4 Architecture Model and Concepts

23.3033GPPProximity-based services (ProSe)Release 17Stage 2TS

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

4.1 General Concept

Proximity Services (ProSe) are services that can be provided by the 3GPP system based on UEs being in proximity to each other.

The 3GPP system enablers for ProSe include the following functions:

– EPC-level ProSe Discovery;

– EPC support for WLAN direct discovery and communication;

– Direct discovery;

– Direct communication;

– UE-to-Network Relay.

4.2 Architectural Reference Model

Figure 4.2-1 shows the high level view of the non-roaming architecture. In this figure, UE A and UE B use a subscription of the same PLMN.

Figure 4.2-1: Non-Roaming Reference Architecture

The following figure 4.2-2 show the high level view of the non-roaming inter-PLMN architecture. In this figure, PLMN A is the HPLMN of UE A and PLMN B is the HPLMN of UE B.

Figure 4.2-2: Inter-PLMN Reference Architecture

Figure 4.2-3 shows the high level view of the roaming architecture. In this figure, UE A uses a subscription of PLMN A and UE B uses a subscription of PLMN B; UE A is roaming in PLMN C while UE B is not roaming.

Figure 4.2-3: Roaming Reference Architecture

NOTE: For EPC-level ProSe discovery the roaming architecture is not specified in this release.

4.3 Reference points

4.3.1 List of Reference Points

PC1: The reference point between the ProSe application in the UE and in the ProSe Application Server. It is used to define application level signalling requirements. This reference point is not specified in this release of the specification.

PC2: The reference point between the ProSe Application Server and the ProSe Function. It is used to define the interaction between ProSe Application Server and ProSe functionality provided by the 3GPP EPS via ProSe Function (e.g. name translation) for ProSe Direct Discovery and EPC-level ProSe discovery.

PC3: The reference point between the UE and the ProSe Function. PC3 relies on EPC user plane for transport (i.e. an "over IP" reference point). It is used to authorise ProSe Direct Discovery and EPC-level ProSe Discovery requests, and perform allocation of ProSe Application Codes / ProSe Restricted Codes corresponding to ProSe Application Identities used for ProSe Direct Discovery. It is used to define the authorisation policy per PLMN for ProSe Direct Discovery (for Public Safety and non -Public Safety) and communication (for Public Safety only) between UE and ProSe Function.

PC4a: The reference point between the HSS and ProSe Function. It is used to provide subscription information in order to authorise access for ProSe Direct Discovery and ProSe Direct Communication on a per PLMN basis. It is also used by the ProSe Function (i.e. EPC-level ProSe Discovery Function) for retrieval of EPC-level ProSe Discovery related subscriber data.

PC4b: The reference point between the SUPL Location Platform (SLP) defined in OMA AD SUPL [2] and the ProSe Function. It is used by the ProSe Function (i.e. EPC-level ProSe Discovery Function) (in the role of LCS client to query the SLP defined in OMA AD SUPL [2].

PC5: The reference point between ProSe-enabled UEs used for control and user plane for ProSe Direct Discovery, ProSe Direct Communication and ProSe UE-to-Network Relay. The lower protocol layers of the PC5 reference point can be based on E-UTRA sidelink capabilities specified in TS 36.300 [17] or on WLAN technology.

PC6: The reference point between ProSe Functions in different PLMNs (EPC-level ProSe Discovery) or between the ProSe Function in the HPLMN and the ProSe Function in a Local PLMN (ProSe Direct Discovery). With ProSe Direct Discovery this reference point is used for HPLMN control of ProSe service authorization. It is also used to authorise ProSe Direct Discovery requests, retrieve the Discovery Filter(s) corresponding ProSe Application ID name(s) and translate the ProSe Application Code to the ProSe Application ID Name.

PC7: The reference point between the ProSe Function in the HPLMN and the ProSe Function in the VPLMN. It is used for HPLMN control of ProSe service authorization. It is also used to authorise ProSe Direct Discovery requests, retrieve the Discovery Filter(s) corresponding ProSe Application ID name(s) and translate the ProSe Application Code to the ProSe Application ID Name.

S6a: In addition to the relevant functions defined in TS 23.401 [5] for S6a, in case of ProSe S6a is used to download ProSe related subscription information to MME during E UTRAN attach procedure or to inform MME subscription information in the HSS has changed.

S1-MME: In addition to the relevant functions defined in TS 23.401 [5] for S1-MME, in case of ProSe it is also used to convey the ProSe direct services authorization from MME to eNodeB.

4.4 Functional Entities

4.4.1 ProSe Function

4.4.1.1 General

The ProSe Function is the logical function that is used for network related actions required for ProSe. The ProSe Function plays different roles for each of the features of ProSe. In this version of the specification it is assumed that there is only one logical ProSe Function in each PLMN that supports Proximity Services.

NOTE: If multiple ProSe Functions are deployed within the same PLMN (e.g., for load reasons), then the method to locate the ProSe Function that has allocated a specific ProSe Application Code or ProSe Restricted Code (e.g. through a database lookup, etc.) is not defined in this version of the specification.

Figure 4.4.1-1: UE to ProSe Function Interfaces for each sub-function

Figure 4.4.1-2: ProSe Function Interfaces to other network elements and PLMNs

The ProSe Function consists of three main sub-functions that perform different roles depending on the ProSe feature:

– Direct Provisioning Function (DPF) is used to provision the UE with necessary parameters in order use ProSe Direct Discovery and Prose Direct Communication. It is used to provision the UEs with PLMN specific parameters that allow the UE to use ProSe in this specific PLMN. For direct communication used for Public Safety DPF is also used to provision the UE with parameters that are needed when the UE is not served by E-UTRAN. For restricted ProSe Direct Discovery, it also generates and maintains the ProSe Discovery UE ID (PDUID).

– Direct Discovery Name Management Function is used for open Prose Direct Discovery to allocate and process the mapping of ProSe Applications IDs and ProSe Application Codes used in ProSe Direct Discovery. It uses ProSe related subscriber data stored in HSS for authorisation for each discovery request. It also provides the UE with the necessary security material in order to protect discovery messages transmitted over the air. In restricted ProSe Direct Discovery, it also interacts with the Application Server via PC2 reference points for the authorization of the discovery requests.

– EPC-level Discovery ProSe Function has a reference point towards the Application Server (PC2), towards other ProSe Functions (PC6), towards the HSS (PC4a) and the UE (PC3). The functionality includes the following:

– Storage of ProSe-related subscriber data and/or retrieval of ProSe-related subscriber data from the HSS;

– Authorization and configuration of the UE for EPC-level ProSe Discovery and EPC-assisted WLAN direct discovery and communication over PC3;

– Storage of a list of applications that are authorized to use EPC-level ProSe Discovery and EPC-assisted WLAN direct discovery and communication;

– Acting as location services client (SLP agent) to enable EPC-level ProSe Discovery;

– Providing the UE with information to assist WLAN direct discovery and communications;

– Handling of EPC ProSe User IDs and Application Layer User IDs;

– Exchange of signalling with 3^rd party Application Servers over PC2 reference point for application registration and identifier mapping;

– Exchange of signalling with ProSe Functions in other PLMNs over PC6 reference points for sending proximity requests, proximity alerts and location reporting;

– Optional support for functionality for requesting UE location via the HSS.

The ProSe Function may support "on demand" announcing requested by UE based on operator’s policy, in case of ProSe restricted discovery model A.

The ProSe Function provides the necessary charging and security functionality for usage of ProSe (both ProSe via the EPC and for ProSe Direct Discovery, ProSe Direct Communication and WLAN direct discovery and communication).

