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11a487756c1524b601027966f11b63c7 | 103 765-5 | 1 Scope | The present document specifies the UE capabilities applicable to an On-Board FRMCS Radio Module. NOTE: The present document does not specify UE capabilities applicable to FRMCS-capable Handhelds and FRMCS-capable Objects. |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 2 References | |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 2.1 Normative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found in the ETSI docbox. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long-term validity. The following referenced documents are necessary for the application of the present document. [1] ETSI TS 138 211 (V18.6.0): "5G; NR; Physical channels and modulation (3GPP TS 38.211 version 18.6.0 Release 18)". [2] GSMA SGP.21 V3.1: "RSP Architecture". [3] GSMA SGP.22 V3.1: "RSP Technical Specification". [4] ETSI TS 103 765-1: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Building Blocks and Functions; Part 1: Transport Stratum". |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 2.2 Informative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long-term validity. The following referenced documents may be useful in implementing an ETSI deliverable or add to the reader's understanding, but are not required for conformance to the present document. [i.1] ETSI TR 103 791: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Terminology for FRMCS specifications". [i.2] CEPT ECC Recommendation (23)01: "Cross-border coordination for Railway Mobile Radio (RMR) in the 1900-1910 MHz TDD frequency band". |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 3 Definition of terms, symbols and abbreviations | |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 3.1 Terms | For the purposes of the present document, the terms given in ETSI TR 103 791 [i.1] apply. ETSI ETSI TS 103 765-5 V1.1.1 (2026-01) 6 |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 3.2 Symbols | Void. |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: 5QI 5G QoS Identifier DL DownLink eUICC embedded Universal Integrated Circuit Card FRMCS Future Railway Mobile Communication System GNSS Global Navigation Satellite System GP Guard Period GPS Global Positioning System GSMA GSM Association NR New Radio PRTC Primary Reference Time Clock RSP Remote SIM Provisioning SCS Subcarrier Spacing SIM Subscriber Identity Module TDD Time Division Duplex UE User Equipment UL UpLink |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 4 Onboard FRMCS Radio Module capabilities | |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 4.1 General capabilities | |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 4.1.1 TDD Frame configuration | For TDD operation in band n101, an Onboard FRMCS Radio Module shall support the reference frame specified in Annex A. |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 4.1.2 FRMCS Profile management | An Onboard FRMCS Radio Module shall be equipped with an eUICC that complies with the GSMA specifications SGP.21 [2] and SGP.22 [3] for Remote SIM Provisioning to enable secure and standardized profile management operations, including profile download, installation, enabling, disabling, and deletion. The Onboard FRMCS Radio Module shall support the ES9+ interface as specified in GSMA SGP.22 [3]. The Onboard FRMCS Radio Module shall support the ES11 interface as specified in GSMA SGP.22 [3]. |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 4.2 Radio Access UE capabilities | The present document does not specify Radio Access UE capabilities for an On-Board FRMCS Radio Module. NOTE: At the time of publication, ongoing industrial testing and validation programs are expected to help identifying any specific Radio Access UE capabilities to mandate from an On-Board FRMCS Radio Module. ETSI ETSI TS 103 765-5 V1.1.1 (2026-01) 7 |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 4.3 5G Core Mobility Management UE capabilities | The present document does not specify 5G Core Mobility Management UE capabilities for an On-Board FRMCS Radio Module. NOTE: At the time of publication, ongoing industrial testing and validation programs are expected to help identifying any specific 5G Core Mobility Management UE capabilities to mandate from an On-Board FRMCS Radio Module. |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 4.4 5G Core Session Management UE capabilities | |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 4.4.1 Introduction | The present document specifies a minimal set of 5G Core Session Management UE capabilities for an On-Board FRMCS Radio Module. NOTE: At the time of publication, ongoing industrial testing and validation programs are expected to help identifying any specific 5G Core Session Management UE capabilities to mandate from an On-Board FRMCS Radio Module. |
11a487756c1524b601027966f11b63c7 | 103 765-5 | 4.4.2 5QI | An Onboard FRMCS Radio Module shall support at least the 5QI identified in ETSI TS 103 765-1 [4], Table 9.3-1. ETSI ETSI TS 103 765-5 V1.1.1 (2026-01) 8 Annex A (normative): Reference TDD frame from ECC Recommendation (23)01 Annex 5 of ECC Recommendation (23)01 [i.2] specifies the reference TDD parameters to be supported by an Onboard FRMCS Radio Module indicated in Table A-1. Table A-1: TDD frame reference parameters (Source: ECC Recommendation (23)01 [i.2]) Parameter Value Reference phase / time clock Aligned with UTC, properly monitored to ensure the local clock drift does not exceed ± 1,5 μs in the event of a PRTC outage. NOTE 1: GNSS (e.g. GPS) is an example of compliant PRTC. Reference frame With Tc := 1/(480000*4096) seconds (Basic time unit for NR as defined in ETSI TS 138 211 [1], clause 4.1): 1. Start-of-frame, aligned with the reference clock 2. Downlink for 3371008*Tc 3. Guard period for 280576*Tc 4. Uplink for 2246656*Tc 5. Downlink for 1685504*Tc 6. Guard period for 280576*Tc 7. Uplink for 1966080*Tc 8. Downlink for 3371008*Tc 9. Guard period for 280576*Tc 10. Uplink for 2246656*Tc 11. Downlink for 1685504*Tc 12. Guard period for 280576*Tc 13. Uplink for 1966080*Tc 14. Back to start-of-frame NOTE 2: Those timings correspond to 5G-NR configuration "DSaUSbU DSaUSbU" with a 15 kHz SCS and S(DL/GP/UL):=(Sa = 10:2:2, Sb = 12:2:0) and 5G NR configuration "DDDS1UUDS2UU DDDS1UUDS2UU" with a 30 kHz SCS and S(DL/GP/UL):=(S1 = 6:4:4, S2 = 10:4:0). NOTE 3: All SCS are acceptable as long as the frame complies with the above timings. Other frame configurations are also deemed compatible if they do not lead to any downlink/uplink overlap (e.g. if they implement a larger guard period). ETSI ETSI TS 103 765-5 V1.1.1 (2026-01) 9 History Version Date Status V1.0.0 July 2025 SRdAP process EV 20251008: 2025-07-10 to 2025-10-08 V1.1.1 January 2026 Publication |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 1 Scope | The present document specifies the FRMCS Transport Stratum for the Future Railway Mobile Communications System (FRMCS). In general, the FRMCS Transport Stratum provides data connectivity and the related services. The present document covers: • 3GPP terrestrial access. • Transport stratum interconnection scenarios in all aspects. • 3GPP access sharing, mobility within transport stratum. • QoS and policy control. • Authentication and authorization for the use of the transport stratum. • Transport stratum common features. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 2 References | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 2.1 Normative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found in the ETSI docbox. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long-term validity. The following referenced documents are necessary for the application of the present document. [1] ETSI TS 123 501 (V18.9.0): "5G; System architecture for the 5G System (5GS) (3GPP TS 23.501 version 18.9.0 Release 18)". [2] ETSI TS 127 001 (V18.0.0): "Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); General on Terminal Adaptation Functions (TAF) for Mobile Stations (MS) (3GPP TS 27.001 version 18.0.0 Release 18)". [3] ETSI TS 127 007 (V18.8.0): "Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; 5G; AT command set for User Equipment (UE) (3GPP TS 27.007 version 18.8.0 Release 18)". [4] ETSI TS 138 201 (V18.0.0): "5G; NR; Physical layer; General description (3GPP TS 38.201 version 18.0.0 Release 18)". [5] ETSI TS 138 300 (V18.5.0): "5G; NR; NR and NG-RAN Overall description; Stage-2 (3GPP TS 38.300 version 18.5.0 Release 18)". [6] ETSI TS 103 765-2: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Building Blocks and Functions; Part 2: Service Stratum". [7] ETSI TS 103 765-3: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Building Blocks and Functions; Part 3: Train On-Board functions and interfaces". [8] FRMCS FFFIS-7950: "FRMCS FFFIS - Form Fit Functional Interface Specification", V2.1.0. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 7 [9] ETSI TS 124 501 (V18.10.0): "5G; Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3 (3GPP TS 24.501 version 18.10.0 Release 18)". [10] ETSI TS 123 502 (V18.9.0): "5G; Procedures for the 5G System (5GS) (3GPP TS 23.502 version 18.9.0 Release 18)". [11] ETSI TS 138 211 (V18.6.0): "5G; NR; Physical channels and modulation (3GPP TS 38.211 version 18.6.0 Release 18)". [12] ETSI TS 138 212 (V18.6.0): "5G; NR; Multiplexing and channel coding (3GPP TS 38.212 version 18.6.0 Release 18)". [13] ETSI TS 138 213 (V18.6.0): "5G; NR; Physical layer procedures for control (3GPP TS 38.213 version 18.6.0 Release 18)". [14] ETSI TS 138 214 (V18.6.0): "5G; NR; Physical layer procedures for data (3GPP TS 38.214 version 18.6.0 Release 18)". [15] ETSI TS 138 321 (V18.5.0): "5G; NR; Medium Access Control (MAC) protocol specification (3GPP TS 38.321 version 18.5.0 Release 18)". [16] ETSI TS 138 322 (V18.2.0): "5G; NR; Radio Link Control (RLC) protocol specification (3GPP TS 38.322 version 18.2.0 Release 18)". [17] ETSI TS 138 323 (V18.5.0): "5G; NR; Packet Data Convergence Protocol (PDCP) specification (3GPP TS 38.323 version 18.5.0 Release 18)". [18] ETSI TS 138 331 (V18.5.1): "5G; NR; Radio Resource Control (RRC); Protocol specification (3GPP TS 38.331 version 18.5.1 Release 18)". [19] ETSI TS 129 522 (V18.9.0): "5G; 5G System; Network Exposure Function Northbound APIs; Stage 3 (3GPP TS 29.522 version 18.9.0 Release 18)". [20] ETSI TS 133 501 (V18.9.0): "5G; Security architecture and procedures for 5G System (3GPP TS 33.501 version 18.9.0 Release 18)". [21] IETF RFC 9113: "HTTP/2". [22] IETF RFC 8259: "The JavaScript Object Notation (JSON) Data Interchange Format". [23] ETSI TS 123 289 (V18.10.0): "5G; Mission Critical services over 5G System; Stage 2 (3GPP TS 23.289 version 18.10.0 Release 18)". [24] ETSI TS 129 513 (V18.9.0): "5G; 5G System; Policy and Charging Control signalling flows and QoS parameter mapping; Stage 3 (3GPP TS 29.513 version 18.9.0 Release 18)". [25] ETSI TS 129 512 (V18.9.0): "5G; 5G System; Session Management Policy Control Service; Stage 3 (3GPP TS 29.512 version 18.9.0 Release 18)". [26] ETSI TS 129 511 (V18.3.0): "5G; 5G System; Equipment Identity Register Services; Stage 3 (3GPP TS 29.511 version 18.3.0 Release 18)". [27] IETF RFC 8684: "TCP Extensions for Multipath Operation with Multiple Addresses". [28] ETSI TS 124 193 (V18.8.0): "5G; 5G System; Access Traffic Steering, Switching and Splitting (ATSSS); Stage 3 (3GPP TS 24.193 version 18.8.0 Release 18)". [29] ETSI TS 129 514 (V18.9.0): "5G; 5G System; Policy Authorization Service; Stage 3 (3GPP TS 29.514 version 18.9.0 Release 18)". [30] ETSI TS 129 214 (V18.4.0): "Universal Mobile Telecommunications System (UMTS); LTE; 5G; Policy and charging control over Rx reference point (3GPP TS 29.214 version 18.4.0 Release 18)". [31] ETSI TS 138 104 (V18.9.0): "5G; NR; Base Station (BS) radio transmission and reception (3GPP TS 38.104 version 18.9.0 Release 18)". ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 8 [32] ETSI TS 138 133 (V18.9.0): "5G; NR; Requirements for support of radio resource management (3GPP TS 38.133 version 18.9.0 Release 18)". [33] Recommendation ITU-T G.8271.1: "Network limits for time synchronization in packet networks with full timing support from the network". [34] Recommendation ITU-T G.8271.2: "Network limits for time synchronization in packet networks with partial timing support from the network". [35] ETSI TS 103 793: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Radio Characteristics". [36] ETSI TS 103 765-5: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Building Blocks and Functions; Part 5: User Equipment (UE) capabilities". [37] ETSI TS 129 591 (V18.9.0): "5G; 5G System; Network Exposure Function Southbound Services; Stage 3 (3GPP TS 29.591 version 18.9.0 Release 18)". [38] ETSI TS 123 122 (V18.10.0): "Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; 5G; Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode (3GPP TS 23.122 version 18.10.0 Release 18)". [39] IETF RFC 8200: "Internet Protocol, Version 6 (IPv6) Specification". |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 2.2 Informative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long-term validity. The following referenced documents may be useful in implementing an ETSI deliverable or add to the reader's understanding, but are not required for conformance to the present document. [i.1] ETSI TR 103 791: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Terminology for FRMCS specifications". [i.2] IETF RFC 5905: "Network Time Protocol Version 4: Protocol and Algorithms Specification". [i.3] IETF RFC 8915: "Network Time Security for the Network Time Protocol". [i.4] ETSI TS 138 413 (V18.5.0): "5G; NG-RAN; NG Application Protocol (NGAP) (3GPP TS 38.413 version 18.5.0 Release 18)". [i.5] ETSI TS 138 423 (V18.5.0): "5G; NG-RAN; Xn Application Protocol (XnAP) (3GPP TS 38.423 version 18.5.0 Release 18)". [i.6] ETSI TS 138 463 (V18.0.0): "5G; NG-RAN; E1 Application Protocol (E1AP) (3GPP TS 38.463 version 18.0.0 Release 18)". [i.7] ETSI TS 138 473 (V18.5.0): "5G; NG-RAN; F1 Application Protocol (F1AP) (3GPP TS 38.473 version 18.5.0 Release 18)". [i.8] ETSI TS 136 423 (V18.4.0): "LTE; Evolved Universal Terrestrial Radio Access Network (E-UTRAN); X2 Application Protocol (X2AP) (3GPP TS 36.423 version 18.4.0 Release 18)". ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 9 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 3 Definition of terms, symbols and abbreviations | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 3.1 Terms | For the purposes of the present document, the terms given in ETSI TR 103 791 [i.1] and the following apply: gNodeB: base station that provides NR radio access for 5G networks multipath dataflow: application flow of IP packets processed by the FRMCS Multipath Function, characterized by its application-related attributes and identified via IP-5-tuples multipath data path: network route within a Transport Domain multipath policy: set of rules assessed by the FRMCS Multipath Function to determine the distribution of a Multipath Dataflow to one or more Multipath Datapaths multipath protocol: protocol operating over an IP transport network supporting the use of multiple network interfaces (such as MP-TCP, MP-QUIC, etc.) |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 3.2 Symbols | Void. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: 5G NR 5G New Radio 5GC 5G Core Network 5G-EIR 5G-Equipment Identity Register 5GS 5G System 5QI 5G QoS Identifier AF Application Function AKA Authentication and Key Agreement AMF Access and Mobility Function API Application Programming Interface APTS Assisted Partial Timing Support ARP Allocation and Retention Priority AUSF Authentication Server Function AVP Attribute Value Pair BSF Binding Support Function CP Control Plane CSC Communication Session Category DL Downlink DN Data Network DNS Domain Name Server DRB Dara Radio Bearer DSCP Differentiated Service Code Point EF Expedited Forwarding ESP Encapsulating Security Payload FFFIS Form Fit Functional Interface Specification FQDN Fully Qualified Domain Name FRMCS Future Railway Mobile Communication System GBR Guaranteed Bit Rate gNodeB Next generation Node B GNSS Global Navigation Satellite System GPSI Generic Public Subscription Identifier GSM-R Global System for Mobile Communications - Railway GW Gateway ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 10 HPLMN Home PLMN HR Home Routed HTTP Hyper Text Transfer Protocol ID Identity IKEv2 Internet Key Exchange version 2 IM Infrastructure Manager IMS IP Multimedia Subsystem IMSI International Mobile Subscriber Identifier IP Internet Protocol IPSec Internet Protocol Security IPv6 IP version 6 I-UPF Intermediate UPF JSON JavaScript Object Notation LBO Local Breakout LIF Lawful Intercept Function MAC Medium Access Control MC Mission Critical MCC Mobile Country Code MCPTT Mission Critical Push To Talk MCS Mission Critical Services MCX Mission Critical Services ME Mobile Equipment (in the 3GPP context) MIMO Multi Input Multi Output MNC Mobile Network Code MNO Mobile Network Operator MO Mobile Originated MOCN Multi Operator Core Network MP Multipath Protocol MPC Multipath Client MPF Multipath Function MPG Multipath Gateway MPLS Multiprotocol Label Switching MPM Multipath Management MP-QUIC Multipath QUIC MP-TCP Multipath TCP MPU Multipath User plane MT Mobile Termination (in the 3GPP context) N9HR N9 Home Routing NAI Network Access Identifier NAS Non-Access Stratum NEF Network Exposure Function NF Network Function NG-RAN Next Generation - Radio Access Network NR SA NR Stand-Alone NR New Radio (In the context of 5G) NRF Network Repository Function NTP Network Time Protocol O&M Operation & Management OB On-Board OTDOA Observed Time Difference of Arrival PCC Policy and Charging Control PCF Policy Control Function P-CSCF Proxy Call Service Control Function PDR Packet Detection Rule PDU Protocol Data Unit PFD Packet Flow Description PLMN Public Land Mobile Network PRTC-A Primary Reference Time Clock - Class A PTP Precision Time Protocol QFI QoS Flow identifier QoS Quality of Service QUIC Quick UDP Internet Connection ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 11 RAN Radio Access Network RAT Radio Access Technology RF Radio Frequency RLC Radio Link Control RMR Railway Mobile Radio RU Railway Undertaking SBA NF Service-Based Architecture Network Function SCP Service Communication Proxy SDI Session Description Information SEG Security Gateway SEPP Security Edge Protection Proxy SIB System Information Block SIM Subscriber Identity/Identification Module SIP Session Initiation Protocol SLA Service Level Agreement SM Session Management SMF Session Management Function SUCI Subscriber Concealed Identifier SUPI Subscriber Permanent Identifier TAP Transport Access Point TCMS Train Control & Monitoring System TCP Transport Control Protocol TDD Time Division Duplex TE Terminal Equipment (in the 3GPP context) UAC Unified Access Control UDM Unified Data Management UDR Unified Data Repository UE User Equipment (in the 3GPP context) UICC Universal Integrated Circuit Card UL Uplink UPF User Plane Function USIM Universal Subscriber Identity Module VAS Voice Application Subsystem VPLMN Visited PLMN WAN Wide/Wireless Area Network |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4 Principles and concept | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.1 General | Clause 4 describes the system architecture of the FRMCS Transport Stratum to support packet switched data connectivity and service enabling deployments. The system architecture applicable for FRMCS is the 3GPP 5G System (5GS) and the related 5GS architecture defined in ETSI TS 123 501 [1]. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.2 Architecture | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.2.1 Common Architecture Principles | The Transport Stratum consists of the access domain and the 5G core network domain (see Figure 4.2.2-1). The transport stratum User Equipment (UE) is part of the transport stratum and requires appropriate credentials necessary to make use of the transport stratum. FRMCS Transport Stratum identities are described in clause 10. The FRMCS Transport Stratum utilizes terrestrial wireless 3GPP access based on 5G NR RAT and shall be implemented as described in ETSI TS 138 201 [4], ETSI TS 138 300 [5] and ETSI TS 123 501 [1]. For 5GC, the UE supports N1-reference point for Non-Access Stratum (NAS) signalling for the types of access. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 12 The 5G core domain used for FRMCS Transport Stratum shall provide the convergence between the types of access for the control plane N2-reference point and for the user plane N3 - reference point. In the case of devices (e.g. VAS controller) integrated in IM/RU internal IT/LAN structures, FRMCS transport access control is granted using best practice methods, and FRMCS service access control is granted based on FRMCS SIP Core and MCX procedures. QoS within the underlying trackside IP network (for both gNodeB - UPF connection or outside of 5G) is based on implementations that map FRMCS QoS towards QoS mechanisms in the IP network. FRMCS SIP Core is as specified in ETSI TS 103 765-2 [6]. In general, a UE in transport stratum is considered to be a logical block is subdivided into several domains separated by reference points. It may consist of one or multiple physical units for different types of access. A UE is subdivided into the UICC and the Mobile Equipment (ME), which can be further subdivided into Mobile Termination (MT) and Terminal Equipment (TE) in accordance with - ETSI TS 127 001 [2] and ETSI TS 127 007 [3]. In a broader sense, the UE allows a service client to obtain transport services for its communication. The FRMCS Transport Stratum shall support IPv6 IP addressing as specified in IETF RFC 8200 [39]. Accordingly, two Transport Access Points (TAPs) shall be provided for interaction between the 5G transport stratum and the service stratum: • TAP Service Client forms the transition to the potential service clients. • TAP Service Agent is located at the edge of the 5G core domain. N5/Rx-reference point or N33-reference point (if NEF is deployed in 5GC) shall be used for the control plane and N6-reference point shall be used for the user plane in accordance with ETSI TS 123 501 [1]. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.2.2 Architecture for a Standalone FRMCS Transport Domain | The Standalone FRMCS Architecture represents a FRMCS network without external connections, neither to foreign FRMCS Domain, nor to a GSM-R system or a Mobile Network Operator's 5G Core domain. FRMCS Access Domain FRMCS MC System Service Agents User Equipment 3GPP capable and non-3GPP via WAN MNO Access Domain NG-RAN Radio Access Network NG-RAN Radio Access Network (See NOTE 2) FRMCS 5GC Domain NR Uu NR Uu N5/Rx UPF AMF SMF N16 N11 N4 PCF N6 N7 UDM AUSF N13 N10 N2 N3 N3 N2 TAP Service Agents Data Network TAP Service Clients IP IP Service Clients Radio Module Board IP IP IP FRMCS On-Board FRMCS Trackside Service Clients Transport Stratum Serving MC Service Server) N14 N12 NOTE 1: N2 and N3 reference points are protected by ESP and IKEv2 certificates-based authentication as per clauses 9.2 and 9.3 in ETSI TS 133 501 [20]. IPsec is mandatory to implement on the gNodeB. On the core network side, a SEG may be used to terminate the IPsec tunnel. NOTE 2: Use of MOCN is subject to subject to FRMCS operator policy. Figure 4.2.2-1: FRMCS Standalone Transport Domain Architecture (non-roaming) The minimum 5G System (5GS) for a standalone FRMCS Domain Architecture shall be based on the non-roaming reference architecture as outlined in clauses 4.2.2 (Network Functions and entities) and 4.2.3 (Non-roaming reference architecture) of ETSI TS 123 501 [1] and shall contain the logical following building blocks: • Authentication Server Function (AUSF). • Access and Mobility Management Function (AMF). ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 13 • Data Network (DN), e.g. operator services, Internet access or 3rd party services. • Policy Control Function (PCF). • Session Management Function (SMF). • Unified Data Management (UDM). • Unified Data Repository (UDR). • User Plane Function (UPF). • User Equipment (UE). • (Radio) Access Network ((R)AN). 4.2.3 Architecture for a FRMCS Transport Domain in interaction with other FRMCS Domains |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.2.3.0 General | A FRMCS Transport Domain in interaction with other FRMCS Domains shall implement a home routed interconnected domain architecture depicted in Figure 4.2.3.0-1, which enables the UE (from the own FRMCS Transport Domain or from another FRMCS Transport Domain) in a visited FRMCS network to communicate with the service stratum of its home network. User Equipment 3GPP capable and non-3GPP via WAN TAP Service Clients Foreign FRMCS Access Domain NG-RAN Radio Access Network Home FRMCS 5GC Domain TAP Service Agents IP NR Uu Foreign FRMCS 5GC domain N2 N3 N5/Rx N32 H-SEPP H-NRF N27 H-UPF H-SMF N16 N4 H-PCF N6 N7 UDM N8 N12 N13 N10 FSNNI Radio Module Board IP Service Clients Data Network IP IP IP Service Clients V-SEPP AUSF AMF V-PCF V-UPF N15 V-SMF N9 N12 N4 N11 N8 N16 FRMCS On-Board FRMCS Trackside Transport Stratum Serving MC Service Server) Home FRMCS MC System Service agents N24 V-NRF N27 N24 NOTE: N2 and N3 reference points are protected by ESP and IKEv2 certificates-based authentication as per clauses 9.2 and 9.3 in ETSI TS 133 501 [20]. IPsec is mandatory to implement on the gNodeB. On the core network side, a SEG may be used to terminate the IPsec tunnel. Figure 4.2.3.0-1: Architecture for a FRMCS Transport Domain in interaction with a foreign FRMCS Domain, MC services provided by the Primary (Home) FRMCS MC system ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 14 The minimum 5G system (5GS) for a FRMCS Transport Domain in interaction with other FRMCS Domains shall be based on the roaming reference architecture as outlined in clauses 4.2.2 (Network Functions and entities) and 4.2.4 (Roaming reference architecture) of ETSI TS 123 501 [1] and shall comprise of the building blocks listed in clause 4.2.2 of the present document and the following additional logical building blocks for security reasons, mostly: • Network Repository Function (NRF). • Security Edge Protection Proxy (SEPP). FSNNI in Figure 4.2.3.0-1 refers to the Network-to-Network Interconnection (NNI), connecting different FRMCS Domains. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.2.3.1 FSNNI reference point (at FRMCS Transport Domain level) | The FSNNI reference point is the reference point between FRMCS Domains. At FRMCS Transport Domain level, it enables mobility of FRMCS Users between FRMCS Domains. The FSNNI reference point is composed of the 5GC reference points listed in Table 4.2.3.1-1 for Local Breakout (LBO), Home Routing (HR) or both. Table 4.2.3.1-1: FSNNI basic reference points Reference point Between Purpose LBO/HR N8 AMF (VPLMN) ↔ UDM (HPLMN) Subscription retrieval Both N9 UPF (VPLMN) ↔ UPF (HPLMN) User-plane traffic forwarding HR N10 SMF (VPLMN) ↔ UDM (HPLMN) Session-related subscription data LBO N12 AMF (VPLMN) ↔ AUSF (HPLMN) Authentication Both N16 SMF (VPLMN) ↔ SMF (HPLMN) Inter-PLMN session management Both N24 PCF (VPLMN) ↔ PCF (HPLMN) Mobility-related policies Both N32 SEPP (VPLMN) ↔ SEPP (HPLMN) Secure inter-PLMN control-plane communication Both NOTE: N14 can be implemented to enable smooth mobility and network selection across different PLMNs in 5G, by allowing AMFs to exchange all necessary information to maintain UE service continuity. A FRMCS Transport Domain shall support the reference points listed in Table 4.2.3.1-1. A FRMCS Transport Domain should implement the N27 reference point to enable SBA NF discovery (under communication model B and C as described in ETSI TS 123 501 [1], clause E.1). |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.2.4 FRMCS National Roaming Architecture (Home Routed) | National roaming allows the use of Mobile Network Operator spectrum in a National Roaming architecture. This architecture uses the FRMCS Access Domain radio module, which is equipped to handle Mobile Network Operator (MNO) spectrum as well, or a separate MNO radio module in the On-Board FRMCS, which is configured to roam on the MNO network. The FRMCS Multipath Function, specified in clause 5.3, determines which On-Board FRMCS Radio Module is used for the Multipath Datapath of the application. In the home routed national roaming architecture (depicted in Figure 4.2.4-1), FRMCS On-Board Service Clients can use FRMCS On-Board UE that is attached to MNO roaming partner's radio access. Home routed FRMCS bearers traverse both the VPLMN MNO's 5G Core and the Home FRMCS 5G core. Serving MC System's FRMCS Service Agents and wireline Service Clients are connected to the Home FRMCS Operator's domain. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 15 Home FRMCS Access Domain User Equipment 3GPP capable and non-3GPP via WAN TAP Service Clients VPLMN (MNO Access Domain) NG-RAN Radio Access Network NG-RAN Radio Access Network Home FRMCS 5G Core Domain TAP Service Agents IP NR Uu NR Uu VPLMN (MNO’s 5G Core Domain) N2 N2 N3 N5/Rx H-SEPP H-NRF N32 N27 H-UPF AMF H-SMF N16 N11 N4 H-PCF N6 N7 UDM N8 N12 N13 N10 N3 FSONI Radio Module Board IP Service Clients V-SEPP AUSF AMF V-PCF N24 V-UPF N15 V-SMF N9 N12 N14 N4 N11 N8 N16 On-Board Trackside Transport Stratum Data Network IP IP IP Service Clients Serving MC Service Server) FRMCS MC System Service agents MNO roaming partner N24 V-NRF N27 N14 NOTE: N2 and N3 reference points are protected by ESP and IKEv2 certificates-based authentication as per clauses 9.2 and 9.3 in ETSI TS 133 501 [20]. IPsec is mandatory to implement on the gNodeB. On the core network side, a SEG may be used to terminate the IPsec tunnel. Figure 4.2.4-1: FRMCS National Roaming Architecture (Home Routed, as per Figure 4.2.4-6 in ETSI TS 123 501 [1]) The interface functionalities and interactions between an MNO core and an FRMCS core is known as the FSONI reference point. The following interdomain reference points shall be supported for national roaming with home routing: • N32: Between the SEPPs of each 5G Core Domain. • N9: Connecting visited UPF and home UPF. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.2.5 FRMCS Roaming Architecture (Local Breakout) | In roaming architecture with Local Breakout (Figure 4.2.5-1), FRMCS On-Board Service Clients use FRMCS On-Board UE that is attached to a foreign FRMCS (LBO roaming partner's) access domain. FRMCS bearers traverse only the foreign FRMCS 5G Core. The Home FRMCS 5G core is accessed for signaling only (e.g. for UE authentication). Serving MC System's FRMCS Service Agents and wireline FRMCS Service Clients are connected to the foreign FRMCS Domain. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 16 Foreign FRMCS MC System Service agents User Equipment 3GPP capable and non-3GPP via WAN TAP Service Clients Foreign FRMCS Access Domain NG-RAN Radio Access Network Home FRMCS 5GC Domain TAP Service Agents IP NR Uu Foreign FRMCS 5GC domain N2 N3 N5/Rx N32 H-SEPP N6 UDM N8 N12 N13 N10 FSNNI Radio Module Board IP Service Clients Serving MC Service Server) Data Network IP IP IP Service Clients V-SEPP AUSF AMF V-PCF N24 V-UPF N15 SMF N12 N4 N11 N8 N10 FRMCS On-Board FRMCS Trackside Transport Stratum H-PCF N24 NOTE: N2 and N3 reference points are protected by ESP and IKEv2 certificates-based authentication as per clauses 9.2 and 9.3 in ETSI TS 133 501 [20]. IPsec is mandatory to implement on the gNodeB. On the core network side, a SEG may be used to terminate the IPsec tunnel. Figure 4.2.5-1: FRMCS Roaming Architecture (Local Breakout, as per Figure 4.2.4-4 in ETSI TS 123 501 [1]) The following reference points shall be supported for roaming with LBO: • N32: Between the SEPPs of each FRMCS Operator's 5G Core Domain. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.3 FRMCS Transport Stratum Capabilities | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.3.1 General | For the use of the FRMCS Transport Stratum certain capabilities, e.g. UE mobility, are required encompassing one or various related functions for proper operation. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.3.2 Access Capabilities | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.3.2.1 3GPP Radio Access | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.3.2.1.1 General | FRMCS assumes the use of a dedicated spectrum n100 and n101 (as specified in ETSI TS 103 793 [35]) as a default approach to radio coverage. FRMCS allows the use of MNO spectrum in a MOCN configuration utilizing specific predefined shared MNO frequencies as described in clause 5.1.2.2. One of the FRMCS system principles is to handle voice and data communications using single path and multipath. Multipath is the coordination of at least two UEs serving in parallel the same On-Board application. This is discussed in the FRMCS Multipath Function, clause 5.3 of the present document. FRMCS allows roaming onto MNO network using the architecture specified in clause 4.2.4. Roaming onto MNO network requires the FRMCS Multipath Function to route the traffic onto FRMCS transport and non-FRMCS transport as appropriate to meet the QoS requirements of the underlying FRMCS application. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 17 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.3.2.1.2 5G NR capabilities | For the provision of point-to-point, the corresponding 5G NR radio bearer type unicast shall be used. For the use of radio bearers, the FRMCS Transport Domain shall support the following functional areas (see Figure 4.3.2.1.2-1): • For the physical layer as specified in the standards ETSI TS 138 211 [11], ETSI TS 138 212 [12], ETSI TS 138 213 [13] and ETSI TS 138 214 [14]: - Physical resources. - Physical channels UL/DL. - Physical signals UL/DL. - Modulation/Demodulation. - Channel Coding, Multiplexing. - Transport Channels. - Physical control and procedures. • For the data link layer as specified in the standards ETSI TS 138 321 [15], ETSI TS 138 322 [16], ETSI TS 138 323 [17] and ETSI TS 138 331 [18]: - Medium Access Control (MAC) for UL/DL. - Radio Link Control (RLC) for UL/DL. - Radio Resource Control. - Packet Data Convergence. - Mobility, Session, QoS. Uplink Downlink Spectra (RMR900 & RMR1900) Physical channels and aggregation Physical resources (grid) Physical signals Mod/Demod Channel Coding, Multiplexing Transport Channels Physical control and procedures Data Link Layer Medium Access Control Radio Link Control Radio Resource Control Packet Data Convergence Protocol Mobility and Sessions handling 5G NR Bidirectional Unicast Radio Bearer Physical Layer Figure 4.3.2.1.2-1: Functional areas for unicast radio bearer ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 18 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.3.3 Core capabilities | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.3.3.1 General | The FRMCS Transport Stratum Core, using the 5GC forms the connectivity layer for the FRMCS Service Stratum. 3GPP access can either be using the FRMCS Access Domain RMR spectrum or shared MNO spectrum. Wireline access is provided by interfacing with the core Data Network. The wireline FRMCS users (e.g. VAS controllers) are outside of the Transport Domain 5G network. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 4.3.3.2 3GPP NAS capabilities | 5G Core capabilities are further detailed in clause 5 and shall apply for use by the FRMCS Transport Stratum. