The path to 5G in Australia: Architecture evolution from 4G to 5G

Transcription

1 The path to 5G in Australia: Architecture evolution from 4G to 5G August 2018 Authors: Dr David Soldani, Dr Malcolm Shore and Mr Jeremy Mitchell

2 Table of Contents Preface... 3 Foreword... 5 Introduction G use cases G definitions and standard updates... 8 Option 2: gnb connected to 5GC... 9 Option 3: Multi-RAT DC with EPC... 9 Option 4: Multi-RAT DC with the 5GC and as Master... 9 Option 5: LTE ng-enb connected to 5GC Option 7: Multi-RAT DC with the 5GC and E-UTRA as Master Family of usage scenarios GPP 5G roadmap Spectrum G reference architecture and migration strategies G core and slicing G security aspects G deployment scenarios References Commercial in confidence Page 2 of 28

3 Preface This position paper outlines the most relevant technology transition options from the current 4G telecommunications network ecosystem into a 5G network ecosystem. In this paper, we set out the frameworks and roadmaps that Australian communication service providers may take to 5G. This is about an evolutionary transition from 4G into 5G and, while there will be fundamental changes in network abilities and services delivered, the network principles remain the same [1]. There is a clear standardised interface and separation between Core Network (CN) and Radio Access Network (RAN) across the whole transition of deployments and in a final 5G standalone environment [2]. The 3GPP 5G System design follows requirement from various organisations. The most prominent input is perhaps the NGMN 5G Whitepaper [3], which provides functional design and migration considerations from a network operator perspective. As in previous 3GPP systems, the 5G Access-Core Network boundary has been set out in the 3GPP global standards with a clear functional split and offers globally accepted principles. This enables the adoption of different business models, and the utilisation of RAN equipment from one vendor and core elements from other network infrastructure providers, as it is currently in 4G networks in Australia. Huawei is one of the major wireless vendors in Australia, delivering Radio Access Network equipment in three of the four foremost communication service providers. Huawei has also delivered Australia s largest private 4G LTE network. Globally Huawei is the only company that can supply a full end to end 5G technology solution, from chipset, devices, Radio Access and Core. In Australia, Huawei is focusing its business opportunities in the same footprint currently undertaken in the 4G networks, i.e. only supplying Radio Access Network technology. That means Huawei will not be tendering for core network opportunities with the major telecom operators. 5G will be the driver of next wave of economic productivity growth across the globe. The Asia Pacific region is leading in the commercial delivery of 5G technology with Japan, South Korea and China already announcing a timetable of commercial 5G rollouts. Huawei is already working closely with operators and governments in these countries. We are also delivering 5G trials in the United Kingdom, Canada and New Zealand and working with the corresponding governments and operators to ensure their citizens have access to best performing, secure and privacy preserving 5G technologies. Commercial in confidence Page 3 of 28

4 We want Australian telecom operators to have the same opportunity to purchase the world s best 5G technology. We also understand the importance of security in these technologies, and this is why we are offering to share our knowledge, ideas and practices in this area and work with the Government to independently evaluate any Huawei products, if necessary. Jeremy Mitchell David Soldani Malcolm Shore Director Corporate Affairs Chief Technology Officer Cyber Security Officer Huawei Australia Huawei Australia Huawei Australia Commercial in confidence Page 4 of 28

5 Foreword The 5G System has been designed for connecting people, homes and organizations, increasing mobile broadband speed, reliability and number of connections per square kilometre. Latency has been also reduced to support a variety of new services, especially from vertical sectors. The 5G System consists of Next Generation Radio Access Network (NG- RAN, New Radio and Evolved LTE) and 5G Core Network (5GC, supporting end to end flow based QoS and network slicing) separated by a standardized, unified and open interface, which allows a multivendor deployment. The paper reflects well the latest developments of 3GPP technical specifications for 5G Systems, and provides a clear path to 5G in Australia. In this nation, Huawei tenders only for the RAN part of the Network, where security risks can be managed as in earlier Network generations. In order to be on the same level playing field as others leading countries, such as USA, UK, Europe, China, South Korea and Japan, Australia needs to allow competition for accessing state of art technologies at competitive price, stimulate and attract new investments from overseas, and assemble top experts in the ICT field, e.g. build an Australian Technology Platform (ATP), to develop a Strategic Research and Innovation Agenda (SRIA) for Australia. Latif Ladid Chair, 5G World Alliance, Luxembourg President, IPv6 FORUM Fellow of the IEEE Chair, EU IPV6 Task Force ( Emeritus Trustee, Internet Society ( This is the most comprehensive document I have seen on 5G, transition from 4G to 5G with sufficient technical depth on radio access network, core network and security and all the interfaces. The document reflects perfectly the global standard set by 3GPP in its Release 15 on 5G and more importantly the approach is standards compliant. From my understating of other equipment vendors and operators plans in other countries and specifically in the UK, all have adopted the same approach which utilises the huge investment already made in 4G deployment whilst modernising their network with 5G capability. Furthermore, due to the fact that Radio Access Network (RAN) is separated from the 5G Core Network and designed only to forward packets transparently to terminals and core, any security risk can be managed as in earlier RAN generation. Rahim Tafazolli Regius Professor of Electronic Engineering Institute for Communication Systems and 5G Innovation Centre ( Director, University of Surrey, UK Commercial in confidence Page 5 of 28

6 5G mobile communications will continue the ever-growing availability of high quality video and broadband data, and unlock a vast array of new applications including IoT, machine-tomachine, and augmented reality services. There are a number of significant leaps forward, compared to 4G technology, while building on many of the successful features of existing equipment and infrastructure, in an approach that allows for a staged and integrated rollout with multi-vendor technology mixes. This paper summarises the main technical aspects of 5G technology and network architecture, highlighting the separation and standardised interfaces between the radio access network (RAN) and the core network functions encompassed in the 5G standard. These aspects underpin the flexibility, security and interoperability of future 5G network architectures and will be key to their success. Iain Collings Professor Fellow of IEEE Deputy Dean School of Engineering Macquarie University Sydney, Australia Commercial in confidence Page 6 of 28

