There are vRAN challenges to overcome – Industry Voices: Madden

Rakuten Mobile has done a good job in building its open vRAN network. After some initial struggles and heroic engineering efforts, it’s on air and it’s working. Hats off to CTO Tareq Amin and his team for proving that vRAN works.

But the problem Rakuten tackled was one-dimensional: getting coverage for an entirely new network. At least at the beginning, high capacity is not necessary, because it has a certain time to build up the capacity of the network. As Rakuten plans for its future success, it clearly recognizes that further improvements are needed. Amin recently commented: “The part that I think the industry desperately needs to address and correct is the DU for radio access… I think the DU of the current open RAN platform is absolutely not. not optimal. And there is a lot missing to do. it’s competitive.

What it is trying to say is that the Virtual Distributed Unit (vDU) available in the market, in most cases, cannot handle some of the high capacity features of 4G / 5G, such as the carrier aggregation, CoMP and interference coordination. These features are essential in LTE networks deployed in single-vendor networks, where proprietary interfaces allow coordination between radios and multiple DUs.

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Industry will add these features. We can expect the O-RAN Alliance and other organizations to standardize interfaces that enable more advanced functionality in an open environment, and companies like Intel are doing a great job of implementing advanced vDU functionality in hardware. standard server. Rakuten should be able to upgrade the software for more capacity as it adds clients over the next few years…. like a Tesla customer who improves their car’s performance with a software upgrade.

RELATED: It’s Now Or Never For vRAN – Industry Voices: Madden

The discussion does not end there. The entirely new networks (Rakuten and DISH) represent only a small part of the overall market. The real challenge is to virtualize a 5G network that coordinates the new spectrum and the existing radios in the old spectrum. Older radios may be running LTE today, or they may have already been software upgraded to 5G NR. They use dynamic spectrum sharing (DSS) in many cases to perform both formats. They use Carrier Aggregation (CA), CoMP, eICIC and other features to extract capacity from these congested legacy networks.

The challenge is to virtualize without sacrificing already optimized legacy performance. Operators cannot abandon CA and DSS for the benefits of the flexibility and scalability of virtualization. This is why we have seen some operators using a vCU only in their 5G deployment, and not a full vRAN with both vCU and vDU.

As with O-RAN networks, I believe that proprietary legacy networks will be able to implement a vDU and achieve high capacity performance at the same time. We see Verizon rolling out the vCU with Samsung now, and Ericsson has launched its vDU with coordination capability between the new spectrum and 7 million existing radios in the field.

In fact, Ericsson coined the term “blue field,“instead of using the terms“ brownfield ”or“ greenfield. ”The distinction is that a“ brownfield ”network is an anchor that the operator has to hang around, like an old 3G network that takes a long time to s On the other hand, a “bluefield” network has the ability to use features like DSS and Carrier Aggregation to coordinate traffic across multiple bands and achieve high capacity. Legacy network becomes an asset, not a liability. .

At the enterprise level, the big question now is whether it is too late for vDU to gain momentum in the 5G cycle. We’ve already seen the huge rollout of 5G in China without vDUs. We are seeing some deployment of vCUs without vDUs in other advanced networks. Even aggressive Korean and Japanese operators refrained from using a vDU. So much of the market has already grown without a real vRAN. After installing dedicated DU hardware, no one will tear it off and replace it with COTS servers.

It’s now. The US deployment of C-band is the last great opportunity to launch this technology on a large scale… or the vRAN will have to wait a few years. Samsung has already deployed its vDU for Verizon in the low bands commercially, and deploys the Verizon vDU in C-band for its commercial service from a few months. We expect Ericsson to also deploy its vDU for Verizon’s C-band network this year. Both of these vendors support advanced high-capacity features that optimize the combination of low-band and C-band radios.

In my predictions, I recently predicted that we will see the US operators come forward and operate the vDU … having been driving a market for over $ 4 billion worth of vDU software In the coming years. This is starting to happen, and we have proof of that with success at Rakuten, followed by success in a coordinated bluefield network at Verizon.

Joe Madden is a Senior Analyst at Mobile Experts, a network of market and technology experts who analyze wireless markets.

“Industry Voices” are opinion columns written by external contributors, often industry experts or analysts, who are invited to the conversation by FierceWireless staff. They do not represent the views of FierceWireless.