5.2.2 Rf message flows

32.2773GPPCharging managementProximity-based Services (ProSe) chargingRelease 17Telecommunication managementTS

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

5.2.2.1 Offline charging message flow for ProSe Direct Discovery

The following ProSe operation flows are based on the procedures defined in TS 23.303 [238]

5.2.2.1.1 Triggers for charging events from ProSe Function for ProSe Direct Discovery

When a charging event is reported to the CDF, it includes details such as subscriber identifier (e.g. IMSI), PLMN ID, Specific ProSe Direct Discovery Model (e.g. Model A, Model B), Specific ProSe UE’s role used (e.g. Announcing UE, Monitoring UE, Discoverer UE, Discoveree UE), Specific ProSe functionality used (e.g. Announcing, Monitoring, Match, restricted Announcing, restricted Discovery Request), Allocation of a ProSe App Code to an Announcing UE and the associated period , Allocation of a set of Filters for a Monitoring UE and the associated period, Match of the ProSe App Code at a Monitoring UE and the timestamp and ProSe App ID for ProSe Direct Discovery Announce Request and Monitoring.

As stated above, the trigger conditions described in Table 5.2.2.1.1.1 are applicable for charging information collection.

Charging Data Request[Event] is sent at successful response to different Discovery Request and Discovery Report.

Table 5.2.2.1.1.1: Charging Data Request messages triggered by messages
for ProSe Function in ProSe Direct Discovery

message

Triggering conditions

Charging Data Request[Event]

Discovery Response to Direct Discovery Request with command (Announce, Monitor restricted Announcing, restricted Monitoring, restricted Discovery Request)

Announce Auth Ack to Announce Authorization messageMonitor response to Monitor Request message

Match Report Ack to Match Report message

Match report information for Match report of Open discovery

Announce Auth Ack to restricted Discovery Request message Model B

Match Report Ack to Model B Discovery reporting

5.2.2.1.2 Message flow for ProSe Direct Discovery Announce Request

ProSe Direct Discovery Announce Request allows a ProSe-enabled UE to request a set of ProSe App Code from the HPLMN ProSe Function, with associated validity timer and security materials, to announce over the air. Charging Data Request[Event] is triggered for Announcing UE after ProSe Function responds to the Discovery Request or to the Announce Authorization message.

When the ProSe Application ID has a scope different from PLMN specific scope (i.e. country-wide or global), the message flows are the same as those for the case of PLMN specific ProSe Application ID provided by the HPLMN.

Figure 5.2.2.1.2.1: Message flow for ProSe Direct Discovery Announce Request (non-roaming)

The detailed description for the message flow is defined in TS 23.303 [238].

1-2. These steps are the same as the ProSe Direct Discovery are defined in TS 23.303[238].

3. The ProSe Function responds with a Discovery Response with:

– (ProSe Application Code, validity timer, PC5_tech) for open discovery.

– (ProSe Application Code, ProSe Restricted Code/ ProSe Restricted Code Prefix[ProSe Restricted Code Suffix pool], validity timer, Discovery Entry ID, Announcing Enabled indicator, PC5_tech) for restricted discovery.

3a. The ProSe Function triggers Charging Data Request[Event] to CDF in HPLMN where event represents Announce. The PF-DD-CDR is generated by CDF for Announcing UE.

3b. The CDF returns Charging Data Response corresponding to the received Charging Data Request[Event].

4. The UE may start announcing the provided ProSe Application Code in HPLMN for open discovery and ProSe Restricted Code in serving PLMN for restricted discovery, using the radio resources authorized and configured by E-UTRAN to be used for ProSe as defined in RAN specifications, or using WLAN, or both.

Figure 5.2.2.1.2.2: Message flow for ProSe Direct Discovery Announce Request (roaming/ inter-PLMN transmission)

The UE is only allowed to announce in the bands signalled from VPLMN. The detailed description for the message flow of open discovery and restricted discovery are defined in TS 23.303 [238] clause 5.3.3.

0-4. If the UE is authorized to announce in VPLMN and is triggered to announce, it shall establish a secure connection with the ProSe Function in HPLMN and it shall then send a Discovery Request and then the ProSe Function in VPLMN authorizes the UE to perform ProSe Direct Discovery Announce.

4a. After the ProSe Function in VPLMN responds to the Announce Authorisation message, the ProSe Function in VPLMN sends Charging Data Request[Event] to CDF in VPLMN. The PF-DD-CDR for Announcing UE is generated by the CDF in VPLMN where event represents Announce.

4b. The CDF in VPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

5. The ProSe Function in HPLMN shall respond to the UE with a Discovery Response with:

– (ProSe Application Code, validity timer, Discovery Entry ID, PC5_tech) for open discovery.

– (ProSe Restricted Code/ProSe Restricted Code Prefix[ProSe Restricted Code Suffix pool], validity timer, Discovery Entry ID, ProSe Enabled Indicator, PC5_tech) for districted discovery.

5a. After the ProSe Function in HPLMN responds to the UE with a Discovery Response, the ProSe Function sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR for Announcing UE is generated by the CDF in HPLMN where event represents Announce.

5b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

6. The UE may start announcing the provided ProSe Application Code for open discovery and ProSe Restricted Code for restricted discovery in the VPLMN or Local PLMN, using the radio resources authorized and configured by E-UTRAN to be used for ProSe as defined in RAN specifications, or using WLAN, or both.

5.2.2.1.3 Message flow for ProSe Direct Discovery Monitor Request

ProSe Direct Discovery Monitor Request allows a ProSe-enabled UE to obtain a set of filters from the HPLMN ProSe Function, which enables the UE to discover Announcing UE of its interest. Charging Data Request[Event] is triggered for Monitoring UE after ProSe Function responds to the Discovery Request or to the Monitor Request message.

Figure 5.2.2.1.3.1: Message flow for ProSe Direct Discovery Monitor Request (non-roaming)

More details and completed message flow for ProSe Direct Discovery Monitor Request for open discovery and restricted discovery are defined in TS 23.303[238] clause 5.3.3.4 and 5.3.3.4.A.

0-2. Monitoring UE sends out Discovery Req message and if there is no associated UE context, the ProSe Function shall check with HSS the authorization for discovery and create a new context for this UE that contains the subscription parameters for this UE for the duration the Discovery Filters will be valid.

For open discovery, if the Discovery Request is authorized, and the ProSe Application ID sent by the UE in step 1 indicates another Local PLMN and for restricted discovery, if the PLMN ID in the Target ProSe Disc UE ID indicates a PLMN different from the HPLMN then steps 3-6 are executed, otherwise (i.e. the ProSe Application ID indicates HPLMN) only steps 5-6 are executed:

3. For open discovery, the ProSe Function in HPLMN shall contact other Local PLMNs in order to resolve the ProSe Application ID Name(s) to mask(s) that corresponds to this ProSe Application ID Name. The request shall also include the UE identity information e.g. IMSI or MSISDN, and PC5_tech in order to allow the ProSe Function in Local PLMN to perform charging.

For restricted discovery, the ProSe Function in the HPLMN contacts the ProSe Function in that PLMN to retrieve the corresponding ProSe Restricted Code with a Monitor Request (RPAUID, UE Identity, Target PDUID, Application ID, Target RPAUID, Discovery Entry ID, and PC5_tech) message.