NOTE: The ProSe Function in HPLMN can be always reached if Home Routed configuration is applied for PDN connection (e.g. PDN GW is located in the HPLMN), when such function is supported by the HPLMN. In case of Local Breakout (e.g. PDN GW is located in the VPLMN), a ProSe Proxy Function can be deployed by the VPLMN to support UE to Home ProSe Function communication, if inter-PLMN signalling is required. Whether a PDN connection is provided by Local Breakout or Home Routed is determined by the HSS configuration described in TS 23.401 [5]. UE is not aware of this and as such will not know which APN can be used for communication with ProSe Function unless specific APN information is configured in the UE indicating that this APN provides signalling connectivity between the UE and the Home ProSe Function.

4.4.1.2 ProSe Function Discovery

The ProSe Functions of HPLMN is discovered through interaction with the Domain Name Service function. The FQDN of a ProSe Function in the Home PLMN may either be pre-configured on the UE or provisioned by the network or self-constructed by the UE, e.g. derived from PLMN ID of the HPLMN. The IP address of a ProSe Function in the Home PLMN may also be provisioned to the UE.

4.4.2 UE

Any ProSe-enabled UE may support the following functions:

– Exchange of ProSe control information between ProSe-enabled UE and the ProSe Function over PC3 reference point.

– Procedures for open and restricted ProSe Direct Discovery of other ProSe-enabled UEs over PC5 reference point.

The ProSe-enabled Public Safety UE may support the following functions:

– Procedures for one-to-many ProSe Direct Communication over PC5 reference point.

– Procedures for one-to-one ProSe Direct Communication over PC5 reference point.

– Procedures to act as a ProSe UE-to-Network Relay. The Remote UE communicates with the ProSe UE-to-Network Relay over PC5 reference point. The Prose UE-to-Network Relay uses layer-3 packet forwarding.

– Exchange of control information between ProSe-UEs over PC5 reference point, e.g. for UE-to-Network Relay Discovery and Group Member Discovery.

– Exchange of ProSe control information between another ProSe-enabled UE and the ProSe Function over PC3 reference point. In the ProSe UE-to-Network Relay case the Remote UE will send this control information over PC5 user plane to be relayed over the LTE-Uu interface towards the ProSe Function.

– Configuration of parameters (e.g. including IP addresses, ProSe Layer-2 Group IDs, Group security material, radio resource parameters). These parameters can be pre-configured in the UE, or, if in coverage, provisioned by signalling over the PC3 reference point to the ProSe Function in the network.

4.4.3 ProSe UE-to-Network Relay for Public Safety

The ProSe UE-to-Network Relay entity provides the functionality to support connectivity to the network for Remote UEs (see figure 4.4.3-1).

A UE is considered to be a Remote UE for a certain ProSe UE-to-Network relay if it has successfully established a PC5 link to this ProSe UE-to-Network Relay. A Remote UE can be located within E-UTRAN coverage or outside of E-UTRAN coverage.

NOTE 1: If a Remote UE maintains both PC5 and Uu, the EPS core network entities on the Uu side of the Remote UE are not aware of the ProSe UE-to-Network Relay path via PC5.

Figure 4.4.3-1: Architecture model using a ProSe UE-to-Network Relay

The ProSe UE-to-Network Relay shall relay unicast traffic (UL and DL) between the Remote UE and the network. The ProSe UE-to-Network Relay shall provide generic function that can relay any IP traffic.

NOTE 2: IP Address preservation is not supported.

One-to-one Direct Communication is used between Remote UEs and ProSe UE-to-Network Relays for unicast traffic as specified in clause 5.4.5.

The ProSe UE-to-Network Relay may also relay eMBMS traffic using one-to-many ProSe Direct Communication as specified in clause 5.4.4.4.

4.4.4 ProSe Application Server

The ProSe Application Server supports the following capability:

– Storage of EPC ProSe User IDs: ProSe Function IDs, ProSe Discovery UE ID, metadata;

– Mapping of Application Layer User IDs and EPC ProSe User IDs;

– Mapping of RPAUID and PDUID for restricted ProSe Direct Discovery;

– Maintaining permission information for the restricted ProSe Direct Discovery using RPAUIDs;

– Allocation of the ProSe Restricted Code Suffix pool, if restricted Direct Discovery with application-controlled extension is used;

– Allocation of the mask(s) for ProSe Restricted Code Suffix, if restricted Direct Discovery with application-controlled extension is used.

4.4.5 MME

In addition to the function defined in TS 23.401 [5] in case of ProSe MME performs the following functions:

– receives subscription information related to ProSe from the HSS;

– provides indication to the E-UTRAN that the UE is authorized to use ProSe.

– maintains a list of Remote UEs handled by a UE-to-Network Relay UE for the specific PDN and forwards the Remote UE information towards S-GW.

4.4.6 P-GW

In addition to the function defined in TS 23.401 [5], the P-GW performs the following functions:

– receives information related to the ProSe UE-to-Network Relay from the S-GW;

– maintains a list of Remote UEs handled by the UE-to-Network Relay UE for the specific PDN.

4.4.7 S-GW

In addition to the function defined in TS 23.401 [5], the S-GW performs the following functions:

– receives information related to the ProSe UE-to-Network Relay from the MME;

– maintains a list of Remote UEs handled by the UE-to-Network Relay UE for the specific PDN and forwards the Remote UE information towards P-GW.

4.5 High Level Function

4.5.1 Provisioning for ProSe Direct Discovery and ProSe Direct Communication

4.5.1.1 Authorization and provisioning for ProSe

4.5.1.1.1 General

The basic principles of service authorization for ProSe Direct Discovery and ProSe Direct Communication are as follows:

– the UE gets authorization to use E-UTRA based ProSe Direct Discovery on a per PLMN basis.

– for WLAN-based ProSe Direct Discovery the service authorisation information provided by the HPLMN contains a list of PLMNs whose ProSe Application IDs the UE may use.

– the UE gets authorization to use ProSe Direct Communication on a per PLMN basis in the serving PLMN by the ProSe Function in the HPLMN,

– the ProSe Function in the HPLMN requests authorisation information from the ProSe Function of the serving PLMN and Local PLMN(s).

NOTE: The UE does not need to be registered in the Local PLMN.

– The ProSe Function in the HPLMN merges authorization information from home, serving and local PLMNs.

– Final authorization always comes from the ProSe Function in the Home PLMN.

The ProSe Function in the Local PLMN or the VPLMN or HPLMN may revoke the authorization at any time. The ProSe Function in the HPLMN shall be notified when authorization is revoked by the Local PLMN or the VPLMN.

OMA DM [30] is used as the protocol to provision ProSe related configuration and authorization information in the ME. Provisioning is performed via the PC3 reference point.

4.5.1.1.2 Provisioning information for ProSe Direct Discovery and ProSe Direct Communication

4.5.1.1.2.1 General

The following information can be contained in the authorisation info that is provided by the ProSe Function to the UE for authorisation of using ProSe Direct Discovery and ProSe Direct Communication in a particular PLMN.

4.5.1.1.2.2 Authorisation for ProSe Direct Discovery

The following information is provisioned to the non-Public Safety UE for open ProSe Direct Discovery authorisation:

1) open ProSe Direct Discovery Model A monitoring authorisation policy:

– PLMNs in which the UE is authorised to perform ProSe Direct Discovery monitoring.

2) open ProSe Direct Discovery Model A announcing authorisation policy:

– PLMNs in which the UE is authorized to perform announcing.

– Authorised discovery range for announcing per PLMN.

