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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Open RAN EXPLAINED A pioneering outline of the concepts that enhance 5G capabilities to revolutionize the telecommunications industry. Open radio-access network, or Open RAN, is a type of network architecture in which baseband and radio unit components from different suppliers can operate seamlessly in concert. Advances in network communication were, until recently, hampered by the proprietary network operations of each mobile operator; the advent of 5G, however, with its service-based architecture model, has finally opened the door to the expansion of connectivity on the Open RAN model. This transformation promises to define the future of mobile network architecture. Open RAN Explained is among the first books dedicated to this groundbreaking technology. Its comprehensive but accessible summary of current and future developments in Open RAN promises to facilitate network deployment and device design, as well as to provide a handy reference for network professionals in a range of different fields. The result is a must-read volume for anyone looking to understand the future of wireless communication. Open RAN Explained readers will also find: * In-depth description of the challenges and opportunities of network modularization * Analysis conversant with the latest release specifications of the O-RAN Allliance, GSMA OP/TIP, and other key emerging technologies * Authors working at the leading edge of 5G network communications Open RAN Explained is ideal for network operators, network element and device manufacturers, telecommunications researchers, and advanced students, as well as industry-adjacent figures such as regulators, consultants, and marketing professionals.
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Veröffentlichungsjahr: 2024
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Table of Contents
Cover
Table of Contents
Title Page
Copyright
Author Biographies
Preface
Acknowledgments
Abbreviations
1 Introduction
1.1 Overview
1.2 Readiness of the Ecosystem
1.3 Focus and Contents
References
2 Open RAN: Journey from Concept to Development
2.1 Overview
2.2 Requirements
2.3 Standards
2.4 Open Source and Open RAN
References
3 Evolution of the RAN
3.1 Architecture of a Mobile Communications System
3.2 Components and Structure of the RAN
3.3 RAN Enhancements from Early Mobile System to 4G
3.4 Role of Information Technology in the Evolution of the RAN in 5G and Open RAN
3.5 RAN Evolution in 5G
3.6 Evolution of the Base Station Architecture
References
4 O‐RAN Alliance Architecture
4.1 High‐Level Objectives of the O‐RAN Alliance Architecture
4.2 O‐RAN Alliance Work on 4G
4.3 O‐RAN 5G Architecture
4.4 O‐RAN Alliance Architecture Innovation
4.5 Service Management and Orchestration Framework
4.6 O‐Cloud
4.7 Real‐Time Intelligent Controller
4.8 Open Fronthaul
References
5 TIP – Commercialization of Open RAN
5.1 Overview
5.2 Fundamental: Requirements and Test Plans
5.3 Testing and Validation, Marketplace
5.4 Experience of OpenCellular
References
Note
6 Open RAN Use Cases
6.1 Introduction
6.2 Open RAN as Enabling Foundation
6.3 Connected Mobility
6.4 Private Networks
6.5 Potential for the Future
References
Notes
7 Open RAN Security Aspects
7.1 General
7.2 User Equipment
7.3 Current Security Landscape
7.4 New Threats
7.5 O‐RAN Interface Protection Aspects
References
8 Open RAN Deployment Considerations
8.1 The Evolution of the RAN Deployment Strategy
8.2 Analysis of the Functional Split of the Base Station and Performance
8.3 Service‐Based Planning Aspects
8.4 Testing and Measurements
8.5 Optimization
8.6 Transition to Open RAN
8.7 Moving Toward the Future Access Agnostic Network: Nonterrestrial Open RAN Scenarios
References
Note
Index
End User License Agreement
List of Tables
Chapter 2
Table 2.1 O‐RAN Alliance board members (as of October 2023).
Table 2.2 Summary of badges: scope and eligibility.
Chapter 3
Table 3.1 Distribution of CU, DU, and RU for different topologies and inter‐...
Chapter 5
Table 5.1 Release 2 Roadmap: deployment scenarios and features.
Table 5.2 Release 2 Roadmap: RU.
Table 5.3 Release 2 Roadmap: DU and CU.
Table 5.4 Release 2 Roadmap: RIA (RIC).
Table 5.5 Release 2 Roadmap: SMO (RAN Orchestration and Management).
Chapter 7
Table 7.1 O‐RAN security‐related specifications and complementing documents....
Table 7.2 Security aspects of Open RAN as per 3GPP.
Table 7.3 Security aspects of Open RAN as per O‐RAN (all defined by WG1 STG ...
Chapter 8
Table 8.1 Test specification references for Open RAN test types.
List of Illustrations
Chapter 1
Figure 1.1 The path toward fully Open RAN deployment involves the prior depl...
Chapter 2
Figure 2.1 3GPP, TSGs, and working groups.
Figure 2.2 O‐RAN Alliance groups (as of October 2023).
Figure 2.3 TIP organization (as of October 2023).
Figure 2.4 Open RAN subgroups (as of October 2023).
Figure 2.5 Stage of commercialization and how organizations collaborate.
Chapter 3
Figure 3.1 System‐level architecture UE/RAN/CORE/external networks.
Figure 3.2 High‐level representation of a traditional base station (RRH + BB...
Figure 3.3 Cellular network representation.
Figure 3.4 Spectral efficiency of different generations of mobile networks....
Figure 3.5 Typical traffic pattern in a 24‐hour period.
Figure 3.6 4G mobile system architecture.
Figure 3.7 CPRI architecture [3].
Figure 3.8 Protocol stack of X2 interface.
Figure 3.9 Split of nodes and new interfaces from traditional architecture t...
Figure 3.10 The concept of network function virtualization.
Figure 3.11 NFV architecture.
Figure 3.12 Simplification of the cloudification concept.
Figure 3.13 Cloudification vs. edge computing.
Figure 3.14 Simplified concept of SDN.
Figure 3.15 Generic architecture of SDN.
Figure 3.16 High‐level RAN architecture in the 5G era.
