BT develops Ultra MIMO radio, taps O-RAN for insights

BT belongs to the O-RAN Alliance, but the British operator is not yet all that enamored with solutions that use O-RAN. However, it is getting value from O-RAN for work that BT is doing in-house to develop an “Ultra MIMO” radio.

Neil McRae, BT’s managing director and chief architect, said its Ultra MIMO radio will leverage the capabilities of massive MIMO, but will take it to a new level, using custom algorithms, signal processing and interference management technologies that BT is developing with its own engineers.

“We’re doing a lot in ultra MIMO,” said McRae, who cited this work as one of the primary reasons the operator is active in the O-RAN Alliance. “O-RAN for us is a way of getting access to some of the radio capabilities in MIMO so we can use some algorithms to get much more capacity from a MIMO platform.”

Asked if BT typically develops these kinds of radio technologies in-house, McRae said that ideally, the company would not do it, but the supply chain in the space is very challenged. He was referring to the fact that the U.S. has attacked China’s Huawei to the point that the vendor has been shunned by many countries around the globe. And this has left the telecom ecosystem with just two major vendors in the RAN space: Ericsson and Nokia.

RELATED: BT says Huawei rip-outs will cost it $658M over 5 years

Despite intense pressure from the U.S., the U.K. government decided in January that Huawei can supply gear for the country’s 5G networks, but it will be restricted to non-core portions, considered less security sensitive.

Of the telecom vendors available to BT, McRae said, “Ericsson and Nokia are fantastic partners. We also use Huawei, also a fantastic partner. But we feel like we need more choice and capability. Our goal is to work with those guys [O-RAN] and others to drive next requirements in radio technology to ultimately give us more capacity.”

O-RAN Alliance

The O-RAN Alliance is creating open APIs so operators can mix and match radios or write their own software for a radio. Sachin Katti, a professor at Stanford University and co-chair of the O-RAN Alliance technical steering committee, said in an interview with FierceWireless last year that the goal of RAN virtualization is to run software on top of x86 or Arm-based hardware, instead of proprietary hardware.

RELATED: O-RAN aims to eliminate vendor lock-in at the radio access network

“I think that’s a worthy cause,” said McRae. But he said BT isn’t “religious” about virtualization for its own sake. “We think sometimes you’re increasing the complexity of operations,” he said. “Today I talk to my supplier and they resolve it. In a disaggregated network, I have to talk to more than one supplier. I have to have a programmer on my own staff to de-bug it. We’ve got a lot to learn in how to operate the infrastructure. We will use the best solution for customer experience and that allows us to make a return. When you look at O-RAN it’s still not clear to me that’s there’s a really strong single direction for the parties involved.”

BT is also not concerned about virtualizing its mobile core network. McRae said the company was using cloud-native capabilities in its core from the usual telco vendors. But it didn’t see a need to try to modernize to the level of what Rakuten’s doing with its greenfield network. He said Rakuten doesn’t have to worry about 20 years or more of legacy equipment. “In cost terms, do we see any benefits of disaggregation in the mobile core? No, we see the opposite,” he said. “It’s more costly to run and with greater likelihood of problems.”