The reason 6Ghz was introduced with WiFi 6E and 7 was because 2.4Ghz and 5Ghz was very busy.
My question is why isn’t there anything in between? Why isn’t there a 3Ghz, 3.5Ghz, 4Ghz, etc?
Also, what if things that require very little data transmission used something lower than 2.4Ghz for longer range? (1Ghz or something?)
Its regulation. You are not allowed to just use any frequency band. 2.4 GHz is free to use for whatever, so a lot of stuff uses it. 5 GHz is already in radar range so the chips have to detect and turn off when detecting radar.
6ghz is even more fun. They must operate and low power unless a gps transceiver is attached to confirm its not interfering with someone that has a license to operate in that location.
ah that makes sense.
2.4 GHz and 5 GHz are both “ISM bands.” These are frequencies that regulators have set aside for unlicensed use.
Fun fact: 2.4 GHz is free to use because of microwave ovens. Microwaves are really noisy around 2.45 GHz. Rather than try to regulate their radio emissions, or make people license their kitchen appliances as radio transmitters, the FCC allocated that patch of spectrum for free use. Any device that can tolerate the noise can use that bit of the radio spectrum.
Ah so the stuff in between that has things like radio stations?
I’m not sure what exactly you mean by “in between” here (between 2.4 and 5 GHz?), but commercial radio in the US is at much lower frequencies than wifi bands. AM radio is typically measured in KHz (the range is something like 600-1400, I can’t be bothered to look it up), while FM radio is in MHz (around 87-108 MHz).
Not like commercial AM/FM radio stations playing music, but radio in the more general sense. 5G cell phones and satellite-to-earth communication systems use that frequency range, for example.
makes sense, using WiFi with those frequencies would make it noisy and clogged up, esp. in crowded cities
Some parts of the spectrum in between 2.4 and 5 GHz are used by the mobile communication standards LTE and 5G (also higher frequencies). GSM, DVB-T, and FM radio operate at lower frequencies.
ah that makes sense
But, the key takeaway there is that those portions of the spectrum where mobile bands are are restricted to those uses. 2.4 and 5 are “free bands,” in which any device can use them (assuming compliance with FCC part 15 in the US). If I built a device and operated it at say 4.3GHz, I’d get in big trouble once found.
Indeed, the regulation authority, e.g. the Bundesnetzagentur in Germany, will knock on your door and inspect your radio and wifi devices. That way, some years ago they’ve found a malefunctioning radio alarm clock in my area.
Also, what if things that require very little data transmission used something lower than 2.4Ghz for longer range? (1Ghz or something?)
No one seemed to touch upon this part, so I’ll chime in. The range and throughput of a transmission depends on a lot of factors, but the most prominent are: peak and avg output power, modulation (the pattern of radio waves sent) and frequency, background noise, and bandwidth (in Hz; how much spectrum width the transmission will occupy), in no particular order.
If all else were equal, changing the frequency to a lower band wouldn’t impact range or throughput. But that’s hardly ever the case, since reducing the frequency imposes limitations to the usable modulations, which means trying to send the same payload either takes longer or uses more spectral bandwidth. Those two approaches have the side-effect that slower transmissions are more easily recovered from farther away, and using more bandwidth means partial interference from noise has a lesser impact, as well as lower risk of interception. So in practice, a lower frequency could improve range, but the other factors would have to take up the slack to keep the same throughput.
Indeed, actual radio systems manipulate some or all of those factors when longer distance reception is the goal. Some systems are clever with their modulation, such as FT8 used by amateur radio operators, in order to use low-power transmitters in noisy radio bands. On the flip side, sometimes raw power can overcome all obstacles. Or maybe just send very infrequent, impeccably narrow messages, using an atomic clock for frequency accuracy.
To answer the question concretely though, there are LoRa devices which prefer to use the ISM band centered on 915 MHz in The Americas, as the objective is indeed long range (a few hundred km) and small payload (maybe <100 Bytes), and that means the comparatively wider (and noisier) 2.4 GHz band is unneeded and unwanted. But this is just one example, and LoRa has many implementations that change the base parameters. Like how MeshCore and Meshtastic might use the same physical radios but the former implements actual mesh routing, while the latter floods to all nodes (a bad thing).
But some systems like WiFi or GSM can be tuned for longer range while still using their customary frequencies, by turning those other aforementioned knobs. Custom networks could indeed be dedicated to only sending very small amounts of data, like for telemetry (see SCADA). That said, GSM does have a hard cap of 35 km, for reasons having to do with how it handles multiple devices at once.
Radio engineering, like all other disciplines of engineering, centers upon balancing competing requirements and limitations in elegant ways. Radio range is the product of intensely optimizing all factors for the desired objective.
Is it due to cost? Does adding more frequencies increase the cost? (maybe that’s why WiFi 6E and 7 routers are so expensive)
Or is it because of compatibility? It would be more difficult to get everyone to agree on so many different wireless frequencies.
Or maybe it’s because of interference? Maybe adding things in between 2.4Ghz and 5Ghz would make the network harder to read as things like 3Ghz, 4Ghz, etc. are too close to either 2.4Ghz and 5Ghz. But if that’s the case, how is 6Ghz okay?
Or maybe things in between 2.4Ghz and 5Ghz ARE being used, but for different things that would break if WiFi started to use them, and if so, what are those things?
Or maybe things in between 2.4Ghz and 5Ghz ARE being used, but for different things that would break if WiFi started to use them, and if so, what are those things?
Warning, this is an extremely large image. You will need to open it in it’s own window and zoom in.
Once you have opened it in a new window, I’m sure you will be able to tell that the entire radio frequency spectrum is absolutely fucking packed to the gills. It’s all accounted for, everything from 3kHz to 300 GHz.
Also, 2.4GHz is the frequency put out by microwave ovens, so they actually do interfere with 2.4GHz Wi-Fi and Bluetooth.
Finally, this is just how the US allocates the radio spectrum. Every country actually has their own different allocation system. If I recall correctly, Wi-Fi bands in the UK are slightly different.
EDIT: Actually, just noticing that this is actually 22 years out of date, since it’s from 2003 (bottom left of image). Things have been changed around and re-allocated several times since then, but you get the idea. There’s a lot of groups who want access to these frequencies. Government agencies, military communications, space exploration, satellite communications, cellular telephone service, television broadcasting, civilian band radio, wi-fi and so on.
Here’s a massive list of the UK allocations: https://static.ofcom.org.uk/static/spectrum/fat.html
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