Figure 3.17 Representation of RAN using gNB split architecture.
Figure 3.18 Split RAN topologies.
Figure 3.19 eCPRI interface architecture.
Figure 3.20 Simplified visualization of the evolution of RAN.
Figure 3.21 System architecture with distributed RAN.
Figure 3.22 System architecture with centralized RAN.
Figure 3.23 System architecture with Cloud RAN.
Figure 3.24 Resource utilization with pooling.
Chapter 4
Figure 4.1 Deployment models for 5G.
Figure 4.2 ng‐eNB standardized interfaces.
Figure 4.3 O‐RAN logical architecture.
Figure 4.4 Options for splitting a base station functionality studied in 3GP...
Figure 4.5 3GPP‐defined base station protocol stack.
Figure 4.6 Physical layer functions of a 5G NR transmitter and receiver Adap...
Figure 4.7 SMO framework architecture view Adapted from [18].
Figure 4.8 Key components involved in/with an O‐Cloud Adapted from [19].
Figure 4.9 Cloud hardware features per component Adapted from [18].
Figure 4.10 High‐level architecture of the RIC. The Non‐Real time RIC works ...
Figure 4.11 High‐level architecture of the Non‐Real‐Time RIC.
Figure 4.12 Architecture of Near‐Real‐Time RIC.
Figure 4.13 Protocol stack of O‐RAN Alliance fronthaul of U‐Plane and C‐Plan...
Figure 4.14 eCPRI transport header fields Adapted from [22].
Figure 4.15 Radio over Ethernet transport header fields Adapted from [22].
Figure 4.16 S‐Plane protocol stack.
Figure 4.17 M‐Plane protocol stack.
Chapter 5
Figure 5.1 Three stages of TIP Release.
Figure 5.2 OpenRAN Trials and Deployments (as of Oct 2022).
Chapter 6
Figure 6.1 Signaling storm illustrated.
Figure 6.2 Concept of GoB and MRO illustrated.
Figure 6.3 MU‐MIMO illustrated.
Figure 6.4 Traffic steering in MR‐DC (only including case with master node)....
Figure 6.5 Concept of dynamic spectrum sharing.
Figure 6.6 RIC‐based DSS architecture.(Not all use cases and related dep...
Figure 6.7 Multi‐vendor slice example (Core network entities not shown)....
Figure 6.8 NSI and NSSI in realizing network slicing.
Figure 6.9 The concept of NaaS.
Figure 6.10 Open RAN MORAN use case architecture.(Not all use cases and ...
Figure 6.11 Six types of V2X communication. (Not all use cases and related d...
Figure 6.12 Commercial drones leveraging 5G.
Figure 6.13 Drone control vehicle application scenario.
Figure 6.14 Difference between public networks and two types of NPN.
Chapter 7
Figure 7.1 O-RAN logical architecture. Source: Adapted from O-RAN Alliance [...
Figure 7.2 Cloud architecture.
Figure 7.3 Software development lifecycle process.
Figure 7.4 Security log management in O‐RAN.
Figure 7.5 SMO architecture. Source: Reproduced from O-RAN Alliance.
Figure 7.6 Architecture of Near‐Real‐Time RIC. Source: Reproduced from O‐RAN...
Figure 7.7 Near‐RT RIC‐related APIs. The near‐RT RIC houses the framework fo...
Figure 7.8 Open RAN security architecture.
Chapter 8
Figure 8.1 Bandwidth requirement for the connection between the units of a d...
Figure 8.2 Mapping different types of RAN architecture against openness and ...
Figure 8.3 Comparison of different RAN splits.
Figure 8.4 Challenges at O‐RAN protocol layers requiring testing, as interpr...
Figure 8.5 The most relevant challenges the ecosystem sees in Open RAN deplo...
Figure 8.6 Challenges and solutions related to Open RAN deployment.
Figure 8.7 The end‐to‐end view for Open RAN testing challenges, as interpret...
Figure 8.8 Interoperability testing procedure for the O‐RU and O‐DU.
Figure 8.9 Comparison of approaches to AI‐native network. (Bar graphs for il...
Figure 8.10 Types of RAN platform that may be considered open.
Figure 8.11 Example of migration from proprietary NMS to SMO‐based network m...
Figure 8.12 Migration from traditional RAN to Open RAN with fully O‐RAN comp...
Figure 8.13 Networking‐RAN architecture with transparent satellite.
Figure 8.14 Regenerative satellite with ISL, gNB processed payload.
Figure 8.15 NG‐RAN with a regenerative satellite based on gNB‐DU.
Guide
Cover
Table of Contents
Title Page
Copyright
Author Biographies
Preface
Acknowledgments
Abbreviations
Begin Reading
Index
End User License Agreement
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Open RAN Explained
The New Era of Radio Networks
Jyrki T. J. Penttinen
Technical Manager, GSMA North America
Michele Zarri
Management Consultant, UK
Dongwook Kim
Technical Officer, European Telecommunications Standards Institute (ETSI), France
This edition was first published in 2024
© 2024 John Wiley and Sons, Ltd
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.
The right of Jyrki T. J. Penttinen, Michele Zarri, and Dongwook Kim to be identified as the authors of this work has been asserted in accordance with law.
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Author Biographies
Jyrki T.J. Penttinen has worked on mobile telecommunications in Finland, Spain, Mexico, and the United States since 1994. His past employers include Telia Sonera, Nokia, G+D Mobile Security Americas, and Syniverse, and he is with GSMA North America Technology Team at present. He is experienced in research and operational activities such as planning, optimization, measurements, system architectures, and services. Dr. Penttinen is also an active lecturer and has authored various books on telecommunication technologies.
Michele Zarri is an independent management consultant. He started his career in Fujitsu R&D working on layer 1 of WCDMA before moving to Deutsche Telekom representing the company in 3GPP. Michele served two terms as 3GPP TSG SA WG1 chairman and has been rapporteur of several specifications and work items. In 2015, Michele joined the GSMA as technical director of the 5G projects.
