‘Fiber-in-air’ 5G network research gets funding

Wireless transmission at data rates of around 45gbps could one day be commonplace, some engineers say. “Fiber-in-air” is how the latest variant of 5G infrastructure is being described. To get there, a Britain-funded consortium of chip makers, universities, and others intend to aggressively investigate the exploitation of D-Band. That part of the radio spectrum is at 151-174.8 GHz in millimeter wavelengths (mm-wave) and hasn’t been used before.

The researchers intend to do it by riffing on a now roughly 70-year-old gun-like electron-sending device that can trace its roots back through the annals of radio history: The Traveling Wave Tube, or TWT, an electron gun-magnet-combo that was used in the development of television and still brings space images back to Earth.

D-Band, the spectrum the researchers want to use, has the advantage that it’s wide, so theoretically it should be good for fast, copious data rates. The problem with it though, and the reason it hasn’t thus far been used, is that it’s subject to monkey-wrenching from atmospheric conditions such as rain, explains IQE, a semiconductor wafer and materials producer involved in the project, in a press release. The team says attenuation is fixable, though. Their solution is the now-aging TWTs.

The group, which includes BT, Filtronic, Glasgow University, Intel, Nokia Bell Labs, Optocap, and Teledyne e2v, has secured funding of the equivalent of $1.12 million USD from the U.K.’s Engineering and Physical Sciences Research Council (EPSRC). That’s the principal public funding body for engineering science research there.

Tapping the power of TWTs

The DLINK system, as the team calls it, will use a high-power vacuum TWT with a special, newly developed tunneling diode and a modulator. Two bands of 10 GHz, each will deliver the throughput, explains Lancaster University on its website. The tubes are, in fact, special amplifiers that produce 10 Watts. That’s 10 times what an equivalent solid-state solution would likely produce at the same spot in the band, they say. Energy is basically sent from the electron beam to an electric field generated by the input signal.

Despite TWTs being around for eons, “no D-band TWTs are available in the market.” The development of one is key to these fiber-in-air speeds, the researchers say.

They will include “unprecedented data rate and transmission distance,” IQE writes.

The TWT device, although used extensively in space wireless communications since its invention in the 1950s, is overlooked as a significant contributor to global communications systems, say a group of French researchers working separately from this project, who recently argue that TWTs should be given more recognition.

TWT’s are “the unsung heroes of space exploration,” the Aix-Marseille Université researchers say in an article on publisher Springer’s website. Springer is promoting the group’s 2019-published paper in the European Physical Journal H in which they delve into the history of the simple electron gun and magnet device.

“Its role in the history of wireless communications and in the space conquest is significant, but largely ignored,” they write in their paper.

They will be pleased to hear it maybe isn’t going away anytime soon.