Kumu Networks brings full-duplex to MWC

Kumu Networks (Kumu)
With Kumu's self-interference cancellation, access and backhaul radios can operate simultaneously on the same frequency. Image: Kumu Networks

BARCELONA, Spain—It’s been a long time since a couple of students at Stanford University questioned why radios don’t transmit and receive in the same channel at the same time. But now the result of that line of questioning, a company called Kumu Networks, is at Mobile World Congress 2017 to talk about how, for the first time, its full-duplex technology is going to be deployed in large, commercial networks as a general availability (GA) product.

Steven Hong, director of Product and a co-founder of Kumu Networks, wouldn’t reveal which carrier in Europe is deploying the product, but he did say it’s particularly conducive to Europe due to the region’s lack of fiber and the density of the area.

“Our first GA product is actually already deployed in Europe and through the course of 2016, we’ve got several commercial field trials to prepare for these deployments and this is the first year to be deploying with commercial GA customers,” Hong told FierceWirelessTech.

But the field trials in 2016 were still two- or three month-deployments to evaluate the technology and use cases to find out where operators would find the most value. This year, “we’re beginning to sell the products in ‘relatively reasonable quantities,’” he said.

That’s a big step for a relatively small company that started in a classroom in 2009 where students questioned how radios were programmed. “All the textbooks that we had read to that point, they just said that it was impossible,” to transmit and receive on the same channel at the same time, he said. “But the second line after ‘impossible’ was it’s impossible because of self-interference. We dug into that. We found that interference is not necessarily an insurmountable obstacle. It is very challenging to eliminate, but it’s not impossible and given the advancements in the performance of the RF components as well as the availability and the lowered cost of compute, it was the time” to use signal processing to increase spectral efficiency and eliminate interference.

Two professors and three PH.d graduates started Kumu. From 2009 to 2012, they spent time researching the theory and raised their first round of venture capital financing in late 2012. The company’s financiers now include several operators—Verizon Ventures, Deutsche Telecom, SingTel Group, Swisscom—and Cisco, among others.   

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At a high level, Kumu has been developing a self-interference technology that allows a radio to completely silence its own transmission, such that it can receive in the same band. The long-term application is to double the spectral efficiency of all the users, but the intermediate effect is where it has developed the product initially: in the full-duplex relay application.

Hong said they’re deploying the cancellation effectively in the relay that sits in between the base station and the phone, so the relay acts as a full duplex mesh network where you’re able to receive from the base station on one side and simultaneously transmit to the user on the other side. Essentially, it’s a self-backhaul small cell that can be deployed anywhere there’s LTE coverage and it enhances the capacity of the network by bringing the users closer to the macro network in terms of the signal strength. “The relay itself has a high-gain directional antenna that allows it to get a very, very good signal and is able to propagate that signal down to all the users,” he added.

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The full duplex relay product is being deployed in a commercial cellular network in Europe and while he can’t disclose the name of the operator, more operators are expected later this year. “In Europe, we’ve seen that the kind of lack of fiber infrastructure plus the capacity demands really necessitate a solution like ours,” he said.

Also good news for operators, Kumu has been exploring a new architecture where cancellation technology is deployed only in the base station and it’s able to achieve full duplex without deploying the cancellation at the handset. It’s not quite small enough yet to go into smartphones. “But we think we can achieve the doubling of spectral efficiency without putting it in the phones,” he said. “A lot of operators are very excited about that,” and eyeing it leading up to the 5G standards.