Acknowledgements xi
About the Editors xiii
List of Contributors xv
1 Introduction 1
Esa Mets¤l¤ and Juha Salmelin
1.1 Introducing 5G in Transport 1
1.2 Targets of the Book 3
1.3 Backhaul and Fronthaul Scope within the 5G System 3
1.4 Arranging Connectivity within the 5G System 4
1.5 Standardization Environment 5
1.5.1 3GPP and other organizations 5
References 8
2 5G System Design Targets and Main Technologies 11
Harri Holma and Antti Toskala 11
2.1 5G System Target 11
2.2 5G Technology Components 12
2.3 Network Architecture 14
2.4 Spectrum and Coverage 21
2.5 Beamforming 22
2.6 Capacity 24
2.6.1 Capacity per Cell 24
2.6.2 Capacity per Square Kilometre 24
2.7 Latency and Architecture 26
2.8 Protocol Optimization 28
2.8.1 Connectionless RRC 28
2.8.2 Contention-Based Access 28
2.8.3 Pipelining 29
2.9 Network Slicing and QoS 30
2.10 Integrated Access and Backhaul 32
2.11 Ultra Reliable and Low Latency 33
2.12 Open RAN 34
2.13 3GPP Evolution in Release 16/17 36
2.14 5G-Advanced 38
References 39
3 5G RAN Architecture and Connectivity â" A Techno-economic Review 41
Andy Sutton
3.1 Introduction 41
3.2 Multi-RAT Backhaul 41
3.3 C-RAN and LTE Fronthaul 43
3.4 5G RAN Architecture 44
3.5 5G D-RAN Backhaul Architecture and Dimensioning 46
3.6 Integrating 5G within a Multi-RAT Backhaul Network 48
3.7 Use Case â" BT/EE 5G Network in the UK 51
3.8 5G C-RAN â" F1 Interface and Midhaul 55
3.9 5G C-RAN â" CPRI, eCPRI and Fronthaul 56
3.10 Connectivity Solutions for Fronthaul 59
3.11 Small Cells in FR1 and FR 2 62
3.12 Summary 62
References 63
4 Key 5G Transport Requirements 65
Kenneth Y. Ho and Esa Mets¤l¤
4.1 Transport Capacity 65
4.1.1 5G Radio Impacts to Transport 65
4.1.2 Backhaul and Midhaul Dimensioning Strategies 67
4.1.3 Protocol Overheads 68
4.1.4 Backhaul and Midhaul Capacity 69
4.1.5 Fronthaul Capacity 70
4.1.6 Ethernet Link Speeds 71
4.2 Transport Delay 73
4.2.1 Contributors to Delay in 5G System 73
4.2.2 Allowable Transport Delay 73
4.2.3 User Plane and Control Plane Latency for the Logical Interfaces 75
4.2.4 Fronthaul (Low-Layer Split Point) 76
4.2.5 Low-Latency Use Cases 77
4.3 Transport Bit Errors and Packet Loss 78
4.3.1 Radio-Layer Performance and Retransmissions 78
4.3.2 Transport Bit Errors and Packet Loss 79
4.4 Availability and Reliability 80
4.4.1 Definitions 80
4.4.2 Availability Targets 81
4.4.3 Availability in Backhaul Networks 82
4.4.4 Recovery Times in Backhaul and Fronthaul 84
4.4.5 Transport Reliability 84
4.4.6 Air Interface Retransmissions and Transport Reliability 87
4.4.7 Packet Duplication in 5G and Transport 88
4.4.8 Transport Analysis Summary for Availability and Reliability 90
4.5 Security 91
4.5.1 Summary of 5G Cryptographic Protection 91
4.5.2 Network Domain Protection 92
4.5.3 Security in Fronthaul 92
4.6 Analysis for 5G Synchronization Requirement 92
4.6.1 Frequency Error 93
4.6.2 Time Alignment Error (Due to TDD Timing) 93
4.6.3 Time Alignment Error (Due to MIMO) 100
4.6.4 Time Alignment Error (Due to Carrier Aggregation) 101
4.6.5 Time Alignment Accuracy (Due to Other Advanced Features) 102
