Progression of Radio Access Network towards Open-RAN

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
p-ISSN: 2395-0072
Volume: 10 Issue: 08 | Aug 2023 www.irjet.net
Progression of Radio Access Network towards Open-RAN
Varshini AR1, Vidya C Raj2
1PG student, Department of Computer Science & Engineering, The National Institute of Engineering, Mysuru-
570008, India
2Professor, Dean (Academic Affairs) Department of Computer Science & Engineering, The National Institute of
Engineering, Mysuru-57008, India
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Abstract - The advent of 5G technology has revolutionized
communication, propelled by the transformative concept of
Open Radio Access Network (ORAN), which aims to reshape
the communications sector. ORAN’s innovative architecture
emphasizes openness, interoperability, and virtualization,
standing in stark contrast to the closed nature of traditional
Radio Access Network (RAN) designs. Guided by principles of
disaggregation and virtualization, ORAN separates hardware
components and enables adaptable, scalable network
functions. By dismantling vendor lock-in, ORAN fosters
collaboration, diversity, and innovation among stakeholders.
Disaggregation drives multi-vendor interoperability, creating
a competitive market where network operators can select
components from various manufacturers, enhancing flexibility.
Virtualization further bolsters performance by transitioning
from hardware to software-based solutions, improving cost-
efficiency, scalability, and agility. ORAN’s strategy enhances
network flexibility, allowing operators to swiftly meet
changing demands and introduce new services. Through its
virtualized architecture, dynamic resource allocation
optimizes resource usage, enhancing user experiences. ORAN
emerges as a transformative force in telecommunications,
challenging conventional closed RAN models and offering a
dynamic vision for the future of communication technology.
Key Words: Open Radio Access Net- work (RAN), RAN’s
evolution, Open-RAN architecture
1.INTRODUCTION
Over the past 50 years, wireless communication technology
has evolved significantly, with recent advancements in IoT
and real-time applications driving a surge in wireless
frameworks. Open Radio Access Network (ORAN) seeks to
separate hardware and software components, facilitating
adaptable integration from multiple suppliers. IoT
emphasizes wide coverage and low power consumption,
while real- time applications require low latency and
dynamic data processing, necessitating a versatile network.
Traditional RadioAccess Network (RAN) models fall short
of meeting these requirements, urging the need for
enhancements. Constructing separate networks for
different applications is impractical, prompting efforts to
create software-driven, virtualized, intelligent, and energy-
efficient mobile networks. Acknowledging the
transformational potential of fifth - generation (5G) wire-
less technology, the telecommunications industry strives
for innovation and improved network capabilities to meet
growing connection demands. Traditional RAN
architectures, reliant on proprietary technology, hinder
interoperability and hinder 5G’s full potential, thus
prompting exploration of virtualization and disaggregation
as solutions.
Disaggregation enables separation of hardware components,
like baseband and radio units, fostering multi-vendor
integration and a competitive market. Simultaneously,
virtualization shifts processing functions to software,
enhancing scalability, efficiency, and cost-effectiveness.
Understanding these principles empowers operators to
respond effectively to evolving needs and harness 5G’s
potential. ORAN, endorsed by players in the telecom sector,
isolates hardware and software, allowing top-tier solutions
from diverse suppliers to integrate flexibly. ORAN signifies a
pivotal shift towards openness, interoperability, and
virtualization in RAN design, supporting competition,
innovation, and network stability. It forms the foundation for
5G and beyond, promoting cooperation, standardization, and
secure operations. Through collaborative efforts, challenges
related to interoperability and security are addressed,
ensuring the effective deployment of ORAN’s promise.
