5.7A Charging

23.4013GPPGeneral Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) accessRelease 18TS

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

5.7A.1 General

Accounting functionality is provided by the Serving GW and the PDN GW. When a Secondary RAT may be used, the Serving GW and PDN GW can be assisted by the E-UTRAN (see clause 5.7A.4).

The Serving GW shall be able to collect and report for each UE accounting information, i.e. the amount of data transmitted in uplink and downlink direction categorized with the QCI and ARP pair per UE per PDN connection. For GTP-based S5/S8 the accounting information is collected and reported per bearer.

The Serving GW shall not collect UE accounting information for packets that are being processed for the sole purpose of indirect forwarding.

The Serving GW for inter-operator charging, and the PDN GW shall be able to interface the OFCS according to charging principles and through reference points specified in TS 32.240 [51].

The PDN GW shall be able to provide charging functionality for each UE according to TS 23.203 [6]. The PDN GW data collection for charging and usage monitoring purposes can be temporarily paused as described in clause 5.3.6A.

A PDN GW without a Gx interface shall be able to support flow based online and offline charging based on local configuration and interaction with the Online and Offline Charging Systems.

The Online Charging System may provide a PRA identifier(s) to the PDN GW to subscribe to notifications about changes of UE presence in Presence Reporting Area as defined in the TS 23.203 [6]. For UE-dedicated Presence Reporting Areas the Online Charging System also provides the list(s) of the elements comprising each subscribed UE-dedicated Presence Reporting Area.

The PDN GW shall be able to collect and report, for each UE, accounting information, i.e. the amount of data received and transmitted in uplink and downlink direction categorized with the QCI and ARP pair per UE per PDN connection. For GTP-based S5/S8 the accounting information is collected and reported per bearer. The PDN GW data collection can be temporarily paused as described in clause 5.3.6A based on operator configuration in the PDN GW.

NOTE: A consequence of pausing the PDN GW data collection is that PDN GW accounting information may not correspond to the volume that traversed the PDN GW and it is therefore not possible to verify accounting information collected at the Serving GW for inter-operator charging.

The Charging identifier(s) generated by the PDN GW per bearer for GTP-based S5/S8 and per PDN connection for PMIP-based S5/S8 and the PDN GW address for control signalling enables the correlation of the reporting from a Serving GW and a PDN GW. The Charging identifier is uniquely assigned within the PDN GW.

The PDN GW receives Charging Characteristics from the Serving GW through GTP-S5/S8, or through PMIP for PMIP-based S5/S8. The handling of the Charging Characteristics in the P‑GW is defined in TS 32.251 [44].

To enable CSG charging function for a subscriber consuming network services via a CSG cell or a hybrid cell, User CSG Information is transferred to the PDN GW as indicated by CSG Information Reporting Action. User CSG Information includes CSG ID, access mode and CSG membership indication. CSG membership indication of whether the UE is a member of the CSG is included if the access mode is hybrid.

The valid CSG information shall be available in the serving GW and PDN GW in connected mode.

The PCRF shall, if deployed, provide User CSG Information reporting rules to the PDN GW at Attach and PDN Connectivity Request. PDN GW sets the CSG Information Reporting Action IE according to the User CSG Information reporting rules and sends it to Serving GW and MME.

To enable the MME to signal the correct RAT Type (NB-IoT or WB-E-UTRAN) to the SGW and PDN GW for accounting information generation purposes, the eNodeB informs the MME of the RAT Type and TAC associated with each cell in the S1 SETUP REQUEST and eNodeB CONFIGURATION UPDATE messages (TS 36.413 [36]). If the eNodeB signals WB-EUTRAN and the UE is of Category M from the UE’s radio capability, the MME reports RAT Type LTE-M to the SGW. See clause 5.11.5 for more details.

5.7A.2 Usage Data Reporting for Secondary RAT

When a Secondary RAT can be used in conjunction with E-UTRAN, the HPLMN or VPLMN operator may wish to record the data volume sent on the Secondary RAT.

In order to reduce the complexity of this procedure, and to align with existing per EPS bearer accounting procedures, the following principles are used in this release:

a) The PLMN locally activates the Secondary RAT Usage Data Reporting by E-UTRAN O&M. The activation can happen separately for Data Volume Reporting of NR and Unlicensed Spectrum. If the PLMN uses this feature, it should ensure that this functionality is supported by all eNodeBs that support NR, Unlicensed Spectrum aggregation (if used to record data volume sent over unlicensed spectrum) as a Secondary RAT.

b) The E-UTRAN reports uplink and downlink data volumes to the EPC for the Secondary RAT on a per EPS bearer basis and per time interval.

NOTE 1: Secondary RAT includes access type NR and usage data reporting for Secondary RAT includes reporting of the combination of NR usage as defined in TS 37.340 [85].

c) At X2 handover and S1 handover, the source eNodeB reports the data volumes to the EPC. The reported data volume excludes data forwarded to the target RAN node.

d) At S1 Release, Connection Suspend, and EPS Bearer Deactivation the eNodeB reports the data volumes to the EPC.

e) To assist "partial CDR" generation at the Serving GW and the PDN GW, E-UTRAN O&M can instruct the E-UTRAN to also make periodic reports if no event has triggered a report before the period expires.

NOTE 2: The timing of these periodic E-UTRAN reports is not expected to align with the timing of partial CDR generation. Hence the frequency of E-UTRAN reports might be greater than that of partial CDR generation.