7 Introduction This document has been prepared for the Critical Infrastructure Centre (CIC), Prime Minister & Cabinet (PMC) and other Australian National Security agencies to clarify some important design and security aspects of 5G systems, and addresses the main questions asked by the Australian Government, especially on the deployment of Next Generation Radio Access Networks (NG-RAN) in mobile communication and information infrastructures in Australia. The paper first presents the most relevant 5G use cases for the Australian market in , and beyond; 5G concept and definitions; 3GPP updates, in terms of system architecture and enabling technologies and corresponding timelines; and spectrum availability, linked to possible 5G deployments in Australia. Then, the paper discusses the 5G functional architecture, possible configuration options, enabling technologies and network migration strategies, and related 5G security aspects, in Australia, and globally. This is followed by a description of the possible 5G deployment scenarios, in a multivendor environment, and the Huawei product portfolio and site solution in Australia. Conclusions are drawn on the main security aspects of the 5G systems. 5G use cases In Australia, carriers have showcased 5G networks at 2018 Gold Coast Commonwealth Games, ahead of the announced 5G services launch in 2019, see for example [4] and [5]. The most important use cases are, as depicted in Figure 1: 1) 5G fixed wireless access (FWA): Complements fibre networks and replace the last m fibre. It provides a Gigabit-Speed Internet experience at home. For each household, the sustainable speed is 100Mb/s in the downlink 3.5GHz/1800MHz with 5G/LTE shared uplink transmission (SUL), and up to 26GHz. See e.g. [6]. 2) Virtual (VR), Augmented (AR) and Mixed Reality (MR): A full immersive and interactive experience for 5G Hotspots, in-vehicle infotainment, gaming, etc. The most important 5G requirements are: Latency < 10 ms; Bandwidth > 1Gbps; and cell capacity with more than 500 connections. See e.g. [7]. 3) Industrial Processes Automation: Remote drilling, wireless service robots, drone traffic management, etc. The 5G system is expected to support latency below 10 ms, and speed above 10 Mb/s. See e.g. [8]. 4) Remote Control of Vehicles: Truck control in mining sector, truck platooning, autonomous driving, etc. The 5G system is expected to support latency below 10 ms, and deliver a speed above 50 Mb/s. See e.g. [9], [10]. As explained in the following sections, the 3) and 4) services are expected to be provided only in specific and safe areas, or deploying dedicated network, such as GSM-R (railways). Commercial in confidence Page 7 of 28

8 Fixed Wireless Access V/A/M Reality Process Automation Remote Control 5G fixed wireless access (FWA) Complement fiber networks Gigabit-Speed Internet 5G Hotspots In-vehicle infotainment Gaming Remote Drilling Wireless Service Robots Drone Traffic Management Truck Control in Mining Truck platooning Autonomous driving 5G Network requirements Sustainable 100Mb/s/h in DL Up to 1Gb/s (mmw) 3.5GHz/1800MHz SUL 26GHz Replace the last m fiber 5G Network requirements Low latency < 10 ms Large bandwidth > 1Gb/s Cell capacity > 500 Connections 5G Network requirements Low latency <10 ms Large bandwidth > 10 Mb/s 5G Network requirements Low latency < 10 ms Large bandwidth > 50 Mb/s Sensor~1ms 10ms 50Mbps UL Live Video For HD FoV Uploading HF Indoor CPE Outdoor CPE Micro on Pole Indoor CPE Screen response ~2ms 120fps ~ 8ms DL Remote Control Processing ~2ms Transmission Network RTT LF HF Macro on Tower 5G E2E Latency 0.12m Break Distance HF+LF Hybrid Networking HF+LF 52.3 km Car & Cameras Remote Control Showcases at 2018 Gold Coast Commonwealth Games (April 4 to ) and launch of 5G service in 2019 Figure 1. Examples of use cases in Australia. The above use cases are examples of services that require the deployment of a new radio technology, and, in some cases, a next generation core network, as none of the previous 3GPP network generations (3GPP releases), i.e. 2G, 3G and 4G, supports all of such stringent performance requirements and targets [9], [10]. 5G definitions and standard updates 5G Wireless is defined as the 3GPP Release 15 (R15) and later releases (R16, 17, etc.) of LTE and New Radio () mobile communication systems. It is thus an LTE advanced pro evolution and a technology that adds to existing networks in a 3GPP Non-Stand Alone (NSA) or 3GPP Stand Alone (SA) architecture configuration. 3GPP will propose its standards to be adopted by ITU, being compliant with the International Mobile Telecommunications (IMT) for 2020 and beyond (ITU IMT 2020), which expands and supports diverse usage scenarios and applications with respect to current mobile network generations, purposed primarily for voice, mobile internet and video experience [9]. The Next Generation Radio Access Network (NG-RAN) represents the newly defined radio access network for 5G, and provides both and LTE radio access [2], see Figure 2. An NG-RAN node (i.e. base station) is either: A gnb (i.e. a 5G base station), providing user plane and control plane services; or An ng-enb, providing LTE/E-UTRAN services towards the User Equipment (UE). The 5G System (5GS) consists of NG-RAN and 5G Core Network (5GC), as shown in Figure 2 a). Commercial in confidence Page 8 of 28

