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I dropped out ouf the 802.11 business a few years ago but it seems I am still relevant, after all the article is about 802.11ac, not something about 802.11ax. O

I dropped out ouf the 802.11 business a few years ago but it seems I am still relevant, after all the article is about 802.11ac, not something about 802.11ax. On the technical side I agree with most of what the author says, but it is only a part of the larger picture. -First I did my own tests of 802.11ac in 2014 and the manufacturers were correct in their claims at that time. You have to understand that the best speed is when you are in ideal radio conditions and simply you are never in ideal conditions and most of the time you are even far from the ideal case. - Second, 802.11 sucks but not about raw speed, the MAC layer of most chip implementations is often ultra simplified and the outcome is that it is difficult to be authentified. This is strange as the Wi-Fi chip most often is a little computer and the MAC is implemented in software. - Third, there are unreasonable economic expectations by users as well as the article's author: Wait you want gigabit speeds, ultra-reliability in challenging radio conditions, and that at a tenth of the cost of a 3G mobile radio? - Fourth: Your phone has more hard time to cope with that throughput, than the Wi-Fi chip has. Android and Linux in general have many internal buffers because there are layers in charge of different features. The usable throughput is the raw radio throughput divided by the number of buffers. There are research OSes which use pointers instead of buffers, but Linux and Windows use buffers.

jimrandomh 9y ago
> The usable throughput is the raw radio throughput divided by the number of buffers. This is not true. Buffers can under some circumstances increase latency, or cause a TCP connection to take longer to get to its steady-state speed, but they don't hurt steady-state throughput unless something else is very wrong.
- JPLeRouzic 9y ago
  You are talking of yet another issue which is real and is related to the way TCP detects a congestion, but this is not specific to Wi-Fi. There are also problems of interoperability between TCP/IP and the Wi-Fi MAC layer, some of them could trigger congestion algorithms, but as the MCDU gets larger and larger this should not be a problem nowadays. Indeed it is a bit strange to have MCDU that are 64k large and IP packets that are 1.5k large. What I discussed was the way the buffers are in series inside the OS, this is known since a long time. A modern operating system throughput could be 5 to 9 faster than Linux: https://www.usenix.org/node/186147 https://www.usenix.org/node/186147
ajross 9y ago
> there are unreasonable economic expectations by users as well as the article's author: Wait you want gigabit speeds, ultra-reliability in challenging radio conditions, and that at a tenth of the cost of a 3G mobile radio? Honestly the big reason mobile radios are more reliable is that they're allowed to transmit at like 20x the power of devices in the ISM band. That's not a cost thing, it's just a regulatory issue steming from (some rather outdated) concerns about interference in the shared environment. I mean, it's true that wifi is sort of a mess. Marketing of the standards has gotten way ahead of real world hardware capability (frankly MIMO as it stands is basically voodoo snakeoil that provides no consumer benefit whatsoever). But it's no less complicated than all the junk going on in LTE either. Everything's a mess. Wifi continues to have the extraordinary advantages of being privately deployable, performant, pervasive, and standard (i.e. ethernet-framed, so everything Just Works the way everyone expects). It's not going anywhere.
- JPLeRouzic 9y ago
  I completely agree.
- freyr 9y ago
  > frankly MIMO as it stands is basically voodoo snakeoil that provides no consumer benefit whatsoever Curious why you say this. In the last few years, I've seen a significant increase in PHY data rate when using multiple spatial streams.
  - dmourati 9y ago
    I bought the snake oil in the form of a high end Ubiquiti WAP. Waiting for myco to issue me a new MBP touch bar so I can test it out.
    - freyr 9y ago
      Yeah, it's not snake oil. There are only a couple reasons it wouldn't work: you're in an unusual and unfortunate indoor environment with insufficient reflectors, or the modem designers were incompetent. Barring those things, you'll get a faster connection.
michaelt 9y ago
Third, there are unreasonable economic expectations by users as well as the article's author: Wait you want gigabit speeds, ultra-reliability in challenging radio conditions, and that at a tenth of the cost of a 3G mobile radio? How are customers supposed to know what "economically reasonable" expectations are if suppliers are flat out making claims they can't deliver? Imagine you're planning a trip to City X, you look online and four-star hotels with brands you've heard of quote $75 a night. If you turn up and it's not a four-star hotel, is it your fault because you had "unreasonable economic expectations"? Should you somehow have known that the going rate for a four-star hotel room was $500 a night, when half a dozen reputable suppliers were offering the same thing at a fraction of the cost? Seems to me it's not your fault - you've been a victim of fraud.
- bsamuels 9y ago
  dont think i've ever seen packaging that advertised that a router works well in a crowded environment
  - deleted 9y ago
    [deleted]
  - paulddraper 9y ago
    And the hotel didn't advertise that they weren't in the ghetto.
  - pixl97 9y ago
    At least on the outside of the packaging, I don't think the vast majority talk about spectrum over allocation. Of course many issues like that could be solved if APs shipped with their signal strength on low rather than blasted to the FCC limits. But I don't think we'll see that changed any time soon.
  - smallnamespace 9y ago
    Unknown unknowns. Does the average consumer even understand that contention is an issue? All the average person sees is the number of bars in their wifi connection UI, which AFAIK doesn't take contention into account, only signal strength.
deleted 9y ago
[deleted]
vinceguidry 9y ago
> Wait you want gigabit speeds, ultra-reliability in challenging radio conditions, and that at a tenth of the cost of a 3G mobile radio? I would be happy with any kind of reliability for a mobile chipset in reasonable radio conditions. Too often, I have to turn off WiFi to get basic connectivity happening. 4G/LTE connections are way better. It would be nice if Apple detected a bad WiFi connection and fell back to cell, but it seems they haven't figured out that trick yet.
- jrullman 9y ago
  Have you tried using the Wi-Fi Assist feature? https://support.apple.com/en-us/HT205296 https://support.apple.com/en-us/HT205296
  - acdha 9y ago
    The problem isn't the fallback to cellular but the function it uses to detect whether the WiFi is actually working. It works if there's a gross network failure but fails to detect networks which have packet loss, captive portal pages which cannot be loaded, etc. With the exception of captive portal pages, this isn't specific to the WiFi implementation either – the cellular stack is just as broken. As far as I can tell, this comes down to two problems: the most obvious technical challenge is the difficulty of detecting soft failures rather than hard failures. What they need to implement is a hard timeout which resets the connection state if the remote end fails to respond correctly within a set interval. I encounter this regularly commuting on the subway or taking underground tunnels between buildings; toggling airplane mode is the only way to get it to accept that the base station (WiFi or cellular) it was talking to 1500 feet back is never going to start responding. The social problem appears to be that nobody considers this a keynote demo feature and so it hasn't advanced beyond iOS 1.0 despite years of bug reports.
    - angry_octet 9y ago
      Even an app which you could program yourself would be excellent. It seems the system has equal belief in the reliability of all wifi networks, in terms of sticking with them. I'd like to give good reputation to my home wifi, but any new wifi should start with low reputation. And anything with a captive portal, you really want your phone to connect via 3G every few minutes to see if the connection is filtered.

