ORAN – The Future of Wireless Networking

Open radio access network (“open RAN” or ORAN) is an emerging mobile network topology that enables network service providers to use non-proprietary components from different suppliers. The open RAN alliance initiates the development of industry-wide standards, which enable telecom ecosystem players to make ORAN more practicable, programmable, intelligent, disaggregated, and virtualized.

The ORAN architecture divides the baseband units (BBUs) and proprietary remote radio heads (RRHs) into radio units (RUs), distributed units (DUs), and centralized units (CUs). Many of these have been virtualized or containerized. These new components have open, interoperable interfaces.

The ORAN Alliance is the standard body for this technology, developing ORAN architecture with standard specifications; other organizations related to ORAN development are the Small Cell Forum, ORAN Software Community, Telecom Infra Project, and many more.

Traditional RAN Challenges Overcome by ORAN

Some challenges faced by traditional RAN, such as:

• Traditional network traffic control optimization requires a lot of manual intervention, which is inefficient and passive, and the feedback response after processing is also slow
• Traffic-intensive and highly interactive applications do not efficiently support the current semi-static QoS framework
• The varying nature of traffic demand and radio environment creates a situation where the default configuration and planning are insufficient to provide the resources needed for services with highly demanding requirements
• Maintaining a steady connection with user devices inside autonomous vehicles when vehicles are moving at high speed

O-RAN architecture improves the flexibility and agility of the wireless network and provides the possibility of RAN automation, where RAN intelligence reduces manual intervention, saving OPEX while avoiding human errors.

• It gives operators more granular control over security decisions and their operations
• It gives operators more direct control of their ecosystem and the ability to build vendor diversity
• It can reduce CAPEX through a thriving multi-vendor ecosystem with scale economics
• It is easy to import new network capability via an easy software upgrade with its native cloud infrastructures
• Interactions between Non-RT RIC and Near-RT RIC are used to optimize and fine-tune control algorithms related to loading, balancing, mobility management, multi-connection control, QoS management, and network energy-saving

Open Radio Access Network: Architecture

O-RAN architecture builds upon the ETSI NFV (Network Functions Virtualization) reference architecture. The NFV Infrastructure (NFVI) includes commercial off-the-shelf (COTS) hardware, such as servers and switches, and virtualization software that enables abstraction in the form of virtual machines (VM) or containers running on the servers. The Virtual Infrastructure Manager (VIM) acts as the control plane of the NFVI for a cloud site, weaving multiple servers together and managing them.

Figure 1: ORAN Architecture

O-RAN components, such as the O-DU, O-CU, O-RU, RIC, etc., have virtualized network functions (VNFs) and run in VMs or containers. The functionalities of the different components in the O-RAN architecture are as follows:

Open Radio Unit (O-RU)

• It processes radio frequencies received by the physical layer of the network
• The processed radio frequencies are sent to the O-DU through a front-haul interface

Open Distributed Unit (O-DU)

• It is a logical node that hosts a set of protocols like radio link control (RLC) protocol, medium access control (MAC) protocol, and the physical interface (PHY)
• It includes a subset of the eNB/gNB functions, depending on the functional split option
• The CU controls its operations

Learn Open Central Unit (O-CU)

• It includes gNB functions like transfer of user data, mobility control, RAN sharing (MORAN), positioning, session management, etc., and controls the operation of several DUs over the mid-haul interface
• It is split into Control Plane (CP) and User Plane (UP) and implements the higher layers of the 3GPP stack, where

1. The Radio Resource Control (RRC) layer manages the life cycle of the connection
2. The Service Data Adaptation Protocol (SDAP) layer manages the Quality of Service (QoS) of the traffic flows (also known as bearers)
3. The Packet Data Convergence Protocol (PDCP) layer takes care of reordering, packet duplication, and encryption for the air interface

Service Management And Orchestration Framework (SMO)

• The SMO connects to and manages the RAN Intelligent Controller (RICs), O-Cloud, O-CU, and O-DU
• It includes an integration fabric and data services for the functions it manages
• It allows managed functions to interoperate and communicate within the O-RAN

RAN Intelligent Controller (RIC)

There are two types of RICs, non-real-time and near-real-time, and both are logical functions for controlling and optimizing the elements and resources of an O-RAN.