9 NG-RAN E-UTRAN 5GC EPC NG-RAN in relation to the 5G System 3GPP Option 3 LTE- Dual Connectivity (EN-DC) AMF/UPF AMF/UPF MME/S-GW MME/S-GW NG Standardised and unified interface NG NG NG S1-U Standardised interface S1-U S1-U S1-U NG NG S1 S1 NG Xn NG S1 X2-U S1 gnb () Xn Xn gnb () en-gnb () X2 X2 en-gnb () Xn X2 ng-enb (elte) ng-enb (elte) enb (LTE) enb (LTE) a) b) Figure 2. Overall 5G Architecture: a) 5G system (5GS); b) 3GPP Option 3. The NG RAN operates in both so-called Stand-Alone (SA) operation and Non-Stand-Alone (NSA) operation. In SA operation, the gnb is connected to the 5G Core Network (5GC); in NSA operation, and LTE are tightly integrated and connect to the existing 4G Core Network (EPC), leveraging Dual Connectivity (DC) toward the terminal. In a DC architecture, a Master Node (MN) and a Secondary Node (SN) concurrently provide radio resources towards the terminal for an enhanced end-user bit rate (speed or throughput) [2]. Moreover, 3GPP has defined the following architecture configurations [2], [11], [12]. Option 2: gnb connected to 5GC In this option, the gnbs are connected to the 5GC through the NG interface. The gnbs interconnect through the Xn interface. Option 3: Multi-RAT DC with EPC In this option, commonly known as Multi-Radio Access Technology (Multi-RAT), LTE- Dual Connectivity (EN-DC), a UE is connected to an enb that acts as a Master Node (MN) and to an en-gnb that acts as a Secondary Node (SN). An en-gnb is different from a gnb in that it only implements part of the 5G base station functionality, which is required to perform SN functions for EN-DC. The enb is connected to the EPC via the S1 interface and to the en-gnb via the X2 interface. The en-gnb may also be connected to the EPC via the S1-U interface and to other en-gnbs via the X2-U interface. Notice that the en-gnb may send UP to the EPC either directly or via the enb. Option 4: Multi-RAT DC with the 5GC and as Master In this option, a UE is connected to a gnb that acts as a MN and to an ng-enb that acts as an Commercial in confidence Page 9 of 28

10 SN. This option requires the 5G Core to be deployed. The gnb is connected to 5GC and the ngenb is connected to the gnb via the Xn interface. The ng-enb may send UP to the 5G Core either directly or via the gnb. Option 5: LTE ng-enb connected to 5GC In this option, the ng-enbs are connected to the 5GC through the NG interface. The ng-enbs interconnect through the Xn interface. Essentially this option allows the existing LTE radio infrastructure (through an upgrade to the enb) to connect to the new 5G Core. Option 7: Multi-RAT DC with the 5GC and E-UTRA as Master In this option, a UE is connected to an ng-enb that acts as a MN and to a gnb that acts as an SN. The ng-enb is connected to the 5GC, and the gnb is connected to the ng-enb via the Xn interface. The gnb may send UP to the 5GC either directly or via the ng-enb[2]. Family of usage scenarios The family of usage scenarios for IMT for 2020 and beyond for 5G include: 1) Enhanced mobile broadband (embb) addressing human-centric use cases for access to multimedia content, services and data; 2) Ultra-reliable-low latency communications (URLLC) with strict requirements, especially in terms of latency and reliability; and 3) Massive machine type communications (mmtc) for a very large number of connected devices and typically transmitting a relatively low volume of non-delay-sensitive information [9]. 3GPP 5G roadmap As illustrated in Figure 3, the completion of the first 5G phase (Phase 1 or Release 15, R15) of the Access technology was in June 2018, in its NSA configuration [12]. The SA option will be finalized by September The 3GPP R15 will support embb and some elements of URLLC, e.g. flexible numerology and reduced scheduling interval. Both LTE and use orthogonal frequency-division multiplexing (OFDM) as the waveform. LTE uses a fixed numerology of 15 khz sub-carrier spacing (SCS) and operates below 6 GHz. The new 5G radio is for all spectrum options. To this end, 5G supports a flexible numerology, which consists of different Sub Carrier Spacing (SCS), nominal Cyclic Prefix (CP), and Transmission Time Interval (TTI), or scheduling interval, depending on bandwidth and latency requirements. At higher SCS, the symbol duration decreases, and hence also the length of a slot. The slot is the basic frame structure at which most physical channels and signals repeat. In, slots can be complemented by a mini-slot based transmissions to provide shorter and more agile transmission units than slots. In LTE and a slot comprises 14 OFDM symbols, which leads to a slot length of 1 ms at 15 khz SCS. Commercial in confidence Page 10 of 28

11 RAN Rel-13 Rel-14 Rel-15 Rel-16 5G = 5G New Radio embn = enhanced Mobile broadband URLLC = Ultra-Reliable and Low Latency Communications mmtc = massive Machine Type Communications Non- Standalone (NSA-) 11-15/06/2018 Completion of New Radio () Access Technology (including URLLC specifics) LTE-Adv Evolution 03/18 Opt. 3 09/18 Opt. 2 03/19 Opt. 7/4/5 Stand alone (SA-) Phase 1 Phase 2 Full IMT Q 2020 ASN.1 (Phase II, R16) Global Launch R15 Framework Waveform & Channel Coding Frame Structure, Numerology Native MIMO Flexible Duplex Spectrum 600MHz to 52.6GHz Architecture UL&DL Decoupling CU-DU Split e2e Slicing ( Others: urllc ) Improvement New Multiple Access embb Enhancement Self-Backhaul Spectrum Up to 100GHz R16 Vertical Digitalization urllc mmtc D2D/ V2X Unlicensed Figure 3. 3GPP definition of 5G: LTE evolution and New Radio (), supporting new usage scenarios [12]. By using higher numerologies in, the slot duration decreases, which is beneficial for lower latencies. The intention of is to support a mix of numerologies on the same carrier. A more profound URLLC analysis can be found, e.g., in [13] and [14]. The second 5G phase (Phase 2 or Release 16, R16), supporting usage scenarios, including URLLC and mmtc, will be frozen in Q1 of 2020, or later [12]. Spectrum 5G is expected to increase spectrum efficiency and support contiguous, non-contiguous, and much broader channel bandwidths than available to current mobile systems. 5G new radio will be the most flexible way to benefit from all available spectrum options from 400 MHz to 90 GHz, including licensed, shared access and license exempt bands, FDD and TDD modes, including Supplementary Uplink (SUL), LTE/ uplink sharing (ULS), and narrowband and wideband Carrier Components (CC) [11]. Operating band combinations for SUL and ULS may be found in [15]. A multi-layer spectrum approach is required to address such a wide range of usage scenarios and requirements [16]: The "Coverage and Capacity Layer" relies on spectrum in the 2 to 6 GHz range (e.g. C- band) to deliver the best compromise between capacity and coverage. The "Super Data Layer" relies on spectrum above 6 GHz (e.g and GHz) to address specific use cases requiring extremely high data rates. The "Coverage Layer" exploits spectrum below 2 GHz (e.g. 700 MHz) providing widearea and deep indoor coverage. Commercial in confidence Page 11 of 28

