5G Radio Access Network Architecture

Discover how the NG-RAN architecture is, and isn't, ready for the challenges introduced by 5G

5G Radio Access Network Architecture: The Dark Side of 5G explores foundational and advanced topics in Radio Access Network (RAN) architecture and why a re-thinking of that architecture is necessary to support new 5G requirements. The distinguished engineer and editor Sasha Sirotkin has included numerous works written by industry insiders with state of the art research at their disposal. The book explains the relevant standards and technologies from an academic perspective, but also explains why particular standards decisions were made and how a variety of NG-RAN architecture options could be deployed in real-life networks.

All major standards and technologies associated with the NG-RAN architecture are discussed in this book, including 3GPP, O-RAN, Small Cell Forum, IEEE, and IETF. Readers will learn about how a re-design of the RAN architecture would ensure that 5G networks can deliver their promised throughput and low latency KPIs consistently and sustainably.

The book is structured as follows:

• An overview of the market drivers of the NG-RAN architecture, like spectrum models, 5G-relevant regulatory considerations, and 5G radio interface technical requirements

• An overview of the 5G System, from the core network, to the RAN, to the radio interface protocols and physical layer, with emphasis on how these are different compared to 4G

• Release-15 RAN architectures defined in 3GPP, O-RAN, and Small Cell Forum

• RAN architecture evolution in Release-16 and Release-17

• Enabling technologies, like virtualization, open source technologies, multi-access edge (MEC) computing, and operations, administration, and management (OAM)

• NG-RAN deployment considerations, objectives, and challenges, like costs, spectrum and radio propagation considerations, and coverage

Perfect for network designers and operators who require a solid understanding of the NG-RAN architecture, 5G Radio Access Network Architecture also belongs on the bookshelves of network engineers who aim to increase their understanding of the standards and technologies relevant to the NG-RAN architecture.

Autorentext

SASHA SIROTKIN is a senior engineer with 20 years of experience in telecommunications, international standardization, IP, machine learning, real-time systems, and open source technologies. He obtained MSc and BSc degrees in computer science and physics from Tel-Aviv University. His primary areas of interest are 4G/LTE and 5G/NR Radio Access Network architecture, as well as licensed and unlicensed spectrum integration and co-existence.

Inhalt
Preface xv

Acknowledgments xvii

List of Contributors xix

Acronyms and Abbreviations xxi

1 Introduction 1

2 Market Drivers **5
**Reza Arefi and Sasha Sirotkin

2.1 Introduction 5

2.2 Key Ideas 7

2.3 Spectrum 9

2.3.1 Spectrum Needs 9

2.3.2 Target Spectrum 12

2.3.3 Spectrum Implications 13

2.4 New Spectrum Models 14

2.4.1 New Ways of Sharing Spectrum 15

2.4.2 Localized Licensing 17

2.5 Regulations Facilitating 5G Applications 18

2.6 Network Deployment Models 19

2.7 Technical Requirements of 5G Radio Interfaces 20

2.8 Business Drivers 23

2.9 Role of Standards 25

2.10 Role of Open Source 29

2.11 Competition 31

2.12 Challenges 32

2.13 Summary 34

References 35

3 5G System Overview 37

3.1 Introduction 37

3.2 5G Core Network 37
Sebastian Speicher

3.2.1 Introduction 37

3.2.2 Service-Based Architecture 39

3.2.2.1 Fostering Functional Reuse 39

3.2.2.2 Overview of 5GC Control-Plane Functions 41

3.2.3 Control-User Plane Separation (CUPS) 43

3.2.4 Common Access-Agnostic Core Network 44

3.2.5 Enablers for Concurrent and Efficient Access to Local and Centralized Services 46

3.2.5.1 Overview 46

3.2.5.2 Single PDU Session-Based Access to Local Services 47

3.2.5.3 Multiple PDU Session-Based Access to Local Services 48

3.2.6 Network Slicing 50

3.2.7 Private Networks 53

3.2.7.1 Overview 53

3.2.7.2 Stand-Alone Non-public Networks 54

3.2.7.3 Public-Network-Integrated Non-public Network 55

References 57

3.3 NG Radio Access Network 59
Sasha Sirotkin

3.3.1 Introduction 59

3.3.2 Network Protocol Stacks 62

3.3.2.1 Control-Plane Protocol Stack 62

3.3.2.2 User-Plane Protocol Stack 62

3.3.2.3 Standards 63

3.3.3 NG Interface 63

3.3.3.1 NG-C Interface 64

3.3.3.2 NG-U Interface 69

3.3.4 Xn Interface 70

3.3.4.1 Xn Control Plane (Xn-C) Interface 70

3.3.4.2 Xn User Plane (Xn-U) Interface 75

3.3.5 Additional NG-RAN Features 76

3.3.5.1 RAN Sharing 76

3.3.5.2 Slicing 77

3.3.5.3 Virtualization 78

3.3.5.4 Non-3GPP Access 78

References 79

3.4 NR Protocol Stack 80
Sudeep Palat

3.4.1 Introduction 80

3.4.2 NG-RAN Architecture 81

3.4.3 NR User Plane 81

3.4.4 Supporting QoS with 5GC 86

3.4.5 NR Control Plane 88

3.4.5.1 RRC States 88

3.4.5.2 RRC Procedures and Functions 89

3.4.6 Summary 97

References 98

3.5 NR Physical Layer 99
Alexei Davydov

3.5.1 Introduction 99

3.5.2 Waveform and Numerology 100

3.5.3 Frame Structure 101

3.5.4 Synchronization and Initial Access 104

3.5.4.1 Downlink Synchronization Signals 104

3.5.4.2 Random Access Channel 106

3.5.5 Downlink Control Channel 107

3.5.6 Uplink Control Channel 109

3.5.7 Reference Signals 112

3.5.7.1 CSI-RS 112

3.5.7.2 DM-RS 114

3.5.7.3 PT-RS 115

3.5.7.4 SRS 116

3.5.8 Beam Management 116

3.5.9 Channel Coding and Modulation 118

3.5.10 Co-Existence with LTE, Forward Compatibility and Uplink Coverage Enhancement 121

References 122

4 NG-RAN Architecture **123
**Colby Harper and Sasha Sirotkin

4.1 Introduction 123

4.1.1 Monolithic gNB Architecture 124 4....