5G Network Architecture and Design

1. 5G Network Architecture and Design Andy Sutton, Principal Network Architect - Chief Architect’s Office, TSO 25th January 2017

2. © British Telecommunications plc Contents • 5G Network Architecture – 3GPP logical network architecture – Functional blocks – Reference points (interfaces) – RAN functional split • Adding 5G to an existing multi-RAT site – RAT types and base station configurations – Scaling mobile backhaul and/or introducing NGFI • 5G Architecture Options – Standalone and non-standalone modes of operation – EPC to NGCN migration scenarios and inter-working • Summary

3. 5G Network Architecture

4. © British Telecommunications plc 3GPP 5G network architecture UE RAN UPF DN AMF SMF PCF UDM AF AUSF NG1 NG7 NG6 NG5 NG4 NG3 NG2 NG8 NG9 - between UPFs NG14 - between AMFs NG10 NG11 NG12 NG13 NG15 NR air i/f Note: Focus on mobile however Access Network (AN) could be fixed

5. © British Telecommunications plc Functional blocks within 5G network architecture 1. AUSF = Authentication Server Function 2. UDM = Unified Data Management 3. AMF = Core Access and Mobility Management Function 4. SMF = Session Management Function 5. PCF = Policy Control Function 6. AF = Application Function 7. UE = User Equipment 8. ((R)AN) = (Radio) Access Network 9. UPF = User Plane Function 10. DN = Data Network, e.g. operator services, Internet or 3rd party services

6. © British Telecommunications plc 5G interfaces (reference points) • NG1: Reference point between the UE and the Access and Mobility Management function. • NG2: Reference point between the (R)AN and the Access and Mobility Management function. • NG3: Reference point between the (R)AN and the User plane function (UPF). • NG4: Reference point between the Session Management function (SMF) and the User plane function (UPF). • NG5: Reference point between the Policy Function (PCF) and an Application Function (AF). • NG6: Reference point between the UP function (UPF) and a Data Network (DN). • NG7: Reference point between the Session Management function (SMF) and the Policy Control function (PCF). • NG7r: Reference point between the vPCF and the hPCF. • NG8: Reference point between Unified Data Management and AMF. • NG9: Reference point between two Core User plane functions (UPFs). • NG10: Reference point between UDM and SMF. • NG11: Reference point between Access and Mobility Management function (AMF) and Session Management function (SMF). • NG12: Reference point between Access and Mobility Management function (AMF) and Authentication Server function (AUSF). • NG13: Reference point between UDM and Authentication Server function (AUSF). • NG14: Reference point between 2 Access and Mobility Management function (AMF). • NG15: Reference point between the PCF and the AMF in case of non-roaming scenario, V-PCF and AMF in case of roaming scenario. • NG16: Reference point between two SMFs, (in roaming case between V-SMF and the H-SMF).

7. © British Telecommunications plc 5G RAN and functional decomposition… UE RAN UPF DNNG6NG3NR air i/f DU CUNGFI ? ? CU = Centralised Unit DU = Distributed Unit NGFI = Next Generation Fronthaul Interface

8. © British Telecommunications plc RAN functional splits and impact on backhaul RRC PDCP Data Low- RLC High- MAC High- PHY Low- MAC Low- PHY RF High- RLC RRC PDCP Data Low- RLC High- MAC High- PHY Low- MAC Low- PHY RF High- RLC Option 1 Option 2 Option 3 Option 4 Option 5 Option 6 Option 7 Option 8 End to end maximum latency Capacity requirement Higher layer splits Lower layer splits

9. Adding 5G to an existing multi-RAT macro-site

10. © British Telecommunications plc Adding 5G to an existing multi-RAT macro-site • Current multi-RAT macro-cell sites typically have backhaul of 1Gbps • Capacity is shared between RATs and in many cases, between network sharing partners (MNOs) • Note: >1Gbps backhaul is being deployed to support certain LTE radio configurations – 1Gbps and beyond on LTE radio interface 2G/4G SRAN (1/GE) 3G MORAN 100M/1GE 4G Net-Share (1GE) 1GE

11. © British Telecommunications plc Adding 5G to an existing multi-RAT macro-site • 5G deployment to macro-cells is very likely to be <6GHz spectrum bands • Massive MIMO is a key concept for 5G – 32/64/128+ antennas • 5G NR channel bandwidths to be larger than current LTE channels • Most spectrum will be unpaired, therefore phase/time synchronisation is required for TDD operation • Assume eMBB is to be the first use case, the maximum capacity is required • Backhaul, or NGFI, will require a minimum of 10GE local connectivity with scalable end to end capacity 2G/4G SRAN (1/10GE) 3G MORAN 100M/1GE 4G Net-Share (1GE) 5G gNB (10GE) ?

12. © British Telecommunications plc Adding 5G to an existing multi-RAT macro-site • 5G deployment to macro-cells is likely to be <6GHz spectrum bands • Massive MIMO is a key concept for 5G – 32/64/128+ antennas • 5G NR channel bandwidths to be larger than current LTE channels • Most spectrum will be unpaired, therefore phase/time synchronisation is required for TDD operation • Assume eMBB is to be the first use case, the maximum capacity is required • Backhaul, or NGFI, will require a minimum of 10GE local connectivity with scalable end to end capacity • mm-wave radio backhaul/x-haul will support 10Gbps+ 2G/4G SRAN (1/10GE) 3G MORAN 100M/1GE 4G Net-Share (1GE) 5G gNB (10GE) Sub-tended mm-wave (10GE+) ?

13. 5G Architecture Options

14. © British Telecommunications plc 5G Architecture Options 12 options identified, not all will be implemented, slides illustrate most likely solutions (options 5, 6, 8 and 8a considered unlikely and therefore not illustrated (option 1 is legacy)) 1: Standalone LTE, EPC connected 2: Standalone NR, NGCN connected eLTE EPC UE 5G NR NGC UE User plane S1-u Control plane S1-c User plane NG3 Control plane NG2 Release 15 UE

15. © British Telecommunications plc 5G migration scenarios 3: Non-standalone/LTE assisted, EPC connected 3a: Non-standalone/LTE assisted, EPC connected eLTE EPC 5G NR NGC UE eLTE EPC 5G NR NGC UE

16. © British Telecommunications plc 5G migration scenarios 4: Non-standalone/NR assisted, NGCN connected 4a: Non-standalone/NR assisted, NGCN connected eLTE EPC 5G NR NGC UE eLTE EPC 5G NR NGC UE

17. © British Telecommunications plc 5G migration scenarios 7: Non-standalone/LTE assisted, NGCN connected 7a: Non-standalone/LTE assisted, NGCN connected eLTE EPC 5G NR NGC UE eLTE EPC 5G NR NGC UE

18. Summary

19. © British Telecommunications plc Summary • 5G standards are still under development within 3GPP • Final technical contributions for the initial 5G standards are being discussed (Release 15) • 5G will support enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC) and massive Machine Type Communications (mMTC) • 5G RAN will be different from previous iteration of C-RAN and D-RAN • NGFI will likely be implemented for 5G and eLTE - exact functional splits tbd • There is significant complexity to manage in the core network, including inter-working with and migration to NGCN • BT is pro-actively developing 5G solutions…

5G Network Architecture and Design

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5G Network Architecture and Design