Executive Summary:

In a move that will help promote multi-vendor interoperability, the Open Networking Foundation (ONF) today announced the formation of the SD-RAN project (Software Defined Radio Access Network) to pursue the creation of open source software platforms and multi-vendor solutions for mobile 4G and 5G RAN deployments. Initially, the project will focus on building an open source Near Real-Time RAN Intelligent Controller (nRT-RIC) compatible with the O-RAN architecture.

The new SD-RAN project is backed by a consortium of leading operators and aligned technology companies and organizations that together are committed to creating a truly open RAN ecosystem. Founding members include AT&T, China Mobile, China Unicom, Deutsche Telekom, Facebook, Google, Intel, NTT, Radisys and Sercomm.  All the project members will be actively contributing, and this includes the operators contributing use cases and trialing the results, according to the ONF. However, the larger cellular base station vendors that are ONF members, Nokia, Samsung, ZTE, Fujitsu, NEC were silent on their participation in this SD-RAN project.

There may be some confusion caused by ONF’s SD-RAN project as it is the third Open RAN consortium.  The O-RAN Alliance and TIP Open RAN project are working on open source hardware and open interfaces for disaggregated RAN equipment, like a 4G/5G combo base station.

In a brief video chat yesterday, Timon Sloane, VP of Ecosystem and Marketing for ONF told me that this new ONF SD-RAN project would be in close contact with the other two Open RAN consortiums and distinguished itself from them by producing OPEN SOURCE SOFTWARE for disaggregated RAN equipment—something he said the O-RAN Alliance and TIP Open RAN project were NOT doing.

That should go a long way in dispelling that confusion, but it nonetheless presents a challenge on how three consortiums can effectively work together to produce meaningful open source software code (ONF) and hardware (O-RAN Alliance and TIP) specifications with joint compliance testing to ensure multi-vendor interoperability.

Sloane told Matt Kapko of SDXCentral: “The operators really are pushing for separation of hardware and software and for enabling new innovations to come in in software without it being tightly coupled to the hardware that they purchase. And xApps are where the functionality of the RAN is to be housed, and so in order to do this in a meaningful way you have to be able to do meaningful functions in these xApps,” Sloane said.

However, no mention was made in the ONF press release of a liaison with either 3GPP or ITU-R WP5D which are producing the standards and specs for 5G and have already done so for 4G-LTE.  Neither of the aforementioned O-RAN consortiums have liaisons with those entities either.

There are other complications with Open RAN (independent of SD-RAN), such as U.S. government’s attempt to cripple Huawei and other China telecom equipment vendors, need for a parallel wireless infrastructure, legacy vs greenfield carriers.  These are addressed in Comment and Analysis section below.

µONOS-RIC:

Central to the project is the development of an open source near-real time RIC called µONOS-RIC (pronounced “micro-ONOS-RIC”).

µONOS is a microservices-based SDN controller created by the refactoring and enhancement of ONOS, the leading SDN controller for operators in production tier-1 networks worldwide. µONOS-RIC is built on µONOS, and hence features a cloud-native design supporting active-active clustering for scalability, performance and high availability along with the real-time capabilities needed for intelligent RAN control.

µONOS-RIC is designed to control an array of multi-vendor open RAN equipment consistent with the O-RAN ALLIANCE architecture. In particular, the O-RAN ALLIANCE E2 interface is used to interface between µONOS-RIC and vendor supplied RAN RU/DU/CU RAN components.

xApps running on top of the µONOS-RIC are responsible for functionality that traditionally has been implemented in vendor-proprietary implementations. A primary goal of the SD-RAN project (and, not coincidentally, for the operators who founded the O-RAN consortium) is to enable an external intelligent controller to control the RAN so that operators have both visibility and control over their RAN networks, thus giving operators ownership and control over how spectrum is utilized and optimized along with the tools to deliver an optimal experience for users and applications.

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Relationship to O-RAN Alliance, O-RAN Software Community and TIP:

The participating members of the SD-RAN project plan to implement, prototype and trial an advanced architecture that enables intelligent RIC xApps to control a broad spectrum of SON and RRM functionality that historically has been implemented as vendor-proprietary features on bespoke base station equipment and platforms. SD-RAN’s focus and goals are complementary to various efforts across the industry, including work taking place within the O-RAN ALLIANCE, the O-RAN Software Community and the TIP OpenRAN Project Group.

SD-RAN will follow O-RAN specifications as they are developed and will also make use of components of existing open source to facilitate interoperability. As the project pioneers new functionality, all extensions and learnings that come from building the system will be contributed back to O-RAN ALLIANCE, with the intent that these extensions can inform and advance the O-RAN specifications.

The SD-RAN work inside the ONF community will take place in parallel with work being contributed to the O-RAN Software Community. The intent is for interoperable implementations to come out of both efforts, so that a mix of open source and vendor proprietary components can be demonstrated and ultimately deployed.

