Single-vendor open RAN is spreading like a virus

Stop press! Verizon now has 130,000 radios geared up for open radio access network (O-RAN) technology, the much-ballyhooed concept about marrying products from different suppliers at the same mobile site. This update, presented this week as if Verizon had just whirled through the local store like a Black Friday shopper, scooping radios off the shelves, "is not really 'news,' as they have been requiring their vendors to comply with future O-RAN standards for the past two years," said Joe Madden, the founder and president of analyst firm Mobile Experts. But the details of this and several other big O-RAN announcements should alarm anyone serious about the concept.

The original purpose of O-RAN, when it bobbed up on the telco horizon in early 2018, was to unlock a problematic interface linking radios on one side to compute or baseband systems on the other, the two main components of the RAN. This "fronthaul" connection was handled by the common public radio interface (CPRI), derided by critics of the giant mobile equipment vendors – Ericsson, Huawei and Nokia – because it apparently forced any operator to shop within the same vendor's system for all these parts.

With a less proprietary alternative, operators would have the freedom to marry a radio from one supplier to a baseband system from another. And this would allow specialists with a radio or software focus to compete against the giants and sell directly to the telcos. Previously, their inability to provide a complete system would have disqualified them from tenders. CPRI was a technological barrier to competition and a protector of a mobile kit oligopoly.

But the open fronthaul interface painstakingly devised by the O-RAN Alliance is not delivering. Six years since that specifications group came into existence, operators that claim to be using it are still buying radios and baseband products for any given site from the same vendor. And specialists have had a negligible impact on the market. Eight established firms – Huawei, Ericsson, Nokia, ZTE, Samsung, NEC, Fujitsu and Datang Mobile – accounted for 98% of all RAN sales in the first nine months of 2023, according to Dell'Oro, a market research company. As many as 30 smaller companies shared the remaining 2%.

Flightless birds

Telco behavior so far has produced the oxymoron of "single-vendor O-RAN." At best, the interface is a switch that has not been flipped. At worst, it is the wings on a flightless bird. Its usefulness must remain in doubt when Adam Koeppe, Verizon's senior vice president of network planning, has reportedly said in recent weeks that multivendor O-RAN remains unproven. And Verizon has confirmed directly to Light Reading that none of its O-RAN-compatible radios, supplied by Samsung and Ericsson, has been matched with baseband from a different vendor.

"Multivendor interaction is the next step," said a spokesperson by email. "There is orchestration work being done now to ensure when we mix and match vendors we will maintain the level of performance our customers expect. To this point, we have tested and are running open RAN in a single-vendor environment."

It is not unique. Announced in December, a huge $14 billion contract between AT&T and Ericsson – the biggest deal in the Swedish kit maker's history – has been publicized as an "open RAN" move. Yet unsurprisingly, given the size of the contract, Ericsson will contribute most products, including radios and baseband systems. While Fujitsu was also named in the official release, its role remains unclear, and it has had a 5G partnership with Ericsson since 2018. Nor has the Japanese company had anything to say about monetary value.

Outside North America, Vodafone UK has started work on a 2,500-site deployment of O-RAN technology to replace Huawei. Under government orders, the Chinese vendor must be evicted from UK 5G networks by the end of 2027. And much like AT&T and Verizon, Vodafone is purchasing both baseband software and radios from the same vendor. In its case, the critical supplier is Samsung. While NEC, another Japanese vendor, was listed as a radio vendor in the original announcement, it had mysteriously disappeared from the last register like a soldier missing in action. Vodafone, however, insists it is still in the fight.

Nokia, which has suffered because of recent US deals, could not resist criticizing developments when it last briefed equity analysts on financial results. "Will it be true O-RAN, or will it be O-RAN where you just have the same supplier on both sides of the interface," said CEO Pekka Lundmark. "We have two real commercial O-RAN deployments ongoing at the moment," he added, drawing attention to work in Japan, with NTT Docomo, and Germany, with Deutsche Telekom.

Interface-off

That suggests multivendor is doable and that the interface is not a problem. Yet a compromise reached last year, after a clash between different parties on specifications, has thrown up several flavors of open fronthaul 7.2x cat-B, the interface designed to support more advanced "massive MIMO" technology.

The compromise allows Ericsson to include important uplink functions – mainly the interference-addressing equalizer – in its radios and have those deemed O-RAN-compliant. "Ericsson builds the equalizer and channel estimation into the RU [radio unit] to get a very fast and more precise setup of channel conditions," explained Madden by email. "To comply with early O-RAN fronthaul specs, they would be forced to turn these functions off, and Ericsson resisted this path. Now, there is a clear path to an Ericsson-friendly O-RAN fronthaul spec without ripping out anything."

Ericsson has firmly ruled out building radios minus those equalizers, which other companies want to see kept in baseband servers. But this option would mean doing channel estimation in both radios and baseband products. There is some concern it could lead to interoperability problems if the radios and baseband come from different vendors.

Whatever the case, massive MIMO was seen as troublesome as recently as November by Joseph Russo, Verizon's president of global networks and technology. "[If] I look at the performance of the O-RAN at this point, it can't do the kind of things like massive MIMO at 16T/16R [to] 64T/64R, those kind of performance measures, we're just not there yet," he told a Wells Fargo conference. "And until we are, it doesn't have a place necessarily in the kind of performance that I want to deliver to my customers."

Even with the new interfaces, combining vendors looks tricky. "The difficulty for open RAN is not in simply plugging things together," said Madden. "The challenge is in achieving high-capacity performance with disparate hardware," He does, nevertheless, sound optimistic about the performance of the Ericsson technology based on the latest specs compared with the original fronthaul interface. "I expect other companies to get on board."

Unfortunately, telco executives in the thick of O-RAN doubt it will ever be a "plug and play" option, regardless of what happens inside the O-RAN Alliance. "That is totally unrealistic," said Yago Tenorio, the head of network strategy for Vodafone, when asked about this in late 2022. Whether it is the operator, the vendor or another third party, someone needs to take on the considerable systems-integration job of ensuring radios from one company will function with another vendor's baseband.

And there are the obvious commercial considerations, too. Verizon is looking at a network of about 85,000 sites that needs multiple radio units for each band at each site, Madden points out. A pre-integrated system bought from an Ericsson or a Samsung could fetch economies of scale and favorable per-unit prices that disappear when radios, software products and systems-integration expertise come from a variety of players.

With their limited resources, smaller telcos are even less likely to shop around and take on the systems-integration effort themselves, an executive at a smaller telco told Light Reading. But unless there is some multivendor momentum soon, the O-RAN movement is at risk of bringing almost no change at all.