jimrandomh 9y ago

> The usable throughput is the raw radio throughput divided by the number of buffers. This is not true. Buffers can under some circumstances increase latency, or cause a TCP connection to take longer to get to its steady-state speed, but they don't hurt steady-state throughput unless something else is very wrong.

JPLeRouzic 9y ago
You are talking of yet another issue which is real and is related to the way TCP detects a congestion, but this is not specific to Wi-Fi. There are also problems of interoperability between TCP/IP and the Wi-Fi MAC layer, some of them could trigger congestion algorithms, but as the MCDU gets larger and larger this should not be a problem nowadays. Indeed it is a bit strange to have MCDU that are 64k large and IP packets that are 1.5k large. What I discussed was the way the buffers are in series inside the OS, this is known since a long time. A modern operating system throughput could be 5 to 9 faster than Linux: https://www.usenix.org/node/186147 https://www.usenix.org/node/186147

ajross 9y ago

> there are unreasonable economic expectations by users as well as the article's author: Wait you want gigabit speeds, ultra-reliability in challenging radio conditions, and that at a tenth of the cost of a 3G mobile radio? Honestly the big reason mobile radios are more reliable is that they're allowed to transmit at like 20x the power of devices in the ISM band. That's not a cost thing, it's just a regulatory issue steming from (some rather outdated) concerns about interference in the shared environment. I mean, it's true that wifi is sort of a mess. Marketing of the standards has gotten way ahead of real world hardware capability (frankly MIMO as it stands is basically voodoo snakeoil that provides no consumer benefit whatsoever). But it's no less complicated than all the junk going on in LTE either. Everything's a mess. Wifi continues to have the extraordinary advantages of being privately deployable, performant, pervasive, and standard (i.e. ethernet-framed, so everything Just Works the way everyone expects). It's not going anywhere.

