5.3.2 Ro message flows
32.2773GPPCharging managementProximity-based Services (ProSe) chargingRelease 17Telecommunication managementTS
5.3.2.1 Introduction
The flows described in the present document specify the exchange between the ProSe Function and the OCS for ProSe Services for different charging scenarios.
Debit Units Request message and Reserve Units Request message as defined in TS 32.299 [50] are used by the ProSe Function to transfer the collected charging information towards the OCS depending on which mode is used: Immediate Event Charging (IEC) mode or Event Charging with Unit Reservation (ECUR) respectively.
5.3.2.2 ProSe Direct Discovery
5.3.2.2.1 Triggers for online charging from ProSe Function for ProSe Direct Discovery
Table 5.3.2.2.1.1: Debit Units Request messages triggered for ProSe Function
in ProSe Direct Discovery
|
message |
Triggering conditions |
|
Debit Units Request[Event] |
After discovery authorization of receiving Direct Discovery Request After discovery authorization of receiving Match Report message After discovery authorization of Model B Restricted Discovery Request After discovery authorization of Model B Restricted Discovery Reporting |
5.3.2.2.2 Message flows for ProSe Direct Discovery Announce Request
Figures 5.3.2.2.2.1 to 5.3.2.2.2.3 define the transactions between ProSe Function and OCS for the successful scenario where an Announcing UE sends a Discovery request in IEC mode for non-roaming case and in IEC and ECUR modes for roaming case.
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 5.3.2.2.2.1: Message flow for ProSe Direct Discovery Announce Request (IEC for non-roaming)
0. The UE is configured with the data structure of the ProSe Application IDs corresponding to HPLMN. This step is performed using mechanisms that are out of scope of 3GPP.
1. If the UE is authorized to announce in HPLMN and is triggered to announce, it shall establish a secure connection with the ProSe Function and it shall send a Discovery Request message for announcing.
2. 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 of the validity timer.
3. ProSe function sends Debit Units Request[Event] indicating Announce to the OCS.
4. The OCS performs Debit Units Request operation for Announcing UE.
5. The OCS returns the Debit Units Response to ProSe Function.
6. If the Discovery Request is authorized, then the ProSe Function shall respond 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.
7. 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 5.3.2.2.2.2: Message flow for ProSe Direct Discovery Announce Request (IEC for roaming/inter-PLMN transmission)
0. The UE is configured with the data structure of the ProSe Application IDs corresponding to HPLMN. This step is performed using mechanisms that are out of scope of 3GPP.
1. The UE establishes a secure connection with the ProSe Function in HPLMN and then sends a Discovery Request message for announcing.
2. If there is no associated UE context, the ProSe Function shall check with HSS the authorization for discovery and, if necessary, create a new context for this UE that contains the subscription parameters for this UE for the duration of the validity timer.
3. ProSe Function sends Debit Units Request[Event] indicating Announce to the OCS.
4. The OCS performs Debit Units Request operation for Announcing UE.
5. The OCS returns the Debit Units Response to ProSe Function.
6. If the Discovery Request is authorized then the HPLMN ProSe Function shall request authorisation from the ProSe Function in VPLMN with the Announce Authorisation (ProSe Application ID, ProSe Application Code, UE Identity, PC5_tech) message.
7. The ProSe Function in VPLMN authorizes the UE to perform ProSe Direct Discovery announcing.
If the Discovery Request is not authorized, the optional refund steps 8 to 10 are required:
8. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
9. The OCS performs Debit Units Request operation for refund.
10. The OCS returns the Debit Units Response to ProSe Function.
11. The ProSe Function in HPLMN shall respond to the UE with a Discovery Response when step 7 is successful.
– (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.
12. The UE may start announcing the provided ProSe Application Code in the VPLMN 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.
Figure 5.3.2.2.2.3: Message flow for ProSe Direct Discovery Announce Request (ECUR for roaming/inter-PLMN transmission)
0-2. same as figure 5.3.2.2.3.2 step 0-2
3. ProSe Function sends Reserve Units Request[Initial, ProSe App ID, cmd = Announce, PC5_tech] to the OCS for requesting units.
4. The OCS performs Reserve Units Request operation for Announcing UE.
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-7. same as figure 5.3.2.2.3.2 step 6-7
8. ProSe Function sends Debit Units Request[Terminate] to the OCS indicating granted units are used. On unsuccessful Announce authorization, granted units are returned.
9. The OCS performs Debit Units operation.
10. The OCS returns the Debit Units Response to ProSe Function.
11-12. same as figure 5.3.2.2.3.2 step 11-12.