4. For open discovery, if the ProSe Function of the Local PLMN stores valid ProSe Application Code(s) corresponding to the requested ProSe Application ID Name(s) and the requested PC5 radio technology, then the ProSe Function of the Local PLMN returns the related mask(s) and the corresponding TTL for each.

For restricted discovery, the ProSe Function in the other PLMN returns to the ProSe Function in the HPLMN the ProSe Restricted Code and the corresponding residual validity timer with a Monitor Response (ProSe Restricted Code, validity timer, PC5_tech) message. The Prose Function in the other PLMN also stores, in the context of the announcing UE, the PDUID of the monitoring UE and the allocated validity timer.

4a. After the ProSe Function of the Local PLMN responds to Monitor Request from the ProSe Function of HPLMN, the ProSe Function of the Local PLMN sends Charging Data Request[Event] to CDF in Local PLMN. The PF-DD-CDR is generated for Monitoring UE where Event represents Monitor.

4b. The CDF in Local PLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

NOTE 1: If the ProSe Function of the Local PLMN does not return any mask, than the ProSe Function in the HPLMN notifies the UE that the Discovery Request has been rejected.

5. The ProSe Function in the HPLMN shall respond with a Discovery Response message:

– Discovery Filter(s), Discovery Entry ID, and PC5_tech for open discovery;

– Discovery Filter(s), Metadata Indicator, Discovery Entry ID, Application Level Container, and PC5_tech for restricted discovery.

5a. After the ProSe Function in the HPLMN responds with a Discovery Response, the ProSe Function sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR is generated for Monitoring UE where Event represents Monitor.

5b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

6. The UE may start monitoring using the Discovery Filter(s) in the radio resources that are authorized and configured by the PLMN(s) to be used for ProSe as defined in RAN specification, or using WLAN, or both s.

Figure 5.2.2.1.3.2: Message flow for ProSe Direct Discovery Monitor Request (roaming/ inter-PLMN transmission)

More details and completed message flow for ProSe Direct Discovery Monitor Request for open discovery and restricted discovery are defined in TS 23.303[238] clause 5.3.3.5 and clause 5.3.3.5.A.

0-4. These steps are defined in TS 23.303 [238] clause 5.3.3.5 for open discovery and clause 5.3.3.5.A for restricted discovery.

4a. After the ProSe Function of the other PLMN responds to Monitor Request from the ProSe Function of HPLMN, the ProSe Function of the other PLMN sends Charging Data Request[Event] to CDF in other PLMN. The PF-DD-CDR is generated for Monitoring UE where Event represents Monitor.

4b. The CDF in other PLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

NOTE 2: If the ProSe Function of the other PLMN does not return any mask, than the ProSe Function in the HPLMN notifies the UE that the Discovery Request has been rejected.

5. The ProSe Function in the HPLMN responds with a Discovery Response message.

– Discovery Filter(s), Discovery Entry ID, PC5_tech) for open discovery. The Discovery Filter(s) consists of the ProSe Application mask(s). The Discovery Filter(s) include the TTL. The TTL(s) in the Discovery Filter(s) indicate for how long the Discovery Filter(s) are going to be valid.

– Discovery Filter(s), Metadata Indicator, Discovery Entry ID, Application Level Container, and PC5_tech for restricted discovery. The Discovery Filter includes the ProSe Restricted Code to be monitored and the TTL that indicates for how long the related ProSe Restricted Code in the Discovery Filter is valid after it is received. If configured by the operator, the Target RPAUID(s) and metadata corresponding to the ProSe Restricted Code(s) may be included in the Discovery Response message.

5b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

5.2.2.1.4 Message flow for ProSe Direct Discovery Match Report

ProSe Direct Discovery Match Report allows a ProSe-enabled UE to report a match of the ProSe Application Code to the HPLMN ProSe Function, and obtain the corresponding ProSe Application ID and metadata. Charging Data Request[Event] is triggered for Monitoring UE after ProSe Function responds to the Match Report message.

When the ProSe Application ID has a scope different from PLMN specific scope (i.e. country-wide or global), the message flows are the same as those for the case of PLMN specific ProSe Application ID.

Figure 5.2.2.1.4.1: Message flow for Match Report of Open Discovery (non-roaming)

More details and completed message flow for ProSe Direct Discovery Match Report for Open discovery(non-roaming) are defined in TS 23.303[238] clause 5.3.4.1.

1. If the UE finds ProSe Application Code(s) that matches the Discovery Filters and does not have ProSe Application ID(s) already locally stored that correspond to this ProSe Application Code(s), it shall (re)establish a secure connection with the ProSe Function in HPLMN to which it shall then send a Match Report (ProSe Application Code(s), UE Identity, Monitored PLMN ID, and PC5_tech) message.

2. The ProSe Function shall check the context for this UE that contains its subscription parameters. The authorization information also contains the PLMN that this UE is allowed to perform discovery.

3. The ProSe Function analyses the ProSe Application Code received from the UE.

If the PLMN ID that assigned the given ProSe Application Code is another Local PLMN then steps 4-7 are executed, otherwise (i.e. the ProSe Application Code was assigned by HPLMN) only step 7 is executed:

4. The ProSe Function in HPLMN sends a Match Report (ProSe Application Code(s), UE identity, PC5_tech) to the ProSe Function of the PLMN that assigned the ProSe Application Code. The UE identity information e.g. IMSI or MSISDN can be used by the ProSe Function in Local PLMN to perform charging.

5. The ProSe Function analyses the ProSe Application Code(s) received from the UE.

6. If the ProSe Application Code is confirmed then the ProSe Function in Local PLMN shall send Match Report Acknowledgement (ProSe Application ID Name(s), validity timer(s) , PC5_tech). This message may also contain certain metadata corresponding to the ProSe Application ID Name e.g. postal address, phone number, URL etc.

6a. After the ProSe Function in Local PLMN sends Match Report Acknowledgement, the ProSe Function in Local PLMN sends Charging Data Request[Event] to the CDF in Local PLMN. The PF-DD-CDR is generated for Monitoring UE where Event represents Match.

6b. The CDF in Local PLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

7. The ProSe Function in HPLMN shall respond to the UE with Match Report Acknowledgment (ProSe Application ID(s), validity timer(s)). This message may also contain certain metadata corresponding to the ProSe Application ID Name e.g. postal address, phone number, URL etc. The validity timer(s) indicate for how long the ProSe Application ID(s) provided are going to be valid. The UE may store the mapping of ProSe Application Code(s) and corresponding ProSe Application ID(s) for the duration of their validity timer.

7a. After the ProSe Function in HPLMN responds to the UE with Match Report Acknowledgment, the ProSe Function in HPLMN sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR is generated for Monitoring UE where Event represents Match, with indication of the PC5 radio technology used for the ProSe Direct Discovery.

7b. The CDF in Local PLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

Figure 5.2.2.1.4.1A: Message flow for Match Report of Restricted Discovery (non-roaming)

More details and completed message flow for ProSe Direct Discovery Match Report for Restricted discovery(non-roaming) are defined in TS 23.303[238] clause 5.3.4.1.A.

1. When the monitoring UE has received a ProSe Restricted Code over the air that matches the Discovery Filter it obtained from monitoring Request procedure, and if the UE does not have a corresponding RPAUID associated with it with a valid TTL, the UE sends a Match Report (RPAUID, UE Identity, Discovery Type, Application ID, ProSe Restricted Code, Metadata Requested, PC5_tech) message to the ProSe Function in the HPLMN to get the Target RPAUID.