2. EVOLUTION OF RAN
Network infrastructure design’s primary objective is secure
and efficient device communication. The Radio Access Net-
work (RAN) is a fundamental concept in telecommunications
that plays a vital role in ensuring seamless connectivity and
effective data transmission between devices and the core
network. Network operators are upgrading RANs to manage
increased device connections, data traffic, and 5G- based
services while optimizing resources and maintaining Quality
of Service/Experience (QoS/QoE).RAN’s deployment,
operations, and maintenance constitute a significant cost,
prompting operators to focus on reducing CapExand OpExby
creating a flexible RAN that accommodates various
deployment options and services. RAN is composed of radio
resource management and radio signal
transmission/reception. Traditional RANs and Distributed
RANs (D-RANs) function independently, but their integrated
architecture calls for denser deployment as user connections
increase, resulting in higher costs for capacity enhancement.
The Cloud RAN (C-RAN) concept emerged as a solution to
© 2023, IRJET | Impact Factor value: 8.226 | ISO 9001:2008 Certified Journal | Page 657

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reduce costs. C-RAN introduced RAN node resource sharing
to address the challenges of base station deployment and
operation.
2.1 C-RAN
C-RAN, also known as Centralized RAN or Cloud RAN,
involves splitting the RAN into separate Remote Radio
Units/Heads (RRUs/RRHs) and a centralized pool of
Baseband Units (BBUs) in a cloud data center. This
architecture supports centralized processing, real-time
networking, and scalability, facilitated by a new FH interface
connecting BBUs and RUs. However, challenges include
single point of failure for BBUs, security concerns, and
limitations related to FH overhead, proprietary interfaces,
and vendor dependence.
2.2 The virtualized RAN (vRAN)
vRAN utilizes virtualization in addition to the same method-
ology as the C-RAN. By utilizing the NFV concepts, vRAN
decouples the software from the hardware and replaces
expen- sive, proprietary hardware with COTS hardware. The
coordination of RAN nodes to allocate network resources
for various services depending on the requirements of those
services is difficult, the complexity of networkadministration
has sub- stantially risen, and a proprietary interface-based
deployment leads to vendor lock-in.
2.3 5G Networks
5G’s new air interface, New Radio (NR), and the Next
Generation RAN (NG-RAN) collectively shape the 5G system.
The 5G NR employs physical connections for radio- based
communication and operates in two modes: Non-Standalone
(NSA) and Standalone (SA), enabling efficient data manage-
ment and higher data rates. In SA mode, direct connectivity
between gNB and the 5GC supports advanced services,while
NSA mode facilitates eMBB class services through a connec-
tion between LTE, NR, and the 4G CN (EPC).
Fig -1: 4G and 5G architectures
Fig 1 illustrates the architectures of both 4G and 5G systems,
where 5G’s NG-RAN allows RAN disaggregation and
configurable functional split options. NG-RAN’s deployment
supports control plane and user plane separation, enabling
flexiblescaling anda variety of deployment choices.However,
challenges remain in achieving virtualization, software-
driven adaptability, interoperability, and energy-efficiency,
which the O-RAN Alliance aims to address through open
interfaces and virtualized edge computing infrastructure.
3. LITERARURE SURVEY
The concept of ”Open RAN” envisions a future for the Radio
Access Network (RAN) with goals including vendor-
independent and AI-driven solutions. With the complexity of
new use cases introduced by 5G and beyond (B5G) networks,
traditional methods impede rapid innovation and standardized
AI application. The Open Radio Access Network (O-RAN)
alliance proposes an architecture based on disaggregated RAN
functions, managed by a RAN controller enforcing decisions via
open interfaces. The O-RAN initiative employs machine learning
techniques, especially deep learning, to facilitate intelligent
RAN applications that meet Quality of Service (QoS)
requirements. In the context of wireless cellular networks,
Device-to- Device (D2D) communication holds promise for
boosting data speeds, reducing latency, and enhancing effi-
ciency. This technology is examined in the context of fifth
generation and beyond (5GB) networks, with a focus on the in-
band (IBD) and out-of-band (OBD) D2D modes. Integration of
D2D communication with other technologies is highlighted for
network performance enhancement, addressing challenges,
possibilities, and future directions within the context of 5G and
even 6G networks.