5.3.2.2.3 Message flows for ProSe Direct Discovery Monitor Request
Figures 5.3.2.2.3.1 to 5.3.2.2.3.4 describe the transactions between ProSe Function and OCS for the successful scenario where a "monitoring UE" sends a Discovery request and gets authorization to access the discovery resources.
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 5.3.2.2.3.1: ProSe Direct Discovery Monitor Request – IEC (non-roaming)
0. The UE is configured with the data structure of the ProSe Application IDs corresponding to PLMNs the UE is authorized to monitor.
1. If the UE is authorized to monitor in at least one PLMN and is interested to monitor certain ProSe Application ID(s), the UE sends a Discovery Request (ProSe Application ID(s), UE Identity, monitor command, application identity, PC5_tech) message for monitoring to the ProSe Function.
2. Interaction between ProSe Function and HSS for authorization process for discovery: check if UE is authorized for ProSe discovery service and for this Application ID, retrieval of PLMNs allowed for discovery. A new context for this UE is created if no associated UE context exists.
3. ProSe Function sends Debit Units Request[Event, ProSe App ID, cmd = Monitor, PC5_tech] to the OCS.
4. The OCS performs the Debit Units operation for Discovery Monitor Request.
5. The OCS returns the Debit Units Response to ProSe Function.
6. 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 and Discovery Entry ID, PC5_tech) message.
7. 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.
In case of unsuccessful scenario, the optional refund steps 8 to 10 are required:
8. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
9. The OCS performs Debit Units Request operation for refund.
10. The OCS returns the Debit Units Response to ProSe Function.
11. The ProSe Function responds with a Discovery Response [Discovery Filter, Discovery Entry ID, PC5_tech] message, when step 7 is successful.. The ProSe Function may use the service units granted in step 5 to determine the Time To Live value(s) of the Discovery Filter.
12. The UE may start monitoring using the Discovery Filter in the authorized radio resources, or using WLAN or both.
Figure 5.3.2.2.3.2: ProSe Direct Discovery Monitor Request – ECUR (non-roaming)
0-2. same as figure 5.3.2.2.3.1 step 0-2.
3. ProSe Function sends Reserve Units Request[Initial, ProSe App ID, cmd = Monitor] to the OCS for requesting units.
4. The OCS performs Reserve Units Request operation for Discovery Monitor Request.
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-7. same as figure 5.3.2.2.3.1 step 6-7.
8. ProSe Function sends Debit Units Request[Terminate] to the OCS indicating granted units are used. On unsuccessful Monitor Response, granted units are returned.
9. The OCS performs the Debit Units operation.
10. The OCS returns the Debit Units Response to ProSe Function.
11-12. same as figure 5.3.2.2.3.1 step 11-12.
Figure 5.3.2.2.3.3: ProSe Direct Discovery Monitor Request – IEC (roaming/inter-PLMN transmission)
0. The UE is configured with the data structure of the ProSe Application IDs corresponding to PLMNs the UE is authorized to monitor. This step is performed using mechanisms out of scope of 3GPP.
1. If the UE is authorized to monitor in at least one PLMN and is interested to monitor certain ProSe Application ID(s), it shall establish a secure connection with the ProSe Function in HPLMN and it shall send a Discovery Request (ProSe Application ID(s), UE Identity, Monitor command, application identity, PC5_tech) message for monitoring.
2. If there is no associated UE context, the ProSe Function shall check with HSS the authorization for discovery and, if necessary, create a new context for this UE that contains the subscription parameters for this UE for the duration the Discovery Filters will be valid.
3. ProSe Function sends Debit Units Request[Event,ProSe App ID, cmd = Monitor, PC5_tech] to the OCS.
4. The OCS performs the Debit Units operation for Discovery Monitor Request.
5. The OCS returns the Debit Units Response to ProSe Function.
6. The ProSe Function in HPLMN shall contact other PLMNs that are indicated by the ProSe Application ID(s) sent by the UE, in order to resolve the corresponding ProSe Application ID Name(s) to mask(s).
7. If the ProSe Function of the other PLMN stores valid ProSe Application Code(s) corresponding to the requested ProSe Application ID Name(s) and the requested PC5 radio technolog, then the ProSe Function of the Local PLMN returns the related ProSe Application mask(s) and the corresponding TTL for each.
In case of unsuccessful scenario, the optional refund steps 8 to 10 are required:
8. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
9. The OCS performs Debit Units Request operation for refund.
10. The OCS returns the Debit Units Response to ProSe Function.
11. The ProSe Function in the HPLMN responds with a Discovery Response message, in case step 7 is successful.
– Discovery Filter(s), Discovery Entry ID, PC5_tech message 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.
