 5.4.1-2: V2X Notify Answer

Information Element Name

Mapping to Diameter AVP

Cat.

Description

Result
(See 6)

Result-Code / Experimental-Result

This IE shall contain the result of the operation.

The Result-Code AVP shall be used to indicate success / errors as defined in the Diameter base protocol.

The Experimental-Result AVP shall be used for V4 errors. This is a grouped AVP which shall contain the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP.

The following errors are applicable:

– User Unknown

– Unknown V2X Subscription

Supported Features

(See 3GPP TS 29.229 [6])

Supported-Features

If present, this information element shall contain the list of features supported by the origin host.

5.4.2 Detailed Behaviour of the V2X Control Function

The V2X Control Function shall make use of this procedure to revoke authorization for V2X service.

The V2X Control Function shall make use of this procedure to inform the HSS when the subscription data is deleted from the V2X Function database due to MMI interaction or automatically.

The V2X Control Function shall send the updated V2X Permission and the PLMN ID for which the V2X Permission is to be updated. If the revocation is for a single UE in the indicated PLMN, the V2X Function shall include IMSI in the request.

5.4.3 Detailed Behaviour of the HSS

When receiving a V2X Notify Request the HSS shall check if the IMSI, if present in the message, exists in the HSS. If not, an Experimental-Result of DIAMETER_ERROR_USER_UNKNOWN shall be returned.

If the IMSI exists but there is not any V2X subscription data for the IMSI and the PLMN ID as indicated by the Visited-PLMN-Id AVP in the request, the HSS shall return an Experimental-Result of DIAMETER_ERROR_UNKNOWN_V2X_SUBSCRIPTION.

If the V2X-Notify-Flags indicates revocation of authorization for V2X service, and

– if the IMSI exists and there is V2X subscription data for the IMSI and the PLMN ID as indicated by the Visited-PLMN-Id AVP in the request, the HSS shall revoke V2X service as indicated by the VNR Flags received in the request on that PLMN for the user and update the V2X Subscription data accordingly. The HSS shall set the result code to DIAMETER_SUCCESS.

– if IMSI is not present in the message, the HSS shall check if there are any users subscribed to V2X subscription for the PLMN as indicated by the Visited-PLMN-Id AVP in the request, and if yes, revoke V2X service as indicated by the VNR Flags received in the request on that PLMN for all the impacted users and update their V2X Subscription data accordingly. The HSS shall set the result code to DIAMETER_SUCCESS.

If the VNR Flags indicates the subscription data is deleted from the V2X Control Function, the HSS shall remove the V2X Function Identity for the subscriber and set the result code to DIAMETER_SUCCESS.

For any other reasons if the HSS cannot fulfil the received request, e.g. due to a database error, it shall set the result code to DIAMETER_UNABLE_TO_COMPLY.

5.5 Reset

5.5.1 General

The Reset Procedure shall be used by the HSS, after a restart, to indicate to the V2X Control Function that a failure has occurred.

The Reset Procedure may also be used by the HSS as part of operation and maintenance actions e.g. to allow planned HSS outage without service interruption.

This procedure is mapped to the commands Reset-Request/Answer (RSR/RSA) in the Diameter application specified in clause 6.

Table 5.5.1-1 specifies the involved information elements for the request.

Table 5.5.1-2 specifies the involved information elements for the answer.

Table 5.5.1-1: Reset Request

Information element name	Mapping to Diameter AVP	Cat.	Description
User Id List (See 3GPP TS 29.272 [10])	User-Id	O	This IE shall contain a list of V2X User-Ids where an V2X User-Id comprises the leading digits of an IMSI (i.e. MCC, MNC, leading digits of MSIN) and it shall identify the set of subscribers whose IMSIs begin with the User-Id. The HSS may include this information element if the occurred failure is limited to subscribers identified by one or more User-Ids.
Supported Features (See 3GPP TS 29.229 [6])	Supported-Features	O	If present, this information element shall contain the list of features supported by the origin host.
Reset-IDs (See 3GPP TS 29.272 [10])	Reset-ID	O	If present, this information element identifies together with the HSS’s realm the set of impacted subscribers.

Table 5.5.1-2: Reset Answer

Information element name

Mapping to Diameter AVP

Cat.

Description

Supported Features

(See 3GPP TS 29.229 [6])

Supported-Features

If present, this information element shall contain the list of features supported by the origin host.

Result

(See 6.4)

Result-Code / Experimental-Result

This IE shall contain the result of the operation.

The Result-Code AVP shall be used to indicate success / errors as defined in the Diameter Base Protocol.

The Experimental-Result AVP shall be used for V4 errors. This is a grouped AVP which shall contain the 3GPP Vendor ID in the Vendor-Id AVP, and the error code in the Experimental-Result-Code AVP.

There are no Experimental-Result codes applicable for this command.

5.5.2 Detailed behaviour of the V2X Control Function

When receiving a Reset message the V2X Control Function shall mark all impacted subscriber records "Subscriber Data Confirmed in HSS" as "Not Confirmed", as defined in 3GPP TS 23.007 [14]. If the Reset-IDs IE is supported and received, the V2X Control Function shall make use of the Reset-IDs (together with the HSS’s realm) in order to determine which subscriber records are impacted (i.e. check whether at least one received Reset-ID is associated with the subscriber, and the HSS’s realm identity received in the Origin-Realm AVP matches the value stored after successful V2X-Subscriber-Information retrieval); otherwise the V2X Control Function shall make use of the HSS Identity received in the Origin-Host AVP (by comparing it with the value stored after successful V2X-Subscriber-Information retrieval) and may make use of the received User-Id-List (if any) in order to determine which subscriber records are impacted.

5.5.3 Detailed behaviour of the HSS

The HSS shall make use of this procedure in order to indicate to all relevant V2X Control Functions that the HSS has restarted and may have lost the current V2X Control Function Identity of some of its subscribers who may be currently roaming in the V2X Control Function Area and that the HSS, therefore, cannot send an Update V2X Subscriber Data messages when needed.

If the Reset-ID feature is not supported by the V2X Control Function and the HSS, the HSS may include a list of User Ids identifying a subset of subscribers served by the HSS, if the occurred failure is limited to those subscribers.

If the Reset-ID feature is supported by the V2X Control Function, the HSS optionally may include one (or several) Reset-ID AVPs identifying e.g. failed hardware components if the occured failure is limited to those subscribers associated with e.g. the identified failed hardware components.