Some of the world's biggest 5G equipment suppliers have begun putting lower spectrum bands – those between 7 GHz and 20 GHz – at the centre of their pitches for 6G. That's a big change from the early 5G noise that centred on the very narrow-band millimetre wave (mmWave) spectrum bands, which run from 24GHz to 40GHz, and earlier 6G speculation that focused on the very narrow terahertz bands above 90GHz.
The terahertz bands suffer from propagation challenges that are even more acute than those facing the mmWave spectrum bands. Signals travel farther in lower bands due to physics, so transmissions in the THz bands may only travel a few feet, whereas transmissions in the mmWave band can sometimes travel several hundred feet. Yet higher bands – like the mmWave bands or the THz bands – are alluring because they are relatively vacant and can handle massive amounts of data.
Because of these inevitable coverage issues, the big 5G vendors now see the THz bands playing a supportive role rather than a leading one in 6G.
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