4 ms·

A novel channel contention mechanism for improving wi-fi's reliability

93 points by belter 2y ago

mark254 2y ago
Sounds like Token Ring...
- gonzo 2y ago
  A token ring like protocol was in an early proposal for what became 802.11
greatgib 2y ago
Regarding how commonly are used wifi and Bluetooth in our everyday life. I don't understand why we haven't more frequency bands available for it. It is more in the public interest than a lot of useless private initiatives like WiMAX that can easily get large frequency bands.
- johnwalkr 2y ago
  On the other hand it seems like a miracle that wifi works pretty seamlessly globally, and there are no countries where you have to pay to use a proprietary service instead.
- PhilipRoman 2y ago
  6GHz is definitely a step in the right direction. Also filters out all the poor people with old devices so you can enjoy radio silence on your 320MHz channel ;)
  - vlovich123 2y ago
    Temporary solution until within 5-10 years everyone has upgraded their routers and devices to sit on 6ghz, 5ghz, and 2.4ghz.
    - dweekly 2y ago
      Eh, also doesn't go as far, which forces higher deployment densities, which helps.
      - vlovich123 2y ago
        The propagation differences between 5Ghz and 6Ghz are minimal compared with 2.4Ghz vs 5Ghz. In fact, given that there's a bunch of other protocol & HW improvements, it wouldn't be surprising to see identical 6Ghz and 5Ghz deployment density.
- the_mitsuhiko 2y ago
  > I don't understand why we haven't more frequency bands available for it Do we really need more frequency? At this point it does not seem like the challenge for Wifi quality is actually the available frequency spectrum. In fact, I have a lot of devices still in this household that cannot connect to more than 2.4GHz and that is not a question of available spectrum but that supporting all those frequency bands apparently is too costly for some chips on the market.
  - foota 2y ago
    Perhaps if the bands were wider it would provide sufficient incentive for adoption, since there would be more channels available (and a wider band would presumably be easier than two separate bands that are further apart).
  - wongarsu 2y ago
    In any moderately dense city environment, apartment complexes, or high traffic areas you can absolutely feel the effects of a lack of frequencies. In American suburbia it might not matter much, but it's definitely an issue for the rest of us
    - the_mitsuhiko 2y ago
      I’m in a dense apartment block in Vienna. The walls are thick enough that I barely see two WiFi’s. Automatic band selection means we end up in different frequencies.
      - AlotOfReading 2y ago
        Not everywhere in the world uses the same concrete walls. It's quite common to see dozens of access points trying to share the same three 20MHz channels available at 2.4GHz in places like the US or dense areas in Asia.
        leguminous 2y ago
        I live in the US and I just counted 65 visible APs on 5GHz. The DFS channels aren't usable in this area, so almost all of those are trying to share the same 2 80MHz channels.
- vkdelta 2y ago
  WiMAX has been dead for more than a decade now. Pretty rest of the spectrum is allocated to licensees for cellular/LTE/5G and other military applications.
- stefan_ 2y ago
  Keep this in mind when someone tells you again what a beautiful demonstration of capitalism the "spectrum auctions" are. Most bits move over spectrum no one paid for.
- Avamander 2y ago
  I think we could utilise the current bands much better than we currently do. As others have mentioned here there are a lot of devices violating the standards or not implementing the parts that would alleviate congestions/interference. I've personally seen plenty of devices that insist on 40MHz operation in an environment that can viably support only 20MHz. Then there's also 802.11ah for unlicensed sub 1GHz networks and 802.11af for licensed networks. If implemented properly, could shift some usage to other bands (especially if those devices can't handle modern features or require excessive transmission power to be reachable). Though giving everyone channel 13 and 14 would indeed be quite nice. It's clear that we can't get rid of 2.4GHz operation.
anotherhue 2y ago
I worked in this field for a while, and had my own novel mechanism for solving a problem. The major issue I had and I suspect this will have, is with devices that don't play by the rules. The unit economics mean the manufacturer is going to squeeze everything out, and if they can 'cheat' and claim higher numbers they will. Back ten years ago the issue was devices ignoring CTS frames but this feels similar.
- avidiax 2y ago
  When I worked on WiFi at Microsoft, we discovered that Apple was cheating. Apple was implemented a random backoff timer to have less range than the spec, which would mean that Apple devices win most contentions. We decided not to copy this into Windows, since it would be a race to the bottom.
  - ajb 2y ago
    Wow. Do you (or anyone) know if they still do it? Was there any pushback on them?
    - avidiax 2y ago
      I don't know. It's possible that it was merely a bug, and maybe it was fixed at some point. But it's also not something that would cause noticeable issues on a network. Apple devices performing slightly better wouldn't be a big red flag. There are many reasons that this could be the case, from a better implementation, better testing, better HW (antennas), a different OS with a better TCP stack, etc.
  - Salgat 2y ago
    What's the legality of devices intentionally violating wifi standards and causing potential issues with other devices? Is this something the FCC could act on?
    - linuxlizard 2y ago
      There's no laws about it. It's mostly a "handshake agreement" enforced via the WiFi Alliance. You go through the WFA certification process to get the "WiFi Certified" sticker. https://www.wi-fi.org/certification https://www.wi-fi.org/certification Usually large vendors try to do the right thing.