The following information is provisioned to the UE for restricted ProSe Direct Discovery authorisation:

1) restricted ProSe Direct Discovery Model A monitoring authorisation policy:

– PLMNs in which the UE is authorised to perform restricted ProSe Direct Discovery Model A monitoring.

2) restricted ProSe Direct Discovery Model A announcing authorisation policy:

– PLMNs in which the UE is authorized to perform restricted ProSe Direct Discovery Model A announcing;

– Authorised discovery range for announcing per PLMN.

3) restricted ProSe Direct Discovery Model B Discoverer operation authorization policy:

– PLMNs in which the UE is authorized to perform Model B Discoverer operation;

– Authorised discovery range for announcing per PLMN.

4) restricted ProSe Direct Discovery Model B Discoveree operation authorization policy:

– PLMNs in which the UE is authorized to perform Model B Discoveree operation.

– Authorised discovery range for announcing per PLMN.

5) restricted ProSe Discovery UE ID for Restricted Direct Discovery, applicable only to non-Public Safety UEs:

– ProSe Discovery UE ID.

NOTE: The authorised discovery range above does not apply to WLAN-based ProSe Direct Discovery. When WLAN-based ProSe Direct Discovery is used the discovery range is determined by the underlying WLAN technology.

4.5.1.1.2.3 Provisioning for ProSe Direct Discovery and ProSe Direct Communication (Public Safety UE)

4.5.1.1.2.3.1 General

The content of clause 4.5.1.1.2.3 is applicable to ProSe-enabled Public Safety UEs only.

Clause 3 provides the definition of a ProSe-enabled Public Safety UE. To comply with international and national regulations, the HPLMN shall endeavour to ensure that the UE only uses the specific Public Safety capabilities in territories in which the HPLMN is authorised to permit such rights to the UE.

For Public Safety usage the operator may pre-configure ProSe-enabled Public Safety UEs with the required provisioning parameters for ProSe Direct Discovery and ProSe Direct Communication, without the need for the ProSe-enabled Public Safety UEs to connect to the ProSe Function to get this initial configuration. The following apply:

– The provisioning parameters for ProSe Direct Discovery and ProSe Direct Communication may be configured in the UICC, in the ME, or in both the UICC and the ME.

– The UICC shall indicate whether the UE is authorized to use provisioning parameters.

– ProSe Direct Discovery and ProSe Direct Communication shall be accessible only when a USIM authorized for ProSe Direct Discovery and ProSe Direct Communication is selected.

– The ME provisioning parameters shall not be erased when a USIM is deselected or replaced.

– If both the USIM and the ME contain the same set of provisioning parameters, the set of parameters from the UICC shall take precedence.

– The UE shall use radio resources for ProSe Direct Communication as follows:

– While a UE has a serving cell and is camped on a cell and the UE intends to use for ProSe the radio resources (i.e. carrier frequency) operated by this cell, then the UE shall use the radio resource description indicated by this cell the UE is camped on and ignore any radio resource description of the same radio resource provisioned in the ME or the UICC. If the cell does not provide radio resources for ProSe, the UE shall not perform ProSe transmission and reception on radio resources operated by this cell.

– If the UE intends to use radio resources (i.e. carrier frequency) for ProSe that are not operated by the UE’s serving cell or if the UE is out of coverage, the UE shall search for a cell in any PLMN that is operating the provisioned radio resources (i.e. carrier frequency) as defined in TS 36.300 [17] and TS 36.304 [32], and:

– If the UE finds such cell in the registered PLMN or a PLMN equivalent to the registered PLMN, and authorisation for ProSe Direct Communication to this PLMN is confirmed, the UE shall use the radio resource description indicated by that cell. If that cell does not provide radio resources for ProSe, the UE shall not perform ProSe transmission and reception on those radio resources.

– If the UE finds such cell but not in the registered PLMN or a PLMN equivalent to the registered PLMN, and that cell belongs to a PLMN authorised for ProSe Direct Communication and provides radio resources for ProSe then the UE shall perform PLMN selection triggered by ProSe Direct Communication as defined in TS 23.122 [31].

– If the UE finds such cell but not in a PLMN authorised for ProSe Direct Communication the UE shall not use ProSe.

– If the UE does not find any such cell in any PLMN, then the UE shall use radio resources provisioned in the ME or the UICC. If no such provision exists in the ME or the UICC or the provision does not authorise ProSe Direct Communication then the UE is not authorised to transmit.

– The UE shall use radio resources for ProSe Direct Discovery as follows:

– While a UE has a serving cell, the UE shall use the radio resource description obtained via dedicated signalling or broadcasted by this cell (same or different from that of the serving cell), if the corresponding PLMN is permitted by the configured authorization information.

– If the UE intends to use radio resources (i.e. carrier frequency) not operated by the UE’s serving cell for ProSe, which are indicated by the UE’s serving cell, and the corresponding PLMN is permitted by the configured authorization information, the UE shall search for a cell with the indicated PLMN operating the indicated radio resources as defined in TS 36.300 [17] and TS 36.304 [32], and obtain the radio resource description for ProSe Direct Discovery from that cell, without performing PLMN selection.

– If the UE intends to use provisioned radio resources (i.e. carrier frequency) not operated by the UE’s serving cell for ProSe Direct Discovery, the UE shall search for a cell with any PLMN operating the indicated radio resources as defined in TS 36.300 [17] and TS 36.304 [32], and

– If the UE finds such a cell belongs to a PLMN authorised for ProSe Direct Discovery and the cell provides radio resources description for ProSe Direct Discovery, then the UE shall use the indicated radio resources description for Direct Discovery.

– If the UE finds such a cell but not in a PLMN authorised for ProSe Direct Discovery, the UE shall not use ProSe Direct Discovery in that carrier frequency.

– If the UE does not find any such cell in any PLMN, then the UE shall use radio resources provisioned in the ME or the UICC.

– The UE provisioning shall support setting Geographical Areas.

NOTE 1: It is possible for a UE to use other radio resources for ProSe based on the Geographical Area instead of those operated by the serving E‑UTRAN cell, when provisioned in the UE, even if the UE’s serving cell offers normal service and the ProSe SIB indicates that the service (discovery or communication or both) is available. This is to cover the scenario when e.g. the radio resources used for ProSe Direct Communication are not owned by the serving network of the UE.

NOTE 2: The UE can only use ProSe Direct Discovery and ProSe Direct Communication when it contains a UICC that has been configured for ProSe, i.e. the selected USIM indicates that the UE is authorized to use the provisioning parameters for ProSe.

NOTE 3: The scenario that a cell is detected and the cell does not provide support for ProSe Direct Communications when the UE attempts to use a carrier frequency configured for ProSe Direct Communication, is considered a configuration error. Therefore the UE does not transmit on that frequency to avoid interference to the network.

– The ProSe Direct Communication is only specified for E-UTRA.

NOTE 4: 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, including user provided location, as determined by local regulations.

NOTE 5: The provisioning and use of of radio resources for ProSe Direct Discovery described in this clause does not apply to WLAN-based ProSe Direct Discovery.

4.5.1.1.2.3.2 Additional provisioning information for ProSe Direct Discovery

In addition to the parameters indicated in clause 4.5.1.1.2.2, the ProSe-enabled Public Safety UE is provisioned with the following information:

1) Authorisation policy when the UE is "not served by E-UTRAN":

– Indicates whether the UE is authorised to perform ProSe Direct Discovery for Model A and Model B when "not served by E-UTRAN".