2. The HPLMN ProSe Function checks the authorization for the monitoring UE to perform restricted discovery.

3-4c. The HPLMN ProSe Function analyses the ProSe Restricted Code and identifies in the UE context of the monitoring UE the corresponding Target RPAUID.

5. The ProSe Function in HPLMN returns a Match Report Ack (Application ID, Target RPAUID, validity timer, metadata) to the UE.

5a. After the ProSe Function of the HPLMN responds to Match Report Request from the UE.The ProSe Function in HPLMN sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR for UE is generated by the CDF in the HPLMN where event represents Match, with indication of the PC5 radio technology used for the ProSe Direct Discovery.

5b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

6. The ProSe Function in HPLMN may optionally send a Match Report Info (RPAUID, Target RPAUID, UE Identity, ProSe Restricted Code, Discovery Type and PC5_tech) to the ProSe Function of the announcing UE.

Figure 5.2.2.1.4.2: Message flow for Match Report of Open Discovery (roaming/inter-PLMN transmission)

More details and completed message flow for ProSe Match Report of open discovery(roaming/inter-PLMN transmission) are defined in TS 23.303[238] clause 5.3.4.2.

1. If the UE finds ProSe Application Code(s) that matches the Discovery Filters and does not have ProSe Application ID(s) already locally stored that correspond to this ProSe Application Code(s), it (re)establishes a secure connection with the ProSe Function in HPLMN and sends a Match Report (ProSe Application Code(s), UE Identity, VPLMN ID, Monitored PLMN ID, PC5_tech) message.

2. The ProSe Function shall check the context for this UE that contains its subscription parameters for this UE. The authorization information also contains the PLMN that this UE is allowed to perform discovery. The UE context also contains the VPLMN ID where the UE is registered.

3. The ProSe Function analyses the ProSe Application Code(s) received from the UE.

If the PLMN ID that assigned the given ProSe Application Code is not the HPLMN, then steps 4-8 are executed, otherwise (i.e. the HPLMN assigned the ProSe Application Code) only steps are executed:

4. The ProSe Function in HPLMN sends a Match Report (ProSe Application Code(s), UE identity, monitored PLMN ID, PC5_tech) to the ProSe Function of the PLMN that assigned the ProSe Application Code (i.e. the ProSe Function of the HPLMN of the Announcing UE).

5. The ProSe Function ensures that the received ProSe Application Code is authorized to be transmitted on the monitored PLMN. The ProSe Function analyses the ProSe Application Code(s) received from the UE, and confirms the ProSe Application Code(s).

6. The ProSe Function shall send Match Report Acknowledgement (ProSe Application ID Name(s), validity timer(s)). This message may also contain certain metadata corresponding to the ProSe Application ID Name e.g. postal address, phone number, URL, etc.

6a. After the ProSe Function in other PLMNs sends Match Report Acknowledgement message, the ProSe Function in other PLMNs sends Charging Data Request[Event] to the CDF in other PLMNs. The PF-DD-CDR is generated for the Monitoring UE where Event represents Match, with indication of the PC5 radio technology used for the ProSe Direct Discovery.

6b. The CDF in other PLMNs returns Charging Data Response corresponding to the received Charging Data Request[Event].

7. The ProSe Function in HPLMN shall respond to the UE with Match Report Acknowledgment (ProSe Application ID(s), validity timer(s)). This message may also contain certain metadata corresponding to the ProSe Application ID Name e.g. postal address, phone number, URL, etc. The validity timer(s) indicate for how long the ProSe Application ID(s) provided are going to be valid. The UE may store the mapping of ProSe Application Code(s) and corresponding ProSe Application ID(s) for the duration of their validity timer.

7a. After the ProSe Function in HPLMN respond to the UE with Match Report Acknowledgment message, the ProSe Function in HPLMN sends Charging Data Request[Event] to the CDF in HPLMN. The PF-DD-CDR is generated for Monitoring UE where Event represents Match, with indication of the PC5 radio technology used for the ProSe Direct Discovery.

7b. The CDF in HPLMNs returns Charging Data Response corresponding to the received Charging Data Request[Event].

8. If in step 4 it was indicated that the Announcing UE is roaming, the ProSe Function in HPLMN may optionally send a Match Report Info (ProSe Application ID(s), UE Identity, PC5_tech) to the ProSe Function of the serving PLMN (i.e. VPLMN) of the Announcing UE.

8a. When receiving a Match Report Info message, the ProSe Function in VPLMN of the Announcing UE sends Charging Data Request[Event] to the CDF in VPLMN of the Announcing UE. The PF-DD-CDR is generated for Announcing UE where Event represents Match.

8b. The CDF in VPLMN of the Announcing UE returns Charging Data Response corresponding to the received Charging Data Request[Event].

Figure 5.2.2.1.4.3: Message flow for Match Report of Restricted Discovery (roaming//inter-PLMN transmission)

More details and completed message flow for ProSe Match Report of restricted discovery(roaming//inter-PLMN transmission) are defined in TS 23.303[238] clause 5.3.4.2.A.

1-5. These steps are the similar with the figure 5.2.2.1.4.1A Message flow for Match Report of restricted discovery (non-roaming).

5b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

6. The ProSe Function in HPLMN may optionally send a Match Report Info (RPAUID, Target RPAUID, UE Identity, ProSe Restricted Code, Discovery Type, PC5_tech) to the ProSe Function in the HPLMN of the announcing UE.

5.2.2.1.5 Message flow for Discovery Request – Model B procedures

The Discovery Request is sent by the Discoveree UE or the Discoverer UE in order to be authorised to access the discovery resources and perform restricted ProSe Direct Discovery, Model B.

Figure 5.2.2.1.5.1: Discoveree UE procedures for Model B restricted discovery (non-roaming)

More details and complete message flow of Discoveree UE procedures for Model B restricted discovery (non-roaming) are defined in TS 23.303 [238] clause 5.3.3A.2.

The user sets the permission for the restricted discovery using application layer mechanisms.

1-3. If the Discoveree UE is authorised to use Model B discovery in the serving PLMN, or if UE intends to use Model B discovery using WLAN-based PC5 and is triggered by the application client to perform a Discoveree Request procedure, the UE shall establish a secure connection to the ProSe Function in the HPLMN and send a Discovery Request (RPAUID, UE Identity, command, Discovery Type, Discovery Model, Application ID, Discovery Entry ID, PC5_tech) message.

After ProSe Function check the authorization, the ProSe Function in HPLMN shall allocate and respond with a Discovery Response (Discovery Model, ProSe Response Code, Discovery Query Filter(s), validity timer, Discovery Entry ID, PC5_tech) message.

3a. After the ProSe Function in HPLMN responds to the Discoveree UE with a Discovery Response (Discovery Model, ProSe Response Code, Discovery Query Filter(s), validity timer, Discovery Entry ID, PC5_tech) message.The ProSe Function in HPLMN sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR for Discoveree UE is generated by the CDF in HPLMN where event represents Model B restricted discovery.

3b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].4. The UE may then obtain the radio resources as authorised and configured by E-UTRAN for ProSe as defined in RAN specifications, or use WLAN or both, to monitor using the Discovery Query Filter(s).

