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Global decisions are made by treaty, through a United Nations organization known as the ITU. Some allocations are harmonized globally. Others are divided up in

by tjohns 4y ago

Global decisions are made by treaty, through a United Nations organization known as the ITU. Some allocations are harmonized globally. Others are divided up into one of three global regions - roughly the Americas, Europe/Africa, and Asia/Oceania. Then these are further divided into one of 90 zones that roughly follow country-specific boundaries. All of this is decided very bureaucratically. In some cases decisions are constrained by the laws of physics (HF signals are going to bounce across the globe), in other cases by practical necessity (aviation/maritime allocations are harmonized to facilitate global movement of vessels, satellites are going to orbit across the globe). However, in some cases allocations will differ between ITU regions or zones (especially local broadcast and land-mobile communications users). Further, priority is usually given on a first-come/first-served basis, but harmonization is encouraged. Individual countries can modify their local allocations, provided this don't interfere with other global users. You can view the global allocations by looking up the ITU Radio Regulations, Article 5. (PDF here: https://www.itu.int/pub/R-REG-RR-2020 https://www.itu.int/pub/R-REG-RR-2020) If you're curious about the process behind all this, look up the World Radiocommunication Conference, which is held every ~3 years: https://en.wikipedia.org/wiki/World_Radiocommunication_Conference https://en.wikipedia.org/wiki/World_Radiocommunication_Confe...

derefr 4y ago
I presume that while "this is decided very bureaucratically", there are at least some use-cases where the use-case preceded the formation of any multilateral body to coordinate usage, and so is essentially "grandfathered in" where the ITU (or any predecessor body) said "I guess we're stuck with that." That's more the case I was curious about with the second one. Also — and this is sort of a hybrid case of "grandfathered in" and "practical necessity" — I presume that, despite the ITU making no ruling on such, the band centered around 2.45GHz has ended up being "commercial use" in pretty much every country? My thinking being that it is the lowest-cost-to-generate dielectric frequency for cooking food, so microwave ovens almost exclusively use that frequency; and microwave ovens are common in pretty much every country (or is there a country that outlaws microwave ovens?); so the local regulatory body of each country is inevitably stuck with that radio interference source on that band, mucking it up for any "dedicated, clear-channel" licensed use; and so they may as well give that band away to industry, to come up with noise-tolerant use-cases for it.
- tjohns 4y ago
  > there are at least some use-cases where the use-case preceded the formation of any multilateral body to coordinate usage The ITU-R was founded in 1927 (it was known as the CCIR back then). At that point, we were mostly worried about telegraph operators using spark gap transmitters, which have been effectively illegal since 1934. There's not much to grandfather in. > I presume that, despite the ITU making no ruling on such, the band centered around 2.45GHz has ended up being "commercial use" in pretty much every country? In the case of 2.45 GHz (the ISM bands), that's done under Part 15 rules (in the US, similar rules elsewhere) that allows for low-power, unlicensed transmitters. Your WiFi signal is intentionally run at extremely low power so that it won't travel more than a few hundred feet before it's attenuated by the environment, and in that frequency range there's no risk of it bouncing off the ionosphere. Meanwhile, your microwave oven is shielded to keep any signal leakage to a minimum. This falls under the "non-interference" provision I mentioned earlier - the signal is unlikely to leave your neighborhood, let alone leave your country, so the ITU doesn't care. They're more concerned with signals that travel hundreds or thousands of miles. If you check the ITU allocation, 2.45 GHz is allocated to radioloation (radar), licensed mobile radios, and fixed broadcast users. Plus a slice for amateur radio just below it. ISM use isn't even mentioned at this level. WiFi and microwave ovens are effectively secondary users here. They get to share any spectrum left over provided they don't interfere with the primary users - and can't complain if they receive interference from the primary users. (In other words: If the government complains that your microwave oven is interfering with their radar station, your microwave oven will lose. Guarenteed.)

by tjohns 4y ago

derefr 4y ago

I presume that while "this is decided very bureaucratically", there are at least some use-cases where the use-case preceded the formation of any multilateral body to coordinate usage, and so is essentially "grandfathered in" where the ITU (or any predecessor body) said "I guess we're stuck with that." That's more the case I was curious about with the second one. Also — and this is sort of a hybrid case of "grandfathered in" and "practical necessity" — I presume that, despite the ITU making no ruling on such, the band centered around 2.45GHz has ended up being "commercial use" in pretty much every country? My thinking being that it is the lowest-cost-to-generate dielectric frequency for cooking food, so microwave ovens almost exclusively use that frequency; and microwave ovens are common in pretty much every country (or is there a country that outlaws microwave ovens?); so the local regulatory body of each country is inevitably stuck with that radio interference source on that band, mucking it up for any "dedicated, clear-channel" licensed use; and so they may as well give that band away to industry, to come up with noise-tolerant use-cases for it.

tjohns 4y ago
> there are at least some use-cases where the use-case preceded the formation of any multilateral body to coordinate usage The ITU-R was founded in 1927 (it was known as the CCIR back then). At that point, we were mostly worried about telegraph operators using spark gap transmitters, which have been effectively illegal since 1934. There's not much to grandfather in. > I presume that, despite the ITU making no ruling on such, the band centered around 2.45GHz has ended up being "commercial use" in pretty much every country? In the case of 2.45 GHz (the ISM bands), that's done under Part 15 rules (in the US, similar rules elsewhere) that allows for low-power, unlicensed transmitters. Your WiFi signal is intentionally run at extremely low power so that it won't travel more than a few hundred feet before it's attenuated by the environment, and in that frequency range there's no risk of it bouncing off the ionosphere. Meanwhile, your microwave oven is shielded to keep any signal leakage to a minimum. This falls under the "non-interference" provision I mentioned earlier - the signal is unlikely to leave your neighborhood, let alone leave your country, so the ITU doesn't care. They're more concerned with signals that travel hundreds or thousands of miles. If you check the ITU allocation, 2.45 GHz is allocated to radioloation (radar), licensed mobile radios, and fixed broadcast users. Plus a slice for amateur radio just below it. ISM use isn't even mentioned at this level. WiFi and microwave ovens are effectively secondary users here. They get to share any spectrum left over provided they don't interfere with the primary users - and can't complain if they receive interference from the primary users. (In other words: If the government complains that your microwave oven is interfering with their radar station, your microwave oven will lose. Guarenteed.)