3 ms·

Rather the opposite, actually. The allowed broadcast strength in the 2.4GHz band is so high that in a (sub)urban environment you won't just receive your own ne

by crote 3y ago

Rather the opposite, actually. The allowed broadcast strength in the 2.4GHz band is so high that in a (sub)urban environment you won't just receive your own network, but also those of literally a dozen neighbors around you - and there are plenty of areas in your house where you can receive your neighbor's network better than your own so you end up in a shouting match. And of course many people "solve" their poor wifi connection by adding a repeater or increasing the transmission power, which fixes the symptoms for them but makes the overall problem worse for everyone around them. 5Ghz has essentially solved the problem, simply because the signal gets killed real quick by things like walls - especially exterior ones. Your signal won't make it much beyond your house so you don't get in a shouting match with your neighbors, and adding a repeater (mostly) does what you'd expect it to.

ssl-3 3y ago
You touched on a couple of things, but I think that the main thing you're describing here is attenuation. 5GHz transmission is much more readily-attenuated by things like walls and trees than 2.4Ghz is, and that helps allow it to actually-work in denser environments. But it isn't so much an issue of power, I don't think: If we erased all of the existing 2.4GHz devices from the world and replaced them with devices that only transmitted 1/10th of the previous power (a 10dB reduction), then: We'd still have to contend with our neighbor's neighbors' 2.4GHz background noise. Like in a room where everyone is shouting all at once: You can't understand what the guy across the room is shouting because of all of the noise. But we still have the same problem in a room where everyone is carefully talking quietly all at once: You still can't understand the guy across the room because of all of the noise. The problem hasn't changed. (Sure, the noise is reduced, but the desired signal is also reduced by the same magnitude) Signal-to-noise ratio doesn't necessarily scale with overall amplitude.
- crote 3y ago
  It's not an issue of SNR. Wifi isn't allowed to transmit when it detects another station is already transmitting - it has to wait for clean air. By reducing everyone's power level the competing transmitter disappears into the noise floor, freeing up air for you to transmit on. A weak-ish signal which can transmit 100% of of the time is better than a strong signal which can only transmit 5% of the time. In theory you could indeed all shout at once, but that breaks down when your conversation partner is way closer to the other shouter - no matter how loud you shout, your message will always be overpowered and will only get through when you wait until the other shouter is silent. That's why wifi chooses to listen first.
  - ssl-3 3y ago
    It is a a simple issue of SNR. Even if we could somehow turn down all 2.4GHz transmitters (we cannot), that won't actually help -- it can never make things behave like 5GHz bands do. Relatedly, hypothetically increasing the transmit power of all 5GHz devices can never make it behave like 2.4GHz does. Walls will still attenuate the higher frequency more than the lower one, and this function of a wall is independent of transmission power. And Wifi devices are nowhere near as polite as you proclaim. They walk all over eachother all the time, for all kinds of reasons. (CCA improves this, but it isn't a magical antidote.) Furthermore, not all 2.4GHz transmitters are Wifi at all. There's (still) a ton of stuff in use on that ISM band, much of which has nothing at all to do with computers or Ethernet. A 2.4GHz video feed doesn't care about neighboring Wifi networks, for instance. It doesn't even have the ability to care. It just transmits video, using whatever modulation it uses to do that, without any regard at all for other users. There's a lot of reasons that 2.4GHz is completely trashed in many areas -- including such offenses as leaky microwave ovens. That's just how it is, and how it is likely to remain. Which sucks, but here we are anyway...

by crote 3y ago

ssl-3 3y ago

You touched on a couple of things, but I think that the main thing you're describing here is attenuation. 5GHz transmission is much more readily-attenuated by things like walls and trees than 2.4Ghz is, and that helps allow it to actually-work in denser environments. But it isn't so much an issue of power, I don't think: If we erased all of the existing 2.4GHz devices from the world and replaced them with devices that only transmitted 1/10th of the previous power (a 10dB reduction), then: We'd still have to contend with our neighbor's neighbors' 2.4GHz background noise. Like in a room where everyone is shouting all at once: You can't understand what the guy across the room is shouting because of all of the noise. But we still have the same problem in a room where everyone is carefully talking quietly all at once: You still can't understand the guy across the room because of all of the noise. The problem hasn't changed. (Sure, the noise is reduced, but the desired signal is also reduced by the same magnitude) Signal-to-noise ratio doesn't necessarily scale with overall amplitude.

crote 3y ago
It's not an issue of SNR. Wifi isn't allowed to transmit when it detects another station is already transmitting - it has to wait for clean air. By reducing everyone's power level the competing transmitter disappears into the noise floor, freeing up air for you to transmit on. A weak-ish signal which can transmit 100% of of the time is better than a strong signal which can only transmit 5% of the time. In theory you could indeed all shout at once, but that breaks down when your conversation partner is way closer to the other shouter - no matter how loud you shout, your message will always be overpowered and will only get through when you wait until the other shouter is silent. That's why wifi chooses to listen first.
- ssl-3 3y ago
  It is a a simple issue of SNR. Even if we could somehow turn down all 2.4GHz transmitters (we cannot), that won't actually help -- it can never make things behave like 5GHz bands do. Relatedly, hypothetically increasing the transmit power of all 5GHz devices can never make it behave like 2.4GHz does. Walls will still attenuate the higher frequency more than the lower one, and this function of a wall is independent of transmission power. And Wifi devices are nowhere near as polite as you proclaim. They walk all over eachother all the time, for all kinds of reasons. (CCA improves this, but it isn't a magical antidote.) Furthermore, not all 2.4GHz transmitters are Wifi at all. There's (still) a ton of stuff in use on that ISM band, much of which has nothing at all to do with computers or Ethernet. A 2.4GHz video feed doesn't care about neighboring Wifi networks, for instance. It doesn't even have the ability to care. It just transmits video, using whatever modulation it uses to do that, without any regard at all for other users. There's a lot of reasons that 2.4GHz is completely trashed in many areas -- including such offenses as leaky microwave ovens. That's just how it is, and how it is likely to remain. Which sucks, but here we are anyway...