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by devanl 1195 days ago
Setting aside issues that can be safety related where consumer equipment overlaps with legacy equipment, there is a tragedy of the commons effect to not attempting to regulate radio power limits.

It's incredible how well WiFi works for the amount of power it uses.

Obviously turning up the transmit power makes it better... for that one person. For everyone else, that channel has a little bit more noise than before, making it harder to receive their signal.

So maybe their neighbors will also want to increase their transmit power to get better range / speed again. Having a limit across the board for all mass manufactured devices prevents an escalating spiral of vendors selling 30, then 40, then 50dbm etc routers.

As mentioned elsewhere, different countries have different power limits, but it's more economical to make a single radio for all markets with software power limits. One hypothetical way for a vendor to get a market advantage is to sell a radio that is software limited, but wink wink can be patched with easily googled instructions to increase the power to work better. Maybe by downloading a tool from some sketchy website that even actually works and can be spammed across the internet or social media.

So the FCC has to strongly discourage anything that could lead to lots of radios deliberately exceeding the regulatory limits and disproportionately making the spectrum worse compared to a compliant device.

I don't think that necessarily justifies rather invasive schemes like geolocated AFC, but preserving the use of the radio spectrum so that everyone can make efficient use of it is the FCC's mandate.

1 comments

> It's incredible how well WiFi works for the amount of power it uses.

Actually, WiFi disproves that we'd have a tragedy of the commons.

> Having a limit across the board for all mass manufactured devices prevents an escalating spiral of vendors selling 30, then 40, then 50dbm etc routers.

No, the AP and the device both have a strong interest to limit the power used: not just to limit interference with other devices inside the home, but also to increase battery life!!

> but wink wink can be patched with easily googled instructions to increase the power to work better

I just don't understand why most posters here assume the worst by default. Most people are nice and want to obey the law.

WiFi proved that very little legal oversight was necessary to make it work.

In fact, it did the opposite: by comparing the efficiency of the use of the 2.4Ghz band (noisy with microwaves etc) to the rest of the spectrum managed by the heavy hand of the FCC, any reasonable person would argue for removing regulations or more parts of the spectrum (starting maybe with the huge chunks waste on HAM radio!)

> No, the AP and the device both have a strong interest to limit the power used: not just to limit interference with other devices inside the home, but also to increase battery life!!

For home routers this is a weak argument. Since most people download more than they upload, you could probably send a weaker signal from mobile devices and drown the air with signal from anything plugged into a wall socket.

> I just don't understand why most posters here assume the worst by default. Most people are nice and want to obey the law.

Maybe it's just where I live, but I don't see that on the road (people risking accidents to gain 30 seconds). People will only follow the law if they think it's worth their inconvenience and lots of people weight this in a bad way.

How many hand-tuned APs does it take to make a whole building lose significant bandwidth? After this the regulation has to become looser so the legal devices can keep working, and it never really gets better.

> you could probably send a weaker signal from mobile devices and drown the air with signal from anything plugged into a wall socket.

How exactly is your mobile device going to ACK those received packets? The mobile device needs to transmit as loudly as the AP for its ack to be received.

Boosting the transmit power higher than your receiving device can transmit leads to very bad wifi links, where the mobile device is receiving a good signal but it's own messages are not received back.

You can use different modulation rates to/from a device (this commonly happens). Lower modulation rates give you better SNR, letting your quiet client do slow weak ACKs to loud large chunks of data from the router.