Research Nudges Terabit Wireless Speeds, but What's the Range?

Japanese researchers are now topping speeds of 100 Gbit/s over a wireless connection -- or over 100 times faster than today's speediest 4G LTE network -- but the question of what range such a signal can cover is as yet unanswered.

Researchers from Hiroshima University and the National Institute of Information and Communications Technology in Japan said Monday that they have developed a terahertz (THz) transmitter capable of transmitting "data at a rate exceeding 100 gigabits per second over a single channel." They add that this translates to being able to download a DVD's worth of data over-the-air in a fraction of a second.

Those 100Gbit/s-plus speeds, by the way, equal 0.1 terabit per second. The researchers say that means the system -- developed with Panasonic Corp. (NYSE: PC) -- enables a connection ten times faster than future 5G networks. This depends, however, on who is talking about 5G speeds. In the US, we've already seen speeds ranging from anywhere between 1 Gbit/s and 15 Gbit/s talked about in different 5G trials. (See Verizon Hits 1-Gig+ in 5G Trials, Eyes Early Applications and US Cellular Tests Fixed 5G With Ericsson .)

The researchers used a single 300GHz channel for the terahertz antenna transmissions. This means that the system is operating at the very highest edge of the millimeter wave band. Millimeter wave (mmWave) radios broadcast on frequencies ranging from 30GHz to 300GHz. Signals above 100GHz are also defined as transmissions in the "terahertz band." (See 60GHz: A Frequency to Watch.)

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This is why the question of antenna signal range is interesting. Terahertz band signals get extremely attenuated over distances of meters rather than kilometers, even with sensitive transmitter and receiver systems.

I've written to the Hiroshima University researchers, asking for details on the range of their terahertz transmitter system. I'll update the story if I get further information.

— Dan Jones, Mobile Editor, Light Reading

Duh! 2/7/2017 | 5:42:31 PM
Re: Say again? Thanks for the link.  It makes sense, now.

The answer to my question: the channel is 290-315 GHz, or 25 GHz wide.

It looks like the main accomplishment was in semiconductor and package engineering, rather than communications engineering. The former paves the way for research and development in the latter.
DanJones 2/6/2017 | 5:00:12 PM
Re: Say again? 105-Gbit/s at 300GHz.

Per the University press release:

"Hiroshima, Japan--Hiroshima University, National Institute of Information and Communications Technology, and Panasonic Corporation announced the development of a terahertz (THz) transmitter capable of transmitting digital data at a rate exceeding 100 gigabits (= 0.1 terabit) per second over a single channel using the 300-GHz band."

Hence "nudging" maybe I should have said barely grazing, not even within spitting distance?

See: https://eurekalert.org/pub_releases/2017-02/hu-twc020317.php

Duh! 2/6/2017 | 4:26:20 PM
Say again? Mr. Jones,

Your article keeps confusing frequency (in Hertz) and bit rate (in bits per second). I'm not sure how to read it. 

Are they transmitting at 1 T bit/s, per the headline, or 100 G bit/s, per the second paragraph?

Are they using a channel that is 300 GHz wide (as in a spectral efficiency of .33 bits/second per Hz)? Or it is a channel of some unspecified bandwidth up in the 300 GHz band? If the latter, what is the bandwidth of that channel and what is the spectral efficiency that they achieved in their experiment?
DanJones 2/6/2017 | 2:44:13 PM
Can't wait to see prototype terahertz devices Like a small truck, you reckon?
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