Open RAN

The O-RAN ALLIANCE, O-RAN Architecture, 5G, and Testing Solutions

Open RAN Solutions

What is Open RAN?

An Open RAN, or Open Radio Access Network is a concept based on interoperability and standardization of RAN elements including a unified interconnection standard for white-box hardware and open source software elements from different vendors. Open RAN architecture integrates a modular base station software stack on off-the-shelf hardware which allows baseband and radio unit components from different suppliers to operate seamlessly together.

Open RAN underscores streamlined 5G RAN performance objectives through the common attributes of efficiency, intelligence and versatility. Open RAN deployed at the network edge will benefit 5G applications such as autonomous, support network slicing use cases effectively, and enable secure and efficient over-the-air firmware upgrades, this is due to the edge providing the low-latency and high-reliability requirements necessary for these applications.

How Can We Help?

End-to-End Portfolio

As a preeminent Open RAN test company, VIAVI has developed an End-to-end Open RAN portfolio encompassing robust test, verification and assurance, solutions from RANtoCore™ that span the entire Open RAN lifecycle.

Support and Collaboration

VIAVI has embraced the challenges of Multi-vendor Interoperability (MV-IOT) by supporting and collaborating with our partners on the development of Open RAN test tools extending from the lab to the field.

How VIAVI Enables the Open RAN Ecosystem

By adopting the O-RAN ALLIANCE fronthaul specifications, developing O-RAN compliant RAN and fronthaul test practices and establishing diverse partnerships within industry workgroups, VIAVI has established a multi-faceted commitment to the success of Open RAN development and deployment. Championing interoperability test methodologies that minimize built-in test dependencies is essential for managing the cost of deployed network infrastructure. This includes the development of methods to evaluate Open RAN field performance.

VIAVI has embraced the end-to-end (E2E) challenges of MV-IOT by supporting and collaborating with our partners on the development of O-RAN Compliant test tools extending from the lab to the field. This includes component level wrap around testing, vendor pairing evaluations to validate the function, performance, robustness and resilience of specific combinations, and protocol compliance testing for open interfaces. Holistic evaluation of multiple combinations and system level testing are integral to success and conformance to O-RAN specifications.

As a preeminent Open RAN test company, VIAVI has spawned the development of an E2E Open RAN portfolio encompassing robust device, antenna and core test solutions than span the entire Open RAN lifecycle. A comprehensive Open RAN test process must meet the challenge of testing each element and combination in every direction.

Validation: The industry-leading TM500 network tester is designed to validate the user experience (UE) by emulating thousands of mobile devices across multiple cells and radio access technologies. The TM500 mitigates the challenges of multi-vendor Open RAN architecture by providing a test platform agnostic to network disaggregation.

The TeraVM is an essential tool for 5G RAN and core network performance testing.

Verification: The T-BERD/MTS-5800 is the industry’s smallest handheld dual-port 100G multi-purpose test instrument. It has found increasing utility in support of emerging technologies like 5G and Open RAN. By performing Open RAN health verification testing, the MTS-5800 can identify high level issues between the O-DU and O-RU. Packet capture and filtering in this interface can enable advanced troubleshooting and analysis using the Wireshark application onboard or externally.

Radio performance testing to validate successful Open RAN 5G deployment includes beamforming performance verification, radio conformance testing, transmit power measurement and DL modulation quality. The CellAdvisor 5G is a comprehensive, portable RAN test solution with a diverse and easily-upgradable feature set tailor made for advanced 5G and Open RAN deployment and certification tasks. 5G route maps are integrated for coverage verification, and test reports are generated with a simple push of a button.

The Open RAN ecosystem is complex, where the functionality of the near-RT RIC is performed by a mix of xApps. These xApps may be from a variety of suppliers, the challenge for operators is that they need assurance across all stages of the product life cycle from sandbox development through to assurance of network operation that can ensure that xApps from disparate sources operate in a coherent and compatible manner when operating either in an independent manner or chained together to produce the required objectives. This includes validation that the heterogeneous xApps in combination are able to implement the policies of the operator across a mix of subscribers consuming the range of services envisaged for the network across multiple network slices and in an appropriate set of mobility profiles. It must also be validated at scale, making it a use case well-suited for VIAVI End-To-End Wireless Network Test.

Visibility: The VIAVI NITRO platform provides the visibility of the network across the breadth of the radio, RAN, transport and core. As a result, with the richest information on network performance, the autonomic network control systems will be most effective where intervention by the operational network management engineers is required, and resolutions can be implemented within the shortest timeframes. These phenomena will vary as the spatial dynamics of demand for services around the network changes. And as the demand for different mixes of services with novel mobility profiles pushing the resource management capability to the limit, new edge failure cases beyond what was tested at the pre-deployment stage can be exposed and manifest as degraded performance.  All of this challenges the network monitoring and assurance system to provide a more complete view of the network, with richer analytics to detect problems, isolate the cause and provide the most appropriate mitigation.