12 Frequencies (MHz) Region 1 Region 2 Region 3 EU Africa Arab C.I.S N.A L.A Asia C-band Y Y Y Y Y Y Y Australia Africa Europe USA GHz MHz Auction in Oct 2018 Already available for IMT / offical plans Considered for IMT by regulators Potential for future IMT use Frequencies (MHz) EU USA Australia Japan 26G Y Y 28G Y Y 39G Others 42G Y 32GHz, 66GHz, and 81GHz China Japan Korea India Russia UAE Figure 4. Global spectrum allocation and upcoming auction of 5G spectrum at 3.6GHz in Australia. 5G networks will leverage the availability of spectrum from these three layers at the same time, and administrations are expected to make available contiguous spectrum in all layers in parallel, to the greatest extent possible. Figure 4 depicts the global availability and planning of the frequency ranges for 5G usage and upcoming auction of 5G spectrum in the 3.6GHz band in Australia. ACMA is preparing to allocate spectrum in the frequency range 3575MHz 3700 MHz (125 MHz) in metropolitan and regional Australia by auction in October 2018 [17]. Frequencies in the 3.4GHz band have been already assigned in Australia. The 700MHz spectrum (band 28) sold at recent auction [18], which adds to the spectrum made available in 2013, will be used extensively throughout Australia to provide 4G mobile broadband or 5G coverage at later time in 2020 or beyond. The allocation of mmwave spectrum, between 24.25GHz and 27.5GHz (26GHz band), is expected in Q G reference architecture and migration strategies The most likely initial deployment options are illustrated in Figure 5 (see e.g. [2] and [19]-[22]). 3GPP Option 3x (NSA LTE plus with EPC) is the configuration that, most likely, more carriers (network operators) adopt, due to minor investments for their initial 5G deployment, and so it is by the local players in Australia. It supports embb and FWA usage scenarios and Voice over IP (VoIP) over LTE (VoLTE) or Circuit Switch Fall Back to earlier network releases (3G, 2G). The 3GPP Option 2 (SA with 5GC) is initially adopted by only a few carriers globally. For taking full advantage from it, a wide coverage rollout is needed, as the interoperation with 4G/EPS is less efficient. Initial partial coverage rollouts may be more suitable for enterprise or overlay deployments. In the long round, it will support all scenarios (embb, URLLC, mmtc), plus other functionalities than Option 3x, such as Network Slicing and Voice over (Vo). The medium-long term migration path of 5G networks is illustrated in Figure 6. Ultimately, all networks will converge to a 3GPP Option 2 architecture configuration (SA with 5GC). Commercial in confidence Page 12 of 28

13 2 Deployment scenarios 3GPP Non standalone (NSA) embb and FWA LTE as anchor with reuse of current EPC + introduction Voice: VoLTE or CSFB 1 3GPP Standalone (SA) embb/fwa, URLLC and mmtc E2E Network Slicing 5GC connected to EPC with min impact on current LTE network Voice: Vo 2 Current SA LTE with EPC EPC 3GPP Option 3x NSA LTE+ with EPC EPC 3GPP Option 2 SA with 5GC 5GC Standardised and unified interface LTE LTE 4G UE 5G(NSA) UE 5G(SA) UE Figure 5. Main initial 5G deployment options [19]-[22]. 3GPP Option 3x NSA LTE+ with EPC EPC GPP Option 7 NSA elte+ with 5GC 5GC Standardised and unified interface LTE 3GPP Option 2 SA with 5GC 5GC Standardised and unified interface 3 elte 5GC 3GPP Option 4 NSA +elte with 5GC Standardised and unified interface Figure 6. Long term migration paths [2]. elte The middle term migration strategies are basically two, depending on the carriers spectrum availability for deploying the [2]: 1. From deployed 3GPP Option 3x (NSA LTE + with EPC) to 3GPP Option 7 (NSA elte + with 5GC). The reasons to go for that are: Leverage 4G (LTE/EPC) installed base; rollout driven by better service (not coverage); and evolved LTE (elte) for all wide area coverage and all use cases. The draw backs are: Full Dual Stack enb/ng-enb in LTE RAN to EPC/5GC; LTE RAN upgrades to elte; and required Interworking between LTE and. UE availability is also, currently, questionable. The migration scenario is shown in Figure From deployed 3GPP Option 3x (NSA LTE + with EPC) to 3GPP Option 4 (NSA + elte with 5GC). This choice is driven by the availability of low band (<3 GHz, <1 GHz for rural). The 5G services are launched with LTE+ NSA on EPC, the and 5GC rollout are driven by needs of 5G coverage; outside the coverage, 5G services may be provided by 3GPP LTE NSA Option 4 with 3GPP Option 5 (SA elte with 5GC). The interworking between elte and is also required. The migration scenario is shown in Figure 8. Commercial in confidence Page 13 of 28

14 EPC LTE EPC LTE 5GC Added LTE Evolves (e)lte LTE 5GC (e)lte Standardised and unified interface Figure 7. Main migration strategy in Australia: From 3GPP NSA Option 3x to 3GPP NSA Option 7. (Option 5) (e)lte EPC EPC LTE coverage (e)lte LTE 5GC (e)lte Standardised and unified interface Figure 8. Other possible migration strategy: From 3GPP NSA Option 3x to 3GPP NSA Option 4. As in previous mobile system generations, 3GPP defines a clear functional split between the Access Network (NG-RAN) and Core Network (5GC) with the overall 5G System architecture defined in [21] and a more convenient overview of the AN and CN functions in [22]. The two network domains are separated by a standardised interface (N2 and N3) defined in a set of specifications, with [23] as the overarching specification which enable multi-vendor RAN CN deployments. Also, this interface has been now unified, meaning that all next generation accesses (trusted/untrusted fixed/mobile 3GPP access points) must support this interface. The NG-RAN supports inter cell radio resource management (RRM), radio bearer (RB) control, connection mobility control, radio admission control, measurements configuration and provisioning, and dynamic resources allocation. The 5GC is responsible for non-access stratum (NAS) security and idle state mobility handling; user equipment (UE) IP address allocation and protocol data unit (PDU) control; and mobility anchoring and PDU session management. The functional split between the NG radio and core domains is shown through Figure 9 to Figure 14, where the multi-vendor implementation (equipment from different vendors) of the corresponding functions is also illustrated. Commercial in confidence Page 14 of 28