12. 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 specifications, or using WLAN or both.
Figure 5.3.2.2.3.4: ProSe Direct Discovery Monitor Request – ECUR (roaming/ inter-PLMN transmission)
0-2. same as figure 5.3.2.2.3.3 step 0-2.
3. ProSe Function sends Reserve Units Request[Initial, ProSe App ID, cmd = Monitor] to the OCS for requesting units.
4. The OCS grants service units in the Reserve Units Response to ProSe Function.
5-6. same as figure 5.3.2.2.3.3 step 5-6.
7. ProSe Function sends Debit Units Request[Terminate] to the OCS indicating granted units are used. On unsuccessful Monitor Response, granted units are returned.
8. The OCS returns the Debit Units Response to ProSe Function.
9-10. same as Figure 5.3.2.2.3.3 step 11-12.
5.3.2.2.4 Message flows for ProSe Direct Discovery Match Report Request
Figures 5.3.2.2.4.1 to 5.3.2.2.4.4 define the transactions between ProSe Function and OCS for the successful scenario where a "Monitoring UE" sends a Match report in non-roaming case and roaming case for IEC and ECUR modes.
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 5.3.2.2.4.1: Message flow for ProSe Direct Open Discovery Match Report Request (IEC for non-roaming)
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 to the ProSe Function in HPLMN.
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. ProSe Function sends Debit Units Request[Event] indicating "Match" to the OCS.
4. The OCS performs the Debit Units operation for "Match".
5. The OCS returns the Debit Units Response to ProSe Function.
6. 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 7-14 are executed, otherwise (i.e. the ProSe Application Code was assigned by HPLMN) only step 14 is executed:
7. 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.
8. The ProSe Function analyses the ProSe Application Code(s) received from the UE.
9. 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).
In case of unsuccessful scenario, the optional refund steps 10 to 12 are required:
10. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
11. The OCS performs Debit Units Request operation for refund.
12. The OCS returns the Debit Units Response to ProSe Function.
13. If it was indicated that the announcing UE is roaming during the Monitor Request process, the ProSe Function in HPLMN shall send a Match Report Info (ProSe Application ID(s), UE Identity, PC5_tech) to the ProSe Function of the serving PLMN of the Announcing UE.
14. The ProSe Function in HPLMN shall respond to the UE with Match Report Acknowledgment (ProSe Application ID(s), validity timer(s)).
Figure 5.3.2.2.4.2: Message flow for ProSe Direct Open Discovery Match Report Request
(ECUR for non-roaming)
1-2. same as figure 5.3.2.2.4.1 step 1-2.
3. ProSe Function sends Reserve Units Request[Initial, ProSe App ID, cmd = Match, PC5_tech] to the OCS for requesting units.
4. The OCS performs the Debit Units operation for "Match".
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-9. same as figure 5.3.2.2.4.1 step 6-9.
10. ProSe Function sends Debit Units Request[Terminate] to the OCS with granted units used. On unsuccessful Match Report, granted units are returned.
11. The OCS performs the Debit Units operation for "Match".
12. The OCS returns the Debit Units Response to ProSe Function.
13-14. same as figure 5.3.2.2.4.1 step 13-14.
Figure 5.3.2.2.4.3: Message flow for ProSe Direct Open Discovery Match Report Request (IEC for roaming/inter-PLMN transmission)
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), Discovery Filter ID(s), UE Identity, VPLMN ID, Monitored PLMN ID, PC5_tech) message to the ProSe Function in HPLMN.
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.
3. ProSe Function sends Debit Units Request[Event] indicating "Match" to the OCS.
4. The OCS performs the Debit Units operation for "Match".
5. The OCS returns the Debit Units Response to ProSe Function.
6. 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 7-14 are executed, otherwise (i.e. the HPLMN assigned the ProSe Application Code) only steps 14 is executed:
7. 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").
8. 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).
9. The ProSe Function shall send Match Report Acknowledgement (ProSe Application ID Name(s), validity timer(s)).
In case of unsuccessful scenario, the optional refund steps 10 to 12 are required:
10. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
11. The OCS performs Debit Units Request operation for refund.
12. The OCS returns the Debit Units Response to ProSe Function.
13. If it was indicated that the Announcing UE is roaming during the Monitor Request process, the ProSe Function in HPLMN shall send a Match Report Info (ProSe Application ID(s), UE Identity, PC5_tech) to the ProSe Function of the serving PLMN of the Announcing UE.
14. The ProSe Function in HPLMN shall respond to the UE with Match Report Acknowledgment (ProSe Application ID(s), validity timer(s)).