The momentum behind Open RAN as a logical counterpart for 5G RAN disaggregation and innovation continues to build. VIAVI is accelerating next-gen Open RAN networks through active participation in cross functional forums across the telecom landscape. The annual O-RAN ALLIANCE Plugfest and Telecom Infrastructure Project (TIP) Summit are two examples of the collaboration engendered when service providers, technology developers, system integrators and test solution leaders pool their resources and expertise.

These workshops, summits and conferences provide a crucial discussion forum for other innovations such as virtual RAN (vRAN). The continuous integration/continuous delivery (CI/CD) approach to vRAN deployment has resulted from an international focus by the telecom community on responsible E2E RAN evolution. This essential spirit of cooperation and open communication can enable the challenges of the O-RAN ALLIANCE to be met and the benefits to be fully realized.


To align the energy and aspirations of the O-RAN ALLIANCE with TIP OpenRAN and minimize duplication of efforts, a liaison agreement between the two organizations has been established. Although TIP remains agnostic regarding O-RAN specifications, the liaison agreement facilitates more cooperation and collaborative solutions that integrate the strengths of each group. A steadfast commitment to specification development by the O-RAN ALLIANCE Technical Steering Committee has allowed the OpenRAN group to remain focused on real-world deployment strategies for disaggregated telecom infrastructure in various environments.

Open RAN Policy Coalition

The Open RAN Policy Coalition has been launched to advocate for policies supportive of the development and introduction of open, interoperable RAN solutions. The thirty-one initial coalition member organizations include many of the largest and most influential telecom, cloud computing, and network technology companies in the world.

The Open RAN Policy Coalition has announced that it is committed to global implementation with an initial emphasis on the education of U.S. legislators and policy makers regarding the importance of the Open RAN paradigm, notably with respect to 5G RAN architecture. Government backing of an open and interoperable RAN ecosystem will foster cross-functional industry cooperation around the world, while cultivating a competitive landscape conducive to vendor diversity. A strongly supportive policy environment will also accelerate the momentum of essential Open RAN technology research and development.

Stay Ahead of the Curve

NITRO Wireless Test Suite

NITRO Wireless Open RAN Test Suite 2024

Understanding 5G: 2nd Edition

Practical Guide to Deploying and Operating 5G Networks

TM500 O-RAN Fronthaul Demonstration

The TM500 O-RU Emulator testing the O-DU connected over O-RAN open fronthaul.

Driving Down the Cost of Deploying and Operating Open RAN

Developing and Validating Open RAN

Global O-RAN Plugfest Participation

Top 5 Test Challenges Infographic

RAN Evolution

Advancing Open RAN Networks

Open RAN Knowledge Hub

The prospect of an Open RAN ecosystem has advanced the formation of synergistic projects, alliances, and working groups each with distinct missions and focus areas. These efforts share the common objective of enabling an Open RAN environment through standardized elements and interfaces.


OpenRAN (no space) is a project group launched by the Telecom Infra Project (TIP) in 2017 with the stated objective of defining and building 2G, 3G, and 4G RAN solutions based on general purpose, vendor neutral hardware and software defined technology. This includes the creation of programable, virtualized RAN solutions based on General Purpose Processing Platforms (GPPP) and disaggregated software that accelerates the pace of innovation. The OpenRAN conglomerate has applied the expertise of their diverse member organizations toward the analysis of use cases and the development of Open RAN fronthaul algorithms.


Although “O-RAN” is a commonly used acronym for “Open RAN”, the hyphenated nomenclature has evolved to represent the O-RAN ALLIANCE more specifically since the group’s founding. Along with the publication of Open RAN architecture specifications, O-RAN ALLIANCE initiatives have focused on incorporating artificial intelligence (AI), specifying interfaces and APIs to drive appropriate standardization, and establishing the requisite supply chain infrastructure. These challenging endeavors provide additional ballast for the underlying O-RAN pillars of openness and intelligence. 


Virtualized RAN (vRAN) is the key enabling technology for Open RAN architecture. Decoupling hardware and software through the application of network function virtualization (NFV) principles allows the RAN to becomes more agile, flexible, and easier to upgrade. The improved efficiency and security intrinsic to vRAN also makes it an essential element of Open RAN 5G implementation with complex uses cases and access technologies necessitating more dynamic control of network resources.

The O-RAN ALLIANCE was established in 2018 by a global consortium of network operators with the stated goal of evolving radio access networks around the world. This can be accomplished through a transition to virtualized network elements, white-box hardware and open interfaces to the RAN.

