vRAN and slicing demonstrations abound, but Orange remains sceptical

The new network architecture will be more significant than the 5G radio itself in transforming the economics of the mobile operator, in terms of cost efficiency and of support for a wide range of new revenue streams. Only with a virtualized platform will MNOs secure the new cost base and flexibility they need; and 5G’s most important contribution may be to make it more achievable to support a fully virtualized RAN, and to use that as a platform for end-to-end, multivendor, multi-operator network slicing.

The most prominent announcement was of yet another AT&T-inspired open industry initiative, ORAN (see separate item), which brings together the US telco’s XRAN effort with the Cloud-RAN Alliance for a concerted attempt to bring white box economics to the radio network.

We will analyze the advances made in virtualized RAN and slicing in more depth in a future edition, but these are some of the innovative contributions we spotted on the show floor.

Turkcell was looking ahead to network slicing even before 5G, integrating a virtualized LTE platform into its network in a trial in Istanbul. It is using the ProgRAN platform, developed by US-based Netsia and its sister company, Argela of Turkey. This claims to support a sliceable RAN even before the 5G standards – which support slicing of the air interface in a uniform way – are fully formed.

Gediz Sezgin, Turkcell’s EVP of network technologies, said: “The integration of Netsia’s Virtual LTE RAN Platform into a commercial LTE core in our labs is an important step forward to demonstrate that an end-to-end network slicing for 5G networks is possible, from the core to the RAN, and how it can be applied to specific service environments, like that of a virtual private LTE network.”

Netsia/Argela have also worked with Telefónica on RAN slicing trials, running a hospital scenario in the telco’s Madrid labs, in which the RAN was optimized for different use cases, with different network requirements, simultaneously.

ProgRAN decouples the data and control planes in the RAN, and allows operators to create, modify or terminate virtual base stations dynamically on existing base station hardware, each programmatically anchored to a corresponding core network. Each virtual base station governs a non-overlapping portion of the wireless resources using its own, use case-optimized control functionalities.

Netsia has integrated design and orchestration capabilities based on the ONAP open source initiative into ProgRAN. At MWC, it was also working with Belgian small cell start-up Accelleran on a dynamically re-deployable vRAN platform. This used Accelleran’s vRAN architecture, which supports RAN network functions in a cloud-native, microservices-based environment. It allows the centralized functions in a vRAN to run on embedded SoCs as well as on cloud or enterprise servers, and a virtual network function can be dynamically redeployed between these environments, and service-chained with edge compute functions.

Frédéric Van Durme, CEO of Accelleran, said: “Multi-tenant solutions supporting our dynamic vRAN solution with Netsia’s ProgRAN running over Accelleran’s E1000 product line, which supports a range of LTE bands including 3.5 GHz and CBRS, vividly illustrate the power of this partnership towards supporting neutral host deployments and adapting to the real world demand shaped by the upcoming 5G.”

Oguz Oktay, VP of wireless solutions at Netsia, added: “Together, we continue developing solutions for service providers that desire for more programmatic control of their radio access networks, enabling rapid development of new services for different business verticals over a common virtualized platform.”

Ericsson was partnering with Swisscom to demonstrate end-to-end network slicing on 4G networks, though as with any 4G-based trial, there are limitations on air interface slicing unless proprietary solutions are used.

“Network slicing is crucial to guarantee the performance of critical communications, and it is a key enabler to maximize the full business potential of 5G,” Joakim Sorelius, head of Ericsson’s product area network systems, said. Swisscom’s CTO, Heinz Herren, highlighted manufacturing, railways and public safety as early applications for a sliced network.

Telefónica has been an early exponent of vRAN and slicing, and at MWC, it used its Unica cloud platform to demonstrate network slicing across four levels, to support services which needed to prioritize connectivity, virtual reality, critical communications and augmented reality. It worked with Ericsson, Nokia and Netsia on the showcase, which ran in the 3.7 GHz band on its stand.