2) Radio parameters for when the UE is "not served by E-UTRAN":

– Includes the radio parameters with Geographical Area(s) that need to be configured in the UE in order to be able perform ProSe Direct Discovery procedures when not "served by E-UTRAN". These radio parameters (e.g. frequency bands) are defined in TS 36.331 [33] and are common for all types of ProSe Direct Discovery (Group Member Discovery, ProSe UE-to-Network Relay Discovery or ProSe UE-to-Network Relay Discovery Additional Information). The UE uses the radio parameters only if the UE can locate itself in the corresponding Geographical Area. Otherwise, the UE is not authorised to transmit.

3) Group Member Discovery parameters:

– For each discovery group that the UE belongs to include the following parameters that enable the UE to perform Group Member Discovery when provisioned in ME from DPF or configured in UICC:

– Application Layer Group ID: Identifies an application layer group that the UE belongs to.

– User Info ID: For Model A, this corresponds to the Announcer Info parameter when the UE is acting as an announcing UE. For Model B, this corresponds to the Discoverer Info in Solicitation messages and the Discoveree Info in Response messages, when the UE is acting as a discoverer or discoveree UE respectively.

NOTE 1: The provisioning of radio parameters for ProSe Direct Discovery described in this clause does not apply to WLAN-based ProSe Direct Discovery.

NOTE 2: User Info ID is expected to be assigned uniquely to a user within the discovery group.

– Discovery Group ID: identifier of a discovery group that the UE belongs to.

NOTE 3: The relationship between the Discovery Group ID and the ProSe Layer-2 Group ID described in clause 4.5.1.1.2.3.3 is out of scope of this specification. It is expected that the Discovery Group ID and ProSe Layer-2 Group ID are of equal bit size.

– Alternatively these parameters can be provided from the 3rd party public safety provider application server (e.g. GCS AS as in TS 23.468 [26]). If UE receives a set of data with the same Application Layer Group ID from AS that has been previously provided by DPF then UE uses the data set provided by AS for Group Member Discovery.

4) ProSe UE-to-Network Relay Discovery parameters:

– Include the parameters that enable the UE to perform ProSe UE-to-Network Relay Discovery when provisioned in ME from DPF or configured in UICC:

– Relay Service Code(s): A Relay Service Code identifies a connectivity service the ProSe UE-to-Network Relay provides to Public Safety applications. The Relay Service Codes are configured in the ProSe UE-to-Network Relays that provide connectivity services to Public Safety applications. The Relay Service Codes are configured in the Remote UEs interested in related connectivity services.

– Alternatively these parameters can be provided from the 3rd party public safety provider application server (e.g. GCS AS as in TS 23.468 [26]). If UE receives the same set of data from AS that has been previously provided by DPF then UE uses the data set provided by AS for ProSe UE-to-Network Relay Discovery.

4.5.1.1.2.3.3 Provisioning information for one-to-many ProSe Direct Communication

The following information is provisioned to the UE for one-to-many ProSe Direct Communication:

1) Authorisation policy:

– When the UE is "served by E-UTRAN":

– PLMNs in which the UE is authorised to perform one-to-many ProSe Direct Communication.

– When the UE is "not served by E-UTRAN":

– Indicates whether the UE is authorised to perform one-to-many ProSe Direct Communication procedures when "not served by E-UTRAN".

2) ProSe Direct Communication policy/parameters:

– For each application layer group supported include the parameters that enable the UE to perform one-to-many ProSe Direct Communication when provisioned from DPF in the ME or configured in the UICC:

– Application Layer Group ID: Identifies an application layer group that the UE belongs to.

– ProSe Layer-2 Group ID;

– ProSe Group IP multicast address

– Indication whether the UE should use IPv4 or IPv6 for that group

– For a specific Group configured to operate using IPv4, optionally an IPv4 address to be used by the UE as a source address. If none is provisioned, then the UE shall use Dynamic Configuration of IPv4 Link-Local Addresses IETF RFC 3927 [16] to obtain a link local address for the Group.

– Include group security related content for one-to-many ProSe Direct Communication.

NOTE 1: More details on the necessary security aspect will be defined in SA3 specifications.

3) Radio parameters for when the UE is "not served by E-UTRAN":

– Includes the radio parameters with Geographical Area(s) that need to be configured in the UE in order to be able perform one-to-many ProSe Direct Communication procedures when "not served by E-UTRAN". These radio parameters (e.g. frequency bands) are defined in TS 36.331 [33] and are common for all types of ProSe Direct Communication (one-to-one, one-to-many or ProSe UE-to-Network Relaying). The UE uses the radio parameters only if the UE can locate itself in the corresponding Geographical Area. Otherwise, the UE is not authorised to transmit.

NOTE 2: The "not served by E-UTRAN" cover the cases when the UE is not served by the E-UTRAN cell operating on the carrier frequency provisioned for ProSe Direct Communication.

4.5.1.1.2.3.3a Provisioning information for one-to-one ProSe Direct Communication

The following information is provisioned in the UE for one-to-one ProSe Direct Communication:

1) Authorisation policy:

– When the UE is "served by E-UTRAN":

– PLMNs in which the UE is authorised to perform one-to-one ProSe Direct Communication.

– When the UE is "not served by E-UTRAN":

– Indicates whether the UE is authorised to perform one-to-one ProSe Direct Communication procedures when "not served by E-UTRAN".

2) ProSe Direct Communication policy/parameters:

– For each application layer group supported include the parameters that enable the UE to perform one-to-one ProSe Direct Communication when provisioned from DPF including Application Layer Group ID and the Layer-2 ID for unicast communication and the related security parameters.

NOTE 1: More details on the necessary security aspect will be defined in SA WG3 specifications.

3) Radio parameters for when the UE is "not served by E-UTRAN":

– Includes the radio parameters with Geographical Area(s) that need to be configured in the UE in order to be able to perform one-to-one ProSe Direct Communication procedures when "not served by E-UTRAN". These radio parameters (e.g. frequency bands) are defined in TS 36.331 [33] and are common for all types of ProSe Direct Communication (one-to-one, one-to-many or ProSe UE-to-Network Relaying). The UE uses the radio parameters only if the UE can locate itself in the corresponding Geographical Area. Otherwise, the UE is not authorised to transmit.

NOTE 2: The "not served by E-UTRAN" cover the cases when the UE is not served by the E-UTRAN cell operating on the carrier frequency provisioned for ProSe Direct Communication but may be served by the E-UTRAN cell operating on some other carrier frequency.

4.5.1.1.2.3.4 Provisioning information for ProSe UE-to-Network Relaying

The following information is provisioned in the UE in support of the UE assuming the role of a ProSe UE-to-Network Relay:

1) Authorisation policy for acting as a ProSe UE-to-Network Relay when "served by E-UTRAN":

– PLMNs in which the UE is authorized to relay traffic for Remote UEs.

2) ProSe Relay Discovery policy/parameters for ProSe UE-to-Network Relay:

– Includes the parameters that enable the UE to perform ProSe Relay Discovery when provisioned from the DPF in the ME or configured in the UICC:

– ProSe UE-to-Network Relay Discovery parameters (User Info ID, Relay Service Code(s)) as described in clause 4.5.1.1.2.3.2;

– The PDN connection parameters (PDN type, APN) to be used for the relayed traffic for each ProSe Relay Service Code;

NOTE 1: The behaviour of the UE in case of missing PDN connection parameters is the behaviour described in TS 23.401 [5]. E.g. if PDN type is not pre-configured the UE requests PDN type IPv4v6.

– Includes security related content for ProSe Relay Discovery for each ProSe Relay Service Code.

NOTE 2: More details on the necessary security aspects are defined in TS 33.303 [29].

– Alternatively these parameters can be provided from a 3rd party public safety provider application server (e.g. a GCS AS as in TS 23.468 [26]). If the UE receives the same set of data from the AS that has previously been provided by the DPF then the UE uses the data set provided by the AS for ProSe Relay Discovery.

