Section: 5.7A Charging 5.7A.1 General
Content: 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[ Telecommunication management; Charging management; Charging architecture and principles ]  [51]. The PDN GW shall be able to provide charging functionality for each UE according to TS 23.203[ Policy and charging control architecture ]  [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 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[ Policy and charging control architecture ]  [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[ Telecommunication management;Charging management;Packet Switched (PS) domain charging ]  [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[ Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP) ]  [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.