Figure 5.2.2.1.5.2: Discoveree UE procedures for Model B restricted discovery (roaming/Inter-PLMN transmission)

More details and complete message flow of Discoveree UE procedures for Model B restricted discovery (roaming/inter-PLMN transmission) are defined in TS 23.303 [238] clause 5.3.3A.3.

0-4. These steps are defined in TS 23.303[238].

4a. After the ProSe Function of the VPLMN or Local PLMN responds to Discovery Request from the ProSe Function of HPLMN, the ProSe Function of the VPLMN or Local PLMN sends Charging Data Request[Event] to CDF in VPLMN or Local PLMN. The PF-DD-CDR is generated for Discoveree UE where Event represents Model B restricted discovery.

4b. The CDF in VPLMN or Local PLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

5. The ProSe Function in HPLMN shall respond with a Discovery Response (Discovery Model, ProSe Response Code, Discovery Query Filter(s), validity timer, Discovery Entry ID, PC5_tech) message.

5a. After the ProSe Function in the HPLMN responds with a Discovery Response (Discovery Model, ProSe Response Code, Discovery Query Filter(s), validity timer, Discovery Entry ID, PC5_tech) message, the ProSe Function sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR is generated for Discoveree UE where Event represents Model B restricted discovery.

5b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

6. The UE may then obtain the radio resources as authorised and configured by E-UTRAN for ProSe as defined in RAN specifications, or use WLAN or both, to monitor using the Discovery Query Filter.

Figure 5.2.2.1.5.3: Discoverer UE procedures for Model B restricted discovery (non-roaming)

More details and complete message flow of Discoverer UE procedures for Model B restricted discovery (non-roaming) are defined in TS 23.303 [238] clause 5.3.3A.4.

0. In this step, the application client in the UE retrieves its own PDUID and provides it to the ProSe Application Server.

1-4. If the Discoverer UE is authorised to use Model B discovery in the serving PLMN and is triggered by the application client to perform a Discoverer Request procedure, the UE shall establish a secure connection to the ProSe Function in the HPLMN and send a Discovery Request (RPAUID, UE Identity, command, Discovery Type, Discovery Model, Application ID, Application Transparent Container, Discovery Entry ID, PC5_tech) message. Based on the Target ProSe Discovery UE ID, Application ID, and Target Restricted ProSe App User ID, the ProSe Function locates the Discoveree UE(s) context, and responds with a Discovery Response (ProSe Query Code(s), ProSe Response Code, validity timer).

4a. After the ProSe Function of the other PLMN responds to Discovery Request (Restricted ProSe App User ID, UE Identity, Target ProSe Discovery UE ID, Application ID, Target Restricted ProSe App User ID, Discovery Entry ID, PC5_tech) from the ProSe Function of HPLMN.The ProSe Function in other PLMN sends Charging Data Request[Event] to CDF in other PLMN. The PF-DD-CDR for Discoverer UE is generated by the CDF in other PLMN where event represents Model B restricted discovery.

4b. The CDF in other PLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

5. The ProSe Function in the HPLMN shall respond with a Discovery Response (Discovery Model, ProSe Query Code(s), Discovery Response Filter(s) validity timer, PC5_tech) message.

5a. After the ProSe Function in HPLMN responds to the Discoverer UE with a Discovery Response (Discovery Model, ProSe Query Code(s), Discovery Response Filter(s) validity timer, PC5_tech) message.The ProSe Function in HPLMN sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR for Discoverer UE is generated by the CDF in HPLMN where event represents Model B ristricted discovery.

5b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

6. The UE may then obtain the radio resources as authorised and configured by E-UTRAN for ProSe as defined in RAN specifications, or use WLAN or both, to announce the ProSe Query Code.

Figure 5.2.2.1.5.4: Discoverer UE procedures for Model B restricted discovery (roaming/inter-PLMN transmission)

More details and complete message flow of Discoverer UE procedures for Model B restricted discovery (roaming/inter-PLMN transmission) are defined in TS 23.303 [238] clause 5.3.3A.5.

0-4. These Steps are defined in TS 23.203 [238].

4a. After the ProSe Function of the other PLMN responds to Discovery Request from the ProSe Function of HPLMN.The ProSe Function in other PLMN sends Charging Data Request[Event] to CDF in other PLMN. The PF-DD-CDR for Discoverer UE is generated by the CDF in the other PLMN where event represents Model B restricted discovery.

4b. The CDF in other PLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

5-6. The ProSe Function in the HPLMN shall inform the ProSe Function in VPLMN or Local PLMN if Announcing PLMN ID is included in step 1 with the Announce Authorisation (Restricted ProSe Application User ID, Application ID, ProSe Query Code(s), validity timer, UE Identity, Discovery Entry ID, PC5_tech) message. The ProSe Function in VPLMN or Local PLMN authorizes the UE to perform ProSe Direct Discovery announcing.

7. The ProSe Function in the HPLMN shall respond with a Discovery Response (Discovery Model, ProSe Query Code(s), Discovery Response Filter(s) validity timer, PC5_tech) message.

7a. After the ProSe Function of HPLMN responds to Discovery Request from UE.The ProSe Function in HPLMN sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR for Discoverer UE is generated by the CDF in the HPLMN where event represents Model B restricted discovery.

7b. The CDF in other PLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

8. The UE may then obtain the radio resources as authorised and configured by E-UTRAN for ProSe as defined in RAN specifications, or use WLAN or both, to announce the ProSe Query Code.

5.2.2.1.6 Message flow for Discovery reporting – Model B procedures

Figure 5.2.2.1.6.1: Match Report procedure for Model B restricted discovery (non-roaming)

More details and complete message flow of Discoverer UE Match Report procedures for Model B restricted discovery (non-roaming) are defined in TS 23.303 [238] clause 5.3.4A.1.

1-5. When the Discoverer UE has received a ProSe Response Code over the air that matches the Discovery Response Filter it obtained from Discoverer Request procedure, and if the UE does not have a corresponding RPAUID associated with it with a valid TTL, the UE sends a Match Report (RPAUID, UE Identity, Discovery Type, Application ID, ProSe Response Code, Metadata Requested, PC5_tech) message to the ProSe Function in the HPLMN to get the Target RPAUID. The ProSe Function in HPLMN returns a Match Report Acknowledgement (Application ID, Target RPAUID, validity timer, metadata (optional)) message to the UE.

5a. After the ProSe Function of the HPLMN responds to Match Report Request from the UE.The ProSe Function in HPLMN sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR for Discoverer UE is generated by the CDF in other PLMN where event represents Model B restricted discovery reporting.

5b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

6. The ProSe Function in HPLMN may optionally send a Match Report Info (RPAUID, Target RPAUID, UE Identity, ProSe Response Code, Discovery Type, PC5_tech) to the ProSe Function of the Discoveree UE.

Figure 5.2.2.1.6.2: Match Report procedure for Model B restricted discovery (roaming/Inter-PLMN transmission)

More details and complete message flow of Discoverer UE Match Report procedures for Model B restricted discovery (roaming/inter-PLMN transmission) are defined in TS 23.303 [238] clause 5.3.4A.2.

1-5. These Steps are defined in TS 23.203 [238].

5a. After the ProSe Function of the HPLMN responds to Match Report Request from the UE.The ProSe Function in HPLMN sends Charging Data Request[Event] to CDF in HPLMN. The PF-DD-CDR for Discoverer UE is generated by the CDF in HPLMN where event represents Model B restricted discovery reporting.