3) Radio parameters for ProSe Relay Discovery:

– Includes the radio parameters with Geographical Area(s) that need to be configured in the UE in order to be able perform ProSe Discovery procedures when acting as a ProSe UE-to-Network Relay. These radio parameters (e.g. frequency bands) are defined in TS 36.331 [33] and are common for all types of ProSe Direct Discovery (Group Member Discovery, ProSe UE-to-Network Relay Discovery or ProSe UE-to-Network Relay Discovery Additional Information). The UE uses the radio parameters only if the UE can locate itself in the corresponding Geographical Area. Otherwise, the UE is not authorised to transmit.

NOTE 3: The provisioning of radio parameters for ProSe Direct Discovery described in this clause does not apply to WLAN-based ProSe Direct Discovery.

4) Radio parameters for ProSe Relay Communication:

– Includes the radio parameters with Geographical Area(s) that need to be configured in the UE in order to be able perform ProSe Communication procedures when acting as a ProSe UE-to-Network Relay. These radio parameters (e.g. frequency bands) are defined in TS 36.331 [33] and are common for all types of ProSe Direct Communication (one-to-one, one-to-many or ProSe UE-to-Network Relaying). The UE uses the radio parameters only if the UE can locate itself in the corresponding Geographical Area. Otherwise, the UE is not authorised to transmit.

5) Mapping rules between ProSe Per-Packet Priority and QCI values.

– Includes the rules that determine how the ProSe UE-to-Network Relay maps the QCI of the EPS bearer into a ProSe Per-Packet Priority value to be applied for the downlink relayed unicast packets over PC5.

The following information is provisioned in the UE in support of the UE assuming the role of a Remote UE and thereby enabling the use of a ProSe UE-to-Network Relay:

1) Authorisation policy for using a ProSe UE-to-Network Relay:

– Indicates whether the UE is authorised to use a ProSe UE-to-Network Relay.

2) Policy/parameters for ProSe Relay Discovery and for enabling connection to the ProSe UE-to-Network Relay after discovery is performed as defined in clause 5.3.7:

– Includes the parameters for ProSe Relay Discovery and for enabling the UE to connect to the ProSe UE-to-Network Relay after discovery when provisioned from the DPF in the ME or configured in the UICC:

– ProSe UE-to-Network Relay Discovery parameters (User Info ID, Relay Service Code(s)) as described in clause 4.5.1.1.2.3.2;

– IP version(s) that can be used for the relay traffic for each ProSe Relay Service Codes;

– Includes security related content for ProSe Relay Discovery for each ProSe Relay Service Codes.

NOTE 4: More details on the necessary security aspect are defined in TS 33.303 [29].

3) Radio parameters for when the UE is not "served by E-UTRAN":

– Includes the radio parameters with Geographical Area(s) that need to be configured in the UE in order to be able perform ProSe Discovery procedures in the role of a Remote UE when not "served by E-UTRAN". These radio parameters (e.g. frequency bands) are defined in TS 36.331 [33] and are common for all types of ProSe Direct Discovery (Group Member Discovery, ProSe UE-to-Network Relay Discovery or ProSe UE-to-Network Relay Discovery Additional Information). The UE uses the radio parameters only if the UE can locate itself in the corresponding Geographical Area. Otherwise, the UE is not authorised to transmit.

– Includes the radio parameters with Geographical Area(s) that need to be configured in the UE in order to be able perform ProSe Communication procedures in the role of a Remote UE when not "served by E-UTRAN". These radio parameters (e.g. frequency bands) are defined in TS 36.331 [33] and are common for all types of ProSe Direct Communication (one-to-one, one-to-many or ProSe UE-to-Network Relaying). The UE uses the radio parameters only if the UE can locate itself in the corresponding Geographical Area. Otherwise, the UE is not authorised to transmit.

NOTE 5: The phrase "not served by E-UTRAN" cover the cases when the UE is not served by the E-UTRAN cell operating on the carrier frequency provisioned for ProSe Direct Discovery but may be served by the E-UTRAN cell operating on some other carrier frequency.

4.5.2 Subscription to ProSe

The user’s profile in the HSS contains the subscription information to give the user permission to use ProSe.

At any time, the operator can remove the ProSe UE subscription rights from user’s profile in the HSS, and revoke the user’s permission to use ProSe.

The following subscription information is defined for ProSe:

– subscription for open ProSe Direct Discovery:

– open ProSe Direct Discovery Model A.

– subscription for restricted ProSe Direct Discovery:

– restricted ProSe Direct Discovery Model A;

– restricted ProSe Direct Discovery Model A with application-controlled extension;

– restricted ProSe Direct Discovery Model A with "on demand" announcing;

– restricted ProSe Direct Discovery Model B.

– subscription for EPC-level ProSe Discovery.

– subscription for EPC support WLAN direct discovery and communication.

– subscription for one-to-many ProSe Direct Communication, applicable only to Public Safety subscribers.

– subscription for one-to-one ProSe Direct Communication, applicable only to Public Safety subscribers.

– subscription for ProSe UE acting as UE-to-Network Relay, applicable only to Public Safety subscribers.

– subscription for Remote UE access to ProSe UE-to-Network Relay, applicable only to Public Safety subscribers.

Additional parameters related to the ProSe Direct service may be stored in the user’s profile, such as:

– the list of the PLMNs where the UE is authorised for open Direct Discovery Model A, i.e. to announce or monitor or both.

– the list of the PLMNs where the UE is authorised for restricted ProSe Direct Discovery Model A, i.e. to announce or monitor or both.

– the list of the PLMNs whether the UE is authorized for restricted ProSe Direct Discovery Model B , i.e. to perform Discoverer operation or Discoveree operation or both.

– the list of the PLMNs where the UE is authorised to perform one-to-many ProSe Direct Communication, applicable only to Public Safety subscribers.

– the list of the PLMNs where the UE is authorised to perform one-to-one ProSe Direct Communication, applicable only to Public Safety subscribers.

4.5.3 IP address allocation

For one-to-many ProSe Direct Communication:

– when the UE is configured to use IPv6 on the direct link, the UE auto-configures a link local IPv6 Address following procedures defined in RFC 4862 [6]. This address can only be used as the source IP address for one-to-many ProSe Direct Communication.

– when the UE is configured to use IPv4 for a certain Group for one-to-many ProSe Direct Communication, then either it uses the configured IPv4 address for the Group or, if it is not configured with an address for the Group, it uses Dynamic Configuration of IPv4 Link-Local Addresses IETF RFC 3927 [16].

For communication with a ProSe UE-to-Network Relay:

a) When the Remote UE uses IPv4 to access the external PDN:

a1) The IPv4 address allocation and IPv4 parameter configuration via DHCPv4 is performed according to RFC 2131 [7] and RFC 4039 [8] procedures. The IPv4 address provided to the Remote UE from the ProSe UE-to-Network Relay by DHCPv4 procedure shall correspond to a local IPv4 address range configured in the ProSe UE-to-Network Relay.

a2) The DHCPv4 request from the Remote UE is always sent subsequent to the establishment of the One-to-one ProSe Direct Communication, see details in clause 5.4.4.3.

b) When the Remote UE uses IPv6 to access the external PDN:

b1) IPv6 network prefix allocation via IPv6 Stateless Address auto-configuration. Router solicitation from the Remote UE is always sent subsequent to the establishment of the One-to-one ProSe Direct Communication, see details in clause 5.4.4.2.

b2) IPv6 parameter configuration via Stateless DHCPv6: The UE may use stateless DHCPv6 for additional parameter configuration.

