O-RAN Opens the Door to 5G Acceleration

As more and more 5G networks go live worldwide, subscriber adoption is accelerating at an unprecedented pace. According to the GSMA, 5G accounted for more than 5% of all mobile connections within 18 months of launch, and the number of 5G connections worldwide is now expected to exceed 1 billion¹ by the end of this year.

With commercial network deployments rapidly gaining momentum, the race to secure 5G market share is heating up. In fact, analyst firm Omdia predicts that 5G will account for nearly 60%² of global mobile service revenues in 2026. Yet today’s mobile network operator (MNO) is faced with rising subscriber acquisition costs and new spectrum licensing fees causing return on investment to decline. This makes it vital that MNO’s increase 5G efficiencies and reduce capital and operational expenses now for their future profitability.

The urgent need to improve total cost of ownership (TCO) is a key driver of the ongoing transition to open radio access network (Open RAN) architectures and standards, such as standardized radio interfaces defined by the O-RAN ALLIANCE and Telecom Infra Project (TIP), among others. The development of a robust Open RAN ecosystem provides the flexibility to select best-of-breed components from a range of suppliers, reducing costs and boosting agility by breaking vendor lock-in. Moreover, Open RAN standards simplify future upgrades by enabling MNOs to mix and match equipment from multiple vendors, further reducing TCO by avoiding expensive rip and replace scenarios.

A growing number of MNOs are actively deploying Open RAN technologies³ to take advantage of greater component choice, reduced costs and improved network performance, helping to bring new 5G services to market faster. In the US, DISH is deploying the first greenfield Open RAN network in the country. In Japan, NTT Docomo and KDDI have deployed extensive O-RAN networks as brownfield deployments, coexisting with their 4G networks. And in the UK, the government has outlined a goal to have 35% of telecom traffic operating over Open RAN architectures by 2030.

Open Door to Disaggregation

Of course, Open RAN infrastructure is not a new concept. While Open RAN has been deployed in 4G networks for some time—primarily in Asia—LTE architecture was generally less open and modular than 5G technology. As a result, the evolution to 5G presents a fresh opportunity to further disaggregate the network, placing Open RAN in a better position to reach its full potential.

Because Open RAN provides standardized interfaces between the Centralized Unit (CU), Distributed Unit (DU) and Radio Unit (RU), MNOs are empowered to use different suppliers for various network elements in the RAN, regardless of which vendors have been used elsewhere in the network. Plus, Open RAN enables CU and DU software to be deployed on more economical commercial-off-the-shelf (COTS) hardware designed for web scale, reducing costs.

Moreover, by breaking the vendor lock-in, MNOs have the choice to mix and match vendors’ radios, DUs and CUs even within the same geographical area. This RAN disaggregation also makes it easier for vendors to specialize and offer components targeted at specific needs or smaller markets. Thus, a larger number of specialty vendors can develop radios for niche applications and new spectrum, which can be deployed in any operator’s network.

As MNOs continue to design and roll out new 5G networks, many initial deployments are focused on more densely populated urban environments where capacity growth and competition between operators is greatest. In this type of dense deployment, MNOs can expand capacity by taking advantage of massive multiple input, multiple output (mMIMO) beamforming. By directing beams towards users, mMIMO increases efficiency and lowers power per bit to further reduce operational expenses. In addition to expanding capacity, mMIMO also can be used to improve coverage; for example, by focusing beams on upper floors of skyscrapers which tend to be difficult to cover effectively with traditional macrocells.

For the most part, MNOs will deploy mMIMO at higher frequencies to take advantage of increased capacity capabilities. However, one size does not fit all. To compensate for the shorter signal range of higher frequency bands, 5G mMIMO deployments will need to be combined with more traditional macrocell configurations. Additionally, many MNOs may choose to complement mMIMO and traditional macrocells with lower cost indoor or outdoor small cells, allowing capacity offload or coverage improvement in localized areas.

RAN Intelligent Control (RIC) functionality can be further enhanced by combining it with artificial intelligence (AI) to foster the introduction of new or enhanced network features and capabilities. With support for O-RAN standardized interfaces, Open RAN RUs can leverage AI technology to enable automated beam steering capabilities to intelligently provide capacity when and where needed.

The combination of 5G mMIMO with macrocells and small cells presents a challenge in terms of selecting the right equipment to be used for deployment in dense urban areas.