References 102
5 Further 5G Network Topics 105
Esa Malkam¤ki, Mika Aalto, Juha Salmelin and Esa Mets¤l¤
5.1 Transport Network Slicing 105
5.1.1 5G System-Level Operation 105
5.1.2 Transport Layers 105
5.2 Integrated Access and Backhaul 108
5.2.1 Introduction 108
5.2.2 IAB Architecture 109
5.2.3 Deployment Scenarios and Use Cases 110
5.2.4 IAB Protocol Stacks 111
5.2.5 IAB User Plane 113
5.2.6 IAB Signalling Procedures 114
5.2.7 Backhaul Adaptation Protocol 116
5.2.8 BH Link Failure Handling 117
5.2.9 IAB in 3GPP Release 17 and Beyond 118
5.3 Ntn 118
5.3.1 NTN in 3GPP 118
5.3.2 Different Access Types 119
5.3.3 Protocol Stacks 121
5.3.4 Transparent Architecture 123
5.3.5 Feeder Link Switchover 124
5.4 URLLC Services and Transport 125
5.4.1 Background 125
5.4.2 Reliability 127
5.4.3 Latency 128
5.5 Industry Solutions and Private 5G 129
5.5.1 Introduction to Private 5G Networking 129
5.5.2 3GPP Features Supporting Private 5G Use Cases 130
5.5.3 URLLC and TSC in Private 5G 133
5.6 Smart Cities 133
5.6.1 Needs of Cities 134
5.6.2 Possible Solutions 135
5.6.3 New Business Models 137
5.6.4 Implications for BH/FH 138
References 139
6 Fibre Backhaul and Fronthaul 141
Pascal Dom, Lieven Levrau, Derrick Remedios and Juha Salmelin
6.1 5G Backhaul/Fronthaul Transport Network Requirements 141
6.1.1 Capacity Challenge 141
6.1.2 Latency Challenge 143
6.1.3 Synchronization Challenge 144
6.1.4 Availability Challenge 144
6.1.5 Software-Controlled Networking for Slicing Challenge 145
6.1.6 Programmability and OAM Challenges 145
6.2 Transport Network Fibre Infrastructure 146
6.2.1 Availability of Fibre Connectivity 146
6.2.2 Dedicated vs Shared Fibre Infrastructure 147
6.2.3 Dedicated Infrastructure 149
6.2.4 Shared Infrastructure 149
6.3 New Builds vs Legacy Infrastructure 150
6.4 Optical Transport Characteristics 151
6.4.1 Optical Fibre Attenuation 151
6.4.2 Optical Fibre Dispersion 152
6.5 TSN Transport Network for the Low-Layer Fronthaul 153
6.6 TDM-PONs 154
6.6.1 TDM-PONs as Switched Transport Network for Backhaul and Midhaul 154
6.6.2 TDM-PONs as Switched Transport Network for Fronthaul 156
6.7 Wavelength Division Multiplexing Connectivity 156
6.7.1 Passive WDM Architecture 156
6.7.2 Activeâ"Active WDM Architecture 158
6.7.3 Semi-Active WDM Architecture 160
6.8 Total Cost of Ownership for Fronthaul Transport Networking 161
References 163
7 Wireless Backhaul and Fronthaul 165
Paolo Di Prisco, Antti Pietil¤inen and Juha Salmelin
7.1 Baseline 165
7.2 Outlook 166
7.3 Use Cases Densification and Network Upgrade 169
7.4 Architecture Evolution â" Fronthaul/Midhaul/Backhaul 172
7.5 Market Trends and Drivers 172
7.5.1 Data Capacity Increase 173
7.5.2 Full Outdoor 174
7.5.3 New Services and Slicing 174
7.5.4 End-to-End Automation 175
7.6 Tools for Capacity Boost 176
7.6.1 mmW Technology (Below 100 GHz) 176
7.6.2 Carrier Aggregation 177
7.6.3 New Spectrum Above 100 GHz 181
7.7 Radio Links Conclusions 183
7.8 Free-Space Optics 183
7.8.1 Introduction 183
7.8.2 Power Budget Calculations 184
7.8.3 Geometric Loss 184