Dongwook Kim is Specifications Manager of the 3GPP, the secretary of 3GPP CT3 working group, and the work plan coordinator of 3GPP TSG CT. He has worked in the industry for 11 years and his past employers include Korea Telecom (KT), GSM Association (GSMA), and Telecom Infra Project (TIP). His career has focused on promoting latest telecom technologies and serving as the industry think tank.
Preface
The primary intention of the standardization of the mobile communications systems is to ensure as good interoperability between the system components as practically feasible. This principle has provided the mobile network operators with means to design and deploy their networks relying upon different equipment vendor solutions for the radio and core segments. Nevertheless, in practice, the network components within the radio access network (RAN) have been typically so tightly integrated by each vendor that it has been all but impossible to mix and match different radio network equipment providers' solutions within the same RAN.
Industry has thus decided to put further efforts, building upon the 3GPP specifications, to extend the current architectures to cover more standardized interfaces also within the RAN itself. This allows operators to disaggregate the RAN into a set of interoperable components. Such disaggregation has in turn facilitated the emergence of totally new stakeholders that are no longer required to be able to provide the full RAN stack but can instead focus on some of its components. The abstraction of these contact points makes the new RAN environment more transparent and interoperable and can have a positive impact on the business of all the involved parties in terms of increased number of available solutions as well as potentially bring more innovation. Operators are provided with more options to choose from to evolve their radio access segment as well as deploy bespoke solutions for some specific scenarios.
The new environment is still in relatively initial phase regardless of the very active efforts the telco industry has invested to evolve the concept, but the Open RAN is getting increasingly real now. There are already several examples of practical deployments, while the standardization efforts continue detailing adequate solutions. The effort is not, however, completely straightforward, and some challenges will require more time to be successfully addressed. For example, new RAN component concepts such as Radio Intelligent Controller (RIC) is not expected to reach its full potential initially, while operators learn how to leverage the underlying machine learning models and various use cases that artificial intelligence solutions can bring. Moreover, the move toward virtualization of the RAN will require operators to become familiar with orchestration strategies.
Evolved measurement techniques, testing, and processes are needed to ensure the new concept works adequately prior to production and deployment while ensuring adequate performance through the rest of the lifetime of the networks. It is important to note that RAN often accounts for around 70% of the CAPEX of a typical operator.
Yet another challenge, regardless of the increasing number of references becoming public, has been the lack of concrete publications detailing the concept, its more concrete possibilities and challenges, and the ways to deploy the Open RAN in practice.
This book answers to the need by presenting the Open RAN concept based on the latest specifications and information sources and walks the readers through some of the very key aspects that the ecosystem needs to understand in the functioning, deployment, and operation of the Open RAN‐based networks.
This effort to summarize sufficiently and concretely the essential between single covers has been challenging due to such fast pace of the development and the lack of adequate references. Our author team is extremely happy to share the result in a form of this book which we hope to serve the ecosystem in our efforts to make sense out of the complex and oftentimes rather fragmented public information sources.
This book is thus a result of rather long exploration of the environment and root sources such as key specifications of the 3GPP and Open RAN Alliance. We hope this effort benefits the mobile communications ecosystem to learn more about the Open RAN, the topic that has rather realistic prospects to become a highly significant – perhaps even elemental – part of the modern telecom systems, and that is expected to work as important driver for generating new business through evolving ecosystem and new stakeholders.
“Mobile telecommunication systems have been an integral part of people's lives for such a long time that only few of us would really like to return to the era of sole fixed telephony. Having seen the development of the wireless industry from many points of view since 1980s through technical engineering career, starting off with radio network measurements of the very first generation, and working posteriorly with operators, manufacturers, security and roaming providers, and membership organizations, I have been fortunate to witness some of the key breakthrough moments of the wireless industry. Some examples include the commercialization of the 2G in Finland back in 1991, the standardization of the first truly IP‐based mobile data service, General Packet Radio Service (GPRS), the pre‐commercial field testing of the 3rd Generation UMTS (Universal Mobile Telecommunications System), and the takeover of the 4G LTE that currently represents the dominating radio technology. This journey is becoming increasingly interesting as the 5G, which I started to research from the specifications prior to its commercial readiness, is maturing firmly and starts offering advanced features and functions such as network slicing and other 5G SA capabilities also in practice.
Based on these personal experiences, I realize the development of mobile communication systems is a constant effort that materializes in cycles of each decade as completely new generation becomes commercially available. Each new generation tackle important lessons learned that the ecosystem has gained through the previous ones. I also reckon that – apart from the actual deployment and commercial start of the new generation – it is hard to think of much more significant and groundbreaking moments than the gradual availability of the Open RAN concept. This new concept has also provided a fantastic opportunity to learn and share latest knowledge, including the security and testing specifications of the Open RAN Alliance.''
Jyrki T. J. Penttinen, Atlanta, Georgia, USA, 2023
“I have been involved in mobile standardization for more than 20 years and I am sure that the rise of the Open RAN “movement” will be remembered as a major milestone along with the creation of 3GPP, the selection of WCDMA as radio technology for 3G, the battle between LTE and WiMAX during the design of 4G and the introduction of service based architecture in 5G.
Besides addressing well‐known shortcomings of the existing RAN architecture, Open RAN drive to transfer to tangible benefits of virtualization, separation of hardware and software and disaggregation that have proven their worth in the IT world, creates the premises for establishing a healthier supply chain, foster innovation and ultimately make the RAN more affordable. A cheaper, better RAN will bring societal benefits such as reducing the digital divide as well as economic benefits by unlocking new commercial opportunity.