5b. The CDF in HPLMN returns Charging Data Response corresponding to the received Charging Data Request[Event].

6. The ProSe Function in HPLMN may optionally send a Match Report Info (RPAUID, Target RPAUID, UE Identity, ProSe Response Code, Discovery Type, PC5_tech) to the ProSe Function of the Discoveree UE.

5.2.2.1.7 Message flow for ProSe Direct Discovery for Public Safety use when the UE is under coverage

Figure 5.2.2.1.7: Offline Charging for ProSe Direct Discovery for Public Safety use (under coverage)

Figure 5.2.2.1.x depicts the message flow for event based charging for ProSe Direct Discovery for Public Safety use. More details and the completed message flow for ProSe Direct Discovery for Public Safety use are defined in TS 23.303[238] clause 5.3.7. Both UE-1 and UE-2 can decide that reporting criteria are met and trigger the usage reporting procedure.

1. UE-1 sends announcement message with model A or solicitation message with model B. In the latter case, UE 2 sends a response message.

2. When the UE-1 decides that reporting criteria are met, according to the pre-configuration, the UE creates the corresponding usage information report.

3. UE-1 triggers the usage reporting procedure by sending the usage information report to the ProSe Function.

4. Upon reception of ProSe Direct Discovery for Public Safety use usage information report, the ProSe Function triggers the Charging Data Request[Event]. The ProSe Function sends the Charging Data Request[Event] to the corresponding CDF.

5. The CDR (PF-DD-CDR) for ProSe Direct Discovery for Public Safety use is generated by CDF for the UE-1.6. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

7. If the announcing radio resource info included in the usage information indicates the PLMN of the radio resource UE-1 used to announce is not the HPLMN, HPLMN ProSe Function shall send the usage information report to the ProSe Function of the PLMN providing the radio resource.

8. Upon reception of ProSe Direct Discovery for Public Safety use usage information report, the ProSe Function triggers the Charging Data Request[Event] . The ProSe Function sends the Charging Data Request[Event] to the corresponding CDF.

9. The CDR (PF-DD-CDR) for ProSe Direct Discovery for Public Safety use is generated by CDF for the UE-1.

10. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

5.2.2.1.8 Message flow for ProSe Direct Discovery for Public Safety use when the UE is out of coverage

Figure 5.2.2.8.y: Offline Charging for ProSe Direct Discovery for Public Safety use (out of coverage)

Both UE-1 and UE-2 can decide that reporting criteria are met and trigger the usage reporting procedure.

1. UE-1 sends announcement message with model A or solicitation message with model B. In the latter case, UE 2 sends a response message.

2. When the UE-1 decides that reporting criteria are met, according to the pre-configuration, the UE creates the corresponding usage information report.

3. The UE-1 stores the usage information, when the UE-1 is out of E-UTRAN coverage and has no connection to the HPLMN ProSe Function.

NOTE : The usage information is stored in a secure environment in the UE-1.

4. When the UE-1 comes back to E-UTRAN coverage, it will trigger the reporting of the usage information.

5. UE-1 triggers the usage reporting procedure by sending the usage information report to the ProSe Function.

6. Upon reception of ProSe Direct Discovery for Public Safety use usage information report, the ProSe Function triggers the Charging Data Request[Event] . The ProSe Function sends the Charging Data Request[Event] to the corresponding CDF.

7. The CDR (PF-DD-CDR) for ProSe Direct Discovery for Public Safety use is generated by CDF for the UE-1.8. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

9. If the announcing radio resource info included in the usage information indicates the PLMN of the radio resource UE-1 used to announce is not the HPLMN, HPLMN ProSe Function shall send the usage information report to the ProSe Function of the PLMN providing the radio resource.

10. Upon reception of ProSe Direct Discovery for Public Safety use usage information report, the ProSe Function triggers the Charging Data Request[Event] . The ProSe Function sends the Charging Data Request[Event] to the corresponding CDF.

11. The CDR (PF-DD-CDR) for ProSe Direct Discovery for Public Safety use is generated by CDF for the UE-1.

12. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

5.2.2.2 Offline charging message flow for ProSe EPC-level Discovery

5.2.2.2.1 Triggers for charging events

When a charging event is reported to the CDF, it includes details related to the services provided, e.g. the EPUID, ALUID, Application ID, window, Range, location of the UE, and the reasons for triggering the event, e.g. due to Proximity Alert, or timeout of window, user request, etc.

The Proximity Request event is triggered when a ProSe Function responds to the first Proximity Request from a UE or another ProSe Function, with the Proximity Request Ack message. The Proximity Request event for a UE triggers a Charging Data Request[Start] message towards the CDF, and the subsequent Proximity Request for the same ALUID , i.e. Proximity Request Renewal event, triggers a Charging Data Request[Interim] message to the CDF. A Proximity Request Reject event, which is triggered by the ProSe Function responding a Proximity Request Reject to a Proximity Request, shall trigger a Charging Data Request[Stop] message to the CDF.

The Proximity Request Cancellation event is triggered when a ProSe Function responds to a Cancel Proximity Request from a UE or another ProSe Function, with the Proximity Request Cancellation or Cancel Proximity Request Ack message, or a Proximity Request expires. Proximity Request Cancellation event triggers a Charging Data Request[Stop] message to the CDF. It shall indicate if a Proximity Alert has been triggered for the UE.

Table 5.2.2.2.1.1 presents a summary of the messages from the ProSe Function and the triggering conditions.

Table 5.2.2.2.1.1: Triggers for charging events in ProSe EPC-level Discovery

Message	Triggering conditions
Charging Data Request [Start]	ProSe Function responded with Proximity Request Ack to the first Proximity Request for a UE.
Charging Data Request [Interim]	ProSe Function responded with Proximity Request Ack to the renewal Proximity Requests for a UE.
Charging Data Request [Stop]	ProSe Function responded with Proximity Request Reject to the Proximity Request for a UE; or ProSe Function responded with Proximity Request Cancellation or Cancel Proximity Request Ack to the Cancel Proximity Request for a UE, or a Proximity Request expires.

5.2.2.2.2 Message flow for ProSe EPC-level Discovery Proximity Request

ProSe EPC-level Discovery Proximity Request allows a ProSe-enabled UE A to request the network to assist it detecting if UE B is in proximity using architecture specified in Figure 4.1.2, where UE A and UE B are using subscription from different networks. Upon this procedure, Charging Data Request is triggered for UE A and UE B, after the respective ProSe Function responded to the Proximity Request message.

Figure 5.2.2.2.2.1 depicts the message flow for ProSe EPC-level Discovery Proximity Request.

Figure 5.2.2.2.2.1: Message flow for ProSe EPC-level Discovery Proximity Request

1 – 7b. These steps are defined in TS 23.303 [238] clause 5.5.5.

7c. After the ProSe Function B responded to ProSe Function A, the ProSe Function B triggers Charging Data Request[Start/Interim/Stop] according to the conditions specified in clause 5.2.2.2.1 to the corresponding CDF B, where the charging event represents Proximity Request.

7d. The ProSe EPC-level Discovery CDR (PF-ED-CDR) is opened/updated/closed for UE B, according to the Charging Data Request.

7e. The CDF B returns Charging Data Response corresponding to the received Charging Data Request.

8a – 8b. These steps are defined in TS 23.303 [238] clause 5.5.5.