Timing and Availability:

The SD-RAN project already has a working skeleton prototype of the µONOS-RIC controller above a RAN emulation platform through the E2 interface.  This implementation is demonstrating handover and load balancing at scale, supporting over 100 base stations and 100,000 user devices with less than 50ms handover latency (less than 10ms latency for 99% of all handovers).

The SD-RAN community is advancing towards a field trial by early 2021, working with RAN vendors to integrate carrier-grade RU/DU/CU components while in parallel implementing xApps to demonstrate SON and RRM functionality.  Interested parties are encouraged to contact ONF for additional information.

Quotes Supporting the SD-RAN Project:

“AT&T strongly supports the development of specifications and components that can help drive openness and innovation in the RAN ecosystem. The O-RAN ALLIANCE’s specifications are enabling the ecosystem, with a range of companies and organizations creating both open source and proprietary implementations that are bringing the open specifications to life. The ONF SD-RAN project, along with the O-RAN OSC, will expand the ecosystem with an nRT-RIC that can support xApps and help demonstrate their interoperability. This project will help accelerate the transition to an open RAN future.”
Andre Fuetsch, President and Chief Technology Officer, AT&T Labs

“China Mobile co-founded O-RAN in order to promote both the opening of the RAN ecosystem for multi-vendor solutions and the realization of RAN with native intelligence for performance and cost improvement.  An open nRT-RIC with support for open xApps that go beyond policy-based control and SON to also enhance Radio Resource Management (RRM) will make it possible for operators to optimize resource utilization and application performance.  We are excited to see the development of an open nRT-RIC and xApps in the SD-RAN project led by ONF, and expect this work to help advance the state-of-art for open and intelligent RAN.”
Dr. Chih-Lin I, Chief Scientist, Wireless Technologies, China Mobile

“China Unicom has been a long-term partner with ONF.  We continue to see the benefits of the ONF’s work and the impact it has on our industry.  The SD-RAN project is now applying the ONF’s proven strategy for disaggregating and creating open source implementations to the 5G RAN space in order to foster innovation and ecosystem transformation. We are excited by this work, and are committed to trialing a solution as it becomes available.”
Dr. Xiongyan Tang, Network Technology Research Institute, China Unicom

“Deutsche Telekom is a huge believer in applying disaggregation and open source principles for our next-generation networks.  DT has ONF’s mobile core platform (OMEC) in production and we are taking ONF’s broadband access (SEBA/VOLTHA) platform to production towards the end of 2020. This journey has shown us the tremendous value that is created when we can build solutions based on interoperable multi-vendor components intermixed with open source components.  ONF’s SD-RAN project is leveraging these same principles to help accelerate innovation in the RAN domain, and we are excited to be an active collaborator in this journey.”
Dr. Alex Jinsung Choi, SVP Strategy & Technology Innovation, Deutsche Telekom

“Connectivity is an integral part of Facebook’s focus to bring people closer together. We work closely with partners to develop programs and technologies that make connectivity more affordable and accessible. Through our collaboration with ONF on their SD-RAN project, we look forward to engaging with the community to improve connectivity experiences for many people around the world.”
Aaron Bernstein, Facebook’s Director of Connectivity Ecosystem Programs

“Google is an advocate for SDN, disaggregation and open source, and we are excited to see these principles now being applied to the RAN domain. ONF’s SD-RAN project’s ambition to create an open source RIC can help invigorate innovation across the mobile domain.”
Ankur Jain, Distinguished Engineer, Google

“Intel is an active participant of the ONF’s SD-RAN project to advance the development of open RAN implementations on high volume servers.  ONF has been leading the industry with advanced open source implementations in the areas of disaggregated Mobile Core, e.g. the Open Mobile Evolved Core (OMEC), and we look forward to continuing to innovate by applying proven principles of disaggregation, open source and AI/ML to the next stepping stone in this journey – the RAN. SD-RAN will be optimized to leverage powerful performance, AI/ML, and security enhancements, which are essential for 5G and available in Intel® Xeon® Scalable Processors, network adapters and switching technologies, including Data-Plane Development Kit (DPDK) and Intel® Software Guard Extensions (Intel SGX).” 
Pranav Mehta, Vice President of Systems and Software Research, Intel Labs

“NTT sees great value in transforming the RAN domain in order to foster innovation and multi-vendor interoperability.  We are excited to be part of the SD-RAN ecosystem, and look forward to working with the community to develop open source components that can be intermixed with vendor proprietary elements using standard O-RAN interfaces.”
Dai Kashiwa, Evangelist, Director of NTT Communications

“Radisys is excited to be a founding member of the SD-RAN project, and we are committed to integrating our RAN software implementation (CU & DU) with O-RAN interfaces to the µONOS-RIC controller and xApps being developed by the SD-RAN project community.  This effort has the potential to accelerate the adoption of O-RAN based RIC implementation and xApps, and we are committed to working with this community to advance the open RAN agenda.”
Arun Bhikshesvaran, CEO, Radisys