While the jury is still out as to whether all these promises will materialize and challenges will be overcome, it is clear that the efforts of TIP and O‐RAN Alliance have not gone unnoticed and acted as a wake‐up call for the established vendors who might have been too slow in adopting new technologies and paradigms.
Moving forward, the most desirable outcome from my point of view is that the principles, components and specifications developed in Open RAN converge in 3GPP avoiding a divergence of mobile communication system standards that may damage in the long run the economies of scale and pace of innovation. Precedents exist of ideas generated outside the “mainstream” that were contributed to and implemented in 3GPP: the IP Multimedia Subsystem initially devised by 3G. IP and the RAN split first introduced by X‐RAN being notable examples. Such convergence of Open RAN and 3GPP would also create the best premises for the development of a successful, global, open 6G.”
Michele Zarri, London, UK, 2023
“Modular architecture and separation of integrated layers is already prevalent in our lives. From Lego in toys to our personal computers, we often mix and match components to build what we want when we want it and how we want it to be. It is no surprise that I witnessed, in the start of my career, similar work in the core network side starting with Network Function Virtualization (NFV), leading to a great success that is still on‐going within the Industry Specification Group NFV at ETSI. This shows that the principles and the trend of Open RAN is not as complicated and strange as it initially seems, it is the quest of the network operator (whether it be traditional network operators or emerging alternative network models in the 5G era) to flexibly and optimally deploy and operate its network.
However, openness can be tricky in that the user/customer needs a degree of knowledge to fully exploit the potential. Taking the Lego example, an average child playing with the toy will not be able to build a gigantic and magnificent masterpiece that you would find in Lego Land, let alone the Lego toy series that manias display in their glass cupboards. In this respect, I believe that this book will set a stepping stone for you to be able to play with Open RAN like the Lego manias do with their Lego toys. Of course, you should not limit yourself to Open RAN per se as mobile networks is a much more complex topic and should be aware of the relevant 3GPP work that Open RAN is based on.”
Dongwook Kim, Sophia Antipolis, France, 2023
Acknowledgments
This book is a result of countless hours of exploration of mobile communications resources through specifications and other available information sources, discussions with our peers, as well as ideation and manuscript drafting, that all were essential steps for us to be able to write down the contents of this book. It has been a challenging task, yet highly rewarding as we wrote this book to provide ecosystem with concrete ways to learn more on the subject.
Our author team would like to acknowledge all the ones we had possibility to discuss the topic throughout this effort, including our colleagues and peers at GSMA and 3GPP. We also appreciate all the support and patience of our close families during this work.
Finally, this book would not be reality without the firm, yet gentle guidance and coordination of the Wiley team. Thank you so much Nandhini Karuppiah, Sandra Grayson, Becky Cowan, and all the ones within Wiley involved in this effort directly and in supporting roles. It has been a pleasure to work under such a professional guidance and friendly spirit.
Abbreviations
1G
first generation of mobile communications
2G
second generation of mobile communications
3G
third generation of mobile communications
3GPP
third generation partnership project
4G
fourth generation of mobile communications
5G
fifth generation of mobile communications
5GS
5G system
6G
sixth generation of mobile communications
A/V
audio/video
AAL
accelerator abstraction layer
AAL
ATM adaptation layer
ACPI
advanced configuration and power interface
ADC
analogue to digital conversion
AI
artificial intelligence
AICPA
American Institute of Certified Public Accountants
ALD
antenna line device
AMF
access and mobility management function (5G)
ANR
automatic neighbor relation
AP
application plane
API
application programming interface
AR
augmented reality
ARIB
Association of Radio Industries and Businesses, Japan
ASIC
application‐specific integrated circuit
ATIS
Alliance for Telecommunications Industry Solutions (North America)
BBU
baseband unit
BoM
bill of material
BSS
business support system
BVLOS
beyond visual LOS
CA
carrier aggregation
CA
certificate authority
CAGR
cumulative annual growth rate
CAPEX
capital expenditure
CCSA
China Communications Standards Association
CCTV
closed circuit television
CD/CT
continuous deployment/continuous testing
CDMA
code division multiple access
CI
cloud infrastructure
CI/CD
Continuous integration (CI) and continuous deployment (CD)
CICA
Canadian Institute of Chartered Accountants
CII
core infrastructure initiative (LF)
CM
configuration management
CMP
certificate management protocol (PKI)
CN
core network
CNF
cloud network function
CoMP
coordinated multi‐point (transmission/reception)
COTS
commercial off‐the‐shelf hardware
CP
circular polarization
CP
control plane
CP
cyclic prefix
CPRI
common public radio interface
CPU
central processing unit
C‐RAN
cloud RAN
CRC
cyclic redundancy check
C‐SCRM
cybersecurity supply chain risk management
CSP
cloud service provider
CSRIC
Communications Security, Reliability, and Interoperability Council
CT
core network and terminals (3GPP TSG)
CU
centralized unit
CU‐CP
CU split to control plane
CUPS
control and user plane separation
CU‐UP
CU split to user plane
DIFI
digital intermediate frequency interoperability
DL
downlink
DMS
deployment management services
DoC
Department of Commerce (USA)
DP
data plane
DRB
data radio bearer
DSRC
dedicated short‐range communication
DSS
dynamic spectrum sharing
DTLS
datagram transport layer security
DU
distributed unit
DUT
device under testing
E2E
end‐to‐end
EM
element management
EMS
element management system
eNB
Evolved NodeB (4G)
ENISA
European Union Agency for Cybersecurity
eNodeB