• The Non-RT RIC learned with AI/ML to enable intelligent management and controlling RAN. It feeds data collected from RAN elements into Near-RT RIC and provides element management and reporting
• Near-RT RIC makes configuration and optimization decisions for multi-vendor RAN and uses AI to anticipate some of the necessary changes

Figure 2: RIC fulfills ORAN use cases

ORAN Protocol Enhances Common Public Radio Interface (eCPRI)

• 3GPP has introduced a new, more efficient enhanced-CPRI (eCPRI) interface with an increased number of functional splits to reduce the overall front-haul bandwidth
• Provides greater flexibility and reliability in positioning the functional split within the BBU physical layer
• Enable efficient and flexible radio data transmission by a packet-based front-haul transport network like IP or Ethernet

ORAN Interfaces

Figure 3: ORAN Interfaces

Organizations For ORAN Development

The major organizations involved in Open RAN’s open-source development are the following:

ORAN Alliance

• Develops, drives, and enforces standards to ensure that equipment from multiple vendors interoperates with each other
• Create a profile for interoperability testing where standards are available
• Fully supporting and complimentary to standard promoted by 3GPP and other industry standard organizations
• Focused on 4G and 5G

Small Cell Forum

• SCF has released interfaces FAPI (Functional application platform interface) and nFAPI (Network FAPI)
• FAPI helps equipment vendors mix PHY & MAC software from different suppliers
• nFAPI is a network interface between the distributed unit (DU) and Radio unit (RU) of a split RAN small cell network solution

ONF SDRAN Project

• Open source software platform for multi-vendor 4G/5G RAN solutions
• The project is initially focused on O-RAN nRT-RIC
• Cooperation with TIP, O-RAN Alliance, O-RAN SC

Telecom Infra Project

• Focus on the RAN implementation on General Purpose Processing (GPP) hardware deployment.
• Open Interfaces between RU/CU/DU/RIC.
• Multiple Architecture options.
• Bare Metal or Virtualized or Containerized Platforms.
• Adoption of New Technologies (AI/ML, CI/CD)

ORAN Software Community

• Collaboration between the O-RAN Alliance and Linux Foundation
• RAN Software implementation
• Software testing, integration, and O-RAN specification alignment

Open RAN Policy Coalition

• Promotion of policies moving on the adoption of Open RAN and interoperable solution
• Promotion solution to enable expanding the wireless technologies supply chain

ORAN Alliance

The O-RAN Alliance is a global community of mobile operators, vendors, and research & academic institutions to reshape Radio Access Networks to be more intelligent, open, virtualized, and completely interoperable. Also, technical Work Groups (WG) have been formed to split up the O-RAN specification project and are governed by the Technical Steering Committee. A specific area of the O-RAN Architecture covered by each WG is presented below:

Figure 4: ORAN Alliance work group

Market Dynamics

The Open RAN wireless network is developing globally, which has sped up the formation of ORAN start-ups that provide O-RAN architecture-compliant solutions, including Altiostar, Mavenir, Accelleran, Airspan, Parallel Wireless, and many more. The market dynamics cover recent activities, and operator challenges in deploying ORAN wireless networks in different areas in terms of the reward-risk ratio, company collaboration, and market innovations.

Recent Market Activities

• Parallel Wireless, the U.S based Open RAN software company delivering all G (5G 4G 3G 2G) cloud-native, Open RAN solutions, is expanding its footprint across the globe
• Telefónica improves the Open RAN ecosystem by successfully validating its new 5G Standalone small-cell
• Rakuten successfully deploys a fully cloud-native commercial mobile network using the ORAN solution
• ORAN Software community recently released source codes E, F, and G Release

Collaborations Related To ORAN

• Vodafone & Nokia

Vodafone and Nokia collaborated to demonstrate an Open RAN baseband solution that uses In-line Layer-1 acceleration to process consumer mobile traffic.

• Dell & Fujitsu

Dell Technologies and Fujitsu are working to simplify and speed up the global implementation of Open RAN solutions for communications service providers.