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5 FRMCS Transport Stratum Constituents | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.1 FRMCS Transport Stratum Access Domain Constituents | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.1.1 General | The access domain for FRMCS shall support one or more of the following types of wireless access networks: • 3GPP terrestrial radio access using 5G NR radio access within FRMCS Access Domain spectrum portions controlled by a FRMCS 5GC. This type of wireless access network is specified in clause 5.1.2.1. • 3GPP terrestrial radio access using 5G NR radio access within Mobile Network Operator (MNO) spectrum portions controlled by a FRMCS 5GC using MOCN architecture. This type of wireless access network is specified in clause 5.1.2.2. • 3GPP terrestrial radio access using 5G NR within Mobile Network Operator (MNO) spectrum portions controlled by a FRMCS 5GC using a national roaming architecture. This type of wireless access network is out of scope of the present document. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.1.2 FRMCS Transport Wireless Access | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.1.2.1 RMR Access | For RMR access, FRMCS Transport Domain shall comply to ETSI TS 103 793 [35], clauses 4 and 5. For RMR access in band n101, FRMCS Transport Domain shall comply to ETSI TS 103 765-5 [36], Annex A. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.1.2.2 MOCN Access | In MOCN access for a FRMCS operator A, a MOCN gNodeB (operated by MOCN operator B which can be an MNO operator or another FRMCS operator B) is shared between FRMCS operator A and MOCN operator B. The traffic belonging to FRMCS operator A will go to the FRMCS core network of the operator A, and the traffic belonging to operator B will go to the core network B of the operator B. The MOCN architecture maintains the same IP and QoS framework as in case where only FRMCS Access Domain access is used. The FRMCS UEs can be configured to be either both FRMCS Access Domain and MOCN capable, or MOCN capable only. The MOCN gNodeB sites broadcast the PLMN ID for the FRMCS operator A as well as PLMN ID of the operator B, whereas FRMCS Access Domain sites broadcast FRMCS PLMN ID of the FRMCS operator A exclusively. When a UE is under both FRMCS Access Domain and MOCN coverage, it constructs neighbour lists of both FRMCS Access Domain and MOCN cells and the UE can select either FRMCS Access Domain or MOCN, based on pre-configured criteria discussed in the Intra-RAT handoff described below. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 19 Subject to the agreement in place with MOCN operator B offering MOCN shared radio resources, the FRMCS Operator A of the FRMCS Transport Domain can select between two QoS mechanisms (or both): • 5QI flow prioritization on the MOCN bands in line with the prioritization configured in the RMR bands. The target will be the prioritization of FRMCS traffic over mobile broadband traffic using the MOCN shared radio resources. • Partitioning the MOCN band so that the FRMCS traffic is isolated for mobile broadband traffic in usage of radio resource blocks. This would guarantee that FRMCS traffic would have exclusive use of radio resources in the MOCN band. In addition, the 5QI flows can be configured in the FRMCS core to apply only on the FRMCS partition of the shared radio access. The standards referenced in ETSI TS 138 331 [18] and ETSI TS 138 413 [i.4] to ETSI TS 136 423 [i.8] are applicable to MOCN. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2 FRMCS Transport - Core | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.1 Core Architectural Element and Functions | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.1.1 Access and Mobility Management Function (AMF) | The Access and Mobility Management Function (AMF) is specified in ETSI TS 123 501 [1], clause 6.2.1. The AMF is responsible for providing the following capabilities in FRMCS: a) Termination of interfacing with RAN Control Plane. b) Termination of NAS, NAS ciphering and integrity protection. c) Registration management. d) Connection management. e) Reachability management. f) Mobility Management; Provide transport for Session Management messages between UE and SMF. g) Transparent proxy for routing of Session Management messages. h) Access Authentication. i) Access Authorization. j) Location Services management and transport. k) UE mobility event notification. The AMF is required to support the following cybersecurity functionalities: a) Signalling data confidentiality. b) Signalling data integrity. c) Subscriber privacy. NOTE: In order to protect the N2 and N3 reference points, it is required to implement IPsec ESP and IKEv2 certificates-based authentication, see clauses 9.2 and 9.3 in ETSI TS 133 501 [20]. IPsec is mandatory to implement on the gNodeB. On the core network side, a SEG may be used to terminate the IPsec tunnel. In a FRMCS Domain, the AMF shall support at least the following reference points: • N1: The reference point between the AMF and the UE. It is used for signaling and management, including authentication and security procedures. N1 messages are delivered to the AMF via the gNodeB through the N2 reference point (hence not depicted in architecture diagrams). ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 20 • N2: The reference point between the AMF and the RAN (gNodeB). It is used for connection management, UE context management, and PDU session management. • N8: The reference point between the AMF and the UDM. It is used to retrieve user data and crucial during the user registration process. • N11: The reference point between the AMF and the SMF. It Is used for session management and mobility handling. • N12: The reference point between the AMF and the AUSF. It is used for exchange of authentication-related data between the two NFs. • N14: The reference point between the two AMF instances. It is used to transfer User Equipment (UE) context during events like handovers, ensuring seamless mobility between cells managed by different AMFs. • N15: The reference point between AMF and the PCF. It is used to exchange information about policy control and access management. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.1.2 Session Management Function (SMF) | The Session Management Function (SMF) is specified in ETSI TS 123 501 [1], clause 6.2.2. The SMF is responsible for providing the following capabilities in FRMCS: a) Session Management. b) UE IP address allocation & management. c) Selection and control of User Plane Function. d) Configures traffic steering at UPF to route traffic to proper destination. e) Termination of interfacing with Policy Control Functions. f) Charging data collection and interfacing support with charging. g) Termination of Session Management parts of NAS messages. h) Downlink Data Notification. i) Determine Session and Service Continuity mode of a session. j) Provisioning of external parameters (Expected UE Behaviour parameters or Network Configuration parameters). k) Support P-CSCF discovery for IP Multimedia Subsystem (IMS) services. If roaming is enabled for a UE, the SMF is responsible for providing the following capabilities in FRMCS: a) Roaming functionality. b) Handle local enforcement to apply QoS SLAs (in the VPLMN). c) Charging data collection and charging interface (in the VPLMN). If Lawful Intercept is applicable, the SMF facilitates Lawful intercept (in coordination with the UPF and the LIF). In a FRMCS Domain, the SMF shall support at least the following reference points: • N4: The reference point between the SMF and the UPF. It is used for managing and establishing user data plane sessions. • N7: The reference point between the SMF and the PCF. It is used for the exchange of session management policy information corresponding to the PDU session of the UE. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 21 • N10: The reference point between the SMF and the UDM. It is used to exchange subscriber data and the UE context information for SMF to manage sessions based on the subscriber's profile and policies defined by the UDM. • N11: The reference point between the SMF and the AMF. It Is used for session management and mobility handling. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.1.3 User Plane Function (UPF) | The User Plane Function (UPF) is specified in ETSI TS 123 501 [1], clause 6.2.3. The UPF is responsible for providing the following capabilities for FRMCS: a) Packet routing and forwarding. b) Packet inspection. c) QoS handling. d) Traffic usage reporting. e) Acts as external PDU session point of interconnect to Data Network (DN). f) Serves as the anchor point for intra- and inter-RAT mobility. If Lawful Intercept is applicable, the UPF facilitates Lawful intercept for User Plane data collection. In a FRMCS Domain, the UPF shall support at least the following reference points: • N3: The reference point between the RAN (gNodeB) and the (initial) UPF. • N4: The reference point between the Session Management Function (SMF) and the UPF. • N6: The reference point between the Data Network (DN) and the UPF. • N9: The reference point between two UPFs (i.e. the Intermediate I-UPF and the UPF Session Anchor). UPFs can be deployed in series and connected via a reference point referred to as N9. There are three main use cases for this: • Network-wide mobility - To provide full mobility with a stable IP anchor across the full network, there may be a need to connect two UPFs depending on the IM network configuration. • Break-out of selected data flows -Ability to apply classification and traffic management in the UPF to selectively send IP packets to different IP destination, for example, to terminate some traffic at, or close to, the edge to ensure low data latency or prevent sensitive data from being intercepted in more central areas of the network. This requires two UPFs connected in series. • Roaming with home routing - 5G roaming is referred to as N9 Home Routing (N9HR) and is needed for some FRMCS applications (e.g. TCMS). NOTE: In order to protect the N2 and N3 reference points, it is required to implement IPsec ESP and IKEv2 certificates-based authentication, see clauses 9.2 and 9.3 in ETSI TS 133 501 [20]. IPsec is mandatory to implement on the gNodeB. On the core network side, a SEG may be used to terminate the IPsec tunnel. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.1.4 Policy Control Function (PCF) | The Policy Control Function (PCF) is specified in ETSI TS 123 501 [1], clause 6.2.4. The PCF is responsible for providing the following capabilities in FRMCS: a) Unified policy framework. b) Policy rules to CP functions. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 22 c) Access subscription information for policy decisions in UDR. In a FRMCS Domain, the PCF shall support at least the following reference points: • N5 or Rx: The reference point between the AF and the PCF. In FRMCS, the AF is either the MC Service Server or the P-CSCF in the FRMCS SIP or IMS Core. • N7: The reference point between the PCF and the SMF. It is used for the exchange of session management policy information corresponding to the PDU session of the UE. • N15: The reference point between the PCF and the AMF. It is used to exchange information about policy control and access management. • N24: The reference point between the vPCF and the hPCF. It is used in roaming architectures for exchange of the policies information for the subscriber session. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.1.5 Authentication Server Function (AUSF) | The Authentication Server Function (AUSF), as defined in ETSI TS 123 501 [1], clause 6.2.8, shall be implemented in FRMCS. The AUSF is responsible for providing the following capabilities in FRMCS: a) Supports authentication for 3GPP access, as specified in ETSI TS 133 501 [20]. In a FRMCS Domain, the AUSF shall support at least the following reference points: • N12: The reference point between the AUSF and the AMF. It is used for exchange of authentication-related data between the two NFs. • N13: The reference point between the AUSF and the UDM. It is used by AUSF to request the authentication vectors from the UDM and for the UDM to provide these vectors to the AUSF. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.1.6 Unified Data Management (UDM) | The Unified Data Management (UDM) is specified in ETSI TS 123 501 [1], clause 6.2.7. The UDM is responsible for providing the following capabilities in FRMCS: a) Generation of Authentication and Key Agreement (AKA) credentials for UEs. b) UE User identification handling. c) UE Access authorization. d) UE Subscription management. In a FRMCS Domain, the UDM shall support at least the following reference points: • N8: The reference point between the UDM and the AMF. It is used to communicate user data crucial for the user registration process. • N10: The reference point between the UDM and the SMF. It is used to exchange subscriber data and the UE context information for SMF to perform session management based on the subscriber's profile and policies defined by the UDM. • N13: The reference point between the AUSF and the UDM. It is used by AUSF to request the authentication vectors from the UDM and for the UDM to provide these vectors to the AUSF. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 23 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.1.7 Unified Data Repository (UDR) | The Unified Data Repository (UDR) is specified in ETSI TS 123 501 [1], clause 6.2.11. The following functions are supported in the UDR: a) Storage and retrieval of subscription data by the UDM. b) Storage and retrieval of policy data by the PCF. c) Storage and retrieval of application-related data (including of Packet Flow Descriptions (PFDs) for application detection). |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.2 Conditional Core Architectural Elements | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.2.1 General | In addition to the minimal architectural components listed in clause 4.2.2, the FRMCS core architecture may require the following conditional architectural components. These components are not mandatory in the minimized FRMCS architecture. They may be required to fulfil national rules or to enhance the operation of FRMCS. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.2.2 5G-Equipment Identity Register (5G-EIR) | The 5G-Equipment Identity Register (5G-EIR) is used to check the status of equipment's identity (e.g. to check that it has not been listed as unauthorized or stolen). If the FRMCS Operator implements 5G-EIR, it shall be implemented according to ETSI TS 129 511 [26] and ETSI TS 123 502 [10]. This element is conditional on national rules requiring that mobile equipment be checked against a prohibited mobile equipment list before a signalling connection is allowed. The reference point N17 (see Figure 5.2.2.2-1) shows the interaction between the 5G-EIR and the Access and Mobility Function (AMF) enabling the check of the status of the mobile equipment identity. N17 / N5g-eir AMF 5G-EIR Figure 5.2.2.2-1: Reference Model - N5g-eir During any procedure establishing a signalling connection with the UE, the network may perform a mobile equipment and identity check with 5G-EIR via the N5g-eir_Equipment Identity Check Service exhibited by 5G-EIR. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.2.3 Network Exposure Function (NEF) | The usage of Network Exposure Function (NEF) is conditional on the requirement to connect the FRMCS Transport Domain to additional Core Application Functions (AF) other than the MC Service Server. The NEF securely exposes network capabilities and events provided by 3GPP Network Functions to Application Functions. The NEF provides means for securely provisioning of information from AF to 3GPP network and may authenticate, authorize and assist in throttling the AF. The NEF translates information exchange between the AF and internal 3GPP NFs. The usage of NEF is left to Infrastructure Manager, and it is subject to cyber security policies of the FRMCS operator. If the FRMCS Operator implements NEF, the NEF APIs shall be implemented according to ETSI TS 129 522 [19] and NEF Services as per ETSI TS 129 591 [37]. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 24 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.2.4 Network Repository Function (NRF) | The Network Repository Function (NRF) is specified in ETSI TS 123 501 [1], clauses 6.2.6, 6.3.26 and 7.2.6. The NRF provides a centralized repository for all the 5G Network Functions (NFs) in the FRMCS Transport Domain. The NRF allows 5G NFs to register and discover each other via a standards-based API. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.2.5 Binding Support Function (BSF) | The Binding Support Function (BSF) is conditional on the need for a geo-redundant 5G core configuration. The Binding Support Function is used to bind sessions with the correct PCF instance(s). If FRMCS Operator implements BSF, it shall be implemented according to ETSI TS 123 501 [1], clause 7.2.15. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.2.6 Service Communication Proxy (SCP) | The Service Communication Proxy (SCP) is conditional on the need for a geo-redundant 5G core configuration or for other functions specified ETSI TS 123 501 [1], clause 6.2.19. It is used in geo-redundant 5G core configurations to provide functionalities such as message forwarding and routing, Delegated Discovery, Indirect Communication, load balancing and distribution between the geo-redundant cores or local 5G core network elements. If FRMCS operator implements SCP, it shall be implemented according to ETSI TS 123 501 [1], clause 6.2.19 and clause 6.3.16. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.2.2.7 Security Edge Protection Proxy (SEPP) | The Security Edge Protection Proxy (SEPP) is specified in ETSI TS 123 501 [1], clause 6.2.17. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3 FRMCS Multipath Function | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.1 General | The FRMCS Multipath Function distributes incoming Multipath Dataflows across one or multiple Multipath Datapaths according to available Multipath Datapaths and Multipath Policy. The FRMCS Multipath Function can make use of Multipath Datapaths over a FRMCS Transport Domain or over a Non-FRMCS Transport Domain. The FRMCS Multipath Function is a distributed function split between a Multipath Client and a Multipath Gateway. The Multipath Client within an On-Board FRMCS can make use of available On-Board FRMCS Radio Modules and other On-Board Radio Modules attached to a single Transport Domain or to multiple Transport Domains. Subject to Multipath Policy, a Multipath Dataflow can be transparently allocated by the FRMCS Multipath Function to a single Multipath Datapath or be allocated, sequentially or simultaneously, to multiple Multipath Datapaths. NOTE: "Transparently" is to be understood as a feature of the FRMCS Multipath Function which lets the application access a communication resource through a defined interface without having to know the details of the resource or underlaying communication network(s). It is to be understood in the common sense that the underlying network is invisible to the application. The FRMCS Multipath Function requires the underlying Transport Domain to provide IP service connections. Transport Domains used by the FRMCS Multipath Function is the 3GPP based 5G network as defined in clause 4 but can explicitly include also other 3GPP based or non-3GPP based transport networks. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.2 FRMCS Multipath Function capability | The FRMCS Multipath Function supports the following features: • Multipath Datapath selection, i.e. determination of one or more eligible Multipath Datapaths based on evaluation of the Multipath Policy associated to a Multipath Dataflow. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 25 • QoS control, i.e. conveyance of QoS requirements to associate to a Multipath Datapath if supported by its Transport Domain. • Multipath Datapath switching, i.e. change the allocation of a Multipath Dataflow from one Multipath Datapath to another Multipath Datapath. • Multipath Datapath splitting, i.e. distribute the packets of a Multipath Dataflow across multiple Multipath Datapaths. • Multipath Datapath duplication, i.e. duplicate the packets of a Multipath Dataflow across multiple Multipath Datapaths. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.3 Architecture | Figure 5.3.3-1 and Figure 5.3.3-2 illustrate the functional architecture of the FRMCS Multipath Function. It is constituted of two functions, the Multipath Client and the Multipath Gateway. The Multipath Client and the Multipath Gateway are connected via two reference points: • FSMPM which enables the FRMCS Multipath control plane function, including Multipath Gateway discovery, information exchange on available Multipath Datapaths. • FSMPU which enables the user plane transport of a Multipath Dataflow based on a Multipath Protocol over one or more Multipath Datapaths. NOTE: The protocol details of FSMPM are not specified in the present document. On the client side, a Multipath Dataflow ingresses/egresses the Multipath Client via the TAP Service Clients and ingresses/egresses the Multipath Gateway via the TAP Service Agents. Multipath Client (MPC) Multipath Gateway (MPG) FRMCS Transport Stratum TAP Service Clients TAP Service Agents FSMPM Transport network 1 Transport network 2 Transport network N Figure 5.3.3-1: Functional architecture of the FRMCS Multipath Function Multipath Client TAP Service Clients FSMPU MPF CTRL Multipath Dataflow Handler (e.g. For MP-TCP dataflows) Multipath Gateway MPF CTRL Multipath Dataflow Handler (e.g. For MP-TCP dataflows) FSMPM Multipath Datapaths (Transport Nw m, n,…) Multipath Datapaths (Transport Nw m, n,…) TAP Service Agents Figure 5.3.3-2: Functional architecture of Multipath Client and Multipath Gateway ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 26 The Multipath Client enables the interaction with TAP Service Clients that represents FRMCS Service Client(s) in Figure 4.1-1 of ETSI TS 103 765-2 [6]. The Multipath Gateway enables the interaction with the TAP Service Agents. The TAP Service Agent is responsible to forward control information and user plane traffic from the FRMCS service control layer to the Multipath Gateway. The Multipath Gateway and Multipath Client are logical entities which contain the following functional entities: • One MPF-CTRL, i.e. the function within the entity responsible for control functions (discovery, negotiation, instantiation of Multipath Dataflow Handlers, etc.). • One or more Multipath Dataflow Handlers, i.e. the function instances implementing a specific Multipath Protocol between a Multipath Client and a Multipath Gateway. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.4 Multipath Gateway | The MPF-CTRL function of Multipath Gateway has the following responsibilities: • Control of multipath setup between a Multipath Client and the Multipath Gateway. • Instantiation of Multipath Dataflow Handlers. • Handling of IP Address management for each Multipath Dataflow Handler. • Allocation of each Multipath Dataflow to a Multipath Dataflow Handler instance. • Configure a Multipath Dataflow Handler for handling of a Multipath Dataflow. • Implementation of a N5/Rx/N33 QoS Proxy: - To handle incoming QoS requests via the TAP service Agent and forward the appropriate QoS Requests towards the associated Transport Domain(s) via the TAP Transport Core Network CP. - To modify/duplicate forwarded QoS requests to reflect the selected set of Multipath Datapaths associated to a Multipath Dataflow. A Multipath Gateway's Multipath Dataflow Handler has the following responsibilities: • Steer a Multipath Dataflow over one or more Multipath Datapaths as configured by the MPF-CTRL of Multipath Gateway. • Duplicate or stop the duplication of the packets of a Multipath Dataflow across multiple Multipath Datapaths as configured by the MPF-CTRL of Multipath Gateway. • Add and remove Multipath Datapaths as configured by the MPF-CTRL of Multipath Gateway or as a result of detecting availability/unavailability of Multipath Datapaths. Figure 5.3.4-1 illustrates the functional architecture of the Multipath Gateway. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 27 Multipath Gateway (MPG) transport network m UP m TAP Service Agents TAP Transport Core Network MP Dataflow Handler 1 (e.g. for MP-TCP Dataflows) MP Datapath x MP Datapath y M PDH1 TS IP MPF CTRL IP TS 1.m MP TS IP Layer IP TS 2.m MPF Rx/N5 Proxy/Mapping MP Dataflow Handler 2 (e.g. For MP-QUIC Dataflows) MP Datapath z MP Datapath w M PDH2 TS IP IP TS 1.n IP TS 2.n IP TS 0.1 Default CTRL IP I/F transport network n CP n UP n TAP Transport Core Network Figure 5.3.4-1: Multipath Gateway |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.5 Multipath Client | The MPF-CTRL function in the Multipath Client has the following responsibilities: • Control of multipath setup between the Multipath Client and a Multipath Gateway, based on control information received from the Multipath Gateway. • Instantiation of Multipath Dataflow Handlers, based on control information received from the Multipath Gateway. • Handling of IP Address management for each Multipath Dataflow Handler. • Allocation of each Multipath Dataflow to a Multipath Dataflow Handler instance. • Configure Multipath Dataflow Handler instance for handling of a Multipath Dataflow. • Send to Multipath GW the transport identities of the underlying transport paths under its control. A Multipath Client Multipath Dataflow Handler has the following responsibilities: • Steer a Multipath Dataflow over one or more Multipath Datapath as configured by the MPF-CTRL of the Multipath Client. • Duplicate or stop the duplication of the packets of a Multipath Dataflow across multiple Multipath Datapaths as configured by the MPF-CTRL of the Multipath Client. • Add and remove Multipath Datapaths as configured by the MPF-CTRL of the Multipath Client or as a result of availability/unavailability of Multipath Datapaths. Figure 5.3.5-1 illustrates the functional architecture of the Multipath Client. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 28 Transport network n FRMCS Multipath Client (MPC) Transport network m TAP Service Client TAP Transport UE IP B3 IP A3 MP Dataflow Handler 1 (e.g. For MP-TCP Dataflows) 3GPP UE1 3GPP UE2 IP UE1 IP UE2 IP OB 1.1 MP Datapath x MP Datapath y M PF1 OB IP (Linklocal) MPF-CTRL IP OB 1.2 MP Dataflow Handler 2 (e.g. For MP-QUIC Dataflows) MP Datapath z MP Datapath w M PDF OB IP (Linklocal) SIM m Mapping of MC client’s or App’s Data Streams to specific MP Dataflows Hanlder (in case of multiple instances) IP OB 0.1 IP OB 2.1 IP OB 2.2 Default CTRL IP I/F Mapped to “primary“ UE1 Dynamic Define Device & IP IPv6 Prefix provided Service Layer IP Address Assignment via DHCP TS Other OB GW Logic function (MC client proxy, NAT, MCClients), ... IP B3‘ IP A3‘ mapping Local IP Address mapping SIM n Figure 5.3.5-1: Multipath Client In Figure 5.3.5-1, the MPF-CTRL of Multipath Client manages control plane exchanges with the MPF-CTRL of Multipath Gateway over the FSMPM reference point. At least one On-Board Radio Module needs to be available to enable those exchanges. In case of unavailability the On-Board Radio Module used to support the FSMPM reference point, the On-Board FRMCS shall switch to another On-Board Radio Module. The MPF-CTRL of Multipath Client also determines which On-Board Radio Module(s) is used for the FSMPU reference point for a given Multipath Dataflow, based on exchanges with the MPF-CTRL of Multipath Gateway. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.6 IP Address Assignment | IP Address assignment is required: a) for public service layer IP address for each Multipath Dataflow Handler; and b) for each transport domain Multipath Datapath for each Multipath Dataflow Handler. The 5G Core provides IPv6 prefix during the initial default data connection establishment to each UE. The procedure is IPv6 Prefix Delegation. The IPv6 prefix is assigned via DHCPv6. As illustrated in Figure 5.3.5-1 (Multipath Client), the transport-related IP addresses on the OB side (IP OB 1.1, IP OB 2.1, etc.) are appended with this prefix. The IPv6 prefix is delegated from the 5G Core directly, thus the IP addresses, that are part of the prefix, are reachable and routable from the 5G Core to the correct UE. The Multipath Client uses the given IPv6 prefix from the 5GC/UE to define the full transport related IP address on the Multipath Client's side (IP OB 1.1, IP OB 2.1, etc.) by IPv6 stateless autoconfiguration: • The transport-related IP addresses on the Multipath Client's side (IP OB 1.1, IP OB 2.1, etc.) are defined locally on the Multipath Client. These IP addresses shall be propagated to the Multipath Gateway so that the Multipath Gateway can populate the mapping table for each Multipath Dataflow Handler to map the correct trackside transport Multipath Datapath IP address to the On-Board transport IP Multipath Datapath address. • The MPF-CTRL of Multipath Client shall assign the IPv6 addresses to the TAP Service Clients interfaces. They may be public addresses (e.g. Global Unicast Addresses, GUA) or Link-Local addresses, based on the specific address plan in use. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 29 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.7 FRMCS Multipath Function procedures | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.7.1 FRMCS Multipath Function discovery procedure | The FRMCS Multipath Function discovery procedure allows a Multipath Client to discover the presence of a Multipath Gateway within a FRMCS Transport Domain. The following high-level steps are undertaken: 1) The MPF-CTRL of Multipath Client shall select a default connection mapped to a locally selected On-Board FRMCS Radio Module on the FRMCS Transport Domain to be used in the following steps for IP connection between the MPF-CTRL of Multipath Client and the MPF-CTRL of Multipath Gateway. The default connection shall use a predefined default QoS setting on the transport network: a) If the default connection over the FRMCS Transport Domain is not available, the next available other transport domain connection shall be used by the Multipath Client. 2) The MPF-CTRL of Multipath Client shall use a configured DNS server IP address and send a DNS request towards the trackside to resolve a predefined generic FQDN representing the next available Multipath Gateway. 3) If the generic FQDN representing the next available Multipath Gateway can be successfully resolved, an IP address for the Multipath Gateway will be received by the Multipath Client: a) The Multipath Client shall negotiate the multipath capabilities with the Multipath Gateway as specified in clause 5.3.7.3. b) The Multipath Gateway shall negotiate the multipath capabilities with the Multipath Client as specified in clause 5.3.7.3. 4) If the generic FQDN representing the next available Multipath Gateway is not successfully resolved or no response to the DNS query is received by the Multipath Client, the latter shall execute the FRMCS Multipath Function fallback procedure as specified in clause 5.3.7.5. 5.3.7.2 FRMCS Multipath Function Multipath Datapaths handling and selection procedure Once the discovery procedure in clause 5.3.7.1 is successful: Multipath Client: 1) shall allocate transport domain IP Addresses for each Multipath Datapath for each Multipath Dataflow Handler based on one of the methods specified in clause 5.3.6; 2) shall allocate public service layer IP Addresses for each Multipath Dataflow based on one of the methods specified in clause 5.3.6; 3) shall instantiate a Multipath Dataflow Handler for each Multipath Dataflow it receives from the TAP service agent. Multipath Gateway: 1) shall allocate public service layer IP Addresses for each Multipath Dataflow based on one of the methods specified in clause 5.3.6; 2) shall allocate transport domain IP Addresses for each Multipath Datapath for each Multipath Dataflow Handler based on one of the methods specified in clause 5.3.6, this assignment shall correspond to the number of Multipath Datapaths defined at the Multipath Client for each Multipath Dataflow Handler; 3) shall instantiate a Multipath Dataflow Handler for each Multipath Dataflow it receives from the MPF-CTRL of Multipath Client. The Multipath Datapath selection shall be executed by the Multipath Dataflows Handler based on application specific Multipath policy and capability negotiation in clause 5.3.7.3. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 30 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.7.3 FRMCS Multipath Function capability negotiation procedure | The FRMCS Multipath Function capability negotiation procedure is executed between a Multipath Client and a Multipath Gateway. The Multipath Gateway shall determine the parameters and Multipath Policy used. The following multipath capability negotiation shall apply on a per Multipath Dataflow Handler basis: 1) Multipath Protocol decision: Table 5.3.7.3-1 lists possible results of multipath capability negotiation. Table 5.3.7.3-1: Possible outcomes of multipath capability negotiation Description Comment MP-NONE No Multipath Gateway function is supported or shall be used for this Multipath Dataflow, and traffic shall be steered via Multipath Client autonomously or not at all if only one On-Board Radio Module is used MP-TCP Multipath Dataflow Handler supports MP-TCP MP-QUIC Multipath Dataflow Handler supports MP-QUIC MP-Tunnel Only Multipath Gateway provides only tunnel termination with no control over path selection NOTE: MP-Tunnel Only is intended for the case when no multipath control is present. It is used to set up a tunnel for failover and packet duplication use cases where QoS control is not needed. The Multipath Client shall provide the information about the On-Board FRMCS Radio Modules available for control including their operating bands and IMSI towards the Multipath Gateway. The Multipath Gateway shall provide in the response a single value which represents the selected Multipath method and Multipath Protocol to be used. The Multipath Client shall respect the method provided by the Multipath Gateway. The Multipath Gateway shall provide the Multipath Client with policy control regarding the use of the UEs under the Multipath Client's control. 2) QoS requirements: The Multipath Client shall indicate the QoS requirements via a string value. The Multipath Client provides the Communication Category value as provided via OBAPP API (communicationCategory::= UTF8String()), as per FRMCS FFFIS-7950 [8], A.2 OBAPP parameters, and ETSI TS 103 765-3 [7], clause 7.3.2.1. The multipath capability negotiation shall be performed via HTTP/2-based REST protocol. The Multipath Gateway acts as HTTP/2 server and the Multipath Client acts as HTTP/2 client: - HTTP/2, as defined in IETF RFC 9113 [21], shall be used. - The data contained in the body of HTTP request; HTTP response shall be encoded in JSON as specified in IETF RFC 8259 [22]. The use of the JSON format shall be signalled by the content type application/json. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.7.4 FRMCS Multipath Function capability definition procedure | If the selected Multipath Protocol decided during Multipath capability negotiation as per clause 5.3.7.3 Point 1 is MP-TCP, the MP-TCP protocol shall be implemented according to IETF RFC 8684 [27]. If the selected Multipath protocol decided during Multipath capability negotiation as per clause 5.3.7.3 Point 1 is MP-QUIC, the MP-QUIC protocol shall be implemented according to the following definitions: • QUIC layer as defined in ETSI TS 123 501 [1], clause 5.32.6.2.2, Item 3) "QUIC layer". Usage of Datagram mode 1 as defined in ETSI TS 123 501 [1], clause 5.32.6.2.2.1, and ETSI TS 124 193 [28], clause 6.4.2 which is using QUIC Datagram frames with unreliable transport but with sequence numbering, packet reordering and congestion control. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 31 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.7.5 FRMCS Multipath Function fallback procedure | The FRMCS Multipath Function fallback procedure shall be executed if the Multipath Client does not get a valid response on the DNS query. This is considered as an indication that there is no trackside MPF available or that it shall not be used. In this case, the IP assignment as per clause 5.3.6 shall be used. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.7.6 FRMCS Multipath Function cleanup procedure | The following steps are undertaken: 1) For each Multipath Dataflow of the Multipath Client, the procedure in clause 5.3.7.7 shall be performed. 2) The Multipath Gateway shall release the Multipath Dataflows Handler. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 5.3.7.7 Release of FRMCS Multipath Dataflow | The following steps are undertaken: 1) The Multipath Client shall request the release of the Multipath Dataflow. 2) The Multipath Gateway shall perform the release of Multipath Dataflow. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 6 Transport Stratum Procedures | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 6.1 On-Board Radio Module Registration Procedure | Upon selection by the On-Board FRMCS of a FRMCS Transport Domain to register to, the On-Board FRMCS Radio Module shall execute the network selection, ETSI TS 123 501 [1], clause 5.2.2. PLMN selection procedure in "manual network selection" mode as specified in ETSI TS 123 122 [38], clause 4.2 towards the designated FRMCS Transport Domain shall be followed. The On-Board FRMCS Radio Module shall perform UE Initial Registration to the designated FRMCS Transport Domain as specified in ETSI TS 123 501 [1], clause 5.3, Registration and Connection Management and in ETSI TS 123 502 [10], clause 4.2. The Initial Registration procedure involves execution of Network Access Control functions as defined in clause 5.2 (i.e. user authentication and access authorization based on subscription profiles in UDM). The On-Board FRMCS Radio Module uses the identities stored in the SIM profile (SUPI/SUCI using IMSI identifier). 6.2 Transport path establishment for Mission Critical signalling procedure The On-Board FRMCS Radio Module shall execute the "UE Requested PDU Session Establishment" procedure as specified in ETSI TS 123 502 [10], clause 4.3.2.2. It covers both the non-roaming and roaming case with LBO case (clause 4.3.2.2.1in ETSI TS 123 502 [10]) and the Home-Routed roaming case (clause 4.3.2.2.2 in ETSI TS 123 502 [10]). MC signalling is assigned a transport bearer with high prioritization according to 5QI settings. The standard 5QI for Mission Critical delay sensitive signalling (e.g. MCPTT signalling, MC Video signalling) is 69. Policy control decision in FRMCS is enabled by dynamic service input provided by the MC Service Server to the PCF through reference point Rx or N5. This may be direct or via the FRMCS SIP Core. The SMF receives policy rules from the PCF via N7 and sends instructions for QoS enforcement, traffic steering and charging control via N4 to the UPF. The UPF enforces the rules via Packet Detection Rules (PDRs) and forwarding actions. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 32 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 6.3 On-Board Radio Module deregistration procedure | The On-Board FRMCS Radio Module shall execute the "UE-initiated Deregistration" procedure as specified in ETSI TS 123 502 [10], clause 4.2.2.3.2. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 6.4 Roaming Home-Routed Transport Path Establishment | In the Home-Routed case, the On-Board FRMCS Radio Module shall execute the "UE Requested PDU Session Establishment" procedure as specified in ETSI TS 123 502 [10], clause 4.2.3.2.2. This procedure is typically used in FRMCS to: • Enable roaming of a UE onto an MNO network with home routing to the Home FRMCS Domain (National Roaming with only home routing). • Enable roaming of a UE onto a foreign FRMCS Domain where home routing to the Home FRMCS Domain is necessary: - In Inter-FRMCS-Domain Transition. - In use cases where home routing to the Home FRMCS Domain is desirable (such as an application of Application Type IV). |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 6.5 Release of transport path | If the transport path is a Multipath Dataflow, the procedure in clause 5.3.7.7 shall be performed. If the transport path is not a Multipath Dataflow, the UE-requested PDU session release as specified in ETSI TS 123 502 [10], clause 4.3.4 shall be performed. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 7 Interaction of Service Stratum and Transport Stratum | The ETSI reference point to be used for interaction between the transport stratum and service stratum including FRMCS SIP core as defined in ETSI TS 103 765-2 [6] and in ETSI TS 123 501 [1], clause 6.2.10. The following functions are supported between the transport stratum and service stratum: a) Interacting with the 5G Policy framework for Policy Control (PCF). b) Interactions of the FRMCS SIP Core and HTTP connection for MC signalling with the 5G Core via the Data Network (DN). 8 FRMCS Transport Stratum Quality of Service Framework |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 8.1 FRMCS Quality of Service Principles | The FRMCS Transport Stratum QoS framework is based on the following principles: a) QoS is applied via PDU sessions (up to 15 per UE) and QoS flows (up to 63 per PDU session). b) QoS is enforced at UE, gNodeB and UPF based on rules propagated from the UDM/PCF or pre-configured. c) QoS policy is controlled from the FRMCS service stratum via messaging over reference points Rx or N5. d) The gNodeB can map multiple QoS flows with similar characteristics to a single Data Radio Bearer (DRB). ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 33 e) QoS flows can be of type GBR (Guaranteed Bit Rate), non-GBR and delay critical GBR. f) Each QoS flow is associated with a QoS profile, including: i) A QFI (QoS Flow identifiers) based on 5QI. ii) An ARP (Allocation & Retention Priority and pre-emption capability and vulnerability indicators). iii) Type specific & optional parameters. IP data is mapped (filtered) to QoS flows at UE (based on QoS rules) and UPF utilizing packet filter sets. The FRMCS Application Function (AF), defined in ETSI TR 103 791 [i.1], shall perform mapping from a Session Description Information (SDI), received within the AF session signalling, to service information passed to the PCF over the N5 or Rx reference points as per ETSI TS 129 513 [24]. The FRMCS AF shall signal the PCF to request resources for media bearers using one of the following options: i) as per ETSI TS 123 289 [23], clause 7.2.2 (see step 3 in Figure 8.1-1) if the FRMCS SIP Core represents the FRMCS AF; or ii) as per ETSI TS 123 289 [23], clause 7.2.3.2 if the MC Service Server represents the FRMCS AF (see step 6 in Figure 8.1-2). MC service client MC service server SIP core 5GS (PCF) 3. Session progress – request for resources 4. Session management procedures (defined in 3GPP TS 23.502 [10]) with PCC enforcement 5. Session progress 1. Session establishment 2. MC service server evaluates need for network resources and media sharing 8. MC service call/session established using unicast PDU session 6. ok 7. ok Figure 8.1-1: MC service call session establishment - FRMCS SIP core-based option ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 34 MC service client MC service server SIP core 5GS (PCF or NEF) 3. Session progress 4. Session progress 1. Session establishment 2. MC service server evaluates the need for network resources and media sharing 8. MC service call/session using unicast mode established 5. Session acknowledgement 6. Request of resources for media flow 7. Session management procedures (defined in 3GPP TS 23.502 [10]) with PCC enforcement Figure 8.1-2: MC service call session establishment - Service server-based option The MC Service Server shall utilize the Npcf_PolicyAuthorization Service as described in ETSI TS 129 514 [29] for N5 or Rx procedures in ETSI TS 129 214 [30], to request policies for the PDU session which the FRMCS MC session is bound to. The PCF shall perform mapping from the service information received over the Rx or N5 reference points to the Authorized QoS parameters that shall be passed to the SMF via the N7 reference point. The Session binding function determines relevant PDU session and associates IP data flows to it. PCF shall consider any 5GC specific restrictions, the AF service information and other information available to the PCF. PCF associates a set of QoS parameters (5QI, ARP, etc.) to each PCC rule as per ETSI TS 129 513 [24]. The SMF shall perform mapping from the Authorized QoS parameters received from PCF to the access specific QoS parameters as per ETSI TS 129 513 [24]. FRMCS AF can use Npcf_EventExposure service to get notifications about the outcomes of UE policies delivery as per ETSI TS 129 512 [25]. The network sets up QoS flow(s) with a suitable QoS and indicates to the UE the QoS characteristics of those QoS flow(s) as per Figure 8.1-3 (reference to ETSI TS 129 513 [24], clause 7.1). ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 35 SMF PCF Flow Service Manager 3) Translation / Mapping function Access- Specific Flow Service Manager (NOTE) UE Translation / Mapping function Access- Specific Flow Service Manager Flow Service Manager Application N7 AF session signalling , possibly with SDI Service information Rx or N5 2) Policy Engine Authorized QoS parameters Authorized QoS parameters Authorized Access-Specific QoS parameters Authorized Access-specific QoS parameters Authorized QoS parameters Authorized Access-Specific QoS parameters Signalling path Only for some PDU session Types and terminals LEGEND AF 1) SDI Mapping function Figure 8.1-3: Flow of QoS-related messages using Rx or N5 FRMCS supports either the N5 or the Rx reference point between AF and PCF. FRMCS shall utilize the afAppID on the N5 reference point or AVP parameter AF-Application-Identifier on the Rx reference point, as described in ETSI TS 129 514 [29] and in ETSI TS 129 214 [30], respectively. This parameter is associated, within the AF, to the <user-requested-priority> provided by the MC Service Client for the AF session, as described in ETSI TS 103 765-2 [6], clause 6.2.5. NOTE: The mapping of the combination of Communication Session Category (CSC) and Sub-category (indicating further priority distinction within a CSC) to the afAppID needs to be consistent between the FRMCS Application Function and the (5GC of) FRMCS Transport Domain which are serving that CSC. FRMCS shall use the resPrio attribute on the N5 reference point or AVP parameter Reservation-Priority on the Rx reference point, as described in ETSI TS 129 514 [29] and in ETSI TS 129 214 [30], respectively. This attribute shall be mapped to the value of the Resource-Priority header field of the SIP INVITE (specified in ETSI TS 103 765-2 [6], clause 6.2.6) according to Table 8.1-1. Table 8.1-1: Mapping of Resource-Priority to resPrio and Reservation-Priority Resource-Priority header field resPrio AVP Reservation-Priority Normal PRIO_1 (lowest priority) 0 (lowest priority) Based on the information (afAppId, resPrio) received from FRMCS AF, PCF shall perform policy decisions for PDU session with particular MC service during SM policy association modification procedure as per ETSI TS 123 502 [10], clause 4.3.3.2, 1b. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 36 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 8.2 FRMCS Unified Access Control (UAC) | In FRMCS, UAC enables the prioritization of access for FRMCS users and helps the gNodeB load control functions to effectively handle the high-load scenarios. Access prioritization is carried out by barring the mobile-originated access and service requests at the UE side. The UE will decide if it is allowed to submit a connection request to a network based on the instructions in the SIB1 message. This is accomplished by verifying the broadcast system data (S1B1 message) that is obtained over the network, along with the user/service data that is kept in the UE. In high traffic load situations, the network may set up the broadcasted system information to restrict requests from certain users. UEs will follow instructions in the SIB1 message, which means no extra load is added to the RAN to restrict access. If the connection request is approved, a user can initiate a normal random-access procedure to connect to the network. In UAC the access barring profile is a combination of FRMCS PLMN, Access Identities, and Access Categories. Barring probability in high load situations is applied according to barring profiles. For an On-Board FRMCS radio module, the USIM file EFUAC_AIC shall be configured with Access Identity equals to 2 and the MCS Indicator bit of the mobile network shall be set to valid within the FRMCS Transport Domain as specified in clauses 4.5.2 and 4.5.2A in ETSI TS 124 501 [9]. On-Board FRMCS radio module in a shared network shall be configured with zero barring probability. UEs with an Access Identity equal to zero and Access Category equal to 9 (MO Data) shall be configured with a high barring probability. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 8.3 5QI and ARP Application per FRMCS Service | The FRMCS Transport Domain shall support at least the 5QI identified in Table 8.3-1. Table 8.3-1: List of 5QI in FRMCS 5QI 4 5 8 65 69 As an example, two of the Communication Session Categories listed (informative) in ETSI TS 103 765-2 [6], Annex A, can be mapped as defined in Table 8.3-2. Table 8.3-2: An example of mapping afAppId/AF-Application-Identifier, 5QI and ARP to FRMCS Communication Session Category Communication Session Category Sub-category afAppID/ AF-Application-Identifier 5QI ARP Default Data N/A "Default Data" 8 8 Voice Urgent Driver-to-Controller "Voice - Urgent Driver-to-Controller" 65 3 Normal Driver-to-Controller "Voice - Normal Driver-to-Controller" 65 5 NOTE: The mapping between Communication Session Category and the afAppId needs to be harmonized between the FRMCS Application Function and the (5GC of) FRMCS Transport Domain. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 37 |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 8.4 5QI to DSCP Mapping | The QoS of FRMCS Transport Stratum traffic is classified using 5QI. Since the traffic flow to some endpoints (Trackside Gateway, VAS controller, etc.) traverses an IP/MPLS backbone the 5QI shall be mapped to a Traffic Class. For each QoS Flow characterized by its 5QI, the mapping of 5QI to DSCP values are done on different nodes depending on the traffic direction: • For UL traffic, the gNodeB maps the 5QI values to transport DSCP values. For DL traffic, the mapping is done by local configuration on the SMF, which provides UPF with the transport DSCP values. The UPF then marks DL traffic on a per QoS Flow basis. The DSCP mapping for mandatory FRMCS 5QIs from Table 8.3-1 is identified in Table 8.4-1. Table 8.4-1: 5QI to DSCP Mapping 5QI DSCP 4 AF43 (DSCP 38) 5 CS5 (DSCP 40) 8 AF12 (DSCP 12) 65 EF (DSCP 46) 69 CS5 (DSCP 40) |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 9 Transport Stratum Synchronization | |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 9.1 Radio Network Synchronization | NR SA TDD radio networks require frequency and phase synchronization. When the Baseband Radio Node is time and phase synchronized, it is also frequency synchronized. FRMCS TDD cells operating at the same frequency in overlapping coverage areas would benefit from time domain isolation to minimize base station-to-base station and UE-to-UE Radio Frequency (RF) interference. There are two requirements to achieve time domain isolation: • The cells need to use the same TDD configuration. • The deviation in frame start timing between cells needs to be below a maximum value specified as cell phase synchronization accuracy in the 3GPP specification. ETSI TS 138 104 [31] and ETSI TS 138 133 [32] provide specifications for frequency and phase synchronization at the radio air interface to meet NR deployment requirements across various use cases. ITU-T (Recommendation ITU-T G.8271.1 [33] and Recommendation ITU-T G.8271.2 [34]) specifies timing profiles and network budget for the transport network to meet those requirements for 5G RAN. These requirements can be classified into: a) NR TDD specific requirements; b) improved NR performance and spectrum efficiency; and c) use case specific requirements. In 3GPP, cell phase synchronization between NR TDD radios is specified as 3 µs. That leaves ±1,5 µs time error accuracy from the common time reference to each radio, and a remainder of ±1,1 µs to the transport network if the common time refence is connected over the backhaul network. The frequency synchronization is specified as 50 ppb at the air interface level, and a budget of 16 ppb is typically assumed for the backhaul transport network. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 38 Location and Positioning using 5G 3GPP techniques demand more stringent accuracy from the 5G NR radios (e.g. location accuracy and position tracking). The measurement of accurate positioning depends on a time difference measured over-the-air interfaces. One such method, observed Time Difference of Arrival (OTDOA), assumes that the relative phase offset between the reference stations are within the defined accuracy limits, and that their relative phase offset is known. 3GPP specifications define a stringent ±100 ns phase accuracy as positioning requirements between adjacent 5G NR radios. Inter-band and intra-band CA, and the use of MIMO antennas, have a very stringent relative time alignment error of 130 ns to 260 ns measured at the antenna air interface. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 9.2 Time-of-Day Synchronization | Network Time Protocol (NTP) (see IETF RFC 5905 [i.2]) or Network Time Security, IETF RFC 8915 [i.3] can be used to synchronize the time of day. The main objective of NTP is long-term event synchronization across core and radio access nodes. The core network elements and elements in the baseband nodes can then send NTP requests via interfacing between O&M functions and the NTP server. |
89a5e71b6365c50edf742ee93d4c0839 | 103 765-1 | 10 Transport Stratum Identities | FRMCS uses the following identities in the transport stratum: • GPSI as external identifier. • SUPI/SUCI using IMSI identifier. • NAI using IMSI with MCC and MNC. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 39 Annex A (informative): Generalities on synchronization This annex is intended as informative on possible approaches to achieve synchronization requirements in the Radio Access Network. Synchronization is typically achieved by syncing towards a common Grandmaster via, e.g. GNSS or the transport network. Clear satellite visibility is critical for the operation of GNSS receivers. However, ionospheric delay variations, solar activities, and weather conditions are additional factors that could impact the performance accuracy of the GNSS receiver in the range of several nanoseconds. The existing single-band GNSS receivers (PRTC-A with ±100 ns accuracy) are limited to mitigate these errors, and 5G NR demands better GNSS receiver technologies to meet previously discussed deployment requirements. GNSS and PTP are valid references for RAN synchronization. The two references (GNSS and PTP/IP) can be used with primary and secondary reference distinguished by priority setting. When synchronization reference fails, the system falls back to the secondary reference and the holdover time can be extended in case it is assisted with Synchronous Ethernet (SyncE) protocol. If outage occurs in the GNSS synchronization reference, the gNodeB enters holdover for a limited time and all radio services are maintained. The holdover period can be extended if the GNSS is assisted with a PTP/IP connection. This is called Assisted Partial Timing Support (APTS). The timing support enables the gNodeB to calculate the timing compensation in the PTP/IP provided by the central PTP/IP Grandmaster while the GNSS is available. The learnt compensation value is then used when switching to the PTP/IP Grandmaster at a GNSS outage. Depending on the network conditions and the duration of the local GNSS signal time and phase synchronization presence before the GNSS outage, a gNodeB can provide accurate timing information for a longer period if the PTP/IP reference remains stable. If the PTP/IP reference is also lost during a GNSS outage, the node loses time and phase synchronization, and the cell eventually goes down. The PTP/IP Grandmaster can be located either centralized in the core or distributed in the network to serve dedicated clusters of gNodeB. The most common scenario for large networks is to have multiple Grandmasters to serve clusters of gNodeB to minimize the potential asymmetry introduced by the transport network. The distributed Grandmasters are then generally located at one of the cell sites in the gNodeB cluster. ETSI ETSI TS 103 765-1 V1.1.1 (2026-01) 40 History Version Date Status V1.0.0 July 2025 SRdAP process EV 20251008: 2025-07-10 to 2025-10-08 V1.1.0 November 2025 SRdAP process VA 20260106: 2025-11-07 to 2026-01-06 V1.1.1 January 2026 Publication |
68307306d039047e470f288ba4891560 | 103 764 | 1 Scope | The present document describes the high-level System Architecture for the Future Railway Mobile Communications System (FRMCS). The interaction between FRMCS domains, high-level procedures, deployment scenarios and IP addressing/routing are also outlined. |
68307306d039047e470f288ba4891560 | 103 764 | 2 References | |
68307306d039047e470f288ba4891560 | 103 764 | 2.1 Normative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found in the ETSI docbox. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long term validity. The following referenced documents are necessary for the application of the present document. [1] ETSI TS 103 765-1: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Building Blocks and Functions; Part 1: Transport Stratum". [2] ETSI TS 103 765-2: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Building Blocks and Functions; Part 2: Service Stratum". [3] ETSI TS 103 765-3: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Building Blocks and Functions; Part 3: Train On-Board functions and interfaces". [4] ETSI TS 103 765-4: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Building Blocks and Functions; Part 4: Trackside functions and interfaces". [5] ETSI TS 103 792: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Interworking with GSM-R". |
68307306d039047e470f288ba4891560 | 103 764 | 2.2 Informative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long term validity. The following referenced documents may be useful in implementing an ETSI deliverable or add to the reader's understanding, but are not required for conformance to the present document. [i.1] UIC FRMCS FFFIS-7950: "FRMCS FFFIS Form Fit Functional Interface Specification". [i.2] UIC FRMCS FIS-7970: "FRMCS FIS Functional Interface Specification". [i.3] UIC FRMCS SRS: FRMCS System Requirements Specification". [i.4] ETSI TR 103 791: "Rail Telecommunications (RT); Future Railway Mobile Communication System (FRMCS); Terminology for FRMCS specifications". ETSI ETSI TS 103 764 V1.1.1 (2026-01) 7 |
68307306d039047e470f288ba4891560 | 103 764 | 3 Definition of terms, symbols and abbreviations | |
68307306d039047e470f288ba4891560 | 103 764 | 3.1 Terms | For the purposes of the present document, the terms given in ETSI TR 103 791 [i.4] and the following apply: open session: session which has not been terminated via MCData procedures session: tunnel established between two MCData clients on behalf of an application |
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