LTE node (4G),
see
eNB
EPC
evolved packet core (4G)
eRE
evolved radio equipment
eREC
evolved radio equipment controller
ERP
enterprise resource planning
eSIM
embedded SIM
EST
enrollment over secure transport protocol
ETSI
European Telecommunications Standards Institute
EU
European Union
E‐UTRAN
evolved universal terrestrial radio access network (4G)
FCAPS
fault, configuration, accounting, performance, and security management
FCC
Federal Communications Commission (USA)
FDMA
frequency division multiple access
FFT
fast Fourier transformation
FH
Fronthaul
FM
fault management
FOCOM
federated O‐cloud orchestration and management
FPGA
field programmable gate array
FR
frequency range
FRMCS
future railway mobile communication system
GEO
geostationary orbit
gNB
next‐generation NodeB (5G)
GoB
grid of beams (MIMO)
GPP
general‐purpose processor
GPS
global positioning system
GPU
graphics processing unit
GSM
global system for mobile communications (2G)
GSMA
GSM association
GSM‐R
GSM‐Railway
GTP
GPRS transfer protocol
GTP‐U
GPRS transfer protocol user plane
GUI
graphical user interface
HARQ
hybrid automatic repeat request
HD
high definition
HDLC
high‐level data link control
HLS
high‐level split
HO
handover
HSM
hardware security module
HW
hardware
i/f
interface
IaaS
infrastructure as a service
ICT
Information and Communication Technology
IDS
intrusion detection system
IEEE
Institute of Electrical and Electronics Engineers
IEFG
Industry Engagement Focus Group (O‐RAN Alliance)
IF
intermediate frequency
iFFT
inverted fast Fourier transform
IMF
infrastructure management framework
IMS
infrastructure management services
IMS
IP multimedia subsystem
IoT
internet of things
IOT
interoperability testing
IP
internet protocol
IPS
intrusion prevention system
IPSec
internet protocol security
IQ
in‐phase (I) and quadrature (Q) component of sinusoids of amplitude modulation
ISG
Industry Specification Group (ETSI)
ISL
inter‐satellite link
ISO
International Organization for Standardization
IT
information technology
ITU
International Telecommunications Union
ITU‐T
ITU Telecommunication Standardization Sector
KPI
key performance indicator
L1
layer 1
LCM
life cycle management
LEO
low earth orbit
LF
linux foundation
LHCP
left‐hand circular polarization
LLS
low‐level split
LMF
location management function
LOS
line‐of‐sight
LP
linear polarization
LSB
least significant bit
LTE
long‐term evolution (4G radio network)
LTE‐A
LTE advanced (4G)
MAC
medium access control
MANO
NFV management and orchestration (ETSI)
MC
mission critical
MCG
Master Cell Group (4G, 5G)
MCPTT
mission critical push‐to‐talk
MEC
multi‐access edge computing
MEO
medium earth orbit
MIMO
multiple‐input multiple‐output
mIoT
massive IoT
ML
machine Learning
MME
mobility management entity (4G)
mMIMO
massive MIMO
MNO
mobile network operator
MOCN
multi operator core network
MORAN
multi operator radio access network
MoU
memorandum of understanding
MP
management plane
MRO
mobility robustness optimization
MSB
most significant bit
MU‐MIMO
multi‐user MIMO
NaaS
network‐as‐a‐service
NB
NodeB (3G)
NB‐IoT
narrow‐band IoT
NE
network element
NE‐DC
NR/E‐UTRA dual carrier (4G, 5G)
NESAS
network equipment security assurance scheme (GSMA)
NETCONF
network configuration protocol
NF
network function
NFO
network function orchestrator
NFV
network function virtualization
NFVI
NFV infrastructure
ng‐eNB
evolved 4G nodeB supporting split model
NGMN
next generation mobile network
NG‐RAN
next generation radio access network
nGRG
Next Generation Focus Group (O‐RAN alliance)
NIB
network information database
NIST
National Institute of Standards and Technology (USA)
NLOS
non‐line of sight
NMS
network management system
NPN
non‐public network
NR
new radio (5G)
nRT‐RIC
near‐real‐time RIC
NSA
non‐standalone (4G, 5G)
NSI
network slice instance
NSSI
network slice subnet instance
NTIA
National Telecommunications and Information Administration (USA)
NTN
non‐terrestrial network
OAM
operations and maintenance
OAuth
open authentication
OCG
Organized Crime Group
O‐Cloud
open cloud (O‐RAN alliance)
O‐CU
Centralized Unit defined by O‐RAN Alliance
O‐CU‐CP
O‐CU control plane
O‐CU‐UP
O‐CU user plane
O‐DU
distributed unit defined by O‐RAN alliance
O‐eNB
O‐RAN evolved radio access node (4G)
OFDM
orthogonal frequency division multiplex
OFH
open fronthaul
OMG
OpenRAN MoU Group
ONAP
open networking automation platform
ONF
The Open Networking Foundation
ONOS
open network operating system
OP
organizational partner
OPEX
operating expenses
O‐RAN
open RAN alliance
O‐RU
radio unit defined by O‐RAN alliance
OS
operating system
OSFG
Open Source Focus Group (O‐RAN alliance)
OSI
open system interconnection
OSM
open‐source MANO
OSS
open‐source software
OSS
operations support system (RAN)
OTIC
open testing and integration centre
OWASP
open web application security project
PaaS
platform as a service
PBX
private branch exchange
PDCP
packet data convergence protocol
PG
Project Group (Telecom Infra Project)
PGW
packet gateway
PGW‐C
PGW control plane
PHY
physical layer
PKI
public key infrastructure
PLMN
public land mobile network
PM
performance monitoring
PNI‐NPN
public network integrated NPN
PoC
proof of concept
PRB
physical resource block
PSTN
public switched telephone network
PTP
point to point
PTT
push‐to‐talk
QoE
quality of experience
QoS
quality of service
RAN
radio access network
RAN
radio access network (3GPP TSG)
rApp
function managed by the non‐real‐time RIC
RAT
radio access technology
RE
radio equipment
RE
resource element
REC
radio equipment controller
RF
radio frequency
RHCP
right hand circular polarization
RIA
RAN intelligence automation
RIC
RAN intelligent controllers
RLC
radio link control
R‐NIB
RAN network information database
RoE
radio over ethernet (FH protocol)
ROMA
RAN orchestration and management
RRC
radio resource control
RRH
remote radio head
RRM
radio resource management
RRU
remote radio unit
RSP
remote SIM provisioning
RTOS
real‐time operating system
RU
radio unit
SA
service and system aspects (3GPP TSG)
SA
standalone (5G)
SaaS
software as a service
SAP
system applications and products
SATCOM
satellite communications
SBOM
software bill of material
SCG
Secondary Cell Group (4G, 5G)
SCTP
stream transmission control protocol
SDAP
service data adaptation protocol
SDFG
Standard Development Focus Group (O‐RAN alliance)