• Cisco & Rakuten

Cisco and Rakuten combine their industry-leading technology portfolios, subject-matter expertise, and service offerings to create and deploy solutions for 4G/5G mobile networks based on Open RAN technology.

• Vodafone & EdgeQ

EdgeQ and Vodafone have collaborated to create the first 5G/4G Software Defined, In-Line L1 acceleration-based Open RAN Platform.

Operators Challenges in ORAN Deployments

Open RAN wireless network is becoming an issue for operators to consider as they set out on the next stages of their RAN migrations. The design has garnered favorable feedback while also addressing challenges in diverse network environments. It carefully considers the risk/reward balance of deploying ORAN before 2026 across various conditions. Vendor revenue from ORAN in 2026 will be USD 45 billion.

• Neutral represents significant rewards, and operators can mitigate the risks
• The reward represents an operator overcoming particular challenges in various networks due to the wireless ORAN deployment
• The risk represents an operator faces a problem in the deployment of wireless ORAN in a particular network

The operator’s readiness to embrace risk hinges on factors such as its market position, commercial objectives, and current infrastructure. Additionally, the deployment scenario also plays a crucial role in determining the level of risk an operator wants to undertake.

Figure 5: ORAN challenges versus network environment

IP Trends

The O-RAN wireless technology is being adopted by various players in the telecommunication domain, which encourages technology developers to boost their technology research to develop new solutions for O-RAN implementation. Since 2018, the major telecommunication technology providers (such as Samsung, Ericsson, Nokia, Huawei, and others) have sped up their patent filing in the technology domains related to wireless O-RAN, such as architecture, communication interfaces, RIC, operational process, etc. Most patents are filed by Samsung, followed by companies like Ericsson, Intel, Qualcomm, etc.

Figure 6: Patent filing by top 10 assignees from year 2018 to 2022

The chart shown in Figure 7 represents the top assignees who have filed patents focused on O-RAN technology with the priority year 2018 or later. The patent filings on the O-RAN technology from 2018 to 2022 include 32% granted patents and 68% patent applications.

Recent Advancements in ORAN Solutions

• Time synchronization of ORAN Equipment

Renesas’ time synchronization hardware and software meet the high time error requirements for eCPRI and Open RAN equipment.

1. It supports Class C telecom boundary clocks and telecom time slave clocks to meet the tight time error requirements of eCPRI and Open RAN equipment
2. The product range consists of system synchronizers for DUs, fronthaul network switches and routers, and radio synchronizers for RUs

Figure 7: Renesas – Fronthaul Time Synchronization Development

• Ontology for ORAN Security Evaluation

The Ben-Gurion University of the Negev developed an ontology for evaluating the security of a system to detect the primary risk areas of O-RAN.

1. Identifies and understands the original target of the attack, the threat model, and attack techniques
2. Exclude alternative threat models and alternative attack techniques
3. Identify the security and overall operational impact of the identified threat
4. Exclude threats from the list that are not relevant

• S5040A Open RAN Studio Player and Capture Appliance

Keysight has designed S5040A to construct, play, capture, and monitor O-RAN traffic over 10 Gbps / 25 Gbps (front haul) Ethernet ports.

1. It is an instrument-grade test and measurement appliance created to function with Keysight’s PathWave Signal Studio and Open RAN Studio
2. To emulate a Distributed Unit (O-DU), record O-RAN uplink communications, and carry out the measurements required to confirm an O-RU’s functional operation and performance

Conclusion

Open RAN-based wireless solutions, like handling complex integration, enabling end-to-end service orchestration, securing consistent network performance, operations & maintenance capabilities, network lifecycle management, and many more, are gradually moving toward the maturity stage. Major technology vendors are incorporating or planning to incorporate wireless ORAN solutions into their portfolios.

Some ORAN-related challenges, such as Open RAN standards, have yet to gain widespread acceptance. Its multi-vendor architecture increased network complexity with system integration. Additionally, the chance of threat rises in the infrastructure surface area. Some organizations, standard bodies, and researchers continue working to improve these challenges and apply trials of ORAN globally. Very soon, the ORAN standards will be widely accepted.