JPLeRouzic 9y ago
I completely agree.
freyr 9y ago
> frankly MIMO as it stands is basically voodoo snakeoil that provides no consumer benefit whatsoever Curious why you say this. In the last few years, I've seen a significant increase in PHY data rate when using multiple spatial streams.
- dmourati 9y ago
  I bought the snake oil in the form of a high end Ubiquiti WAP. Waiting for myco to issue me a new MBP touch bar so I can test it out.
  - freyr 9y ago
    Yeah, it's not snake oil. There are only a couple reasons it wouldn't work: you're in an unusual and unfortunate indoor environment with insufficient reflectors, or the modem designers were incompetent. Barring those things, you'll get a faster connection.

michaelt 9y ago

Third, there are unreasonable economic expectations by users as well as the article's author: Wait you want gigabit speeds, ultra-reliability in challenging radio conditions, and that at a tenth of the cost of a 3G mobile radio? How are customers supposed to know what "economically reasonable" expectations are if suppliers are flat out making claims they can't deliver? Imagine you're planning a trip to City X, you look online and four-star hotels with brands you've heard of quote $75 a night. If you turn up and it's not a four-star hotel, is it your fault because you had "unreasonable economic expectations"? Should you somehow have known that the going rate for a four-star hotel room was $500 a night, when half a dozen reputable suppliers were offering the same thing at a fraction of the cost? Seems to me it's not your fault - you've been a victim of fraud.

bsamuels 9y ago
dont think i've ever seen packaging that advertised that a router works well in a crowded environment
- deleted 9y ago
  [deleted]
- paulddraper 9y ago
  And the hotel didn't advertise that they weren't in the ghetto.
- pixl97 9y ago
  At least on the outside of the packaging, I don't think the vast majority talk about spectrum over allocation. Of course many issues like that could be solved if APs shipped with their signal strength on low rather than blasted to the FCC limits. But I don't think we'll see that changed any time soon.
- smallnamespace 9y ago
  Unknown unknowns. Does the average consumer even understand that contention is an issue? All the average person sees is the number of bars in their wifi connection UI, which AFAIK doesn't take contention into account, only signal strength.

deleted 9y ago

[deleted]

vinceguidry 9y ago

> Wait you want gigabit speeds, ultra-reliability in challenging radio conditions, and that at a tenth of the cost of a 3G mobile radio? I would be happy with any kind of reliability for a mobile chipset in reasonable radio conditions. Too often, I have to turn off WiFi to get basic connectivity happening. 4G/LTE connections are way better. It would be nice if Apple detected a bad WiFi connection and fell back to cell, but it seems they haven't figured out that trick yet.

jrullman 9y ago
Have you tried using the Wi-Fi Assist feature? https://support.apple.com/en-us/HT205296 https://support.apple.com/en-us/HT205296
- acdha 9y ago
  The problem isn't the fallback to cellular but the function it uses to detect whether the WiFi is actually working. It works if there's a gross network failure but fails to detect networks which have packet loss, captive portal pages which cannot be loaded, etc. With the exception of captive portal pages, this isn't specific to the WiFi implementation either – the cellular stack is just as broken. As far as I can tell, this comes down to two problems: the most obvious technical challenge is the difficulty of detecting soft failures rather than hard failures. What they need to implement is a hard timeout which resets the connection state if the remote end fails to respond correctly within a set interval. I encounter this regularly commuting on the subway or taking underground tunnels between buildings; toggling airplane mode is the only way to get it to accept that the base station (WiFi or cellular) it was talking to 1500 feet back is never going to start responding. The social problem appears to be that nobody considers this a keynote demo feature and so it hasn't advanced beyond iOS 1.0 despite years of bug reports.
  - angry_octet 9y ago
    Even an app which you could program yourself would be excellent. It seems the system has equal belief in the reliability of all wifi networks, in terms of sticking with them. I'd like to give good reputation to my home wifi, but any new wifi should start with low reputation. And anything with a captive portal, you really want your phone to connect via 3G every few minutes to see if the connection is filtered.