Figure 5.3.2.2.4.4: Message flow for ProSe Direct Open Discovery Match Report Request (ECUR for roaming/ inter-PLMN transmission)
1-2. same as figure 5.3.2.2.4.3 step 1-2.
3. ProSe Function sends Reserve Units Request[Initial, ProSe App ID, cmd = Match, PC5_tech] to the OCS for requesting units.
4. The OCS performs the Debit Units operation for "Match" Report Request.
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-9. same as figure 5.3.2.2.4.3 step 6-9.
10. ProSe Function sends Debit Units Request[Terminate] to the OCS with granted units used. On unsuccessful Match Report, granted units are returned.
11. The OCS performs the Debit Units operation for "Match".
12. The OCS returns the Debit Units Response to ProSe Function.
13-14. same as figure 5.3.2.2.4.3 step 13-14.
Figures 5.3.2.2.4.a to 5.3.2.2.4.d define the transactions between ProSe Function and OCS for the successful scenario where a "Monitoring UE" using ProSe direct restricted discovery model A sends a Match report in non-roaming case and roaming case for IEC and ECUR modes.
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 5.3.2.2.4.a: Message flow for Match Report of Restricted Discovery-model A(IEC for non-roaming)
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. ProSe Function sends Debit Units Request[Event] indicating "Restricted Match" to the OCS.
4. The OCS performs the Debit Units operation for "Restricted Match".
5. The OCS returns the Debit Units Response to ProSe Function.
6. The HPLMN ProSe Function analyses the ProSe Restricted Code and identifies in the UE context of the monitoring UE the corresponding Target RPAUID.
7. Optionally, the ProSe Function sends a Auth Request (RPAUID, Target RPAUID, Request Type) to the ProSe Application Server. The ProSe Function locates the ProSe Application Server based on the Application ID. The Request Type is set to "restricted discovery/match". If the Metadata Requested is included in the Match Report in step 1, the ProSe Function shall send the Auth Request message.
8. If, based on the permission setting, the RPAUID is allowed to discover the Target RPAUID, the ProSe Application Server returns a Auth Response (PDUID, Target PDUID, Response Type, metadata) message. The PDUID corresponds to RPAUID, the Target PDUID corresponds to the Target RPAUID stored in the ProSe Application Server. The Response Type is set to "restricted discovery/match ack". This message may also contain certain metadata corresponding to the Target PDUID, e.g. welcome message, etc.
9. The ProSe Function verifies that the returned PDUID belongs to the requesting UE, and the Target PDUID is the same as the stored Target PDUID.
In case of unsuccessful scenario, the optional refund steps 10 to 12 are required:
10. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
11. The OCS performs Debit Units Request operation for refund.
12. The OCS returns the Debit Units Response to ProSe Function.
13. The ProSe Function in HPLMN returns a Match Report Ack (Application ID, Target RPAUID, validity timer, metadata) to the UE. The UE stores the mapping between the RPAUID, the ProSe Restricted Code and the Application ID for the duration of the validity timer.
14. 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 of the announcing UE. Discovery Type is set to "restricted discovery".
Figure 5.3.2.2.4.b: Message flow for Match Report of Restricted Discovery-model A (ECUR for non-roaming)
1-2. same as figure 5.3.2.2.4.a step 1-2
3. ProSe Function sends Reserve Units Request [Initial, RPUID, cmd = Restricted Match, PC5_tech] to the OCS for requesting units.
4. The OCS performs the Debit Units operation for "Restricted Match".
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-9. same as figure 5.3.2.2.4.1 step 6-9.
10. ProSe Function sends Debit Units Request[Terminate] to the OCS with granted units used. On unsuccessful Match Report, granted units are returned.
11. The OCS performs the Debit Units operation for "Restricted Match".
12. The OCS returns the Debit Units Response to ProSe Function.
13-14. same as figure 5.3.2.2.4.a step 13-14.
Figure 5.3.2.2.4.c: Message flow for Match Report of Restricted Discovery-model A (ICE for roaming//inter-PLMN transmission)
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, Monitored PLMN ID, 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. ProSe Function sends Debit Units Request[Event] indicating "Restricted Match" to the OCS.
4. The OCS performs the Debit Units operation for "Restricted Match".
5. The OCS returns the Debit Units Response to ProSe Function.
6. The HPLMN ProSe Function analyses the ProSe Restricted Code and identifies in the UE context of the monitoring UE the corresponding Target RPAUID.
7. Optionally, the ProSe Function sends a Auth Request (RPAUID, Target RPAUID, Request Type) to the ProSe Application Server. The ProSe Function locates the ProSe Application Server based on the Application ID. The Request Type is set to "restricted discovery/match". If the Metadata Requested is included in the Match Report in step 1, the ProSe Function shall send the Auth Request message.