15 Figure 9. NG-RAN and Core Function Splits in 3GPP Standard [19]. Figure 10. Overall NG-RAN architecture [2], [19]. Both the user plane and control plane architectures for NG-RAN follow the same high-level architecture scheme, as depicted in Figure 10. Figure 11 and Figure 12 show the 3GPP 4G and 5G protocol stacks for user and control plane, respectively. The two systems, with similar architecture, also use the same protocols, except for the Service Data Adaptation Protocol (SDAP). The SDAP has been introduced in 5G for flow based QoS, as described in the following sections. It provides mapping between QoS flows and data radio bearers and marking QoS flow ID (QFI) in both DL and UL packets. There is a single SDAP entity for each PDU session (GTP Tunnel) [19]. In 4G, the non-access stratum (NAS) supports mobility management (MM) functionality and user plane bearer activation, modification and deactivation; it is also responsible for ciphering and integrity protection of NAS signalling [20]. In 5G, NAS-MM supports registration management functionality, connection management functionality and user plane connection activation and deactivation; as well as ciphering and integrity protection of NAS signalling. NAS-Session Management (SM) is responsible for user plane PDU Session Establishment, modification and release; it is transferred via the AMF, and transparent to the AMF [21]. Commercial in confidence Page 15 of 28

16 As in the previous 3GPP network releases, the NG-RAN and 5GC have crystal clear boundaries, regardless the implementation. Hence security risks in NG-RAN are manageable as in previous RAN generations. In Australia, the Huawei equipment is only in the access part of the network. The core network is provided by other vendors, such as, for example, Nokia and Ericsson. Application IP IP 4G PDCP Relay PDCP GTP-U Relay GTP-U GTP-U GTP-U RLC RLC UDP/IP UDP/IP UDP/IP UDP/IP MAC MAC L2 L2 L2 L2 UE LTE-Uu enodeb S1-U Serving GW S5/S8 a PDN GW SGi Application RAN Standardised and unified interface Core PDU Layer PDU Layer 5G SDAP SDAP Relay GTPU GTPU Relay 5G UP Encapsulation 5G UP Encapsulation PDCP PDCP UPD/IP UDP/IP UDP/IP UDP/IP RLC MAC RLC MAC L2 L2 L2 L2 UE gnodeb UPF UPF N3 N9 N6 Figure 11. 4G/5G User Plane protocol stack [20], [21]. 4G NAS RRC PDCP RRC PDCP Relay S1-AP SCTP NAS S1-AP SCTP RLC MAC RLC MAC IP L2 IP L2 UE LTE-Uu enodeb S1-MME MME RAN Standardised and unified interface Core NAS-SM NAS-SM 5G NAS-MM Relay NG-AP Relay NAS-MM NG-AP 5G-AN Protocol Layer 5G-AN Protocol Layer SCTP IP L2 SCTP IP L2 N11 N11 UE 5G-AN N2 AMF N11 SMF Figure 12. 4G/5G Control Plane protocol stack [20], [21]. Commercial in confidence Page 16 of 28

17 Scenario 1 Multiple BBU Add BBU for Scenario 2 Single BBU BBU() BBU(LTE) BBU() BBU(LTE) Figure 13. Huawei co-located CU-DU units running on Huawei dedicated hardware and software. 3GPP NG-RAN (, or gnb in 3GPP) comes with two possible configurations: Central Unit (CU)-Distributed Unit (DU) split: The RAN non-real time protocol stack is implemented in the CU and the functions more sensitive to delays in the DU close to the antennas. CU-DU co-located at the Edge of the network: All RAN base band functionalities are running into one box placed closed to the antenna units. In Australia, only the Huawei CU-DU co-located option using dedicated hardware and software will be deployed. Huawei has demonstrated that this proprietary solution turns out to be much more efficient to handle and cost effective with respect to using common hardware. 4G and NG-RAN elements the base band units (BBU) will be actually deployed on the same site, with no needs of reducing dual connectivity transmission capacity between sites with a centralized CU deployment. As a result, Huawei and mainstream carriers have agreed on CU and DU integrated deployment, being 4G/5G co-site deployment the main industry trend. An example of Huawei site solution is illustrated in Figure 13. Furthermore, none of the above Huawei NG-RAN solutions that are offered for the Australian market supports functionalities of core network or external servers. Notice that any local breakout, e.g. to a Multi-access Edge Computing (MEC) server, or remote break out to internal (operators networks, data centres) or external data networks, such as the Internet, is via third party equipment, as described in the following paragraphs. 5G core and slicing The 5G core (5GC) supports many new enabling network technologies [21], [22]. Among other fundamental technology components, as depicted in Figure 14, the 5GC is characterized by a layered and service oriented architecture, with control plane (CP) and user plane (UP) split, and interfaces to subscription, state and policy data. Moreover, the 5GC supports: User plane session continuity, while the terminal moves across different access points; interworking with untrusted non-3gpp access; a comprehensive policy framework for access traffic steering, switching and splitting; and wireless-wireline convergence. Commercial in confidence Page 17 of 28