4. OPEN-RAN ARCHITECTURE
Fig -2: Open-RAN Architecture

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The 3GPP 5G System laid the foundation for the O-RAN
architecture, enhancing RAN features and introducing open,
interoperable interfaces. O-RAN aims to diversify the supply
chain, reduce deployment costs, and foster interoperability
among vendors. Unlike NG-RAN, O-RAN incorporates new
nodes, open interfaces, and cloud infrastructure, allowingfor
a virtualized RAN with AI/ML-powered intelligent radio
controllers. The O-RAN reference architecture includescom-
ponents like RICs, O-CU, O-DU, O-RU, O-Cloud, O-eNB, andO-
UEs, interlinked through various interfaces to form a
dynamic network.
4.1 SMO FRAMEWORK
O-RAN’s vision for 5G RAN emphasizes adaptability,
scalability, and multi-vendor interoperability, with a strong
focus on management and automation. The SMO
framework plays a central role in managing and
orchestrating various O- RAN components, resembling the
NFV MANO entity and operating through standardized
service-based interfaces to ensure interoperability, while
providing FCAPS management functionalities and offering
orchestration, workflow management, RAN optimization,
and non-RT RIC capabilities.
4.2 O-RU (OPEN-RAN RADIO UNIT)
Fig-3:Open-RAN ArchitecturewithFunctional Splits
At the physical layer of the network, the O-RU, a radio unit
found at cell sites, transmits, receives, and processes radio
signals. The radio signals are exchanged between the O-RU
and the O-DU in the O-RAN reference architecture usingthe
Open FH interface. The O-RU implements the PHY-Lowand
Radio Frequency (RF) processing capabilities in
accordance with the functional split option 7.2x, as
indicated in Fig 3.
4.3 RIC’s and Closed -loop control
4.4 O-DU (OPEN-RAN DISTRIBUTED UNIT)
O-DU is a dynamic logical node in O-RAN, hosting proto- col
functions like PHY-High, MAC, and RLC for base station tasks
based on functional split option 7.2x. It consists of two logical
nodes, one for PHY-High and another for MAC and RLC
functions, often implementing the Small Cell Forum’s
proposed standard interface known as FAPI.
4.5 O-CU (OPEN-RAN CENTRAL UNIT)
O-CU is a logical node in O-RAN that handles protocols like
SDAP, PDCP, and RRC, divided into CU-CP and CU- UP using
the SDN-inspired concept of control plane/user plane
separation. This architectural division allows for scalable
and cost-effective solutions using the E1 interface, while
edge cloud hosts O-DU, O-CU-CP, and O-CU-UP, with RICs
capableof operating in either the edge or regional cloud.
4.6 O-CLOUD (OPEN-RAN CLOUD)
O-Cloud comprises physical infrastructure nodes hosting O-
RAN functions, software components, and management
tasks. It communicates with O-RAN functions via theO-Cloud
Notification interface, with edge and regional clouds hosting
RAN functionalities such as O-DU, O-CU-CP, and O-CU-UP
based on latency requirements, while non-RT RIC is
deployed in regional cloud, and near-RT RIC can be placed in
either edge or regional cloud, all managed and coordinated
by O- Cloud and SMO.
4.7 O-gNB (OPEN-RAN ENABLED ENB)
An eNB or ng-eNB that supports O-DU and O-RU functions
with an Open FH interface between them is called an O-eNB.
Additionally, O-eNB offers operations and features linked to
the E2 interface, and it is connected to the near-RT RIC by
E2-interface.
The O-RAN Alliance aims to leverage AI/ML technologies for
automated RAN deployment and operations. It introduces
two types of RAN Intelligent Controller (RIC) software-
defined components: the non-Real-Time RIC for longer-term
operations and the near-Real-Time RIC for more real-time
tasks. These RICs communicate through the A1 and E2
interfaces, utilizing control loops to optimize networks with
real-time intelligence. The O-RAN architecture provides non-
RT, near-RT, and RT control loops, operated by the
respective RICs and E2 nodes, addressing varying time
scales. These control loops use AI and ML algorithms, along
with data from O-RAN functions, to automate operations,
create an abstract network view, and enable optimized RAN
actions.
