Getting the latest on Rakuten’s 5G rollout

Cloud RAN, containerisation, and the Airbus network model.

Some interesting insights from a Rakuten press call this morning, following its 5G launch yesterday. Rakuten launched 5G at no extra cost to consumers over its 4G offer, which is already way under the bar set by the other Japanese MNOs.

It can do that partly because it is passing on huge cost savings it has made in building its network – up to 40% savings compared to a traditional model, according to CTO Tareq Amin. So here’s some of how it is driving those costs down.

Rollout and upgrades

Amin didn’t really want to say how many 5G sites the company has live at launch. The operator is building out 5G in mmWave (28GHz) using a small cell – technically a distributed Radio Unit (dRU) that combines a mmWave antenna array with a virtual Distributed Unit (DU) – from AirSpan and a 32T/R active antenna unit at sub 6GHz (3.7 GHz) from NEC.

Asked directly how many of these it has deployed at launch, Rakuten instead repeated that it has a license commitment to build 15,787 of the 3.7 GHz sites and 7,948 mmWave sites at a “bare minimum.” With about three antenna units per site, you see how many of the mmWave and AAUs Rakuten has bought from NEC and AirSpan. But we don’t know how many it has deployed yet. Amin hinted that one potential hold up, one that affects all the Japanese operators, is that base stations operating in 3.7 GHz need to be controlled so that they don’t interfere with satellite communications in the band. 

Amin did say that the company would be exceeding even the pace of deployment that the company achieved in 4G. It has scaled its hardware platforms for supporting 5G rollout from six server form factors down to just two.

It is also moving over the next 18 months from the Virtual Machine-based vRAN it deployed for its 4G launch, to a cloud-native, containerised RAN software capability – again with Altiostar. That reduces the code base footprint from “GBs down to MBs”, meaning that updates and new spin-ups are that much quicker. It will also move from its current support for a single 100MHz carrier at 28GHz to combining four carriers available to it in the band. That may come from November and is not too complex, Amin said, requiring some “tweaking” of the CPU inside the Airspan dRU. The company also wants to further optimise the digital beamforming of the 2-layer, 256 QAM, NEC unit, to gain an extra 20% capacity enhancement. 

The company is currently taking two radio software updates a day from its suppliers – “no other network on the planet today could take that without disruption”.

Open RAN

Although the company is a bit of a poster child for Open RAN, it hasn’t actually used any of the O-RAN Alliance specifications within its rollout. Amin said, in effect, that was because they weren’t ready. Now the company is getting more engaged in O-RAN and looking to contribute its own experience.

Amin said that even if the interfaces are not O-RAN compliant per se, then they de facto have achieved the disaggregation that O-RAN Alliance members want to achieve. (The Altiostar 4G CU-DU-RU architecture mirrors the O-RAN specification of the 3GPP 7.2 Split. The Airspan dRU is built on a 3GPP Split 2 design.)

“When we launched 4G LTE our implementation was to my belief what ORAN wanted to do. We did not want to be hampered… we are fully compliant to 3GPP to achieve what O-RAN wants to achieve. If we have used a very small FPGA to convert open CPRI to eCPRI, to me it’s trivial, once standards get agreed, for Rakuten to be compliant. There was a lot of debate and to be honest did not have time to wait for debates to mature and crystallise; we thought we could achieve the same level of disaggregation that O-RAN wanted to achieve.”


Amin likes to state that the Rakuten network was built from the ground up with a new approach. Which is true. But some of the innovation claims can be taken with the merest pinch of salt.

He said that he found container orchestrator after a late night Google search for the” concept of a container appstore.” That’s no doubt true, but is not an unknown quantity in this area – it had already been working with Open RAN player Parallel Wireless since 2018, for example, on lifecycle automation for Parallel’s cloud RAN. 

Again, Amin said that the company co-developed NEC’s 3.7GHz AAU “from the ground up”. But NEC had already announced a mid-band 5G NR AAU to the market, before Rakuten’s engagement.

Another example – Amin said that Rakuten’s SON provider was a company in San Diego that nobody wanted to work with, but it had 60 SON patents and was able to plug in to Rakuten’s platform. That SON company is AirHop, to be fair a pretty well known SON company, and one that had already worked extensively with Reliance Jio, Amin’s previous company.

But even if in each case there’s an element of exaggeration, it’s absolutely fair to say that Rakuten goes much further and deeper in its relationships with vendors. With NEC, the company had an existing chip relationship for its product, but Amin used his influence and purchasing power with Intel to get that company to supply FPGA-based chips that would drive the AAU at much lower prices. So it’s probably fair to say that the companies disassembled what NEC had already and re-built to Rakuten’s specification. And he asked NEC for open book accounting on its cost of production, with an agreed margin on top.

With, Amin said he knew the company had big gaps in terms of being able to deliver everything he envisioned for the cloud application platform, but the two worked together to “put an ecosystem” around the company, including integrating with Intel’s  OpenNESS  (Open Network Edge Services Software) platform to help address gaps require for an underlying cloud architecture “to really host apps like radio”.

That, he said, mirrors the way the company worked with Altiostar on the vRAN, creating an ecosystem around them.

There’s a deeper point here than self-celebration. As Rakuten expands its ambitions for the Rakuten Communications Platform, it wants to show that operators can work with vendors to build networks in a different way. The RCP can provide the underlying cloud architecture, but operators can work with vendors of their choice on top of that framework.

There’s also the wider issue of fostering vendor diversity. Referencing its partnership with Telefonica as an “inclusive” not exclusive club, Amin said he admires the way that Airbus planes are assembled and built collaboratively across Europe. “We felt we could do a lot with European countries, regulators and governments to show how a diversified telco supply chain could become more a reality than it is today.”

Clearing up the Qualcomm/Intel presence within Rakuten’s 5G network

There has been some confusion about Qualcomm driving Open RAN within Rakuten, so here’s the actual chip support. The NEC 5G NR AAU is based on Intel FPGAs in the massive mimo panel, with Intel CPUs doing L2 processing.

The Airspan mmWave dRU – remember that’s a mmMwave small cell that combines the antennas with a vDU in the same box that then connects back to Altiostar’s vCU – has the Qualcomm FSM100xx module for RFIC, modem and the radio baseband, and also has Intel CPU to manage L2 processing. 

So that clears that up.