I'm curious about the use cases for 275 ghz wireless communication, are microwave links still common? it's almost far infrared
Yes, they have their purposes. I work in finance and we use microwave links to talk between systems in Chicago & New York. Fiber links are the backup, here! The reason is purely latency as the bandwidth of the fiber links is orders of magnitude higher. The major downside is the microwave links drop quite frequently as they're sensitive to the totality of the weather between data centers (e.g. any sort of precipitation as a crow flies between NYC & CHI and there's potential for dropped links).
Optical has the advantage to bouncing off walls, but EHF may have bandwidth advantages.
This wouldn't be useful for microwave links since it is absorbed by the atmosphere and has short range.
275 GHz is one the edge of EHF. Terahertz is 300 GHz to 3 THz. Above that is infrared.
Nit-pick; 275GHz isn't terrible for atmospheric absorption. What gets you is the phase dispersion when the humidity is high.
> Requirements for 6G include extremely high data rates (>100 Gbit/s), ultra-low latency (<0.1 ms)....
> For the wireless communication of the 6G era, new radio frequency bands in sub-THz, ranging from 100 GHz to 300 GHz, have been identified as one of the most promising bands.
> There is also a technical challenge for seamlessly connecting wireless communication systems with fiber-optic communication networks
edit: forgot about 60ghz wifi