O-RAN Alliance

Built on the complementary pillars of openness and intelligence, the O-RAN ALLIANCE has established eight discrete working groups with ambitious technical objectives including open fronthaul architecture, RAN cloudification and software specifications for the new radio (NR) protocol stack.

As a key contributor to the O-RAN ALLIANCE, VIAVI collaborates on essential multi-vendor interoperability testing (MV-IOT) to ensure confidence in disparate Open RAN fronthaul components, disaggregated software and hardware elements from multiple suppliers operating in concert. 

VIAVI is actively engaged in O-RAN ALLIANCE working and focus groups contributing to interoperability test specifications, E2E test framework, Open fronthaul, xHaul Transport, Plugfest, and Test & Integration Focus Group (TIFG).

The reference O-RAN architecture introduced by the O-RAN ALLIANCE was envisioned with an eye towards next-gen RAN infrastructure with virtualized RAN on open hardware and artificial intelligence intrinsic to radio control.

Functional modules of O-RAN architecture include the RIC non-Real-Time layer to perform operations including policy management and analytics, and the RIC near Real-Time layer to perform time sensitive functions such as load balancing, handover and interference detection. Layer integration allows the RIC near Real-Time layer to benefit from intelligently trained models and real time control functions distributed by the RIC non-Real-Time layer.

The multi-RAT CU protocol stack, deployed on a virtualization platform, supports protocol processing for 4G or 5G while establishing security isolation and virtual resource allocation, among other functions. The open radio unit (O-RU) and open distributed unit (O-DU) elements are integrated through an O RAN fronthaul interface with a well defined lower level split (LLS) that supports eCPRI and RoE. Further definition and standardization of these interfaces will drive interoperability, competition and innovation into the O-RAN supply chain.

Open RAN 5G

Disaggregation is essential for 5G deployment and evolution, enabling mobile operators to open the RAN network and leverage multi-vendor solutions. Open RAN provides new avenues for RAN customization and flexibility that are commensurate with the diversity of 5G use cases and requirements.

By lowering the barrier to entry for new participants into the Open RAN 5G ecosystem, the innovation needed to meet ever evolving customer expectations can be fully unlocked. Operators will be empowered to utilize best-of-breed components based on their individual network use case profile. This opens opportunities to reduce development cycles by developing different parts of the network separately while harnessing more innovation horsepower collectively.

O-RAN Architecture

Operational efficiencies have been realized through past RAN innovations such as cloud RAN (cRAN), but previous advancements did not free operators from vendor lock-in. By enabling an open, multi-vendor RAN ecosystem, Open RAN introduces cloud-scale economies and competition to the RAN. Marketplace factors, combined with a more elastic and flexible RAN architecture that is already taking shape through virtualization, can enable much faster time to market (TTM) than was previously possible.

Moving away from the vendor-specific RAN paradigm not only enables more flexibility for operators, it also minimizes the “secret sauce” that leaves them reliant on a single vendor for all aspects of RAN implementation and optimization.

Competition and proliferation resulting from new entrants can potentially drive down Open RAN equipment costs. The inter-carrier, interoperability aspects of Open RAN can also be used to increase efficiencies for existing LTE networks as they continue to incorporate the virtualization and disaggregation that are prerequisite 5G RAN deployment. 

Creating seamless interoperability in a multi-vendor, open ecosystem introduces new test, management and integration challenges that require diligence and cooperation to overcome. In the single-vendor model, accountability is a foregone conclusion and problem isolation and troubleshooting are managed through an established command structure.

Dispersion of vendors could potentially lead to finger pointing when root cause identification is inconclusive. These same complications could plague on-time launch schedules and revenue growth by diluting management and orchestration responsibilities across an array of new Open RAN players.

The enticing Open RAN concept of flexible interoperability also brings challenges for test and integration. To fulfill the Open RAN promise of reduced OPEX and total cost of ownership (TCO), operators must take responsibility for multi-vendor, disaggregated elements and make sure they perform together to maintain QoE standards.

With Open RAN reducing the barrier to entry for dozens of new players, interoperability is a paramount concern for both the O-RAN ALLIANCE and OpenRAN group. To address this challenge, the Open Test and Integration Center (OTIC) in Berlin, Germany has been established as a collaborative hub for commercial Open RAN development and interoperability testing. The operator led OTIC initiative benefits from the support of global telecom organizations with a shared commitment to verification, integration testing, and validation of disaggregated RAN components. 

The OTIC lab provides a structured environment with common test platforms and practices that enable software developers, equipment manufacturers, and system integrators to verify functional compliance to O-RAN ALLIANCE specifications. Interoperability of disaggregated 5G access infrastructure elements can be fully validated prior to network deployment. As additional OTIC labs are planned and established around the globe, VIAVI remains committed to multi-vendor interoperability testing efforts in O-RAN ALLIANCE led initiatives.

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