This as an exciting time for semiconductors, says Santiago Tenorio, which is why his company, Vodafone, wants to exploit this period to benefit the radio access network (RAN), the most costly part of the wireless network for telecom operators.
The telecom operators want greater choice when buying RAN equipment.
Santiago Tenorio
As Tenorio, a Vodafone Fellow (the company’s first) and its network architecture director, notes, there were more than ten wireless RAN equipment vendors 15 years ago. Now, in some parts of the world, the choice is down to two.
“We were looking for more choice and that is how [the] Open RAN [initiative] started,” says Tenorio. “We are making a lot of progress on that and creating new options.”
But having more equipment suppliers is not all: the choice of silicon inside the equipment is also limited.
“You may have Fujitsu radios or NEC radios, Samsung radios, Mavenir software, whatever; in the end, it's all down to a couple of big silicon players, which also supply the incumbents,” he says. “So we thought that if Open RAN is to go all the way, we need to create optionality there too to avoid vendor lock-in.”
Vodafone has set up a 50-strong research team at its new R&D centre in Malaga, Spain, that is working with chip and software companies to develop the architecture of choice for Open RAN to expand the chip options.
Open RAN R&D
Vodafone’s R&D centre’s 50-staff are organised into several streams, but their main goal is to answer critical issues regarding the Open RAN silicon architecture.
“Things like whether the acceleration is in-line or look-aside, which is a current controversy in the industry,” says Tenorio. “These are the people who are going to answer that question.”
With Open RAN, the virtualised Distributed Unit (DU) runs on a server. This contrasts with specialised hardware used in traditional baseband units.
Open RAN processes layer 1 data in one of two ways: look-aside or in-line. With look-aside, the server’s CPU performs certain layer 1 tasks, aided by accelerator hardware to perform tasks like forward error correction. This requires frequent communication between the two that limits processing efficiency.
In-line solves this by performing all the layer 1 processing using a single chip. Dell, for example, has an Open RAN accelerator card that performs in-line processing using Marvell’s silicon.
When Vodafone announced its Open RAN silicon initiative in January, it was working with 20 chip and software companies. More companies have since joined.
“You have software players like middleware suppliers, also clever software plug-ins that optimise the silicon itself,” says Tenorio. “It's not only silicon makers attracted by this initiative.”
Vodafone has no preconceived ideas as to the ideal solution. “All we want is the best technical solution in terms of performance and cost,” he says.
By performance, Vodafone means power consumption and processing. “With a more efficient solution, you need less [processing] cores,” says Tenorio.
Vodafone is talking to the different players to understand their architectures and points of view and is doing its own research that may include simulations.
Tenorio does not expect Vodafone to manufacture silicon: “I mean, that's not necessarily on the cards.” But Vodafone must understand what is possible and will conduct lab testing and benchmark measurements.
“We will do some head-to-head measurements that, to be fair, no one I know does,” he says. Vodafone’s position will then be published, it will create a specification and will drive vendors to comply with it.
“We've done that in the past,” says Tenorio. “We have been specifying radios for the last 20 years, and we never had to manufacture one; we just needed to understand how they're done to take the good from the bad and then put everybody on the art of the possible.”
Industry interest
The companies joining Vodafone's Open RAN chip venture are motivated for different reasons.
Some have joined to ensure that they have a voice and influence Vodafone’s views. “Which is super,” says Tenorio.
Others are there because they are challengers to the current ecosystem. “They want to get the specs ahead of anybody to have a better chance of succeeding if they listen to our advice, which is also super,” says Tenorio.
Meanwhile, software companies have joined to see whether they can improve hardware performance.
“That is the beauty of having the whole ecosystem,” he says.
The Open RAN architecture showing (R to L) the Distributed Unit (DU) and the Radio Unit (RU). Source: ONF
Work scale
The work is starting at layer 1 and not just the RAN’s distributed unit (DU) but also the radio unit (RU), given how the power amplifier technology is the biggest offender in terms of power consumption.
Layers 2 and 3 will also be tackled. “We're currently running that on Intel, and we're finding that there is a lot of room for improvement, which is normal,” says Tenorio. “It's true that running the three layers on general-purpose hardware has room for improvement.”
That room for improvement is almost equivalent to one full generation of silicon, he says.
Vodafone says that it also can’t be the case that Intel is the only provider of silicon for Open RAN.