The PDN type of the PDN connection used for the relay traffic shall support the IP version used by the Remote UE. If the Remote UE initiates an allocation of IPv4 address or an IPv6 prefix when the requested IP version is not supported in the corresponding PDN connection then IP address/prefix allocation fails.

In case of IPv4 the ProSe UE-to-Network Relay performs IPv4 NAT between IPv4 addresses assigned to the Remote UEs and the IPv4 address assigned to the PDN connection used for the relay traffic. In case of IPv6 the ProSe UE-to-Network Relay assigns IPv6 prefixes from IPv6 prefix range that have been assigned to the PDN connection used for the relay traffic via IPv6 prefix delegation.

For one-to-one ProSe Direct Communication between two UEs neither of which acts as a ProSe UE-to-Network Relay the following mechanism for IP address/prefix allocation may be used:

a) DHCP-based IPv4 address allocation with one of the two UEs acting as a DHCP server.

b) IPv6 Stateless Address auto configuration specified in RFC 4862 [6] for assignment of IPv6 prefix, with one of the two UEs acting as IPv6 default router.

NOTE: Which UE acts as a DHCPv4 server or IPv6 default router is negotiated during secure layer-2 link establishment.

c) IPv6 link-local addresses as defined in RFC 4862 [6] are formed by UEs locally. The IPv6 link-local addresses are exchanged during the establishment of a secure layer-2 link over PC5. The UEs shall disable duplicate address detection after the layer-2 link is established.

4.5.4 ProSe UE-to-Network Relaying

A UE supporting ProSe UE-to-Network Relaying shall include the following functions:

– ProSe Direct discovery for ProSe UE-to-Network Relay;

– One-to-one ProSe Direct Communication;

– Acting as a default router to the Remote UEs forwarding IP packets between the UE-ProSe UE-to-Network Relay point-to-point link and the corresponding PDN connection;

– Relaying eMBMS traffic using one-to-many ProSe Direct Communication;

– ProSe Per-Packet Priority handling for unicast and eMBMS downlink traffic;

– IPv6 prefix allocation and delegation if IPv6 is used;

– IPv4 address allocation and IPv4 NAT function if IPv4 is used.

In order to use a ProSe UE-to-Network Relay a ProSe-enabled Public Safety UE shall include the following functions:

– ProSe Direct discovery for ProSe UE-to-Network Relay;

– One-to-one ProSe Direct Communication with dynamic IP address/prefix allocation.

NOTE 1: The aspects of the radio layers for the PC5 reference point are defined in RAN specifications.

In order to support mission critical applications (e.g. MCPTT) for Remote UEs, policy control and charging functionality as defined in TS 23.203 [35] needs to be provided for the UE-to-Network Relay UE to enable resource utilisation for Remote UEs.

In this release of the specification, the following functionalities shall be provided to enable support for policy control for Remote UEs:

– The Remote UEs shall be assigned a /64 IPv6 Prefix from a shorter IPv6 prefix by the UE-to-Network Relay.

– The UE-to-Network Relay UE and the PCRF and the PDN GW supporting the PDN connection shall support the extended TFT filter format, so that services can be authorized separately for each Remote UE.

– The UE-to-Network Relay UE and PDN GW shall support the TFT packet filter attribute Local Address and Mask as defined in TS 23.060 [36], clause 15.3.2.2A.

– There shall be a dedicated PDN connection to provide support for UE-to-Network Relay connectivity.

– The UE-to-Network Relay UE, the PDN GW and PCRF shall be configured with a dedicated APN for UE-to-Network Relay connectivity.

NOTE 2: If Local Breakout configuration is supported for relay connectivity, the dedicated APN needs to be well-known APN to allow seamless operation across various operators’ networks.

– The AF determines the PCRF realm using the IPv6 prefix of the Remote UE and contacts the PCRF serving the UE-to-Network Relay PDN connection.

NOTE 3: If the AF and the PCRF are in different PLMNs, the AF appears as a third party application server as described in TS 23.203 [35], clause 5.2.1.

– The PCRF validates any Remote UE related service information from the AF based on roaming agreement and the dedicated APN for UE-to-Network Relay functionality.

NOTE 4: Once the AF has derived the PLMN ID of the PCRF and contacted the corresponding domain, then the session binding can continue using procedures defined in TS 23.203 [35].

4.5.5 ProSe Proxy Function

ProSe Proxy Function enables support for UE to Home ProSe Function/ProSe Key Management Function communication as defined in clause 4.4.1.1 and in TS 33.303 [29], where the Home ProSe Function/ProSe Key Management Function is not located in the same network as the PDN GW for the PDN connection being used. Such proxy functions are needed when requirements on security are not met by signalling over Internet. Inter-PLMN signalling may be used in that case. Due to restrictions on the inter-PLMN network, the UE to Server traffic over the user plane may not be sent between networks directly. Only tunnelled server to server traffic may be sent between networks.

A roaming UE, which has a Local Breakout PDN Connection in the VPLMN, uses this access to reach a ProSe Function in the Home network and a ProSe Key Management Function in the Home network or another network. UE is not aware of the presence of a ProSe Proxy Function.

A ProSe Proxy implemented in the VPLMN on the SGi interface may be used to reach the ProSe Function located in the HPLMN. The ProSe Proxy Function forwards signalling traffic between the UE and the ProSe Function in the HPLMN.

A ProSe Proxy implemented in either the HPLMN or the VPLMN on the SGi interface may be used to reach a ProSe Key Management Function located in a different network. The ProSe Proxy Function forwards the signalling traffic (as defined in clause 6.2.2.3.1 in TS 33.303 [29]) between the UE and the ProSe Key Management Function.

4.5.6 Support for ProSe for UEs in limited service state

ProSe-enabled non-Public Safety UE shall not use ProSe when in limited service state.

ProSe-enabled Public Safety UEs that are authorised to use ProSe Direct Communication and/or ProSe Direct Discovery shall be able to use ProSe Direct Communication and/or ProSe Direct Discovery when in limited service state following the procedures defined in clause 4.5.1.1.2.3.1 for ProSe Direct Communication and ProSe Direct Discovery when the UE enters in limited service state:

– because it cannot find a suitable cell of the selected PLMN as described in TS 23.122 [31] or

– as the result of receiving one of the following reject reasons defined in TS 23.122 [31]:

– a "PLMN not allowed" response to a registration request or;

– a "GPRS not allowed" response to a registration request

A ProSe-enabled Public Safety UE in limited service state shall only use ProSe mechanisms available in ECM-IDLE, for details see TS 36.300 [17].

A ProSe-enabled Public Safety UE in limited service state shall not use ProSe in ECM-CONNECTED mode.

ProSe-enabled Public Safety UEs shall not use ProSe Direct Communication or ProSe Direct Discovery if the UE has entered in limited service state due to all other situations (e.g. no SIM in the MS, an "illegal MS" or "illegal ME" response to a registration request, or an "IMSI unknown in HLR" response to a registration request) defined in TS 23.122 [31], where the UE is unable to obtain normal service from a PLMN.

4.6 Identifiers

4.6.1 Identifiers for EPC-level ProSe Discovery

The following identities are used for EPC-level ProSe Discovery: EPC ProSe User ID, Application Layer User ID and Application ID.

The ProSe Function is identified by an FQDN that the UE constructs using the HPLMN ID.

4.6.2 Identifiers for EPC support for WLAN direct discovery and communication

The following identifier is used in addition to those in clause 4.6.1 for EPC support for WLAN direct discovery and communication: WLAN Link Layer ID.