8. If, based on the permission setting, the RPAUID is allowed to discover the Target RPAUID, the ProSe Application Server returns a Auth Response (PDUID, Target PDUID, Response Type, metadata) message. The PDUID corresponds to RPAUID, the Target PDUID corresponds to the Target RPAUID stored in the ProSe Application Server. The Response Type is set to "restricted discovery/match ack". This message may also contain certain metadata corresponding to the Target PDUID, e.g. welcome message, etc.
9. The ProSe Function verifies that the returned PDUID belongs to the requesting UE, and the Target PDUID is the same as the stored Target PDUID.
In case of unsuccessful scenario, the optional refund steps 10 to 12 are required:
10. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
11. The OCS performs Debit Units Request operation for refund.
12. The OCS returns the Debit Units Response to ProSe Function.
13. The ProSe Function in HPLMN returns a Match Report Ack (Application ID, Target RPAUID, validity timer, metadata (opt.)) to the UE. The UE stores the mapping between the RPAUID, the ProSe Restricted Code and the Application ID for the duration of the validity timer.
14. 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. Discovery Type is set to "restricted discovery". If the Monitored PLMN ID is different from that of the Target PDUID, i.e. the "announcing UE" is roaming or performs inter-PLMN discovery transmission, the ProSe Function in HPLMN of the Monitoring UE may send another Match Report Info (RPAUID, Target RPAUID, UE Identity, ProSe Restricted Code, Discovery Type) to the ProSe Function of the PLMN indicated by the Monitored PLMN ID. 
Figure 5.3.2.2.4.d: Message flow for Match Report of Restricted Discovery-model A (ECUR for roaming//inter-PLMN transmission)
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, Monitored PLMN ID, 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. ProSe Function sends Reserve Units Request [Initial, RPUID, cmd = Restricted Match] to the OCS for requesting units.
4. The OCS performs the Debit Units operation for "Restricted Match".
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6. The HPLMN ProSe Function analyses the ProSe Restricted Code and identifies in the UE context of the monitoring UE the corresponding Target RPAUID.
7. Optionally, the ProSe Function sends a Auth Request (RPAUID, Target RPAUID, Request Type) to the ProSe Application Server. The ProSe Function locates the ProSe Application Server based on the Application ID. The Request Type is set to "restricted discovery/match". If the Metadata Requested is included in the Match Report in step 1, the ProSe Function shall send the Auth Request message.
8. If, based on the permission setting, the RPAUID is allowed to discover the Target RPAUID, the ProSe Application Server returns a Auth Response (PDUID, Target PDUID, Response Type, metadata) message. The PDUID corresponds to RPAUID, the Target PDUID corresponds to the Target RPAUID stored in the ProSe Application Server. The Response Type is set to "restricted discovery/match ack". This message may also contain certain metadata corresponding to the Target PDUID, e.g. welcome message, etc.
9. The ProSe Function verifies that the returned PDUID belongs to the requesting UE, and the Target PDUID is the same as the stored Target PDUID.
In case of unsuccessful scenario, the optional refund steps 10 to 12 are required:
10. ProSe Function sends Debit Units Request[Terminate] to the OCS with granted units used. On unsuccessful Match Report, granted units are returned.
11. The OCS performs the Debit Units operation for "Match".
12. The OCS returns the Debit Units Response to ProSe Function.
13. The ProSe Function in HPLMN returns a Match Report Ack (Application ID, Target RPAUID, validity timer, metadata (opt.)) to the UE. The UE stores the mapping between the RPAUID, the ProSe Restricted Code and the Application ID for the duration of the validity timer.
14. 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. Discovery Type is set to "restricted discovery". If the Monitored PLMN ID is different from that of the Target PDUID, i.e. the "announcing UE" is roaming or performs inter-PLMN discovery transmission, the ProSe Function in HPLMN of the Monitoring UE may send another Match Report Info (RPAUID, Target RPAUID, UE Identity, ProSe Restricted Code, Discovery Type) to the ProSe Function of the PLMN indicated by the Monitored PLMN ID.
5.3.2.2.5 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 5.3.2.2.5.1: Discoveree UE procedures for Model B restricted discovery (IEC for 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.
0-2a. If the Discoveree UE is authorised to use Model B discovery in the serving PLMN 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. ProSe Function in the HPLMN check the authorization with the HSS.
3. ProSe Function sends Debit Units Request [Event] indicating "Restricted Announce" to the OCS.
4. The OCS performs the Debit Units operation for Discoveree UE.
5. The OCS returns the Debit Units Response to ProSe Function.
6. 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.