8c. After the ProSe Function A responded to UE A, the ProSe Function A triggers Charging Data Request[Start/Interim/Stop] according to the conditions specified in 5.2.2.2.1 to the corresponding CDF A, where the charging event represents Proximity Request.

8d. The ProSe EPC-level Discovery CDR (PF-ED-CDR) is opened/updated/closed for UE A.

8e. The CDF A returns Charging Data Response corresponding to the received Charging Data Request.

5.2.2.2.3 Message flow for ProSe EPC-level Discovery Proximity Request Cancellation

ProSe EPC-level Discovery Proximity Request cancellation is triggered by either the UE or network. It is cancels the proximity detection for a particular pair of UEs, e.g. UE A and UE B. Therefore, upon this procedure, Charging Data Request[Stop] is triggered for UE A and UE B, after the respective ProSe Function responded to the Cancel Proximity Request message.

Figure 5.2.2.2.3.1 depicts the message flow for ProSe EPC-level Discovery Proximity Request Cancellation.

Figure 5.2.2.2.3.1: Message flow for ProSe EPC-level Discovery Proximity Request Cancellation

1 – 5. These steps are defined in TS 23.303 [238] clause 5.5.9.

5a. After the ProSe Function B sends a Cancel Proximity Request Ack to the ProSe Function A, the ProSe Function B triggers Charging Data Request[Stop] to the corresponding CDF B, where the event represents Proximity Request Cancellation. This shall also indicate if a Proximity Alert has been sent to UE B.

5b. The corresponding ProSe EPC-level Discovery CDR (PF-ED-CDR) is closed for UE B.

5c. The CDF B returns Charging Data Response corresponding to the received Charging Data Request.

6. This step is defined in TS 23.303 [238] clause 5.5.9.

6a. After the ProSe Function A sends a Proximity Request Cancellation to the UE A, the ProSe Function A triggers Charging Data Request[Stop] to the corresponding CDF A, where the charging event represents Proximity Request Cancellation. This shall also indicate if a Proximity Alert has been sent to UE A.

6b. The corresponding ProSe EPC-level Discovery CDR (PF-ED-CDR) is closed for UE A.

6c. The CDF A returns Charging Data Response corresponding to the received Charging Data Request.

5.2.2.3 Offline charging message flow for ProSe Direct Communication

5.2.2.3.1 Triggers for charging events at ProSe Function

5.2.2.3.1.1 Triggers for charging events at ProSe Function for event based charging

This reporting is achieved by sending Charging Data Request[event] from the ProSe Function to the CDF.

The Received Direct Communication Usage Report event for a group is triggered by the ProSe Function receiving a usage information report from the UE for the group over PC3. The ProSe Function goes through the reported usage information, and if it contains valid ProSe Direct Communication usage data for a specific group, the ProSe Function sends the events to the CDF, which triggers the generation of the PF-DC-CDR for a specific group. It is possible that a single UE usage information report triggers multiple Received Direct Communication Usage Report events, each for a particular group.

The Received Direct Communication Usage Report event for the one-to-one communication is triggered by the ProSe Function receiving a usage information report from the UE for the one-to-one communiction over PC3 and from the ProSe UE-to-Network relay UE for the one-to-one communication via UE-Network relay. The Prose Function goes through the reported usage information, and if it contains valid ProSe Direct Communication usage data for the one-to-one communication, the ProSe Function sends the events to the CDF, which triggers the generation of the PF-DC-CDR for the one-to-one communication.

The ProSe charging operation flows in the following subclauses are based on the above triggers and the procedures defined in TS 23.303 [238].

5.2.2.3.1.2 Triggers for charging events at ProSe Function for session based charging

The ProSe Function may be configured to use session based charging in order to reduce the number of CDRs generated.

The Charging Data Request[Start] is sent when the ProSe Function receives a Received Direct Communication Usage Report event, and there is no open charging session for the group communication and one-to-one communication including the UE-Network-relay

The Charging Data Request[Interim] is sent when the ProSe Function receives a Received Direct Communication Usage Report event, and there is an open charging session for the group communication and one-to-one communication including the UE-Network-relay.

The Charging Data Request[Stop] is sent when the ProSe Function decides one of the following conditions is met:

– operator configured maximum number of reports, or

– operator configured maximum time limit.

5.2.2.3.2 Message flow for ProSe one-to-many Direct Communication when the UE is under coverage of E-UTRAN (event based)

Figure 5.2.2.3.2.1 depicts the message flow for ProSe one-to-many Direct Communication for non-roaming and roaming case, when UE is under coverage of E-UTRAN.

Figure 5.2.2.3.2.1: Offline Charging for ProSe one-to-many Direct Communication

1. The ProSe Function in HPLMN configures the UE on the usage information collection and reporting using the Service authorization and provisioning mechanism defined in TS 23.303 [238]. The configuration parameters are delivered as defined in TS 24.333 [241].

This step is optional, as the UE can be pre-configured with the corresponding information.

2-3. UE performs one-to-many Direct Communication as defined in TS 23.303 [238].

4. When the UE decides that reporting criteria are met, according to the configuration in step 1, and the connection to the ProSe Function is available, the UE triggers the usage reporting procedure.

NOTE 1: The UE has a connection to the HPLMN ProSe Function when any PDN Connection is available, as specified in TS 23.303 [238].

5. UE sends the usage information report to the ProSe Function, according to the configuration in step 1.

When the usage information report in step 5 includes information for multiple groups, step 6 to 8 are repeated for each of the group.

6. Upon reception of direct communication usage information report, the ProSe Function triggers the Charging Data Request[Event] . The ProSe Function sends the Charging Data Request[Event] to the corresponding CDF.

7. The ProSe one-to-many Direct Communication for Public Safety use CDR (PF-DC-CDR) for the group is generated by CDF for the UE.

8. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

NOTE 2: The delivery of the charging data to the VPLMN in roaming case is handled outside of 3GPP.

NOTE 3: The procedure applies to UE1 to UE3 independently, i.e. each of the UE sends the respective usage information reports about the group communication to the network using either the under coverage procedure or out of coverage procedure.

5.2.2.3.3 Message flow for ProSe one-to-many Direct Communication when the UE is out of coverage of E-UTRAN (event based)

Figure 5.2.2.3.3.1 depicts the message flow for ProSe one-to-many Direct Communication for non-roaming and roaming case, when UE is out of coverage of E-UTRAN.

Figure 5.2.2.3.3.1: Offline Charging for ProSe one-to-many Direct Communication (out of coverage)

1. When the UE is out of coverage of the E-UTRAN, it makes use of the pre-configured resources in USIM or ME for the ProSe one-to-many Direct Communication for public safety use. The mechanism to decide on the resources to use is defined in TS 23.303 [238].

2-3. UE performs one-to-many Direct Communication as defined in TS 23.303 [238].

4. When the UE decides that reporting criteria are met, according to the pre-configuration, the UE create the corresponding usage information report.

5. The UE stores the usage information, when the UE is out of E-UTRAN coverage and has no connection to the HPLMN ProSe Function.

NOTE 1: The usage information is stored in a secure environment in the UE.

6. When the UE comes back to E-UTRAN coverage, it will trigger the reporting of the usage information.

7. UE sends the usage information report to the ProSe Function, according to the pre-configuration or new configuration from the HPLMN ProSe Function.