4.8 UE’s
To access services simultaneously utilizing MR-DC, UEs are
connected to O-RAN via the Ue interface and can connect to
O-eNB and O-gNB. Smartphones used by humans and/or

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equipment, and vehicles) supporting variousverticalservices
can serve as UEs.
5. IMPLEMENTATION OF OPEN – RADIO ACCESS
NETWORK
The techniques and essential components of the Open-
RAN implementation include:
1) Define Network Management : Specify coverage,
capacity, performance, and scalability requirements.
Consider current infrastructure and future growth.
2) Planning and Strategy: Determine ORAN scope,
evaluating benefits, drawbacks, and costs.
3) Vendor Choice : Select multi-vendor components
(vB- BUs, RUs, controllers) for interoperability.
4) Radio Unit Deployment: Decouple baseband and
radio components, flexible placement for coverage.
5) BBU Virtualization: Use SDN and NFV for virtualized
baseband processing, scalability, cost-effectiveness.
6) RIC Integration: Integrate RIC with virtualized base-
band and radio modules for centralized orchestration.
7) Testing Interoperability: Ensure components from
different vendors integrate smoothly through open
interfaces.
8) Deployment and Optimization: After testing, deploy
ORAN network, adjust settings for desired quality.
9) Evolution and Upgrades: Evolve ORAN with new
features, swiftly upgrade network for increased flexibility
and benefits.
6. ADVANTAGES OPEN – RADIO ACCESS NETWORK
Disaggregating hardware and software allows O-RAN to
create a unified architecture, which has a lot of benefitslike
low latency and network slicing. O-RAN offers network
automation as well as the following advantages:
1) Agility: Due to the unification of the software-enabled
architecture, the network is suitable for both current/past
and future generations.
2) Deployment Flexibility: Because of software
association and dis-aggregation, the network is adaptable
for installation, upgrades, and extensions.
3) Real-time responsiveness: The O-RAN software-
driven, service-specific network gives real-time services
precedence over less important services and adapts its
behavior based on the service it is aimed at.
7. OPEN ISSUES AND CHALLENGES
1) Architectural Aspects : O-RAN architecture has
evolved since 2018, aiming to align with 3GPP design and
improve5G technologies. Adding features, blocks, and
functions to enhance functionality is crucial. Future
research should address O-RU termination of the O1
interface, virtualization opportunities, and coordination of
multiple near-RT RICs.
2) Performance Aspects : Virtualizing O-RAN network
services offers a chance to boost performance through
dynamic node transfers based on demand and failures.
Managing traffic congestion, resource migration, and
supporting time-sensitive use cases while maintaining
quality and service continuity pose challenges in large and
dynamic RAN deployments.
3) Security Aspects: O-RAN Alliance Working Group 11
researches security factors in the architecture, including
threat modeling, risk assessment, security requirements,
mechanisms, and testing. Security considerations for
various entities, interfaces, shared cloud infrastructure,
node integration, open-source software, and lifecycle
management need further exploration.
4) Energy-saving aspects: As AI and ML techniques
utilizing deep neural networks demand high
computational power, their integration into O-RAN for new
services and RIC automation might raise energy
consumption concerns. Balancing advanced AI/ML
approaches with energy-efficient designs is important in
addressing environmental impacts.
