“Could we build the network we have today in the UK purely with Open RAN? Right now the answer to that is absolutely no, we couldn’t.”
“Could that be a future? Absolutely it could.”
BT’s relationship with Open RAN is a bit like that of the music fan who sees the tiny indie group they discovered go on to be massively famous. “I was here before you lot,” it says, “where were you when Open RAN was playing acoustic sets to an empty research lab near Ipswich?”
At a briefing held in London, BT’s Chief Architect Neil McRae took journalists on a “deep dive” into BT’s relationship with Open RAN. In essence, the message was, “We’re fully aware of the pros and cons of Open RAN. We’ve been researching it and playing with it for years, contribute to TIP a lot, O-RAN a bit, and we’re going to use it when it suits us best. Which is soon, in some cases.”
McRae has a point. And not to get too Open RAN hipster ourselves, we can prove it. Here’s TMN covering BT investing in Software Defined Radio with Lime Microsystems in 2017, as part of an overall strategy to diversify potential solutions to extend its network.
Here’s us [picture, below] covering BT working with Acceleran, Mavenir and Adva Optical back in February 2018, with a disaggregated RAN demo at MWC. And here’s BT in a TIP paper from the same timeframe, proposing use cases for non ideal backhaul/fronthaul for Cloud RAN.
And here’s us again in mid-2019 reporting on more work with Mavenir, this time on a neutral host small cell deployment, with the radios based in near-edge datacentres.
OK, so we were both here for the early stuff, before they went all commercial. But it’s also true that despite this, BT has been less committed in public to Open RAN, and its CTIO did state in a network strategy update in July this year that it sees Open RAN as mainly a post-2025 rollout option.
Watson says OpenRAN will be more critical towards late 2020s, not in current stage of 5G rollout.
Must be fully compliant with additional needs we have for ESN. BT is working to “accelerate OpenRAN maturity so it becomes a a viable scale option as as soon as possible”
— Keith Dyer (@keithdyer) July 14, 2021
Where BT is focussed now
Despite its caution compared to some of the more go-ahead messaging from other operators, it’s not the case that BT is down on Open RAN. McRae was clear, “Open RAN will absolutely play a significant part in our network. We are running two RFIs right now. One focused around small cells and one around neutral host. And we believe that today Open RAN is very well placed for those two applications.”
McRae is one of those, and there are many, who think that the increased deployment flexibility of Open RAN makes it a better initial fit for scenarios where macro networks need to be extended or densified, and where deployment flexibility is key. That’s partly because – being based on cloud technology with disaggregrated network functions as software – Open RAN solutions might fit deployments where space and power are limited. Additionally, its open architecture also promises to offer more dynamic control of radio resources.
The RIC trick?
Related to that, another key area that BT is investigating is the RIC. Here it sees great potential to use its own AI and ML skills, along with those of the market, to develop more network automation and a more responsive and intelligent network. That would be by deploying its own and third party xApps and rApps on near real time and non-real time RICs.
Paul Crane, Converged Network Research Director, BT, said that about a third of all the network research he is leading is now related to AI and ML.
“For me, I think this is the really, really interesting part of the Open RAN architecture,” he said. “What the RIC should do is to present you with a series of APIs where you can develop your own applications to optimise your network, to control multiple vendors, and potentially build new services. I think that this is potentially, for an operator like ourselves, the major benefit of Open RAN.”
And McRae seemed to hint that BT have some news up their sleeves in this area. Asked if existing suppliers such as Nokia and Ericsson are likely to open up their own interfaces to enable control via O-RAN RICs, McRae said, “Watch this space.”
So the topline message was that BT is indeed engaged, and that it is mainly engaged to marry the benefits of Open RAN’s open architecture to its own research and operational priorities.
McRae told press and analysts: “Open RAN is in its early stages. As an open source developer, having seen the pace that it’s moved over the last two years, it’s insane how quickly things are developing.
“But it’s still got some big hurdles to overcome… like the challenges of running a radio system in a place like this [a high density shopping mall and restaurant campus] where you need high parallelisation of processing, you need really super strong ability to analyse the beam paths, to demodulate stuff, to run the control plane and ensure the whole thing works – and works at high bandwidth. So you know, Open RAN is on that journey.”
Again, McRae re-iterated the message from CTIO Watson early in the year.
“Could we build the network we have today in the UK? Right now the answer to that is absolutely no, we couldn’t.
“Could that be a future? Absolutely it could. And that’s where we are engaged. And again, in our network we have some very specific idiosyncrasies. We have spectrum ranging from 700 MHz to 3.6 GHz and even into microwave bands we haven’t done much with. We have features like ESN where we have to provide blue light services and a million other requirements that have to be built into Open RAN. And we are contributing to, and trying to accelerate the pace of, innovation and capability.”
And it’s that innovation that McRae says he is most excited by.
“In my mind one of the biggest myths is that Open RAN will save us money. I look at that with a lot of scepticism. I know how to write open source code, I know how much Intel CPUs cost and how much the other five guys who make L1 chips cost. Does it provide a future where the path may introduce new suppliers and create new competition and innovation? For sure. And it’s that innovation that excites us the most.”