7.8.4 Atmospheric Attenuation 185
7.8.5 Estimating Practical Link Spans 186
7.8.6 Prospects of FSO 188
References 189
8 Networking Services and Technologies 191
Akash Dutta and Esa Mets¤l¤
8.1 Cloud Technologies 191
8.1.1 Data Centre and Cloud Infrastructure 191
8.1.2 Data Centre Networking 194
8.1.3 Network Function Virtualization 196
8.1.4 Virtual Machines and Containers 198
8.1.5 Accelerators for RAN Functions 202
8.1.6 O-RAN View on Virtualization and Cloud Infrastructure 204
8.2 Arranging Connectivity 206
8.2.1 IP and MPLS for Connectivity Services 206
8.2.2 Traffic Engineering with MPLS-TE 208
8.2.3 E-vpn 208
8.2.4 Segment Routing 210
8.2.5 IP and Optical 211
8.2.6 IPv4 and IPv 6 212
8.2.7 Routing Protocols 212
8.2.8 Loop-Free Alternates 214
8.2.9 Carrier Ethernet Services 215
8.2.10 Ethernet Link Aggregation 216
8.3 Securing the Network 217
8.3.1 IPsec and IKEv 2 217
8.3.2 Link-Layer Security (MACSEC) 219
8.3.3 Dtls 220
8.4 Time-Sensitive Networking and Deterministic Networks 220
8.4.1 Motivation for TSN 220
8.4.2 IEEE 802.1CM â" TSN for Fronthaul 221
8.4.3 Frame Pre-emption 223
8.4.4 Frame Replication and Elimination 223
8.4.5 Management 225
8.4.6 Deterministic Networks 226
8.5 Programmable Network and Operability 227
8.5.1 Software-Defined Networking Initially 227
8.5.2 Benefits with Central Controller 228
8.5.3 Netconf/YANG 229
References 230
9 Network Deployment 233
Mika Aalto, Akash Dutta, Kenneth Y. Ho, Raija Lilius and Esa Mets¤l¤
9.1 NSA and SA Deployments 233
9.1.1 Shared Transport 233
9.1.2 NSA 3x Mode 235
9.1.3 SA Mode 237
9.2 Cloud RAN Deployments 237
9.2.1 Motivation for Cloud RAN 237
9.2.2 Pooling and Scalability in CU 240
9.2.3 High Availability in CU 242
9.2.4 Evolving to Real-Time Cloud â" vDU 244
9.2.5 Enterprise/Private Wireless 250
9.3 Fronthaul Deployment 251
9.3.1 Site Solutions and Fronthaul 251
9.3.2 Carrying CPRI over Packet Fronthaul 252
9.3.3 Statistical Multiplexing Gain 253
9.3.4 Merged Backhaul and Fronthaul 255
9.4 Indoor Deployment 257
9.5 Deploying URLLC and Enterprise Networks 262
9.5.1 Private 5G Examples 262
9.5.2 Private 5G RAN Architecture Evolution 264
9.5.3 IP Backhaul and Midhaul Options for Private 5G 266
9.5.4 Fronthaul for Private 5G 266
9.5.5 Other Transport Aspects in Private 5G Networks 267
9.6 Delivering Synchronization 268
9.6.1 Network Timing Synchronization Using PTP and SyncE 269
9.6.2 SyncE 269
9.6.3 IEEE 1588 (aka PTP) 270
9.6.4 ITU-T Profiles for Telecom Industry Using SyncE and PTP 270
9.6.5 Example of Putting All Standards Together in Planning 271
9.6.6 Resilience Considerations in Network Timing Synchronization 275
9.6.7 QoS Considerations in Network Timing Synchronization 276
9.6.8 Special Considerations in Cloud RAN Deployment 276
9.6.9 Satellite-Based Synchronization 277
9.6.10 Conclusion for Synchronization 278
References 278
10 Conclusions and Path for the Future 279
Esa Mets¤l¤ and Juha Salmelin
10.1 5G Path for the Future 279
10.2 Summary of Content 280
10.3 Evolutionary Views for Backhaul and Fronthaul 280
Index 283