18 Data Policy Data Session Data Subscription Data 5G Core Control Plane 5G-Uu (N3IWF-UP) IMS AMF = Access and Mobility Management UPF = User Plane Function NSSF = Network Slice Selection Function SMF = Session Management UDM = Unified Data Management PCF = Policy Control Function AUSF = Authentication Server Function DN = Data Network (External) AF = Application Function Non-3GPP (untrusted) Y2 5G Core User Plane Multi-access Edge Computing (MEC) Standardised and unified interface Figure 14. 5G Core (5GC) functions and interfaces [20], [22]. The separation of control and user planes provides deployment flexibility and independence. The distribution of core functionality, especially user plane functions, closer to the radio nodes, i.e. at the edge of the network, enables the placement of applications in the proximity of the end-user, reducing transport network load and latency. The service based architecture including the related Network Repository Function (F) for 5GC control plane functions allows flexible addition and extension of network functions. Slicing and related Network Slice Selection Function (NSSF) enable a flexible assignment of users to different network slice instances that may be tailored to different use cases. The 5GC also supports unified subscriber management, authorization and authentication functions. The NG-RAN is not aware of any subscription data. Also, as in earlier network generations, all user plane and signalling traffic is forwarded to the 5GC through secure tunnels and third party security gateways, as detailed in the next section. Other fundamental 5G enabling technologies, end to end, are [11]: Flow based QoS, with a much higher level of granularity than LTE, which is limited to the bearer service concept (single pipe between terminal and core network); multi-connectivity, where the 5G device can be connected simultaneously to 5G, LTE, and WiFi, offering a higher user data rate and a much more reliable connection; terminal assisted Network Slicing, and E2E network management and orchestration, with in-built support for cloud implementation and edge computing. The 5G flow based QoS and slicing concept are illustrated in Figure 15. The NG-RAN and UE are only Slice and QoS aware. Slices consisting of chains of virtual network functions (VNFs) are supported by the 5GC only [11]. 3GPP for terminal (UE) assisted network slicing defines a new parameter denoted as Single- Network Slice Selection Assistance Information (S-NSSAI). Each S-NSSAI assists the network in selecting a network slice instance. The S-NSSAI is composed by the following attributes: Slice/Service Type (SST): 1 (embb), 2 (URLLC), 3 (MIoT) are the standardised values for roaming; operator specific settings are also possible; A Slice Differentiator (SD): Tenant ID, for further differentiation during the NSI selection. Commercial in confidence Page 18 of 28

19 Standardised and unified interface Slice/QoS aware only UE NSSAI (Up to 8 S-NSSIs) (QoS) N1 NG-RAN () N2 UDM NSSF F AMF NSSAI NSSAI NSSAI NSSAI N3 SMF UPF Slice A 5GC Slice/QoS Control (E2E) DNN#A SMF NSSAI PDU Session S-NSSAI Slice B (QoS) UPF DNN#B QoS (IP) Flows UDM = Unified Data Management NSSF = Network Slice Selection Function F = Network Repository Function Figure 15. E2E QoS management and 5GC Slicing [11], [20], [22]. The Network Slice Selection Assistance Information (NSSAI) consists of a collection of S-NSSAIs. Maximum eight S-NSSAIs may be sent in signalling messages between the UE and the Network. The NSSAI is configured (Configured NSSAI) in the UE per Public Land Mobile Network (PLMN) by the Home PLMN (HPLMN). The terminal uses the Requested NSSAI (UE) during the Registration Procedure and the Allowed NSSAI, received from the Access and Mobility Function (AMF), within its Registration Area (RA). The RA allocated by the AMF to UE has homogeneous support of network slices. The 5GC supports AMF level slicing per UE type, and SMF and UPF level slicing per Service or per Tenant, based on S-NSSAI and DNN. An example of two network slices for one terminal type is illustrated in Figure 15. IP Flows are mapped onto QoS Flows, which are mapped onto one or more data radio bearers (DRBs). DRBs are associated to one PDU Session, which is mapped onto one S-NSSAI. The S- NSSAI is mapped onto one Network Slice Instance (NSI), i.e. one Network Slice; and the NSI is mapped onto a single Data Network Name (DNN). However, it is not true the vice versa, as described in the following text. This is how 5G handles the 5G flow based QoS within a given NSI [11], [20], [22]. The NG-RAN is aware of the slice at PDU Session level, because the S-NSSAI is included in any signalling message containing PDU Session info, see Figure 16 from 3GPP [19]. Pre-configured slice enabling in terms of NG-RAN functions is implementation dependent. An example of NG- RAN slicing is depicted in Figure 17. The medium access control (MAC) scheduling based on radio resource management (RRM) policy related to the servile level agreement (SLA) in place, between communication service provider and tenant, for the supported slice and QoS differentiation within the slice is vendor dependent [19]. The 5GC has full control of slice and QoS management, end to end (E2E). Commercial in confidence Page 19 of 28

20 Figure 16. 3GPP RAN Support for Network Slicing [12]. 5GC Control (E2E) PDU Session S-NSSAI QoS (IP) Flows GTP-U Slice B Slice A PDU-Sessions NG-RAN RAN-T CU CU RAN-RT DU High Level Split (3GPP R15 selected ) DU Slice/QoS aware scheduling Low Level Split (ecpri) RF 5G(SA) UE Figure 17. NG-RAN Slicing [11], [19], [20]. 5G security aspects 5G System security is based on the well-established and proven 4G/EPS security, which has been further enhanced [24], [25]. NAS security and keying hierarchy are as in 4G. NAS security is established via the 3GPP Authentication and Key Agreement between NAS entities in UE and CN (AMF), see Figure 10 and Figure 12. Figure 18 shows the 5GS keying hierarchy, which is comparable to 4G for the functionality towards the RAN, i.e. all keys for the Access Stratum (AS = RAN or AN) are derived from the NAS security parameters inside the Core Network and Commercial in confidence Page 20 of 28

21 signalled the RAN. The main new model of the 5GS is on how the security functionality is decomposed and distributed inside the Core Network. This enables also that the globally unique 5G Subscription Permanent Identifier (SUPI, which is comparable to the IMSI of earlier system generations) is always signalled encrypted via the RAN towards the CN. It is decrypted by the home-plmn and delivered from there to the serving Core Network for any user service, management and regulatory purposes. In contrast to earlier system generations, where the IMSI was used in the RAN for recovering from network failures and enabled thereby certain attacks, the 5G System never exposes the SUPI to the RAN nor does it transfer it in clear via the radio. Further, 3GPP 5G Release 15 adds an option to perform user plane integrity protection between UE and gnb. In 3GPP Release 16, security algorithms use up to 256-bit keys [23], see Figure 19. With the offered Huawei RAN running on vendor-specific hardware, any security assurance considerations on running RAN software on a 3rd parties platform and on interactions with the platform s security does not apply to the Huawei offering. Furthermore, Huawei provides trusted 5G equipment to ensure that unauthorised software cannot be implanted and concealing keys cannot be accessed, ensuring element management security. The CN of the 5GS is designed to leverage softwarisation and virtualisation techniques and how to mitigate related security risks is not discussed in this document, as Huawei is not tendering for CN in Australia. Figure 18. Key hierarchy generation in 5GS [24]. Commercial in confidence Page 21 of 28

