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9 March 2021

Marvell targets whole spectrum of O-RAN with Facebook alliance

As argued in the editorial above, the support of large-scale chip vendors is a critical enabler of affordable open networks platforms. There are many interesting initiatives, some focused on open source architectures such as RISC-V, but once companies look beyond private or small cell networks and towards the high performance 5G vRAN, many challenges arise.

It is clear that considerable development and funding will be needed to deliver an open semiconductor platform that can perform even the most demanding Layer 1 and 2 RAN tasks to the same level as the major equipment vendors’ inhouse architectures. It is encouraging for the open RAN community, then, to see big names such as Intel and Marvell supporting this drive.

Nokia’s missteps with its 5G base stations in 2019 highlight the critical importance of getting the underlying silicon right, but confidence is boosted each time a significant RAN provider announces a tie-up with a merchant chip vendor. Marvell has scored several points on this front, and has RAN engagements with Nokia itself, Samsung, and most recently, Fujitsu.

Fujitsu has been little known in the RAN market, though it is a long-standing partner of NTT Docomo in its native Japan. But it aims, like compatriot NEC, to use the O-RAN platform to bring its advanced radio expertise to a wider audience, and has already been selected as one of Dish Network’s 5G radio suppliers in the USA. Now it has taken another step towards the mainstream with a deal to Marvell’s baseband processors for future 5G equipment. It will use the Octeon Fusion baseband processors for 5G microcells and O-RAN distributed units (DUs).

Working with a large-scale merchant chip provider may help Fujitsu speed up delivery of commercial units to Dish, which has said its “large purchase” of 5G O-RAN radios is running late and has been a factor in delays to Dish’s own 5G roll-out. The new partnership could help Fujitsu adapt to an open ecosystem, from its history of providing heavily customized products for Docomo.

“Marvell’s baseband technology allows us to develop a variety of RAN solutions that can address the needs of network operators, regardless of the network topology being deployed,” Masaki Taniguchi, head of Fujitsu’s Mobile System Business unit, said in a statement.

But major chip vendor support is also important to drive scale into less cutting edge platforms, designed for affordable deployment to users everywhere, and here Marvell’s new partnership with Facebook provides indicators of how a large-scale market could be enabled by support from a few big processor makers.

Marvell is to join the Evenstar program, run by Facebook Connectivity under the auspices of TIP, which was set up a year ago with the goal of enabling remote radio units (RRUs) priced below $1,000. So far, several players have developed radios based on Evenstar specs, including a partnership of Mavenir and Taiwan’s MTI, and an inhouse project of Vodafone’s. Marvell is targeting the latest Evenstar activity, in the distributed unit.

The presence of a tier 1 merchant chip provider could help accelerate progress, as Intel has done in other Facebook/TIP activities; and Marvell highlights the expansion of the Evenstar platform into the distributed unit (DU) element of the open RAN, where most processing of low layer virtualized network functions will take place.

Marvell will work with Facebook on a reference design for a 4G/5G Open RAN DU based on its Octeon Fusion baseband processors and Octeon multicore digital processing units (DPUs). The aim is for this to support commercial products next year. Marvell will supply a fully integrated DU reference board based on the Octeon Fusion-O baseband, supporting 4G and 5G physical layer (PHY) processing, and an Octeon DPU to run software functions.

Facebook Connectivity will help with integration and validation of software operations on this platform and use its ecosystem influence to encourage multiple vendors to port their protocol stack software, and then to use the resulting reference design as the basis of commercial product developments. The DU supports up to 16 downlink layers at 100 MHz channelization with 10Gbps downlink and 5Gbps uplink performance, said Marvell.

Marvell is forecasting that up to 10% of DUs will be Open RAN-based within 3-5 years, helped by government incentives, especially in the USA, to avoid Chinese equipment and support new vendors.

Architectures such as Evenstar look to focus on general purpose processors (GPP) with accelerators, even for demanding low layer RAN tasks, as they are less expensive than the field-programmable gate arrays (FPGAs) or single-purpose ASICs that are traditionally used. But performance levels, compared to those of vendors’ own ASICs, have been questioned by O-RAN skeptics. Marvell said it designed its Octeon TX2 specifically for RAN base stations or DUs, rather than adapting a more general purpose product, and so it claims it can match the performance of an ASIC. This enables vendors without the resources to develop inhouse chips to enter the 5G game, while also providing a new option for companies like Nokia, that want to reduce their inhouse silicon costs.

Jaydeep Ranade, director of wireless engineering for Facebook Connectivity, said in a statement: “Marvell’s experience in baseband and DPU processors is a great addition to Evenstar as we work together to accelerate the adoption of high performance, innovative Open RAN solutions globally.”

While Facebook Connectivity has been the leading voice behind Evenstar in recent months, providing briefings geared to rural deployment, it is also an area of interest for tier one MNOs with their sights on more ambitious performance levels and use cases. The first operators to back Evenstar, when it was announced in February 2020, were

Deutsche Telekom and Vodafone, along with Facebook itself; two vRAN vendors (Mavenir and Parallel Wireless); and two radio specialists (MTI Mobile and AceAxis).

AceAxis is a reminder of how long a journey it has been to disaggregate the RAN, let alone do this around open interfaces that would be supported by any vendor’s radio . As AxisNT (before it was acquired by Korea’s Ace), it was early to spot the opportunity provided by the trend to separate the radio unit from the baseband, placing them at the top and bottom of the tower respectively and connected by fiber. It became a supplier of third party radio heads which could, in theory at least, be procured separately from the basebands, though in reality, the fronthaul issue meant that most sales were to OEMs for end-to-end networks.

Vodafone’s Santiago Tenorio, the new chair of TIP, said the RRU would be a “killer radio” and that the program would later extend to other elements such as the DU, as the Marvell announcement highlights.

Attilio Zani, TIP’s executive director, said Evenstar was “important because it meets the stated aims of what we’re trying to achieve – to reduce cost and increase flexibility. That’s very central to our mission statement.”

The first RRU specs covered 2x20W RRUs for B3, B20 and B7 and 2x40W RRUs for B5, B28 and B71. In future more SKUs will be added, including FDD B3 (4T4R 4X40W) and B28 2T4R 2x80W.