SDLC
software development lifecycle
SDN
software‐defined networking
SDO
standard developing organization
SD‐RAN
software‐defined radio access network
Sec
security
SFG
Security Focus Group (O‐RAN alliance)
SGW
serving gateway
SGW‐C
SGW control plane
SIEM
security information and event management
SIM
subscription identity module
SLA
service level assurance/agreement
SMF
session management function (5G)
SMO
service management and orchestration framework
SMS
short message service
SNCF
Sociedad Nacional de Ferrocarriles Franceses
SNMP
simple network management protocol
SNPN
stand‐alone non‐public network
SON
self‐organizing network
SP
service provider
SRB
signaling radio bearer
SRI
satellite radio interface
SSDF
secure software development framework
SSH
secure shell protocol
SuFG
Sustainability Focus Group (O‐RAN alliance)
SW
software
TCO
total cost of ownership
TCP
transmission control protocol
TDD
time division duplex
TDF
traffic detection function
TDF‐C
TDF control plane
TDM
time division multiplexing
TDMA
time division multiple access
TIFG
Testing and Integration Focus Group (O‐RAN alliance)
TIP
telecom infra project
TLS
transport layer security
TSC
Technical Steering Committee (O‐RAN Forum)
TSDSI
Telecommunications Standards Development Society, India
TSG
Technical Specification Group
TTA
Telecommunications Technology Association, South Korea
TTC
Telecommunication Technology Committee, Japan
UAV
uncrewed aerial vehicle
UDP
user datagram protocol
UE
user equipment
UE‐NIB
UE network information base
UI
user interface
UIC
International Union of Railways
UL
uplink
UMTS
universal mobile telecommunications system (3G)
UP
user plane
UPF
user plane function (5G)
URLLC
ultra‐reliable low latency communications
V2C
vehicle to cloud
V2D
vehicle to device
V2G
vehicle to grid
V2I
vehicle to infrastructure
V2N
vehicle to network
V2P
vehicle to pedestrian
V2V
vehicle to vehicle
V2X
vehicle‐to‐everything
VLAN
virtual local area network
VM
virtual machine
VNF
virtualized network function
Vo5GS
voice over 5G system
vO‐CU
virtual open RAN centralized unit
vO‐DU
virtual open RAN distributed unit
VoNR
voice over new radio
VR
virtual reality
vRAN
virtualized RAN
WAP
wireless application protocol
WG
workgroup (O‐RAN alliance)
WG
working group (3GPP)
X2AP
X2 application protocol
xApp
near real‐time RIC multi‐vendor programmable application
XR
extended reality
xRAN
extensible RAN (forum)
ZTA
zero trust architecture
1Introduction
1.1 Overview
Mobile networks have provided consumers location‐independent communications since the 1980s. New mobile communication networks and generations build upon the technical insights and experiences of the earlier versions to provide better performance, capacity, and quality to the end users. The fifth generation is no exception to this evolutionary path.
Although the network architectures have evolved, the basic principles of the radio and core networks have remained largely the same. Traditionally, mobile operators manage a set of network elements and their hardware and software dedicated to their respective functions. Only recently, and largely thanks to the service‐based architecture model introduced along with the new fifth generation of mobile communications (5G), the virtualization of network functions has become possible natively in the design. At the same time, the established and new standardization bodies update the traditional models to reflect this evolution. Therefore, the operators have additional options to design and deploy modern networks such as virtual and Open radio access network (Open RAN) models [1].
The radio network is the most critical and challenging part of the communications path of the wireless systems. Some of the reasons for this are the unpredictable characteristics of the radio interface with hard‐to‐predict variables such as deviations in peak and average load. The radio link budget provides good approximation for the operators to predict the average situation, but the unknown aspects remain, altering the final radio quality. The new concepts enhance the performance of the radio networks as they can adapt more optimally to the varying situations in terms of the offered capacity and achievable performance.
Not only the unpredictable radio interface can be a potential issue, but the radio network architectures and their interfaces represent typically rather closed environment for network infrastructure providers. It has been thus challenging, if not impossible, for new players to join the ecosystem, providing alternative or parallel radio network functions [1].
After several years of conceptual discussions, the Open RAN is now becoming a reality, especially along with the deployment of the second phase of the 5G system. O‐RAN Alliance has already produced concrete specifications that complement the ones of the 3GPP to further abstract the radio access network (RAN) and interfaces. This gives room for advanced deployment scenarios involving increasing number of incumbent and nontraditional stakeholders alike that can provide and use truly interoperable modules for the radio networks.
1.2 Readiness of the Ecosystem
1.2.1 Virtualization
The radio networks of the mobile communication systems have enhanced dramatically since the 1G networks became a reality. This evolution path that the 3GPP standardization has driven includes the optimization of the architectural models (the LTE and 5G base stations integrate the control functions that separate elements managed in 2G and 3G) and split models for the control and user plane separation (distributed unit [DU], central unit [CU], and radio unit [RU], respectively).
The benefits of these technologies include optimization of the capacity as operators can rededicate it automatically among their base stations, and they provide advanced ways to expand the networks, thanks to the possibility to dedicate more capacity considering more granular modules instead of a mere base station unit. The 3GPP has also specified virtualized RAN (vRAN) model that provides, in theory, more open environment for the radio network deployment. Nevertheless, the vRAN model still has practical interoperability challenges in offering operators with means to implement common interfaces and functions.