7. 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 5.3.2.2.5.2: Discoveree UE procedures for Model B restricted discovery (IEC for 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.
0-2a. These steps are defined in TS 23.303[238].
3. ProSe Function sends Reserve Units Request [Initial, RPUID, cmd = Restricted Announce, PC5_tech] to the OCS for requesting units.
4. The OCS performs Reserve Units Request operation for Discoveree UE.
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-7. These steps are defined in TS 23.303[238].
If the Discovery Request is not authorized, the optional refund steps 8 to 10 are required:
8. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
9. The OCS performs Debit Units Request operation for refund.
10. The OCS returns the Debit Units Response to ProSe Function.
11. 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. After the ProSe Function in the HPLMN responds with a Discovery Response,
12. 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 5.3.2.2.5.3: Discoveree UE procedures for Model B restricted discovery (ECUR for 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.
0-2a. These steps are defined in TS 23.303[238].
3. ProSe Function sends Reserve Units Request [Initial, RPUID, cmd = Restricted Announce, PC5_tech] to the OCS for requesting units.
4. The OCS performs Reserve Units Request operation for Discoveree UE.
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-7. These steps are defined in TS 23.303[238].
8. ProSe Function sends Debit Units Request[Terminate] to the OCS indicating granted units are used. On unsuccessful Announce authorization, granted units are returned.
9. The OCS performs Debit Units operation.
10. The OCS returns the Debit Units Response to ProSe Function.
11. 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. After the ProSe Function in the HPLMN responds with a Discovery Response,
12. 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 5.3.2.2.5.4: Discoverer UE procedures for Model B restricted discovery (IEC for 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.
0-2a. 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. ProSe Function in the HPLMN check the authorization with the HSS. 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.
3. ProSe Function sends Debit Units Request [Event] indicating "Restricted Monitor" with the requested PC5 radio technology to the OCS.
4. The OCS performs the Debit Units operation for Discoverer UE.
5. The OCS returns the Debit Units Response to ProSe Function.
6-7. These steps are defined in TS 23.303[238].
If the Discovery Request is not authorized, the optional refund steps 8 to 10 are required:
8. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
9. The OCS performs Debit Units Request operation for refund.
10. The OCS returns the Debit Units Response to ProSe Function.
11. The ProSe Function in HPLMN shall responds with a Discovery Response (ProSe Query Code(s), ProSe Response Code, validity timer, PC5_tech).
12. The UE may then obtain the radio resources to monitor using the Discovery Query Filter, as authorised and configured by E-UTRAN for ProSe as defined in RAN specifications.
Figure 5.3.2.2.5.5: Discoverer UE procedures for Model B restricted discovery (IEC for 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.
0-2a. 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. ProSe Function in the HPLMN check the authorization with the HSS. 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.
3. ProSe Function sends Debit Units Request [Event] indicating "Restricted Monitor" with the requested PC5 radio technology to the OCS.
4. The OCS performs the Debit Units operation for Discoverer UE.
5. The OCS returns the Debit Units Response to ProSe Function.
6-9. These steps are defined in TS 23.303[238].
If the Discovery Request is not authorized, the optional refund steps 8 to 10 are required:
10. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
11. The OCS performs Debit Units Request operation for refund.
12. The OCS returns the Debit Units Response to ProSe Function.
13. The ProSe Function in HPLMN shall responds with a Discovery Response (ProSe Query Code(s), ProSe Response Code, validity timer, PC5_tech).
14. 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 5.3.2.2.5.6: Discoverer UE procedures for Model B restricted discovery (ECUR for 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.
0-2a. 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. ProSe Function in the HPLMN check the authorization with the HSS. 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.
3. ProSe Function sends Reserve Units Request [Initial, RPUID, cmd = Restricted Monitor, PC5_tech] to the OCS for requesting units.
4. The OCS performs Reserve Units Request operation for Discoverer UE.
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-9. These steps are defined in TS 23.303[238].
10. ProSe Function sends Debit Units Request[Terminate] to the OCS indicating granted units are used. On unsuccessful Monitor authorization, granted units are returned.
11. The OCS performs Debit Units operation.
12. The OCS returns the Debit Units Response to ProSe Function.
13. The ProSe Function in HPLMN shall responds with a Discovery Response (ProSe Query Code(s), ProSe Response Code, validity timer, PC5_tech).
14. 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.
5.3.2.2.6 Message flow for Discovery reporting – Model B procedures
Figures 5.3.2.2.6.1 to 5.3.2.2.6.4 define the transactions between ProSe Function and OCS for the successful scenario where a "Discoverer UE" sends a Match report for Model B restricted discovery in non-roaming case and roaming case for IEC and ECUR modes.