8. RESULTS
The radio unit obtains a special relevance within the context
of Open Radio Access Network (Open RAN), resulting from
the coordinated efforts of several manufacturers. Each
element of its development requires careful attention to
detail, which is provided by these firms collectively. The
product’s name, a unique product number signifying its
uniqueness, and a thorough explanation of the factors
essential to its operational construct are some of its
primary characteristics. This thorough overview also
includes current operational status information for the radio
device in real-time. The Open RAN philosophy values
flexibility, which is demonstrated by the radio unit’s
programmable framework. Users may precisely modify the
functionalities of the radio unit thanks to this adaptive
architecture, ensuring a harmonious alignment with
particular operational requirements. This adaptability
supports the architecture’s ability to accommodate a variety
of use scenarios. The Open RAN’s radio unit software
further enhances the radio unit’s capabilities by
supplementing its hardware components. It provides
information about the current Open radio unit software

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9. FUTURE WORK DIRECTIONS
The integration of SDN, NFV, and other technologies into 5G
networks poses challenges related to decentralization,
transparency, privacy, and security. Blockchain technologyis
being explored as a promising solution due to its attributes
like auditability, immutability, and distributed architecture.
TheO- RAN Alliance is developing Blockchain-enabled RAN
(BE- RAN) to enhance security and authentication, aiming
to overcome the centralized Certificate Authority’s single
point of failure. Additionally, the O-RAN Alliance’s Next
Generation RG (nGRG) is exploring Digital Twin Networks
(DTNs) to address the complexity of network
disaggregation, offering accurate network simulations to
forecast states, offer current status,andfacilitateinteractions
withother network components.
10. CONCLUSION
The Open Radio Access Network (Open RAN) introduces an
innovative approach to the telecom sector, fostering open,
interoperable, and intelligent RAN solutions while
improving performance and cost-effectiveness. This article
presents a comprehensive overview of Open RAN’s
evolution, standardization by the O-RAN Alliance,
architecture, security, deployment considerations, and
open-source initiatives, while also addressing unresolved
challenges and future research directions. It serves as a
valuable resource for understanding Open RAN’s
standardization efforts and guiding further research in the
field.
REFERENCES
[1] Azadeh Arnaz, Justin Lipman, Mehran Abolhasan, Matti
Hiltunen(IEEE Access [Volume 10] Published in theyear
17 June 2022 Toward Integrating Intelligence and
Programmability in Open Radio Access Networks.
[2] Zhirong Zhang, Jiangang Chen, Jia Hou (2021
International Wireless Communications and Mobile
Computing) Published in the year 28 June 2021 - 02 July
2021 Analysis of the Evolution Scheme of NSA RAN
Sharing to SA RAN Sharing.
[3] Huaning Niu, Clara Li, Apostolos Papathanassiou, Geng
Wu (2014 IEEE Wireless Communications and
Networking Conference Workshop Published in the year
06-09 April 2014 RAN architecture options and
performance for 5G network evolution.
[4] Rony Kumer Saha, Shinobu Nanba, Kosuke Nishimura,
Young-Bin Kim, Kosuke Yamazaki (2018 IEEE 29TH
Annual International Symposium on Personal Indoor
and Mobile Radio Communications (PIMRC), Pub- lished
in the year 09-12 September 2018 RAN Architectural
Evolution Framework toward 5G and Beyond Cellular-
An Overview.
[5] Nischal Aryal, Emmanuel Bertin, Noel Crespi (2023 26th
Conference on Innovation in Clouds, Internet and
Networks and Workshops (ICIN), Published in the year
06-09 March 2023 Open Radio Access Network
challenges for Next Generation Mobile Network.
[6] Bouziane Brik, Karim Boutiba, Adlen Ksentini (IEEE
Open Journal of the Communications Society[Volume:
3]), Published in the year 28 January 2022 Deep
Learning for B5G Open Radio Access Network:
Evolution, Survey, Case Studies, and Challenges.
version as well as improved security features, brand-new
features, and performance improvements. This software
version also adds a user-friendly interface that is adjusted
to the requirements of contemporary users and
strengthened for compatibility with modern devices. The
user interface of the program acts as a conduit for
interaction with the features of the radio unit in the real
world. Its importance in enabling a thorough assessment of
alarm alterations within the larger context of alarm
management is especially significant. This crucial task
makes sure that changes are transparent ,improving overall
management and control of the Open RAN’s operational
integrity.

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