The next step in this evolution is the O‐RAN that the O‐RAN Alliance has specified. It expands the virtual RAN model of the 3GPP, extends interfaces and technical solutions providing better interoperability between stakeholders, and provides technical means for additional providers of different modules to join the infrastructure.
The Open RAN is already a reality. Yet, the ecosystem lacks information sources to understand the concept and its potential. This book is designed to help operators, equipment manufacturers, service providers, regulators, and educational institutes alike understand and explore the principles and details of the Open RAN.
The recent public news indicates that the interest in Open RAN continues to grow and that the industry works toward networks that can be deployed and operated based on mixing and matching components from different suppliers. As an example, Deutsche Telekom, Orange, Telefónica, and Vodafone Group have signed a Memorandum of Understanding (MoU) to implement Open RAN across Europe.
The move aims to promote the timely deployment of Open RAN technologies and ensure that a strong ecosystem of companies emerges in Europe; Orange has stated that it wants all its network upgrades to be Open RAN by 2025 and puts pressure on traditional equipment suppliers to adapt to new open standards. There are similar examples, e.g. in the United States (advances of Parallel Wireless in Open RAN products and plans of DISH Network to deploy their nationwide 5G network based on the Open RAN paradigm) and Japan (Rakuten is one of the members of the Open RAN Alliance and is considered oftentimes a reference for early‐stage multi‐vendor RAN deployments).
Not only the standard‐setting bodies, device manufacturers, and operators are in a key position to pave the way for the new technology but also the regulators have an important role. As an example, Nokia states in their public source that some countries are looking at Open RAN to introduce new suppliers to the market, while Open RAN can considerably reduce entry barriers for new stakeholders. Furthermore, some countries are looking at Open RAN as an opportunity to drive local 5G innovation.
1.2.2 Industry Forums
Open RAN has had already a long journey. The role of 3GPP has been instrumental in this path, and the resulting technical specifications allow operators to deploy RANs by splitting the RAN structure into the controlled division of the RU, DU, and centralized unit (CU). The 3GPP specifications provide flexibility that optimizes the signaling, capacity, and processing of the RAN in such a way that part of the base station functionalities can be run elsewhere, such as in an edge cloud.
In recent years there have been efforts to extend the 3GPP solutions to enable even more open interfaces within the RAN. This would allow more diverse “mix and match” of RAN components in applying ideally “plug and play” principles. Although there are practical challenges in achieving such a goal, the integration of different vendor solutions within a single RAN area has become a reality.
3GPP has played an essential role in the evolution of mobile systems. As a result, the 3GPP‐defined 5G defines a gNB functions split separating the CU and a DU, through the F1 interface. The CU can be split further into a control plane (CU‐CP) and user plane (CU‐UP), which has resulted in the introduction of the E1 interface. This split model is essential for the further work of the industry to also ensure that the rest of the interfaces are compatible among different vendors.
The currently most important entities, building upon the 3GPP standards for the evolution path for the RAN, are O‐RAN Alliance and Telecom Infra Project (TIP). They complement and build definitions upon the split architecture that the 3GPP has facilitated. There are also additional groups that contribute to the development of the O‐RAN concept, such as Open Networking Foundation (ONF) and Open RAN Policy Coalition.
The O‐RAN Alliance (O‐RAN) is committed to evolving RANs with its core principles being intelligence and openness. As stated in [2], it aims to drive the mobile industry toward an ecosystem of innovative, multi‐vendor, interoperable, and autonomous RAN, with reduced cost, improved performance, and greater agility. The O‐RAN architecture is the foundation for building a vRAN on open hardware and cloud, with embedded AI‐powered radio control. The O‐RAN provides specifications that complement the 3GPP definitions for the Open RAN concept to ensure the select RAN interfaces are truly interoperable. The O‐RAN also provides whitepapers and guidelines through their portal.
The O‐RAN specifications present solutions to provide disaggregated, virtualized, and software‐based components through open and standardized interfaces. The aim of the O‐RAN is to have these interfaces interoperable across multiple vendors building upon the technical principles of 3GPP 4G and 5G RANs, especially on the split models. In practice, the O‐RAN focuses on the extension of the 3GPP NR 7‐2 split model for the radio network, disaggregating the functions of the base station into a RU, CU, and DU. In addition, the O‐RAN specifies the connection to RAN Intelligent Controllers (RIC), covering both near‐real‐time RIC (nRT‐RIC) and non‐real‐time RIC and including their respective control and policies. These RIC components manage and control the network providing near‐real‐time performance (10–1000 ms) and non‐real‐time performance (1 seconds and beyond).
TheTelecom Infra Project (TIP) contributes to Open RAN concept. As stated in [3], TIP is a global community of companies and organizations that are driving infrastructure solutions to advance global connectivity. The motivation is to enhance the possibilities for the world's population to access the internet with sufficient quality and to drive consumer and commercial benefits and economic growth. TIP has reasoned that a lack of flexibility in the current solutions and a limited choice in technology providers make it challenging for operators to efficiently build and upgrade networks.
TIP was founded in 2016 to facilitate the cooperation between companies, such as service providers, technology partners, and systems integrators, among other connectivity stakeholders. The work of the project includes the development, testing, and deployment of open, disaggregated, and standards‐based solutions. TIP thus adopts the O‐RAN Alliance specifications and drives Open RAN initiatives focusing on the enablement of testing and Open RAN deployments by facilitating the discussions among operators, vendors, and system integrators.