4.6.3 Identifiers for ProSe Direct Communication

4.6.3.1 ProSe UE ID

This is a link layer identifier that is used as a source Layer-2 ID in all the packets the UE sends for one-to-many and one-to-one ProSe Direct Communication.

When bearer-level security is configured to be used, the ProSe UE ID is assigned by the ProSe Key Management Function as defined in TS 33.303 [29]. The ProSe Key Management Function ensures that the ProSe UE ID is unique in the context of one-to-many ProSe Direct Communication for this group.

When bearer-level security is configured not to be used (including the case of Layer-2 broadcast communication required to support Dynamic Configuration of IPv4 Link-Local Addresses IETF RFC 3927 [16]), the ProSe UE ID is either configured in the UE or self-assigned by the UE.

Assuming that global uniqueness of ProSe UE ID cannot be ensured, the UE should be prepared to handle conflicts of ProSe UE IDs using mechanisms that are out of scope of this release of the specification (e.g. by self-assigning a new ProSe UE ID when a conflict is detected).

4.6.3.2 ProSe Layer-2 Group ID

This is a link layer identifier that identifies the group in the context of one-to-many ProSe Direct Communication. It is used as a destination Layer-2 ID in all the packets the UE sends to this group for one-to-many ProSe Direct Communication.

4.6.4 Identifiers for ProSe Direct Discovery

4.6.4.1 ProSe Application ID

For Open ProSe Discovery, (as described in TS 22.278 [25]) the ProSe Application ID is called the Public ProSe Application ID. The geographic scope of the Public ProSe Application ID may be PLMN-specific, country specific or global.

Each Public ProSe Application ID is composed of the following parts:

a. The ProSe Application ID Name is described in its entirety by a data structure characterized by different levels e.g., broad-level business category (Level 0) / business sub-category (Level 1) / business name (Level 2) / shop ID (Level 3). For the purpose of presentation, a ProSe Application ID Name is usually displayed as a string of labels in which the labels represent hierarchical levels.

b. The PLMN ID that corresponds to the PLMN that assigned the ProSe Application ID Name.

NOTE: If the Public ProSe Application ID is country specific then the Mobile Network Code (MNC) of the PLMN ID is wild carded. If global, both the MCC and MNC are wild carded. The use of wild carded ProSe Application IDs is further explained in Annex B.

4.6.4.2 ProSe Application Code

For the announcing UE, the ProSe Application Code is obtained from the HPLMN ProSe Function using the Announce Request procedure (see clauses 5.3.3.1 and 5.3.3.2). The ProSe Application Code is contained in the message that is actually transmitted over the radio interface (on PC5) by a UE engaged in the ProSe Direct Discovery procedure (see clause 5.3) to "monitoring" UEs.

For the "monitoring" UE, Discovery Filter(s) to monitor the ProSe Application Code(s) over the radio interface (on PC5) are obtained from the HPLMN ProSe Function using the Monitor Request procedure (see clauses 5.3.3.4 and 5.3.3.5).

Each ProSe Application Code is composed of the following parts:

a. A temporary identity that corresponds to the ProSe Application ID Name. Given the data structure associated with the Public ProSe Application ID, each ProSe Application ID can be associated with various temporary identities that contains as many identifiers as there are levels in the corresponding ProSe Application ID Name: this allows partial matching at the monitoring UE side using a ProSe Application Mask (see clause 4.6.4.2b) or a Discovery Filter, making more effective and flexible the filtering of the received temporary identity in a monitoring UE. See clause 4.6.4.2a..

b. The PLMN ID of the ProSe Function that assigned the ProSe Application Code, i.e. Mobile Country Code (MCC) and Mobile Network Code (MNC).

NOTE 1: In this version of the specification the ProSe Application Code is always assigned by a HPLMN ProSe Function.

ProSe Application Code matching considers all components listed above. In ProSe Application Code matching, the "monitoring" UE shall consider it a full match, if both PLMN ID and temporary identity match with the corresponding contents of the Discovery Filter. A partial match is obtained if the PLMN ID matches fully and the temporary identity matches partially with the corresponding contents of the ProSe Application Mask (see clause 4.6.4.2b).

A ProSe Application Code is allocated per "announcing" UE and per application and has an associated validity timer that runs both in the ProSe Function and in the UE.

In case of Open ProSe Discovery:

– when the "announcing" UE wants to announce something, it shall send a Discovery Request containing the Public ProSe Application ID to the ProSe Function, and the ProSe Function assigns a ProSe Application Code.

– when the "monitoring" UE wants to monitor something, it shall send a discovery request containing the full or a subset of the Public ProSe Application ID, e.g. it may provide 2 out of the n levels of the full Public ProSe Application ID.

NOTE 2: The ProSe Application ID Name data structure is not expected to change often.

4.6.4.2a Discovery Filter

In open ProSe Direct Discovery, a Discovery Filter consists of a ProSe Application Code, ProSe Application Mask(s) and a time to live (TTL). In restricted ProSe Direct Discovery, a Discovery Filter consists of a ProSe Restricted Code, ProSe Application Masks(s) and a TTL. A TTL indicates for how long the related Discovery Filter is valid after it is received.

NOTE: In order for the ProSe Application Mask not to change often, the ProSe Application Mask does not extend to the last level of the corresponding Prose Application ID data structure (typically the leaf, i.e. the lowest level).

A Discovery Filter is provided to a monitoring UE by its HPLMN ProSe Function. It is used by the monitoring UE to selectively match ProSe Application Codes or ProSe Restricted Codes received on the PC5 interface.

In Model B discovery, Discovery Filters are provided to the Discoveree UE and Discoverer UE. The Discoveree UE needs to obtain a Discovery Query Filter before it can participate in the discovery operation. The Discoveree UE applies the Discovery Query Filter to determine which of the ProSe Query Codes that it monitors is to be responded to. For each of the ProSe Query Codes it is configured to announce, the Discoverer UE needs to be configured with one or more Discovery Response Filters for processing the ProSe Response Codes that may be received in response.

Discovery Filters allow full matching and partial matching of as many parts of ProSe Application Code or ProSe Restricted Code as are contained in the ProSe Application Mask. A Discovery Filter may contain more than one mask in order to support allocation of masks for different parts of the ProSe Application Code or ProSe Restricted Code.

4.6.4.2b ProSe Application Mask

A ProSe Application Mask shall be used for partial matching of ProSe Application Codes or ProSe Restricted Codes received on the PC5 interface. A ProSe Application Mask is contained in a Discovery Filter.

NOTE 1: It is up to stage 3 specifications whether a ProSe Application Mask is used in case of full matching, or the lack of the ProSe Application Mask indicates the need of full matching.

A ProSe Application Mask consists of one or more applicable parts of temporary identities of ProSe Application Codes or ProSe Restricted Codes to allow partial matching.

NOTE 2: The ProSe Application Mask is not expected to change often.

4.6.4.3 Identifiers for ProSe UE-to-Network Relay discovery and selection

The following parameters are used in the UE-to-Network Relay Discovery Announcement message (Model A):

– ProSe Relay UE ID: link layer identifier that is used for direct communication and is associated with a Relay Service Code. A UE-to-Network Relay shall have a distinct ProSe Relay UE ID for each Relay Service Code. For support of multiple PDN Connections, the ProSe UE-to-Network Relay is assigned a different ProSe Relay UE ID for each PDN Connection.

– Announcer Info: provides information about the announcing user.