22 Option 2 Option 3 4G Support of UP Encryption Expose User ID in initial Access 128-bit keys UP and CP support Both Encryption and Integrity Protection Permanent User ID Encrypted All time 128-bit keys & 256-bit keys 5G UE NAS: ciphering, integrity RRC: ciph., int. UP: ciph., int. gnb AMF e.g. L=256 L=256 L=128 Enhanced User Data Protection R15 Enhancement Enhanced Privacy Protection Stronger Security Algorithm R16 Enhancement Figure 19. E2E Security Enhancement with 5G Evolution [24], [25]. Also, as in 4G, the transport network layer within the RAN and between RAN and core network domains is protected using IPSec tunnels. Examples of security deployment scenarios for 3GPP NSA Option 3x (which is the same as with 4G) and SA Option 2, NSA Option 7 and NSA Option 4, architecture configurations are illustrated in Figure 20 and Figure 21, respectively. As shown in the figures, here with 3GPP Option 2 as an example, the 5G system RAN related transport adopts the same means as 4G and, therefore, for this aspect, it has the same level of security as 4G and as 3GPP Option 3x. The Security GateWay (SeGW) is a 3 rd party product. In summary, it can be concluded that the 5G RAN security level is at the same or higher level than for 4G, depending on deployment options, and is fully under operator control. 3GPP aims at ensuring the security of data transmission. The Packet Data Convergence Protocol (PDCP) encryption in the RAN (downlink), see Figure 17, and UE (uplink), ensures security over the air interface. Carriers ensure the security of Intranet transmission (transport network layer connecting the access and core network equipment. The application layer ensures the security of services. NG-RAN BBU (CU&DU) S1-U IPSec Tunnel SeGW X2 IPSec Tunnel (3 rd party) EPC LTE BBU Standardised interface Regional DC (POC1) NG-RAN BBU (CU&DU) N2/N3-C/U IPSec Tunnel SeGW Xn IPSec Tunnel BBU (CU&DU) Standardised and unified interface (3 rd party) 5GC Regional DC (POC1) Figure 20. 3GPP NSA Option 3 and SA Option 2 security deployments. The Security Gateway (SeGW), Evolved Packet Core (EPC) and 5G Core Network (5GC) are 3 rd party equipment, e.g. from Nokia or Ericsson. Commercial in confidence Page 22 of 28

23 Option 7 NG-RAN BBU (CU&DU) Xn IPSec Tunnel N2/N3-U IPSec Tunnel SeGW (3 rd party) 5GC elte BBU Standardised and unified interface Regional DC (POC1) Option 4 NG-RAN BBU (CU&DU) Xn IPSec Tunnel N2/N3-C/U IPSec Tunnel SeGW (3 rd party) 5GC elte BBU Standardised and unified interface Regional DC (POC1) Figure 21. 3GPP NSA Option 7 and NSA Option 4 security deployments. The Security Gateway (SeGW), Evolved Packet Core (EPC) and 5G Core Network (5GC) are 3rd party equipment, e.g. from Nokia or Ericsson. 5G deployment scenarios The 5G deployment scenarios using an NSA and NSA/SA architecture configuration as suggested for Australia are depicted in Figure 22 and in Figure 23, respectively. All network domains, except the Huawei RAN, may run on cloud infrastructures. The far edge hosts the CU&DU (BBU) functions, as illustrated in Figure 17. This is the area where Huawei equipment (antennas, radio and base band units) may be deployed. The edge/regional cloud hosting CN, application server and MEC functions is separated from the far edge zone, i.e. the RAN, by the standardised NSA RAN or SA RAN interfaces, see Figure 9, Figure 10, Figure 11, Figure 12, and Figure 14, maintaining a clear logical and physical separation between radio access and core network elements. Any wanted local break out (e.g. for MEC) is above the RAN and located in the Edge/Regional data centres, using 3 rd party equipment. The core network functionalities may be deployed in the Edge/Regional and Central part of the infrastructure, with no possibility of running them in Huawei equipment, e.g. through and end to end VNF orchestration. IoT and application enablement platforms are also placed in the Central part of the network. The introduction of the 5G core may be based on software upgrades of the core functions instantiated in the Edge/Regional segment, namely in the Metro and Edge areas, as shown in Figure 23, where an example of three network slices is also illustrated for different SLAs, in terms of throughput, latency and reliability. Commercial in confidence Page 23 of 28

24 Standardised interface Far Edge Edge/Regional Central LTE E-Band (71-76 and GHz) (1-10 Gbps link/carrier) 1-2 DC/metro area Metro DC SDN-C 4G UE 10xGE BNG CDN Core (CP) Core (UP) Access WAN DC 5G(NSA) UE LTE HB+LB X2 BBU LB HB Indoor CPE HB Macro on Outdoor CPE Tower Indoor CPE Micro on Pole 1-5 ms RTT (5-30 km) S1 S DC/metro area Edge DC MEC epc+ (UP) IP/ MPLS n*10ge (100GE SD-WAN) nx10xge Metro DC RNC BNG CDN IP/ MPLS nx10ge/100ge/wdm BSC Core (CP) Core (UP) App Enablement Platform IoT Platform Central Core Central Cloud < 10 ms RTT ( km) 10 s 100 s of ms RTT ( km) Figure 22. 5G 3GPP NSA deployment scenario with existing core network in Australia. 4G UE LTE (Throughput) Far Edge W-band ( GHz) and D-band ( GHz) (100 Gb/s link/multicarrier) Standardised and unified interface 10xGE Edge/Regional 1-2 DC/metro area Metro DC UPF CDN Core (CP) Core (UP) Central SDN-C Access DC WAN 5G(NSA) UE (Latency) 5G(SA) UE Indoor CPE (Reliability) Indoor CPE HB LB elte Micro on Pole Outdoor CPE HB 1-5 ms RTT (5-30 km) HB+LB BBU Macro on Tower N2/N3 Xn N2/N DC/metro area Edge DC < 10 ms RTT ( km) UPF MEC epc (UP) IP/ MPLS n*10ge (100GE SD-WAN) nx10xge Metro DC UPF BNG CDN 10 s 100 s of ms RTT ( km) IP/ MPLS nx10ge/100ge/wdm Core (CP) Core (UP) App Enablement Platform IoT Platform Central Core Central Cloud NEF Figure 23. 5G 3GPP NSA/SA deployment scenario with 5GC in Australia, and example of network slices with different SLAs, in terms of throughput, latency and reliability parameters. North Bound Interface (3GPP CORBA) Operator NMS NG-RAN 5GC EMS Firewall (3 rd Party) AAU South Bound Interface (Proprietary) CPRI/eCPRI DU 3GPP: F1 RANCU 3GPP: S1/N2/N3 3GPP: S1/N2/N3 Security Gateway EPC/5GC Core Firewall Internet UE RRU+Antenna BBU (CU&DU) Australia Standardized and unified interface Figure 24. Huawei 5G RAN (NG-RAN) EMS Deployment in Australia. Commercial in confidence Page 24 of 28