Figure 5.3.2.2.6.1: Match Report procedure for Model B restricted discovery (IEC for 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.
1-2. These Steps are defined in TS 23.203 [238].
3. ProSe Function sends Debit Units Request[Event] indicating "Match" to the OCS.
4. The OCS performs the Debit Units operation for "Match ".
5. The OCS returns the Debit Units Response to ProSe Function.
6-7. The HPLMN ProSe Function analyses and optionally sends an Auth Request to the ProSe Application Server. The ProSe Function verifies that the returned PDUID.
In case of unsuccessful scenario, the optional refund steps 8 to 10 are required:
8. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
9. The OCS performs Debit Units Request operation for refund.
10. The OCS returns the Debit Units Response to ProSe Function.
11-12. The ProSe Function in VPLMN returns a Match Report and may optionally send a Match Report Information.
Figure 5.3.2.2.6.2: Match Report procedure for Model B restricted discovery (ECUR for 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.
1-2. These Steps are defined in TS 23.203 [238].
3. ProSe Function sends Reserve Units Request[Initial] to the OCS for requesting units.
4. The OCS performs the Debit Units operation for "Match".
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-7. The HPLMN ProSe Function analyses and optionally sends an Auth Request to the ProSe Application Server. The ProSe Function verifies that the returned PDUID.
8. ProSe Function sends Debit Units Request[Terminate] to the OCS with granted units used. On unsuccessful Match Report, granted units are returned.
9. The OCS performs the Debit Units operation for "Match".
10. The OCS returns the Debit Units Response to ProSe Function.
11-12. The ProSe Function in VPLMN returns a Match Report and may optionally send a Match Report Information.
Figure 5.3.2.2.6.3: Match Report procedure for Model B restricted discovery (IEC for 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.
1-2. These Steps are defined in TS 23.203 [238].
3. ProSe Function sends Debit Units Request[Event] indicating "Match" to the OCS.
4. The OCS performs the Debit Units operation for "Match ".
5. The OCS returns the Debit Units Response to ProSe Function.
6-7. The HPLMN ProSe Function analyses and optionally sends an Auth Request to the ProSe Application Server. The ProSe Function verifies that the returned PDUID.
In case of unsuccessful scenario, the optional refund steps 8 to 10 are required:
8. ProSe function sends Debit Units Request[Event] to the OCS for refund purpose.
9. The OCS performs Debit Units Request operation for refund.
10. The OCS returns the Debit Units Response to ProSe Function.
11-12. The ProSe Function in VPLMN returns a Match Report and may optionally send a Match Report Information.
Figure 5.3.2.2.6.4: Match Report procedure for Model B restricted discovery (ECUR for 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.2.1-2. These Steps are defined in TS 23.203 [238].
3. ProSe Function sends Reserve Units Request[Initial] to the OCS for requesting units.
4. The OCS performs the Debit Units operation for "Match".
5. The OCS grants service units in the Reserve Units Response to ProSe Function.
6-7. The HPLMN ProSe Function analyses and optionally sends an Auth Request to the ProSe Application Server. The ProSe Function verifies that the returned PDUID.
8. ProSe Function sends Debit Units Request[Terminate] to the OCS with granted units used. On unsuccessful Match Report, granted units are returned.
9. The OCS performs the Debit Units operation for "Match".
10. The OCS returns the Debit Units Response to ProSe Function.
11-12. The ProSe Function in VPLMN returns a Match Report and may optionally send a Match Report Information.
5.3.2.3 ProSe EPC-level Discovery
5.3.2.3.1 Triggers for ProSe EPC-level Discovery online charging
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.
Debit/Reserve Unit Request[Initial/Update] is triggered for UE A, when a Proximity Request is received and the App Server provides the valid mapping information. Debit/Reserve Unit Request[Initial] is triggered when there is no active discovery session for the same pair of UE A and UE B identified by EPC ProSe User ID A (EPUID_A) and EPC ProSe User ID B (EPUID_B). Debit/Reserve Unit Request[Update] is triggered when there is an existing discovery session for the same pair of UE A and UE B.
Debit/Reserve Unit Request[Terminate] is triggered for UE A, when a Proximity Request Reject or Proximity Request Cancellation is sent.
Debit/Reserve Unit Request[Initial/Update] is triggered for UE B, when a Proximity Request is received. Debit/Reserve Unit Request[Initial] is triggered when there is no active discovery session for the same pair of UE A and UE B identified by EPC ProSe User ID A (EPUID_A) and EPC ProSe User ID B (EPUID_B). Debit/Reserve Unit Request[Update] is triggered when there is an existing discovery session for the same pair of UE A and UE B.
