TeraHertz WiFi Moves Closer as Scientists Achieve Speeds of 34Gbps+

Researchers from Japan have managed to boost the speed of WiFi data transmissions to 34Gbps (Gigabits per second) by harnessing the 500GHz band of radio spectrum, which falls within the TeraHertz range (300GHz+). Even faster speeds are coming, but distance may be a problem.

At present most home WiFi networks use the 2.4GHz and 5GHz bands, which with the right setup can deliver more or less “whole home” coverage and top speeds of up to several Gigabits per second (note: you’d have to be sitting right on top of the router to get that). A minority of routers are also starting to harness 60GHz for ultrafast short-range connectivity too.

However over the past two years we’ve seen a growing focus on developing wireless communications using the higher frequency TeraHertz (THz) band, such as this one where a team demonstrated a 160Gbps wireless transmission by using one THz emitter and modulating 25GHz spaced 8 channels (20 Gbps per channel) in the 300-500 GHz band.

We’ve also reported on another team that claimed it could hit 100Gbps by pushing into the TeraHertz band (here), but the viable range of such an approach has tended to be a problem. Many such lab tests have measured the distance of their transmissions in centimetres, which is rather limiting.

Now a team from the Tokyo Institute of Technology (TIT – *childish giggle*), which since 2012 has been working on the direct intensity modulation and wireless data transmission characteristics of terahertz-oscillating resonant tunnelling (RTD), has managed to achieve a speed of 34Gbps in the 500GHz band and they think its final range could reach up to 10 metres.

Crucially this setup works at room temperature and the device size could be made much smaller, which would make using THz frequencies in Smartphones’ a realistic option. So it might not be as fast as some experiments, but it’s arguably much closer to becoming a commercially viable solution.

Naoto Oshimo, One of the Authors of the Research, said:

“Using the improved device, an error-free transmission up to a data rate of 22 Gbit/s, and a transmission with a bit error rate less than the forward error correction limit up to 34 Gbit/s, was achieved. The device performance is almost sufficient for short-distance wireless communication such as KIOSK downloads, which might be its first application.”

Previously one of the problems with getting higher speeds to work in such a setup has been the low cut-off frequency of the modulation (RTD oscillator) at 1.5GHz, which limits the speed to a maximum of 3Gbps. However Naoto’s team were able to go much faster by cutting out the “parasitic components” of the RTD and thus improving the cut-off frequency to 15GHz. The output power for this is still low, at ∼60 µW.

The THz frequency range is handy because it’s home to ultra-wide bandwidth of several tens of GHz, which makes it potentially suitable for short-range speeds of 100Gbps+ and in fact Naoto expects to achieve a sharp rise in speed that might eventually deliver data rates in excess of 1Tbps (Terabit per second)! Check out the IET Digital Library for the relevant paper (paywall).

We should point out that the power levels for all this are likely to be kept quite low and so should NOT become a health hazard. However at present the THz frequency is only available for research purposes, although this is expected to be debated at the 2019 World Radiocommunications Conference (WRC).