– Relay Service Code: parameter identifying a connectivity service the ProSe UE-to-Network Relay provides to Public Safety applications. The Relay Service Codes are configured in a ProSe UE-to-Network Relay for advertisement. Additionally, the Relay Service Code also identifies authorized users the ProSe UE-to-Network Relay would offer service to, and may select the related security policies or information e.g. necessary for authentication and authorization between the Remote UE and the ProSe UE-to-Network Relay (e.g. a Relay Service Code for relays for police members only would be different than a Relay Service Code for relays for Fire Fighters only, even though potentially they provided connectivity to same APN e.g. to support Internet Access).

The following parameters are used in the UE-to-Network Relay Discovery Solicitation message (Model B):

– Discoverer Info: provides information about the discoverer user.

– Relay Service Code: information about connectivity that the discoverer UE is interested in. The Relay Service Codes are configured in the Remote UEs interested in related connectivity services.

– ProSe Relay UE ID: link layer identifier of a UE-to-Network Relay that is used for direct communication and is associated with a Relay Service Code. A UE-to-Network Relay shall have a distinct ProSe Relay UE ID for each Relay Service Code. The ProSe Relay UE ID is optional.

The following parameters are used in the UE-to-Network Relay Discovery Response message (Model B):

NOTE: It is up to stage 3 specifications how the UE-to-Network Relay indicates in the response message which Relay Service Code it can support.

– Discoveree Info: provides information about the discoveree.

4.6.4.4 ProSe Query Code

The ProSe Query Code is used for Model B discovery. It is obtained by a Discoverer UE from its HPLMN ProSe Function. The ProSe Query Code is sent by the Discoverer UE over the air.

4.6.4.5 ProSe Response Code

The ProSe Response Code is used for Model B discovery. It is obtained by a Discoveree UE from its HPLMN ProSe Function before its starts the discovery operation. There is one ore more Discovery Query Filter(s) associated with the ProSe Response Code and provided to the Discoveree UE. The Discoveree UE sends the ProSe Response Code over the air when a monitored ProSe Query Code matches the Discovery Query Filter(s).

4.6.4.6 ProSe Restricted Code

The ProSe Restricted Code is used for restricted ProSe Direct Discovery.

For the announcing UE, the ProSe Restricted Code is obtained from the HPLMN ProSe Function using the Announce Request procedure (see clause 5.3.3.2A, and 5.3.3.3A). The ProSe Restricted Code is contained in the message that is transmitted over the radio interface (on PC5) by a UE engaged in the ProSe Direct Discovery procedure (see clause 5.3) to monitoring UEs.

For the announcing UE requesting "on demand" announcing in restricted ProSe Direct Discovery Model A, the ProSe Restricted Code can be allocated by the HPLMN ProSe Function using the Announcing Alert procedures (see clause 5.3.5).

The monitoring UE, a set of Discovery Filter(s) to monitor the ProSe Restricted Code(s) over the radio interface (PC5) are obtained from the HPLMN ProSe Function using the Monitor Request procedure (see clause 5.3.3.4A and 5.3.3.5A).

Each ProSe Restricted Code is composed of the following parts:

a. A temporary identifier that corresponds to one or more RPAUIDs.

b. The PLMN ID of the ProSe Function that assigned the ProSe Restricted Code.

It is up to the policy in the ProSe Function whether to allocate the same ProSe Restricted Code for all RPAUIDs or different ProSe Restricted Codes for different RPAUIDs. The ProSe Restricted Code has an associated validity timer that runs both in the ProSe Function and in the UE.

The ProSe Function may update the ProSe Restricted Code or the Discovery Filter(s) using the Restricted Discovery Authorization Update procedure in clause 5.3.6A.

To support restricted Direct Discovery with application-controlled extension, the ProSe Restricted Code contains a prefix, which is assigned by the ProSe Function in the HPLMN, and a suffix which is assigned by the ProSe Application Server.

4.6.4.7 ProSe Discovery UE ID (PDUID)

The 3GPP layer identity of the UE is concealed from application layer via the creation by the ProSe Function of a corresponding PDUID. The mapping of the PDUID to the 3GPP layer UE ID is maintained by the ProSe Function.

The ProSe Protocol layer in the UE gets the PDUID during the procedure of service authorisation for ProSe Direct Discovery, from the ProSe Function of the HPLMN. The PDUID is stored in the ProSe Function as part of the service authorization information, and is associated with a validity timer. The ProSe function may update the PDUID using the ProSe service notification message before the validity timer expires.

4.6.4.8 Restricted ProSe Application User ID (RPAUID)

The application layer user identity is concealed from 3GPP network via the creation by the ProSe Application Server of a corresponding Restricted ProSe Application User ID. The mapping of the RPAUID to the actual application layer identity is maintained by the ProSe Application Server.

NOTE: RAPUID is a temporary identifier and can be changed by ProSe Application Server, e.g. in order to further protect the application level user identity.

The structure and value of the RPAUID is out of scope of 3GPP. The UE obtains the RPAUID using application layer signalling prior to the execution of the Discovery Request procedures described in clause 5.3.3.

4.6.4.9 Identifiers for Group Member Discovery

The following parameters are used in the Group Member Discovery Announcement message (Model A):

– ProSe UE ID: link layer identifier that is used for subsequent direct one-to-one and one-to-many communication.

– Announcer Info: provides information about the announcing user.

– Discovery Group ID: identifier of a discovery group that the UE belongs to.

The following parameters are used in the Group Member Discovery Solicitation message (Model B):

– Discoverer Info: provides information about the discoverer user.

– Discovery Group ID: identifier of a discovery group that the targeted UE should belong to.

– Target Info: provides information about the targeted discoverees (single user or group). The Target Info is provided by the upper layers of the UE.

The following parameters are used in the Group Member Discovery Response message (Model B):

– ProSe UE ID: link layer identifier that is used for subsequent direct one-to-one and one-to-many communication.

– Discoveree Info: provides information about the discoveree.

– Discovery Group ID: identifier of the discovery group that the discoveree UE belongs to.

4.6.4.10 Identifiers for Relay Discovery Additional Information

The following parameters may be used in the Relay Discovery Additional Information message:

– Relay Service Code: the Relay Service Code associated with the message. The Relay Service Code is used to identify the security parameters needed by the receiving UE to process the discovery message as specified in TS 33.303 [29].

– ProSe Relay UE ID: link layer identifier that is used for direct communication and is associated with a Relay Service Code.

– Announcer info: provides information about the announcing user.

– TMGI: indicates the MBMS the ProSe UE-to-Network Relay is relaying.

– ProSe Layer-2 Group ID: link layer identifier of the group that transmits the MBMS traffic corresponding to the TMGI.

– ECGI: indicates the ECGI of the serving cell of the ProSe UE-to-Network Relay.

A single Relay Discovery Additional Information message may carry:

– the ECGI that the ProSe UE-to-Network Relay is camped on or;

– one or more advertised TMGIs and their corresponding ProSe Layer-2 Group IDs up to the maximum allowed message size or;

– the ECGI that the ProSe UE-to-Network Relay is camped on, and one or more advertised TMGIs and their corresponding ProSe Layer-2 Group IDs up to the maximum allowed message size.

4.6.4.11 Metadata Index

Some bits of the ProSe Application Code may be used as Metadata Index to reflect the current metadata version. It is allocated and updated by the Home ProSe Function when new metadata are uploaded and stored in the ProSe Function for a given ProSe Application ID. The length of the Metadata Index is decided by the ProSe Function under operator’s control.

4.6.4.12 Metadata Index Mask

The Metadata Index Mask indicates the part used for the Metadata Index in the ProSe Application Code. It is provided to the monitoring UE during the Match Report procedure for the ProSe Application Code(s) containing a Metadata Index. The monitoring UE can use the Metadata Index Mask to locate the Metadata Index in the ProSe Application Codes.