For macrocells, MNOs will want to select high-power, high-performance radios to optimize reach and coverage, requiring vendors with highly sophisticated engineering expertise. However, the quality and durability of the radio is also critical, as replacement of a macrocell radio mounted on a tall tower can be time-consuming and costly.

On the other hand, beam management expertise and antenna design knowledge are even more critical when choosing mMIMO RUs, DUs and CUs, requiring in-depth specialized knowledge of beamforming techniques.

And when deploying small cells or indoor networks, the primary consideration is affordability. MNOs will want to choose low-cost equipment, given the large quantity of radios needed for small cell configurations.

Yet not all radio vendors will necessarily offer the particular expertise required in each scenario within this complex RAN configuration. Because different vendors may specialize in various capabilities, the optimum solution for most MNOs will be a combination of different vendors’ products. With the open interfaces of Open RAN, operators are free to select the optimum combination of best of breed resources in the Open RAN ecosystem.

Moreover, multi-user mMIMO (MU-MIMO) radios provide the capability to increase total cell throughput by allowing the base station to send multiple data streams, one per user device, using the same time-frequency resources. Commercialization of Open RAN 5G mMIMO radios is being validated by programs such as the TIP Evenstar⁴ program, as evidenced by Fujitsu’s contribution of mMIMO RUs to the TIP Exchange Marketplace.⁵

Opportunities to Evolve

As the Federal Communications Commission (FCC) strives to keep up with the coverage and capacity needs of 5G, a significant amount of spectrum has been made available to operators recently, including C-band⁶ and other mid-band⁷ frequencies. Each time new spectrum is introduced to the network, operators need to consider a number of network design challenges. By implementing Open RAN at the same time new spectrum is introduced, MNOs have an ideal opportunity to deploy overlays of Open RAN without needing as much integration with proprietary legacy RAN networks.

The evolution to Open RAN architecture also introduces a new network function with RAN Intelligent Control (RIC). RIC functionality enables rapid development and introduction of apps to improve mobility and interference management, as well as admission control. By opening RIC to third-party developers, operators can introduce innovations more quickly without having to wait for an incumbent vendor to deliver a whole new release. Applications need only be developed a single time for multiple vendors in an O-RAN network.

RIC functionality can be further enhanced by combining it with artificial intelligence (AI) to foster the introduction of new or enhanced network features and capabilities. With support for O-RAN standardized interfaces, Open RAN RUs can leverage AI technology to enable automated beam steering capabilities to intelligently provide capacity when and where needed.

Unlike competing proprietary solutions, the Open RAN RIC function allows MNOs to not only benefit from access to increased innovation, but also enables features to be deployed consistently across their entire multi-vendor network. Plus, an Open RAN RIC application may be developed to perform analytics on both legacy LTE and 5G O-RAN portions of the network, using 3GPP to O-RAN mediation of the LTE telemetry. Because O-RAN standard interfaces allow RIC applications to control network functions, the RIC application can help compensate for legacy network deficiencies by dynamically adjusting the 5G service coverage and capacity.

Unlocking Possibilities

Whether the goal is to achieve cost savings, optimize performance, improve reliability or all the above, a growing number of operators are embracing Open RAN network transformation. And as more MNOs take advantage of the throughput and spectral efficiency improvements enabled by mMIMO technology, the benefits of implementing mMIMO in an Open RAN architecture become ever more apparent.

REFERENCES AND NOTES
1.    https://www.prnewswire.com/news-releases/mobile-momentum-5g-connections-to-surpass-1-billion-in-2022-says-gsma-301493951.html
2.    https://www.digitaltveurope.com/2022/05/09/omdia-5g-to-surpass-1-3-billion-connections-in-2022/
3.    https://www.rcrwireless.com/20220510/open_ran/is-5g-open-rans-big-chance
4.    https://www.facebook.com/connectivity/solutions/evenstar
5.    https://exchange.telecominfraproject.com/marketplace
6.    https://www.pcmag.com/news/what-is-c-band
7.     https://www.networkworld.com/article/3651512/fcc-announces-new-5g-spectrum-auction-in-25ghz-band.html

ABOUT THE AUTHOR

Rob Hughes is Head of Wireless Marketing at Fujitsu Network Communications, overseeing solution and marketing strategy for the Fujitsu wireless portfolio. For more information, please email [email protected]. You can also visit https://www.fujitsu.com/us/products/network/. Follow Fujitsu on Twitter @fujitsufnc, LinkedIn: company/fujitsu-network-communications, and YouTube: https://www.youtube.com/channel/UC1PdkNvj-oNmjXqPk_6ttYw.