Japanese Scientists Push 100Gbps Wireless Broadband Using 300GHz

Last week we reported that Japanese scientists had managed to build a wireless network that could send data at a speed of 56Gbps (Gigabits per second) using the 72-100GHz (GigaHertz) radio frequency bands (here) and now another team claims it can hit 100Gbps by pushing into the TeraHertz (300GHz+).

At present most existing home WiFi networks prefer to use the 2.4GHz and 5GHz bands, with a few newer services (802.11ad) also starting to make use of 60GHz to deliver peak network speeds of around 4.6Gbps over a short distance. As a general rule, the higher the frequency the lower its coverage but the more data you can push (more frequency for you to use).

The future generation of 5G based Mobile Broadband services may also aim to harness the performance of even higher frequency ranges (e.g. 6GHz to 100GHz) for ultrafast speeds (10Gbps), although such networks would need much more powerful signals and a greater density of expensive infrastructure. Indoor coverage could also be a big problem as the signals would struggle to penetrate through walls.

By comparison the latest development of a TeraHertz (THz) transmitter (300GHz+), which was implemented as a silicon CMOS integrated circuit and can transmit a signal running at 10Gbps per data channel over multiple channels in the 275-305GHz band, is yet another big leap forwards.

Prof. Minoru Fujishima, Hiroshima University, said:

“Now THz wireless technology is armed with very wide bandwidths and QAM-capability [quadrature amplitude modulation]. The use of QAM was a key to achieving 100 Gigabits per second at 300 GHz.

Today, we usually talk about wireless data-rates in megabits per second or gigabits per second. But I foresee we’ll soon be talking about terabits per second. That’s what THz wireless technology offers. Such extreme speeds are currently confined in optical fibers. I want to bring fiber-optic speeds out into the air, and we have taken an important step toward that goal.

We plan to develop receiver circuits for the 300-GHz band as well as modulation and demodulation circuits that are suitable for ultrahigh-speed communications.”

However the practical problems of operating a wireless network in the THz band should not be underestimated and crucially we’re not told precisely what distance would be needed to achieve 100Gbps. For comparison, the speed of 56Gbps using the 72-100GHz band was only achieved over a distance of just 10cm (centimetres), but that wasn’t the same setup.

On the other hand the new approach could provide another way for devices, such as different parts of a computer, to communicate without needing to run a physical link between each section. Similarly it might potentially be used as a new means of connecting devices that are in close proximity, such as a TV and Tablet in your living room.

Sadly the THz band is presently only available for research purposes, although its future allocation is due to be discussed at the 2019 World Radiocommunications Conference (WRC). But it’s worth pointing out that the terahertz region also sits close to the region where lasers are associated, so there may be health considerations too.