More specifically, the Open RAN workgroup of TIP realizes the mission of OpenRAN: that is to accelerate innovation and commercialization in RAN domain with multi‐vendor interoperable products and solutions that are easy to integrate into the operator's network and are verified for different deployment scenarios. TIP's OpenRAN program supports the development of disaggregated and interoperable 2G/3G/4G/5G NR RAN solutions based on service provider requirements [4]. The goal of the TIP OpenRAN is to bring the ecosystem together to take a holistic approach toward building next‐generation RAN. For this, TIP OpenRAN collaborates with other industry organizations, including GSMA, ONF, and O‐RAN Alliance.
TheOpen Networking Foundation (ONF) is involved in mobile network projects, creating open‐source solutions in the rapidly evolving mobile infrastructure space. One of the areas of the ONF is the SD‐RAN, which is building open‐source components for the mobile RAN space, complementing O‐RAN's focus on architecture and interfaces by building and trialing O‐RAN‐compliant open‐source components. The aim of this setup is to foster the creation of multi‐vendor RAN solutions and help invigorate innovation across the RAN ecosystem.
The SD‐RAN of the ONF develops the Near Real‐Time RIC and a set of exemplar xApps for controlling the RAN. This RIC is cloud‐native and builds on several of ONF's platforms including the ONOS SDN Controller. The architecture for the SD‐RAN near Real‐Time RIC will leverage the O‐RAN architecture and vision. SD‐RAN also follows the O‐RAN specification advances, and the SD‐RAN project creates new functionality and extensions and feeds the respective learnings back to the O‐RAN Alliance with the aim of these extensions to help advance the O‐RAN specifications [5].
The Open RAN Policy Coalition is a group of companies formed to promote policies that will advance the adoption of open and interoperable solutions in the RAN to create innovation, spur competition, and expand the supply chain for advanced wireless technologies including 5G [6].
1.2.3 Statistics
The telecom industry is advancing with the practical Open RAN deployments. According to reference [7], iGR Research identified 23 publicly announced mobile network operators (MNOs) around the world using equipment from multiple vendors who had deployed Open RAN in commercial networks in 2023.
The related business is growing significantly based on the observations of ABI Research that estimates that total spending on O‐RAN RUs for the public outdoor macro‐cell network will reach US$ 69.5 billion market by 2030 [8]. Furthermore, reference [9] reasons that 5G‐based Open RAN deployments will accelerate after 2025, along with various mobile operators stepping onboard, and as the open interface standards evolve and mature sufficiently for the actual interoperability testing. Reference [9] also states that by 2030 there will be 1.3 million O‐RAN cells deployed, and their total value is US$ 19.2 billion, as per the Rethink Technology Research's wireless forecasting service – RAN Research report.
As indicated in [10], Parallel Wireless, Mavenir, Altiostar, Samsung, and Radisys are examples of the virtual RAN vendors. The rather large list of present O‐RAN RU vendors includes NEC, Fujitsu, Gigatera, Lime Microsystems, Nokia, Airspan, Sercomm, and VANU. Intel, Qualcomm, Xilinx, NVIDIA, and Saankhya Labs are some of the examples of the O‐RAN chipset vendors, and the O‐RAN system integrator list includes NEC, Rakuten, Everis, Tech Mahindra, and Amdocs.
As for the initial phase of the Open RAN deployment landscape, reference [9] reasons that the early Open RAN adopters have typically been greenfield sites regardless of the region. In the beginning of the deployments, Japan was the forerunner because of the active work of the 5G greenfield operator Rakuten Mobile.
In the United States, DISH Network is an example of early Open RAN adopters along with the greenfield 5G network deployment. The respective early Open RAN adoption is thus free from the potential challenges of the legacy equipment accommodation.
1.2.4 Path Toward Open RAN Networks
The evolution toward the deployment of Open RAN networks can be presented by main phases that are depicted in Figure 1.1. The following list summarizes the key aspects of these phases, as interpreted from references [10] and [11]:
Open fronthaul
(stage 1): In this scenario, the
baseband unit
(
BBU
) is connected to the RU based on proprietary hardware platforms. This stage provides an open interface between the RU and DU and represents the fronthaul interface covering the RAN split option 7‐2x. To truly work in practice, the open fronthaul requires that the participating vendors support it between the RU and DU.
Open baseband unit
(stage 2): In this scenario, the RU is connected to DU, which, in turn, connects to CU based on
Commercial Off‐the‐Shelf
(
COTS
) hardware platforms. This scenario is the next step in the evolution toward open interfaces and extends the previous scenario of opening the F1 interface between the DU and CU as per the 3GPP RAN model's higher layer split. In order to provide a true interoperability among CU and DU vendors, they must support the open standard. This scenario helps evolve also the previously applied proprietary hardware approach to allow the use of COTS for the DU and CU.
Open, intelligent, and programmable environment
(stage 3): In this scenario, the RU is connected to DU, which connects to RIC, CU‐CP, and CU‐UP, based on COTS and cloud platforms. This scenario extends the disaggregation of the CU so that it is divided into separate user and control planes. The RIC is essential in this scenario to house real‐time analytics, self‐optimized network concepts, and radio resource management applications so that the CU and RIC reside in edge cloud.
Figure 1.1 The path toward fully Open RAN deployment involves the prior deployment models for open fronthaul and open BBU. The thick lines represent the O‐RAN‐defined open interfaces.
This list presents the major steps that augment the level of disaggregation and openness. It should be noted that the development of the interfaces for open management of all the relevant components plays an essential role in taking the O‐RAN concept work in practice. Observing Figure 1.1, apart from the depicted interfaces, the M‐plane of the O‐RAN fronthaul thus connects to the O‐RAN entities, COTS hardware (O‐cloud) as well as the core network segment.
As a result, the Open RAN movement allows new stakeholders to develop focused products through the defined open interfaces. The O‐RAN Alliance has made this reality for the respective signaling and data flows and has developed the RAN architecture to be virtual, intelligent, and interoperable.
The first chapters of this book describe the principles of the Open RAN concept, further detailing the respective deployment aspects in Chapter 8.