The operator expects new hardware variants based on ARM, perhaps AMD, and maybe the RISC-V architecture at some point.
“We will be there to make it happen,” says Tenorio.
Other chip accelerators
Does such hardware as Graphics Processing Units (GPUs), Data Processing Units (DPUs) and also programmable logic have roles?
“I think there's room for that, particularly at the point that we are in,” says Tenorio. “The future is not decided yet.”
The key is to avoid vendor lock-in for layer 1 acceleration, he says.
He highlights the work of such companies like Marvell and Qualcomm to accelerate layer 1 tasks, but he fears this will drive the software suppliers to take sides on one of these accelerators. “This is not what we want,” he says.
What is required is to standardise the interfaces to abstract the accelerator from the software, or steer away from custom hardware and explore the possibilities of general-purpose but specialised processing units.
“I think the future is still open,” says Tenorio. “Right now, I think people tend to go proprietary at layer 1, but we need another plan.”
“As for FPGAs, that is what we're trying to run away from,” says Tenorio. “If you are an Open RAN vendor and can't afford to build your ASIC because you don't have the volume, then, okay, that's a problem we were trying to solve.”
Improving general-purpose processing avoids having to go to FPGAs which are bulky, power-hungry and expensive, says Tenorio but he also notes how FPGAs are evolving.
“I don't think we should have religious views about it,” he says. “There are semi-programmable arrays that are starting to look better and better, and there are different architectures.”
This is why he describes the chip industry as ‘boiling’: “This is the best moment for us to take a view because it's also true that, to my knowledge, there is no other kind of player in the industry that will offer you a neutral, unbiased view as to what is best for the industry.”
Without that, the fear is that by acquisition and competition, the chip players will reduce the IC choices to a minimum.
“You will end up with two to three incumbent architectures, and you run a risk of those being suboptimal, and of not having enough competition,” says Tenorio.
Vodafone’s initiative is open to companies to participate including its telco competitors.
“There are times when it is faster, and you make a bigger impact if you start things on your own, leading the way,” he says.
Vodafone has done this before: In 2014, it started working with Intel on Open RAN.
“We made some progress, we had some field trials, and in 2017, we approached TIP (the Telecom Infra Project), and we offered to contribute our progress for TIP to continue in a project group,” says Tenorio. “At that point, we felt that we would make more progress with others than going alone.”
Vodafone is already deploying Open RAN in the UK and has said that by 2030, 30 per cent of its deployments in Europe will be Open RAN.
“We've started deploying open RAN and it works, the performance is on par with the incumbent architecture, and the cost is also on par,” says Tenorio. “So we are creating that optionality without paying any price in terms of performance, or a huge premium cost, regardless of what is inside the boxes.”
Timeline
Vodafone is already looking at in-line versus look-aside.
“We are closing into in-line benefits for the architecture. There is a continuous flow of positions or deliverables to the companies around us,” says Tenorio. “We have tens of meetings per week with interested companies who want to know and contribute to this, and we are exchanging our views in real-time.”
There will also be a white paper published, but for now, there is no deadline.
But there is an urgency to the work given Vodafone is deploying Open RAN, but this research work is for the next generation of Open RAN. “We are deploying the previous generation,” he says.
Vodafone is also talking, for example, to the ONF open-source organisation, which announced an interest in defining interfaces to exploit acceleration hardware.
“I think the good thing is that the industry is getting it, and we [Vodafone] are just one factor,” says Tenorio. “But you start these conversations, and you see how they're going places. So people are listening.”
The industry agrees that layer 1 interfacing needs to be standardised or abstracted to avoid companies ending in particular supplier camps.
“I think there'll be a debate whether that needs to happen in the ORAN Alliance or somewhere else,” says Tenorio. “I don’t have strong views. The industry will decide.”
Other developments
The Malaga R&D site will not just focus on Open RAN but other parts of the network, such as transport.
Transport still makes use of proprietary silicon but there is also more vendor competition.
“The dollars spent by operators in that area is smaller,” says Tenorio. “That's why it is not making the headlines these days, but that doesn't mean there is no action.”
Two transport areas where disaggregated designs have started are the disaggregated backbone router, and the disaggregated cell site gateway, both being sensible places to start.
“Disaggregating a full MPLS carrier-grade router is a different thing, but its time will come,” says Tenorio, adding that the centre in Malaga is not just for Open RAN, but silicon for telcos.