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open RAN

Rakuten Mobile claims 5G open RAN breakthrough

Tareq Amin, CTO of Japan's disruptive Rakuten Mobile, appeared to let slip an announcement he was holding back for next month (but perhaps it wasn't too much of a surprise for seasoned watchers of the open RAN space).

In a conference call with European journalists, Amin flagged an upcoming unveiling of what he called the "world's first" massive 5G MIMO remote radio head (RRH), using a 32T/32R configuration, and which is "fully compliant" with open interface specifications laid out by the O-RAN Alliance.

The new RRH can support a wideband channel of 100MHz, deliver up to 1.7 Gbit/s throughput, and allows digital beamforming. Oh, and it weighs less than 22Kg.

Why is all this important? Built by Intel and NEC, the new RRH goes to the heart of what Amin describes as his "component vendor strategy." This is apparently shaving huge chunks off Rakuten's open RAN capex bill compared with traditional rollout of mobile networks.

Bye-bye, middleman
By not going to a so-called "middleman" – which Amin seemed to imply was a "traditional OEM" – Rakuten Mobile avoids, in the words of the CTO, "unbelievable [price] inflation on hardware."

(For Rakuten's 4G rollout, 4T/4R RRHs were used from "traditional OEM" Nokia – the first large-scale open RAN deployment by the Finnish vendor – which, said Amin, helped trim capex by 35% compared with conventional LTE rollout.)

"Our MIMO 32T32R panels are exactly 50% the cost of traditional OEM infrastructure," enthused Amin. "For mmWave, honestly speaking, I think it's even north of 60% cheaper."

Helping the 5G business case further, said Amin, are "affordable" Qualcomm modems used in mobile devices but now adapted for Rakuten's 5G basestation infrastructure. Qualcomm also provides the basestation RF frontend, enabling a 128-antenna array and analog beamforming.

Rakuten has both 3.7GHz and 28GHz millimeter wave (mmWave) spectrum assets at its disposal for 5G, which, after a bit of delay – attributed it seems to COVID-19 – is now set to go live in either the last week of September or the first week of October.

Amin did not reveal the RRH price point, but the Facebook-backed Telecom Infra Project (TIP) seems to be a bit behind what Rakuten is doing here – if not on price then certainly on functionality.

TIP's OpenRAN Project is aiming to get a sub-$1000 RRH to market during the first quarter next year, but it's a traditional 4T/4R configuration.

In a recent webinar hosted by Light Reading, Santiago Tenorio, TIP's chairman – and Vodafone Group's head of network strategy and architecture – pointedly noted that massive MIMO was "difficult to do."

We didn't want to be a systems integrator, but we had to
If you are a software company looking to impress Amin, the one thing you must not say is "vertical stack."

In an enlightening glimpse as to what it was like to work with various vendors in the run-up to Rakuten's commercial 4G launch in early April, Amin spoke of the huge challenge of having to convince them to deploy their virtual machines on top of a common cloud infrastructure.

"Most of them would come to me and say, 'Tareq, we just want to give you the vertical stack.' And I would say, 'This is not going to happen. If you're going to give me a vertical stack, then there's no partnership. You need to integrate with my horizontal cloud.'"

Given these difficulties, Amin concluded early on that if Rakuten was going to be successful it would need to be the systems integrator. "We had to become the glue among all these vendors," said the CTO.

US software company Altiostar was selected, said Amin, not because of any RFP, but because "I respected the possibilities of what they could do," even though they had "massive gaps."

First Japan, then the world
Although Amin doesn't like Rakuten to be labelled a systems integrator (SI) – he prefers "platform provider" – the SI experience has enabled the company to package what it's learned in Japan over the last three years into what the CTO calls a "pod," which can be used as a sort of a template for operators elsewhere to get open RAN and virtualized cores up and running more quickly.

"We are more than willing and open to collaborate and partner to make this platform even much better than it is today," said Amin.

Rakuten Mobile is slated to announce some partnerships with European operators on September 14.

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— Ken Wieland, contributing editor, special to Light Reading

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