NOTE 3: RAN needs to be able to partition the measurements in a report to indicate usage that occurred before and after an absolute time. An example of the absolute time is that RAN is configured to partition data usage reports that occurred before and after midnight.

f) As an option, the Serving Gateway sends the data volume reports on to PDN GWs identified in bilateral roaming agreements.

5.7A.3 Secondary RAT Usage Data Reporting Procedure

The procedure in Figure 5.7A.3-1 may be used to report Secondary RAT usage data from eNodeB to the MME. It is executed by the eNodeB to report the Secondary RAT usage data information which is then included in messages on S11 towards Serving GW and S5/S8 interface to the PGW (e.g. during I-RAT handover procedures, S1 handover, X2 handover). This then further uses existing EPC signalling of the procedures involved.

The procedure in Figure 5.7A.3-2 may be used to report the Secondary RAT usage data from MME to the Serving GW. Optionally, it is used to report the Secondary RAT usage data from Serving GW to the PDN GW when the reporting to PDN GW is activated.

If the Secondary RAT usage data is provided by an S1AP message from eNodeB to MME other than the one indicated in Figure 5.7A.3-1, the procedures in clause 5.7A.3-2 may be used to transfer the secondary RAT usage data to the Serving GW and PDN GW (e.g. during S1 Release procedure). The eNodeB may also provide the user location information, e.g. ECGI, PSCell ID.

During IRAT handovers, the procedures 5.7A.3-1 to 5.7A.3-2 in its entirety is executed to provide reporting of Secondary RAT usage data to the Serving GW and to the PDN GW if PGW secondary RAT usage data reporting is active.

Handover related signalling of IRAT procedures may be used to provide reporting of Secondary RAT usage data to the Serving GW instead of the signalling of figure 5.7A.3-2, when PGW secondary RAT usage data reporting is not active.

Figure 5.7A.3-1: RAN Secondary RAT usage data Reporting procedure

1. The eNodeB, if it supports Dual Connectivity with Secondary RAT (using NR radio (see clause 4.3.2a on Support for Dual Connectivity), using unlicensed spectrum in the form of LAA/LWA/LWIP/NR-U (see clause 4.3.30)) and it is configured to report Secondary RAT usage data for the UE, depending on certain conditions documented in this specification, it shall send a RAN usage data Report message to the MME including the Secondary RAT usage data for the UE. The eNodeB will send only one RAN usage report for a UE when the UE is subject to handover by RAN. The RAN usage data report includes a handover flag to indicate when the message is sent triggered by X2-handover.

If Dual Connectivity is active or had been activated by that eNodeB, the eNodeB shall add the PSCell ID (and the time elapsed since the Dual Connectivity was released if Dual Connectivity is no longer activated) to the RAT usage data Report message.

In the case of X2 handover, the MME is expected to handle a secondary RAT data reporting received from the source eNodeB within a short time after Path Switch Request by forwarding it to the SGW, e.g. using the GW Secondary RAT usage data Reporting procedure.

Figure 5.7A.3-2: GW Secondary RAT usage data Reporting procedure

The eNodeB, if it supports Dual Connectivity with Secondary RAT (using NR radio (see clause 4.3.2a on Support for Dual Connectivity), using unlicensed spectrum in the form of LAA/LWA/LWIP/NR-U (see clause 4.3.30)) and it is configured to report Secondary RAT usage data for the UE, it shall send include the Secondary RAT usage data for the UE to the MME in certain messages depending on certain conditions documented elsewhere in this TS.

Secondary RAT usage reporting from the eNodeB is provided using S1 signalling message which are either at the UE level (eg. Path Switch Request, etc), or at bearer level (eg. E-RAB modification indication, Deactivate bearer response, etc.) as captured in relevant clauses in this specification. If Secondary RAT usage report is provided in bearer level signalling message by the eNodeB, the Secondary RAT usage report is related only to the specific bearer.

1. The MME forwards the Secondary RAT usage data and User Location Information, PSCell ID to the SGW in a Change Notification Request (Secondary RAT usage data) message. If the SGW is requested to forward Secondary RAT usage data to the PGW, the MME includes a flag causing the SGW to forward this to the PGW. Also, the MME informs the Serving GW if the secondary RAT usage data shall not be processed by the Serving GW (e.g. during Serving GW relocation when the usage data is to be forwarded via the target Serving GW).

2. The Serving GW may, based on flags received in the previous message and local configuration in the Serving GW, send the Change Notification (Secondary RAT usage data) message to the PDN GW.

3. The PDN GW acknowledges receiving the Secondary RAT usage data for the UE by a Change Notification Ack() message to the Serving GW.

4. The SGW acknowledges by sending a Change Notification ack() message back to the MME.

5.7A.4 Secondary RAT Periodic Usage Data Reporting Procedure

Periodic reporting of the Secondary RAT usage data is an optional function. When eNodeB, as defined in bullet e) of clause 5.7A.2, is configured with a "time interval for Secondary RAT usage data reporting", the eNodeB shall send a RAN Usage Data Report message for periodic reporting purposes to the MME only when this timer expires for a UE for which Secondary RAT usage data reporting is ongoing. The timer runs from the last usage reporting for the UE. The MME also indicates to SGW if secondary RAT usage data reporting to the PGW is active.

The procedures 5.7A.3-1 to 5.7A.3-2 in its entirety is executed to provide periodic reporting of Secondary RAT usage data to the Serving GW and to the PDN GW when PGW secondary RAT usage data reporting is active. At use for periodic usage data reporting, the procedure 5.7A.3-1 uses signalling from eNodeB which does not include a handover flag.