93 points by belter 2y ago

mark254 2y ago

Sounds like Token Ring...

gonzo 2y ago
A token ring like protocol was in an early proposal for what became 802.11

greatgib 2y ago

Regarding how commonly are used wifi and Bluetooth in our everyday life. I don't understand why we haven't more frequency bands available for it. It is more in the public interest than a lot of useless private initiatives like WiMAX that can easily get large frequency bands.

johnwalkr 2y ago
On the other hand it seems like a miracle that wifi works pretty seamlessly globally, and there are no countries where you have to pay to use a proprietary service instead.
PhilipRoman 2y ago
6GHz is definitely a step in the right direction. Also filters out all the poor people with old devices so you can enjoy radio silence on your 320MHz channel ;)
- vlovich123 2y ago
  Temporary solution until within 5-10 years everyone has upgraded their routers and devices to sit on 6ghz, 5ghz, and 2.4ghz.
  - dweekly 2y ago
    Eh, also doesn't go as far, which forces higher deployment densities, which helps.
    - vlovich123 2y ago
      The propagation differences between 5Ghz and 6Ghz are minimal compared with 2.4Ghz vs 5Ghz. In fact, given that there's a bunch of other protocol & HW improvements, it wouldn't be surprising to see identical 6Ghz and 5Ghz deployment density.
the_mitsuhiko 2y ago
> I don't understand why we haven't more frequency bands available for it Do we really need more frequency? At this point it does not seem like the challenge for Wifi quality is actually the available frequency spectrum. In fact, I have a lot of devices still in this household that cannot connect to more than 2.4GHz and that is not a question of available spectrum but that supporting all those frequency bands apparently is too costly for some chips on the market.
- foota 2y ago
  Perhaps if the bands were wider it would provide sufficient incentive for adoption, since there would be more channels available (and a wider band would presumably be easier than two separate bands that are further apart).
- wongarsu 2y ago
  In any moderately dense city environment, apartment complexes, or high traffic areas you can absolutely feel the effects of a lack of frequencies. In American suburbia it might not matter much, but it's definitely an issue for the rest of us
  - the_mitsuhiko 2y ago
    I’m in a dense apartment block in Vienna. The walls are thick enough that I barely see two WiFi’s. Automatic band selection means we end up in different frequencies.
    - AlotOfReading 2y ago
      Not everywhere in the world uses the same concrete walls. It's quite common to see dozens of access points trying to share the same three 20MHz channels available at 2.4GHz in places like the US or dense areas in Asia.
      - leguminous 2y ago
        I live in the US and I just counted 65 visible APs on 5GHz. The DFS channels aren't usable in this area, so almost all of those are trying to share the same 2 80MHz channels.
vkdelta 2y ago
WiMAX has been dead for more than a decade now. Pretty rest of the spectrum is allocated to licensees for cellular/LTE/5G and other military applications.
stefan_ 2y ago
Keep this in mind when someone tells you again what a beautiful demonstration of capitalism the "spectrum auctions" are. Most bits move over spectrum no one paid for.
Avamander 2y ago
I think we could utilise the current bands much better than we currently do. As others have mentioned here there are a lot of devices violating the standards or not implementing the parts that would alleviate congestions/interference. I've personally seen plenty of devices that insist on 40MHz operation in an environment that can viably support only 20MHz. Then there's also 802.11ah for unlicensed sub 1GHz networks and 802.11af for licensed networks. If implemented properly, could shift some usage to other bands (especially if those devices can't handle modern features or require excessive transmission power to be reachable). Though giving everyone channel 13 and 14 would indeed be quite nice. It's clear that we can't get rid of 2.4GHz operation.

anotherhue 2y ago

I worked in this field for a while, and had my own novel mechanism for solving a problem. The major issue I had and I suspect this will have, is with devices that don't play by the rules. The unit economics mean the manufacturer is going to squeeze everything out, and if they can 'cheat' and claim higher numbers they will. Back ten years ago the issue was devices ignoring CTS frames but this feels similar.

avidiax 2y ago
When I worked on WiFi at Microsoft, we discovered that Apple was cheating. Apple was implemented a random backoff timer to have less range than the spec, which would mean that Apple devices win most contentions. We decided not to copy this into Windows, since it would be a race to the bottom.
- ajb 2y ago
  Wow. Do you (or anyone) know if they still do it? Was there any pushback on them?
  - avidiax 2y ago
    I don't know. It's possible that it was merely a bug, and maybe it was fixed at some point. But it's also not something that would cause noticeable issues on a network. Apple devices performing slightly better wouldn't be a big red flag. There are many reasons that this could be the case, from a better implementation, better testing, better HW (antennas), a different OS with a better TCP stack, etc.
- Salgat 2y ago
  What's the legality of devices intentionally violating wifi standards and causing potential issues with other devices? Is this something the FCC could act on?
  - linuxlizard 2y ago
    There's no laws about it. It's mostly a "handshake agreement" enforced via the WiFi Alliance. You go through the WFA certification process to get the "WiFi Certified" sticker. https://www.wi-fi.org/certification https://www.wi-fi.org/certification Usually large vendors try to do the right thing.