The augmented reality demo combined HD video with localized virtual information, by separating control and data planes and leaving the data traffic in the user’s environment rather than the core network, to reduce latency.

An emergency services demo created a private LTE network, which could be sub-divided into further slices to support applications with different performance, latency and radio resource requirements.

Group CTIO Enrique Blanco said: “We have devoted many years to creating and transforming our networks, because we understand that it is essential to be flexible and scalable, and because only through virtualization we can respond to the requirements posed by the industry, which are radically varied and even contradictory among themselves.”

In Italy, TIM and Ericsson have been working to digitalize the operator’s RAN on a national basis, and they have deployed their first vRAN in Turin. “Our vRAN partnership with TIM shows that the evolution towards 5G through the virtualization, automation and digitalization of radio access networks is not just a talking point but an action point, as seen by the successful deployment in Turin. We are working closely with TIM to turn this city deployment into a nationwide deployment,” said Fredrik Jejdling, EVP at Ericsson.

Verizon is working with Nokia and Intel on a new vRAN architecture to reduce its capex and opex. It has already trialled vRAN 1.0 in Oklahoma City, with the virtualized baseband functions running on Nokia’s AirScale cloud base station server and Intel’s Xeon processors. Now the trio are developing vRAN 2.0. Verizon has also run vRAN trials with Ericsson and Samsung as part of its broad Open RAN initiative in 4G and future 5G.

Nicola Palmer, the operator’s chief network engineer and head of the carrier’s wireless networks, told LightReading: “We have thousands of these C-RAN hubs throughout the US. They’ve already been identified. They are built out and equipped. And we have been in the process of centralizing those baseband units.” She explained that, as a result, 15 to 50 centrally managed cells can work together, using LTE-Advanced features like remote electrical tilt (RET), which can point an antenna array toward high traffic areas during the day and then tilt them up at night to improve coverage.

The next step is to “do a lot more … The C-RAN hubs become vRAN hubs, and now you have flexibility because they can be more quickly deployed. They can be scaled up and down. They can now communicate across C-RAN hubs. … You can scale horizontally instead of vertically.”

Like many operators, Verizon and Palmer are keen to open up their supply chains. Where one vendor, such as Ericsson, provides an end-to-end system, “you basically have an Ericsson market,” Palmer said, adding:  “Our view is that you need to have those pieces disaggregated. By separating hardware and software, you can get best of breed on each one. And that allows us, for example, to take a Samsung radio with an Ericsson baseband. … And that allows us to play the suppliers against each other. And to their strengths, to be honest.”

But many operators remain sceptical about vRAN. Orange’s director of spectrum strategy and planning, Yves Bellego, said the French telco’s vRAN trials had been strong technically but had failed to show any major business benefits.

“We did not go beyond trials or a proof of concept because of the business case,” Bellego said. “As of today it remains cheaper and simpler to upgrade each and every site.”

One of the key objectives of the new ORAN initiative, and of the RAN aspect of the Facebook-inspired Telecom Infra Project, will be to change that calculation and make a white box vRAN a significantly cheaper and more efficient option for MNOs than traditional build-outs where the basebands and radio/antennas remain integrated or close to one another. One important cost item to address will be fronthaul links between the centralized baseband unit and the sites – usually requiring high quality fiber. Facebook TIP is one industry initiative which has a group examining more cost-effective ways to support fronthaul in future.

While Orange was an early exponent of virtualization in general, and vRAN in particular, it made it very clear, a couple of years ago, that it would no longer be satisfied with justifying these architectural changes on the basis of cost alone. It would also insist on seeing new revenue streams or system capabilities, and Bellego reiterated that view.

“We do not think savings is the initial driver,” he said. “There are initial costs we must take care of and so there must be other drivers. We have been looking to see if there are additional capabilities on radio. Could we improve capacity by having pooled functions? Pooling BBUs [baseband units] could help with automation and edge computing.”