When the usage information report in step 7 includes information for multiple groups, step 8 to 10 are repeated for each of the group. When the usage information report in step 7 includes multiple reports for a group, e.g. the UE has been out of coverage for a long time, step 8 to 10 are repeated for each of the report.

8. Upon reception of direct communication usage information report, the ProSe Function triggers the Charging Data Request[Event] for each of the group in the report. The ProSe Function sends the Charging Data Request[Event] to the corresponding CDF.

9. The ProSe one-to-many Direct Communication for Public Safety use CDR (PF-DC-CDR) for the group is generated by CDF for the UE.

10. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

NOTE 2: The procedure applies to UE1 to UE3 independently, i.e. each of the UE sends the respective usage information reports about the group communication to the network using either the under coverage procedure or out of coverage procedure.

5.2.2.3.4 Message flow for ProSe one-to-many Direct Communication when the UE is under coverage of E-UTRAN (session based)

Figure 5.2.2.3.4.1 depicts the message flow for session based charging for ProSe one-to-many Direct Communication for non-roaming and roaming case, when UE is under coverage of E-UTRAN.

Figure 5.2.2.3.4.1: Offline Charging for ProSe one-to-many Direct Communication
(under coverage, session based charging)

This step is optional, as the UE can be pre-configured with the corresponding information.

2-3. UE performs one-to-many Direct Communication as defined in TS 23.303 [238].

4. When the UE decides that reporting criteria are met, according to the configuration in step 1, and the connection to the ProSe Function is available, the UE triggers the usage reporting procedure.

NOTE 1: The UE is provided a connection to the HPLMN ProSe Function as specified in TS 23.303 [238].

5. UE sends the usage information report to the ProSe Function, according to the configuration in step 1.

When the usage information report in step 5 includes information for multiple groups, step 6 to 8 are repeated for each of the group.

6. If the ProSe Function is configured to use session based charging, upon reception of direct communication usage information report for a group, the ProSe Function triggers the Charging Data Request[Start] when there is no open charging session for the group, according to 5.2.2.3.1.2. The ProSe Function sends the Charging Data Request[Start] to the corresponding CDF, and starts a charging session for the group.

7. The ProSe one-to-many Direct Communication for Public Safety use CDR (PF-DC-CDR) for the group is opened by CDF for the UE.

8. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

9. UE triggers the usage reporting procedure when the reporting criteria are met.

10. UE sends the usage information report to the ProSe Function.

When the usage information report in step 10 includes information for multiple groups, step 11 to 13 are repeated for each of the group.

11. If there is a charging session for the group, upon reception of direct communication usage information report for the group, the ProSe Function triggers the Charging Data Request[Interim], according to clause 5.2.2.3.1.2. The ProSe Function sends the Charging Data Request[Interim] to the corresponding CDF.

12. The ProSe one-to-many Direct Communication for Public Safety use CDR (PF-DC-CDR) for the group is updated by CDF for the UE.

13. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

NOTE 2: Step 9 to 13 may happen multiple times before step 14.

14. UE triggers the usage reporting procedure when the reporting criteria are met.

15. UE sends the usage information report to the ProSe Function.

When the usage information report in step 15 includes information for multiple groups, step 16 to 18 are repeated for each of the group.

16. The ProSe Function decides that the charging session should be closed, according to clause 5.2.2.3.1.2, and triggers the Charging Data Request[Stop]. The ProSe Function sends the Charging Data Request[Stop] to the corresponding CDF.

17. The ProSe one-to-many Direct Communication for Public Safety use CDR (PF-DC-CDR) for the group is closed by CDF for the UE.

18. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

5.2.2.3.5 Message flow for ProSe one-to-many Direct Communication when the UE is out of coverage of E-UTRAN (session based)

Figure 5.2.2.3.5.1 depicts the message flow for session based charging for ProSe one-to-many Direct Communication for non-roaming and roaming case, when UE is out of coverage of E-UTRAN.

Figure 5.2.2.3.5.1: Offline Charging for ProSe one-to-many Direct Communication
(out of coverage, session based)

2-3. UE performs one-to-many Direct Communication as defined in TS 23.303 [238].

4. When the UE decides that reporting criteria are met, according to the pre-configuration, the UE create the corresponding usage information report.

5. The UE stores the usage information, when the UE is out of E-UTRAN coverage and has no connection to the HPLMN ProSe Function.

NOTE 1: The usage information is stored in a secure environment in the UE.

6. When the UE comes back to E-UTRAN coverage, it will trigger the reporting of the usage information.

7. UE sends the usage information report to the ProSe Function, according to the pre-configuration or new configuration from the HPLMN ProSe Function.

When the usage information report in step 7 includes information for multiple groups, step 8 to 10 are repeated for each of the group.

8. If the ProSe Function is configured to use session based charging, upon reception of direct communication usage information report for a group, the ProSe Function triggers the Charging Data Request[Start] when there is no open charging session for the group, according to clause 5.2.2.3.1.2. The ProSe Function sends the Charging Data Request[Start] to the corresponding CDF, and starts a charging session for the group.

9. The ProSe one-to-many Direct Communication for Public Safety use CDR (PF-DC-CDR) for the group is opened by CDF for the UE.

10. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

When the usage information report in step 7 includes multiple reports for a group, e.g. the UE has been out of coverage for a long time, step 12 to 14 and 16 to 18 may be triggered without step 11 or 15.

11. UE sends the usage information report to the ProSe Function when the reporting criteria are met.

When the usage information report in step 11 includes information for multiple groups, step 12 to 14 are repeated for each of the group.

12. If there is a charging session for the group, upon reception of direct communication usage information report for the group, the ProSe Function triggers the Charging Data Request[Interim], according to clause 5.2.2.3.1.2. The ProSe Function sends the Charging Data Request[Interim] to the corresponding CDF.

13. The ProSe one-to-many Direct Communication for Public Safety use CDR (PF-DC-CDR) for the group is updated by CDF for the UE.

14. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

15. UE sends the usage information report to the ProSe Function when the reporting criteria are met.

When the usage information report in step 15 includes information for multiple groups, step 16 to 18 are repeated for each of the group.

17. The ProSe one-to-many Direct Communication for Public Safety use CDR (PF-DC-CDR) for the group is closed by CDF for the UE.

18. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

5.2.2.3.6 Message flow for Direct communication via ProSe UE-to-Network Relay(event based)

A ProSe UE-to-Network Relay capable UE may attach to the network (if it is not already connected) and connect to a PDN connection enabling the necessary relay traffic, or it may need to connect to additional PDN connection(s) in order to provide relay traffic towards Remote UE(s). PDN connection(s) supporting UE-to-Network Relay shall only be used for Remote ProSe UE(s) relay traffic.

Figure 5.2.2.3.6. 1: Offline Charging for Direct Communication via ProSe UE-to-Network Relay

More details and complete message flow of ProSe UE-to-Network Relay procedures are defined in TS 23.303 [238] clause 5.4.4.

1-4. These steps are the same as message flow for ProSe UE-to-Network Direct Communication in figure 5.4.4.1-1 of TS 23.303[238].

5. The ProSe UE-to-Network Relay sends a Remote UE Report (Remote User ID, IP info) message to the MME for the PDN connection associated with the relay. The MME forwards the Remote UE Report message to the S-GW and S-GW forwards the message to the P-GW of the UE-to-Network Relay UE.