“As a leading manufacturer of small cell RAN equipment and an avid supporter of the open RAN movement, Sercomm is excited to collaborate with the SD-RAN community to open E2 interfaces and migrate some of our near-real-time functionalities from the RAN equipment into xApps running the μONOS-RIC controller. This is a nascent yet dynamic area full of potential, and we are committed to working with the SD-RAN ecosystem to build solutions ready for trials and deployment.”
Ben Lin, CTO and Co-Founder, Sercomm

“TIP’s OpenRAN solutions are an important element of our work to accelerate innovation across all elements of the network including Access, Transport, Core and Services.  We are excited about the collaboration between our RIA subgroup and ONF’s SD-RAN project to accelerate RAN disaggregation and adoption of open interfaces. Through this collaboration we will enable the OpenRAN ecosystem to leverage the strengths of data science and AI/ML technologies to set new industry benchmarks on performance, efficiency and total cost of ownership.”
Attilio Zani, Executive Director for Telecom Infra Project (TIP)

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Comment and Analysis of Open RAN Market:

Disclaimer:  Like all IEEE Techblog posts, opinions, comment and analysis are ALWAYS by the authors and do NOT EVER represent an opinion or position by IEEE or the IEEE Communications Society.  This should be obvious to all in the 11 1/2 years of this author’s contribution to the IEEE Techblog and its predecessor- ComSoc Community blogs.

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Besides NOT having a liaison with either 3GPP or ITU-R, the following Open RAN issues may limit its market potential.  These are NOT specific to the ONF SD-RAN project, but generic to Open RAN deployments.

1. U.S. officials promoting Open RAN as a way to decrease the dominance of Huawei, the world’s biggest vendor of mobile equipment by market share and also to thwart the rise of other vendors like ZTE and China Information and Communication Technology Group (CICT) which recently won a small part of s China Mobile contract.   Obviously, China’s government will fight back and NOT allow any version of Open RAN to be deployed in China (likely to be the world’s biggest 5G market by far)!  That despite China Mobile and China Unicom’s expressed interest in Open RAN (see Quotes above).  Remember, that the three big China carriers (China Mobile, China Telecom, China Unicom) are all state owned.
2. Dual infrastructure: If a legacy wireless carrier deploys Open RAN, existing wireless infrastructure equipment (base stations, small cells, cell tower equipment, backhaul, etc) must remain in place to support its customers. Open RAN gear (with new fronthaul and backhaul) won’t have wide coverage area for many years.  Therefore, current customers can’t simply be switched over from legacy wireless infrastructure to Open RAN gear.  That means that a separate separate and distinct WIRELESS INFRASTRUCTURE NETWORK must be built and physically installed for Open RAN gear. Yet no one seems to talk or write about that! Why not?
3. Open RAN is really only for greenfield carriers with NO EMBEDDED WIRELESS INFRASTRUCTURE.  Rakuten and Dish Network are two such carriers ideally suited to Open RAN.  That despite a lot of noise from AT&T and Deutsche Telekom about Open RAN trials. All the supporting quotes from legacy carriers are indicative of their interest in open source software AND hardware: to break the stranglehold the huge wireless equipment vendors have on cellular infrastructure and its relatively high costs of their proprietary network equipment and element management systems.
4. Open RAN should definitely lower initial deployment costs (CAPEX), but may result in INCREASED maintenance cost (OPEX) due to the difficulty of ensuring multi-vendor interoperability, systems integration and MOST IMPORTANTLY tech support with fault detection and rapid restoration of service.

Conclusions:

Considering all of the above, one may conclude that traditional cellular infrastructure,  based on vendor specific equipment and proprietary interfaces, will remain in place for many years to come.  As a result, Open RAN becomes a decent market for greenfield carriers and a small market (trial or pilot networks) for legacy carriers, which become brownfield carriers after Open RAN is commercially available to provide their cellular services.

Given a smaller than commonly believed market for Open RAN, this author believes the SD-RAN project is a very good idea. That’s because it will make open source software available for Open RAN equipment, something that neither the O-RAN Alliance of TIP Open RAN project are doing. Of course, having more vendors producing Open RAN white boxes and software does add to the systems integration and tech support that only large (tier 1) telcos (like AT&T, Deutsche Telekom, NTT and cloud companies (like Google, Facebook, Microsoft) have the staff to support.

In a follow up phone conversation today, Timon Sloane told me that network operators want a fully functional and powerful RAN Intelligent Controller (RIC) to gain visibility and control over their RANs, but that has yet to be realized.  To date, such controllers have been proprietary, rather than open source software.

The ONF µONOS-RIC is a key software module to realize that vision, Timon said.  It is very much  like a (near) real time operating system for an Open RAN.  If successful, it will go a long way to promote multi-vendor interoperability for Open RAN deployments. Success and good luck ONF!

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References:

https://www.prnewswire.com/news-releases/onf-announces-new-5g-sd-ran-project-301117481.html

https://www.sdxcentral.com/articles/news/onf-picks-up-where-o-ran-alliance-falls-short/2020/08/

https://www.lightreading.com/open-ran/open-ran-gets-even-more-convoluted-with-onfs-arrival/d/d-id/763425?