25 Figure 24 shows the Huawei Element Management System (EMS) for the Huawei 5G RAN (NG- RAN) in Australia. The Huawei EMS connects to Huawei RAN elements, and handles performance management (PM), fault management (FM), configuration management (CM), inventory management (IM) and software management (SM) data of Huawei equipment, only. Operators have full control on the access of 5G RAN EMS, e.g. firewall and security control systems such as Citrix System, as currently used with 4G, provide port filtering and monitoring. Huawei 5G RAN EMS manages RAN elements through its proprietary South Bound Interface (SBI), which is not standardised by 3GPP. Third Party EMS cannot manage Huawei RAN, as the EMS is a vendor-specific 5G RAN hardware and software solution. Huawei 5G RAN EMS can be installed and run only on dedicated Huawei hardware. The 5GS supports subscriber tracing as 4G also in the RAN and is described in [26]. As in 4G there will be not any subscriber identities given to the RAN for this. Figure 25 paints a high level end-to-end security deployment and management process. It is the operators responsibility to ensure network security. For example, the management plane (MP), control plane (CP) and user plane (UP) must be isolated; in all nodes, security features, at the different interface, must be enabled for encrypted transmission between elements; unused ports shall be shut down; and EMS rights controlled and restricted. Furthermore, as depicted in Figure 26, carriers should deploy a 3 rd party Bastion host between the operation and maintenance (O&M) personnel and the Huawei EMS, which is the only path for anyone to access the EMS. The bastion host supports, but is not limited to: Complete identity management and authentication; authorisation based on users; target hosts and time segments; real-time monitoring; complete operation of the entire process; complete session audit and playback. App RAN CN TN Data Host Network Network security deployment FW Infrastructure Security network planning Security network design Security implementation Security management Vendors security design Operator design for security and management 3GPP and other security standards Figure 25. End to end security deployment and management. Commercial in confidence Page 25 of 28

26 As shown in Figure 27, ultra-reliable low-latency services must be provided only in confined (specific) areas or using dedicated mobile networks, in order to comply with the corresponding service level agreements, e.g. five nines reliability, dependability and safety requirements. Also, for services demanding a high level of security, end-to-end security should be applied at the application layer. Ultimately, to avoid any potential concerns, in Australia, Huawei does not offer and provide any kind of network managed services. Those are either from other vendors or handled by the network operators themselves. Security audit Firewall External maintenance personnel Bastion host EMS Internal O&M personnel The only path for O&M personnel to access the Huawei EMS Complete identity management and authentication Authorization based on users, target hosts, and time segments Real-time monitoring Complete operation of the entire process Complete session audit and playback Figure 26. Example of 3 rd party Bastion host for Huawei EMS logs. High-reliability services are provided only in specific areas High-reliability services are provided using private networks (E.g. GSM-R) Carrier network Area 1 Area 2 Private network access Application/S ervice Remote power distribution control Regional automatic driving Platform Application layer self-security mechanisms Figure 27. Examples of deployment of high-reliability and secure services. Commercial in confidence Page 26 of 28

27 Conclusions 5G is defined by 3GPP Release 15 and Release 16 as an LTE advanced pro evolution and a NG- RAN/5GS developed in parallel to address different markets and migration scenario needs. 3GPP has already defined the security mechanisms for R15, which have been enhanced with respect to previous network generations, and Huawei products comply with all of them. In 2019, the initial 5G deployment is assumed to be based on 3GPP Option 3x, which consists of a Non Standalone (NSA) architecture configuration of LTE combined with and an Evolved Packet Core Network (EPC), which re-uses the same 3GPP security mechanisms as 4G. End to end network slicing and a range of 5G specific services/kpis/use cases are not supported. Looking at 2020 and beyond, the main migration strategy is to move from 3GPP Non- Standalone (NSA) architecture Option 3x to 3GPP NSA architecture Option 4, which consists of a Multi-RAT Dual Connectivity (DC) with the 5G Core Network (5GC) and New Radio () as Master. In Release 15 (R15), Standalone (SA) Option 2, and later releases (R16, R17, etc.), 3GPP defines additional security enhancements, such as IMSI encryption and user-plane integrity protection (R15), roaming security enhancement and 256bit encryption (R16), and Huawei products implement and will support them. Ultra-reliable low-latency (URLLC) communication services may be provided only in confined (specific) areas or using dedicated mobile networks, to comply with the corresponding service level agreements, dependability and safety requirements. Also, for services demanding a high level of security, such as driverless cars, service robots, etc. the application system must support end to end security protection. In 3GPP specifications, as in previous network generations, the 5GC and NG-RAN functions are separated by a standardised interface, which enables a multi-vendor deployment. The NG- RAN remains a pipe between user equipment and core network. The situation is comparable to 4G and earlier generations and any security risk in the NG-RAN can be managed as done for earlier network generations. Huawei is providing secure NG-RAN equipment, and operators are ensuring a secure 5G deployment and security maintenance and management, end to end. Huawei welcomes any Security Assurance Programme and related 3 rd Party Evaluation Centre in Australia, under the Australian Government supervision, and/or any type of experimental assessment of any security aspect of Huawei NG-RAN. Huawei is open to any kind of collaboration on 5G Security with public and private sectors (organizations) in Australia, and globally. Commercial in confidence Page 27 of 28