Debit/Reserve Unit Request[Terminate] is triggered for UE B, when a Proximity Request Reject or Proximity Request Cancellation is sent.
5.3.2.3.2 Message flow for ProSe EPC-level Discovery Proximity Request
Figure 5.3.2.3.2.1 depicts the message flow for ProSe EPC-level Discovery Proximity Request for UE A.
Figure 5.3.2.3.2.1: Message flow for ProSe EPC-level Discovery Proximity Request (UE A)
1 – 3. These steps are defined in TS 23.303 [238] clause 5.5.5.
4a. ProSe Function A sends Debit/Reserve Units Request[Initial/Update] according to the conditions specified in 5.3.2.3.1 to the corresponding OCS A.
4b. The OCS A performs Debit/Reserve Units operation for the UE.
4c. The OCS A returns the Debit Units Response to ProSe Function A.
5. ProSe Functions A sends the Proximity Request to ProSe Function B if step 4c indicates success.
6. ProSe Function B triggers the corresponding EPC-level discovery procedure for UE B, as depicted in figure 5.3.2.3.2.2.
7a ProSe Function B rejects the Proximity Request with the Proximity Request Reject (Cause) message.
If ProSe Function received Proximity Request Reject in step 7a, the following step 7b to 7e will executed. Otherwise, step 8 to 9b will be executed.
7b. ProSe Function A sends the Proximty Request Reject (Cause) to UE A.
7c ProSe Function A sends Debit/Reserve Units Request[Terminate] the corresponding OCS A.
7d. The OCS A performs Debit/Reserve Units operation for the UE.
7e. The OCS A returns the Debit Units Response to ProSe Function A.
8. ProSe Function B sends Proxmity Request Ack message to ProSe Function A.
9a. ProSe Function A sends LCS Locaiton Reporting Request for UE A to SLP A.
9b. ProSe Function A sends Proximity Request Ack to UE A.
Figure 5.3.2.3.2.2 depicts the message flow for ProSe EPC-level Discovery Proximity Request for UE B.
Figure 5.3.2.3.2.2: Message flow for ProSe EPC-level Discovery Proximity Request (UE B)
1. EPC-level discovery operation for UE A is executed, as depicted in step 1 to 4c in figure 5.3.2.3.2.2.
2. ProSe Functions A sends the Proximity Request to ProSe Function B.
3a. ProSe Function B sends Debit/Reserve Units Request[Initial/Update] according to the conditions specified in 5.3.2.3.1 to the corresponding OCS B.
3b. The OCS B performs Debit/Reserve Units operation for the UE.
3c. The OCS B returns the Debit Units Response to ProSe Function B.
4. If step 3c indicates success, the ProSe Function B obtains from HSS the last known location of UE B.
5. ProSe Function B may reject the request based on the information obtained in step 4, and send a Proximity Request Reject (Cause) message to ProSe Function A.
6. ProSe Function B validates the Proximity Request with UE B if it decides to accept the Proximity Request.
7a. ProSe Function B sends LCS Location Reporting Request to SLP B for UE B.
7b. ProSe Function B sends Proximity Request Ack message to the ProSe Function A.
The following step 8a to 8c are executed only when 5 is executed or step 6 validation fails.
8a. ProSe Function B sends Debit/Reserve Units Request[Terminate] the corresponding OCS B.
8b. The OCS B performs Debit/Reserve Units operation for the UE.
8c. The OCS B returns the Debit Units Response to ProSe Function B.
9. EPC-level discovery operation for UE A is executed, as depicted in step 7a to 9b in figure 5.3.2.3.2.2.
5.3.2.3.3 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, Debit/Reserve Unit Request[Termiante] is triggered for UE A and UE B, after the respective ProSe Function responded to the Cancel Proximity Request message.
Figure 5.3.2.3.3.1 depicts the message flow for ProSe EPC-level Discovery Proximity Request Cancellation.
Figure 5.3.2.3.3.1: 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 Debit/Reserve Units Request[Termiante] to the corresponding OCS B. This shall also indicate if a Proximity Alert has been sent to UE B.
5b. OCS B perform the Debit/Reserve Unit operation for UE B.
5c. The OCS B returns Debit/Reserve Units Response.
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 Debit/Reserve Units Request[Termiante] to the corresponding OCS A. This shall also indicate if a Proximity Alert has been sent to UE A.
6b. OCS A perform the Debit/Reserve Unit operation for UE A.
6c. The OCS A returns Debit/Reserve Units Response.