6. When remote UE decides that reporting criteria are met according to the configuration, the Remote UE triggers the usage reporting procedure and creates the corresponding usage information report.

7. The Remote UE sends the usage reporting to ProSe UE-to-Network Relay UE.

8. When the ProSe UE-to-Network Relay decides that reporting criteria are met according to the configuration, and the connection to the ProSe Function is available, the ProSe UE-to-Network Relay triggers the usage reporting procedure and creates the corresponding usage information report.

9. ProSe UE-to-Network Relay sends the usage reporting to ProSe Function.

NOTE 1: Step 8 and Step 9 can occur before Step 6 and Step 7.

10. The ProSe Function triggers the Charging Data Request[Event]. The ProSe Function sends the Charging Data Request[Event] to the corresponding CDF.

11. The ProSe Direct communication via UE-to-Network Relay use CDR (PF-DC-CDR) is generated by CDF for the Remote UE.

12. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

5.2.2.3.7 Message flow for ProSe one-to-one direct communication when the UE is under coverage (event based)

Figure 5.2.2.3.7.1: Offline Charging for ProSe one-to-one Direct Communication (under coverage)

Figure 5.2.2.3.7.1 depicts the message flow for event based charging for ProSe one-to-one Direct Communication. More details and the completed message flow for ProSe one-to-one Direct Commnication are defined in TS 23.303[238] clause 5.4.5.

1.UE-1 sends a Direct Communication Request message to UE-2 in order to trigger mutual authentication.

2-3. UE-2 initiates the procedure for mutual authentication. The successful completion of the authentication procedure completes the establishment of the secure layer-2 link over PC5 and then UE performs one-to-one Direct Communication.

4. UE-1 sends a Disconnect Request message to UE-2 in order to release the layer-2 link and deletes all context data associated with.

5. Upon reception of the Disconnect Request message UE-2 responds with a Disconnect Response message and deletes all context data associated with the layer-2 link.

6. When the UE-1 decides that reporting criteria are met, according to the pre-configuration, the UE creates the corresponding usage information report.

NOTE 1: Both UE-1 and UE-2 can decide that reporting criteria are met and trigger the usage reporting procedure.

7. Upon reception of the Disconnect Response from UE-2, the UE-1 triggers the usage reporting procedure.UE-1 sends the usage information report to the ProSe Function.

8. Upon reception of Direct Communication usage information report, the ProSe Function triggers the Charging Data Request[Event] . The ProSe Function sends the Charging Data Request[Event] to the corresponding CDF.

NOTE 2: The step 6 can occur before step 4 and 5.

9. The ProSe one-to-one Direct Communication for Public Safety use CDR (PF-DC-CDR) is generated by CDF for the UE-1 and UE-2.

10. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

5.2.2.3.8 Message flow for ProSe one-to-one direct communication when the UE is out of coverage (event based)

Figure 5.2.2.3.8.1: Offline Charging for ProSe one-to-one Direct Communication (out of coverage)

1-5. These steps are the same as offline charging for ProSe one-to-one Direct Communication in figure 5.2.2.3.8.1.

6. When the UE-1 decides that reporting criteria are met, according to the pre-configuration, the UE-1 creates the corresponding usage information report.

7. The UE-1 stores the usage information, when the UE-1 is out of E-UTRAN coverage and has no connection to the HPLMN ProSe Function.

NOTE 1: The usage information is stored in a secure environment in the UE-1.

8.When the UE-1 comes back to E-UTRAN coverage, it will trigger the reporting of the usage information.

NOTE 2: Both UE-1 and UE-2 can decide that reporting criteria, store the usage information and trigger the reporting when out of coverage.

9-12. These steps are the same as the step 7-10 offline charging for ProSe one-to-one Direct Communication in figure 5.2.2.3.8.1.

5.2.2.3.9 (Void)

5.2.2.3.10 Message flow for ProSe one-to-one Direct Communication when the UE is under coverage (session based)

Figure 5.2.2.3.10-1: Offline Charging for ProSe one-to-one Direct Communication (under coverage)

Figure 5.2.2.3.10-1 depictes the message flow for session based charging for ProSe one-to-one Direct Communication. More details and the completed message flow for ProSe one-to-one Direct Commnication are defined in TS 23.303[238] clause 5.4.5. Both UE-1 and UE-2 can decide that reporting criteria are met and trigger the usage reporting procedure.

1-3. These steps are the same as offline charging for ProSe one-to-one Direct Communication in figure 5.2.2.3.7.1.

4. When the UE decides that reporting criteria are met, according to the configuration, and the connection to the ProSe Function is available, the UE triggers the usage reporting procedure.

5. UE sends the usage information report to the ProSe Function, according to the configuration.

6. If the ProSe Function is configured to use session based charging, upon reception of one-to-one direct communication usage information report, the ProSe Function triggers the Charging Data Request[Start] when there is no open charging session for the session of one-to-one direct communication. The ProSe Function sends the Charging Data Request[Start] to the corresponding CDF, and starts a charging session.

7. The CDR for the ProSe one-to-one Direct Communication for Public Safety use is generated and opened by CDF for the UE.

8. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

9. UE triggers the usage reporting procedure when the reporting criteria are met.

10. UE sends the usage information report to the ProSe Function.

11. If there is a charging session for the session of one-to-one direct communication, upon reception of direct communication usage information report for the session, the ProSe Function triggers the Charging Data Request[Interim]. The ProSe Function sends the Charging Data Request[Interim] to the corresponding CDF.

12. The CDR for the ProSe one-to-one Direct Communication for Public Safety use is updated by CDF for the UE.

13. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

NOTE 1: The Step 11 to 13 may occur multiple times for update.

14. Upon reception of the Disconnect Request message UE2 responds with a Disconnect Response message and deletes all context data associated with the layer-2 link.

15. Upon reception of the Disconnect Response from UE-2, the UE-1 triggers the usage reporting procedure.UE1 sends the usage information report to the ProSe Function,

16. UE sends the usage information report to the ProSe Function.

NOTE 2: The Step 16 may occur before step 14 and step 15.

17. The ProSe Function decides that the charging session should be closed, and triggers the Charging Data Request[Stop]. The ProSe Function sends the Charging Data Request[Stop] to the corresponding CDF.

18. The CDR for the ProSe one-to-one Direct Communication for Public Safety use is closed by CDF for the UE.

19. The CDF returns Charging Data Response corresponding to the received Charging Data Request.

5.2.2.3.11 Message flow for ProSe one-to-one Direct Communication when the UE is out of coverage (session based)

Figure 5.2.2.3.11-1: Offline Charging for ProSe one-to-one Direct Communication (out of coverage)

Both UE-1 and UE-2 can decide that reporting criteria, stores the usage information and trigger the reporting when out of coverage.

1-3. These steps are the same as the steps 1-3 in offline charging for ProSe one-to-one Direct Communication in figure 5.2.2.3.7.1.

4.-6. These steps are the same as the steps 6-8 in offline charging for ProSe one-to-one Direct Communication in figure 5.2.2.3.8.1.

7-20. These steps are the same with the steps 5-8(Charging Data Request[Start] and Response), steps 10-13(Charging Data Request[Interim] and Response), steps 14-15(Disconnect procedure), step 16-19(Charging Data Request[Stop] and Response) in offline charging for ProSe one-to-one Direct Communication in figure 5.2.2.3.10-1.

NOTE: The Step 17 may occur before step 15 and step 16.