6 ms·

Neglected channels could add Wi-Fi capacity

69 points by teklaperry 10y ago

elif 10y ago
I think as we are continuing to balloon request sizes, stream more and higher quality video, increasingly populate urban cores, etc. finding more spectrum to pollute is an untenable long-term solution. I think a more reasonable approach is to start putting wire in house-wrap, and perhaps putting a repeater antenna outside the Faraday cage for cell signals.
- specialist 10y ago
  "...a more reasonable approach..." Municipal broadband (wifi) is inevitable. I'd much rather pay the landlord or utility or someone to just handle it. Much as I hate Comcast, I'm loving that XfinityWifi is ever more common.
  - Nullabillity 10y ago
    What does municipal broadband have to do with that connection being worthless? If anything, that would just cause even more pollution. We need to stop considering Wi-Fi the default mode of connectivity, and go back to it being a stopgap for devices where it's unpractical to have a wire. Perhaps it's time to start building powerline connectivity into phone and laptop chargers?
  - chimeracoder 10y ago
    > Municipal broadband (wifi) is inevitable. As long as cell networks implement data caps, maybe. But I don't see why municipal wifi is inherently inevitable (or even desirable). New York is starting to roll out combination charging/wifi stations across the city, and I think they're horrible for a whole number of reasons. But the biggest thing is that public wifi isn't really any better in terms of bandwidth or latency than mobile networks to begin with - the only real advantage they have is that they bypass data caps[0]. [0] Oh, and they make it trivial for the city to track your whereabouts at all times.
- DiabloD3 10y ago
  Actually, we sort of already solved it. Wifi was never meant to go insanely long distances, and now spamming APs inside of even a smaller home is a cheap and effective way of dealing with signal problems. 60ghz (Added by 802.11ad) can't penetrate sheetrock effectively, let alone bother your neighbors, a much smaller distance than 5ghz (which has half-solved the dense urban environment issue on it's own, but not completely; the article overplays issues significantly). I support abandoning 2.4ghz for Wifi and anything else that is high bandwidth. The good news is, the 802.11 Working Group and the major Wifi impl manufs agree with me, which is why 802.11ac is 5ghz only, and 802.11ad is 60ghz first, both of them removing 2.4ghz for anything but 802.11 b/g/n legacy connectivity. Also, as a side note, I want the FCC to ban the LTE-over-5ghz plan. 5ghz is ours; they can have 2.4ghz, we're done with it.
  - pimlottc 10y ago
    But then how I am going to leech free wifi off the coffee shop without going inside?
    - DiabloD3 10y ago
      I know you meant that as a joke, but when has "free Wifi" ever resulted in something better 1-2 mbit? I live in an extremely bad cell phone signal area, and not a single "free Wifi" area around here is usable, and I'd still rather use my cell phone signal for data given how bad the "free Wifi" is.
      - profmonocle 10y ago
        There are plenty of free hotspots in my city that are 20+ Mbps. It probably has more to do with the cost of Internet access in your area than the Wi-Fi connections themselves.
      - ClassyJacket 10y ago
        The free wifi at Telstra stores is pretty fast, often over 100Mbps. But then you're standing awkwardly outside a Telstra store with a laptop looking suspicious.
specialist 10y ago
Should I stop hoping that we'll get consumer grade ultra-wide band devices, mooting the whole frequency licensing issue? "Did the NSA help kill UWB?" http://www.cringely.com/2014/05/15/nsa-help-kill-uwb/
jrockway 10y ago
Wifi stations only interfere when they're transmitting at the same time, and other stations can hear it. Channels are a very simplistic way of understanding WiFi sharing, time and space are also important dimensions. If Station A and Client A want to communicate, they will not interfere with Station B and Client B if they pick different times to talk, or cannot "hear" each other at all. There is some good work going on to improve this. Faster WiFi speeds mean that less time is needed to transmit the same number of bytes, meaning that stations are less likely to interfere. (This is why everyone hates your 802.11b-only client that can do a maximum of 11Mbps. It ties up the entire channel for no good reason.) The default rate control built into most APs is awful, and makes things worse than they need to be. For example, let's say sending at 100Mbps, there's a 50% chance that the message won't be decodable, and sending at 1Mbps, there's a 99.999% chance that the message will get through. APs will try sending at the high rate, notice an error, and then go to the low rate. But that's wrong: it doesn't minimize the use of airtime. Sending 100Mb at 100Mbps twice is much more time-efficient than sending it at 1Mbps once. Some work is under way to improve this algorithm and get it in consumer routers. There is also work to make APs transmit to stations at a transmit power tuned to be as low as possible. If a station is close, the AP only needs a small amount of power to send a decipherable message to the station. And, because the power is low, it interferes with less space. I believe this is now working under Linux with ath9k chipsets. Anyway, "channels" is a terrible way to understand WiFi performance, because space and time are the other critical dimensions. Unfortunately, most "WiFi analyzers" only show which channels have APs, which is a meaningless metric. Here's an interesting talk about how this all works in the real world: http://apenwarr.ca/diary/wifi-data-apenwarr-201602.pdf http://apenwarr.ca/diary/wifi-data-apenwarr-201602.pdf
- chrisfosterelli 10y ago
  Could WiFi analyzers effectively determine information about space from a single location? Time is obviously possible, but isn't it inherently providing information about space by providing power readings from a single point?
  - jrockway 10y ago
    Which WiFi analyzer actually looks for traffic? Most of the ones I've seen (a popular Android app) just show you beacons. Seeing beacons != seeing traffic.
ryao 10y ago
For those who are unaware, these are the channels that caused the FCC to effectively ban OSS firmware in wifi routers. As far as I know, Ubiquiti and Mikrotik could be configured to use them unconditionally, which caused problems with radar.

69 points by teklaperry 10y ago

elif 10y ago

I think as we are continuing to balloon request sizes, stream more and higher quality video, increasingly populate urban cores, etc. finding more spectrum to pollute is an untenable long-term solution. I think a more reasonable approach is to start putting wire in house-wrap, and perhaps putting a repeater antenna outside the Faraday cage for cell signals.

specialist 10y ago
"...a more reasonable approach..." Municipal broadband (wifi) is inevitable. I'd much rather pay the landlord or utility or someone to just handle it. Much as I hate Comcast, I'm loving that XfinityWifi is ever more common.
- Nullabillity 10y ago
  What does municipal broadband have to do with that connection being worthless? If anything, that would just cause even more pollution. We need to stop considering Wi-Fi the default mode of connectivity, and go back to it being a stopgap for devices where it's unpractical to have a wire. Perhaps it's time to start building powerline connectivity into phone and laptop chargers?
- chimeracoder 10y ago
  > Municipal broadband (wifi) is inevitable. As long as cell networks implement data caps, maybe. But I don't see why municipal wifi is inherently inevitable (or even desirable). New York is starting to roll out combination charging/wifi stations across the city, and I think they're horrible for a whole number of reasons. But the biggest thing is that public wifi isn't really any better in terms of bandwidth or latency than mobile networks to begin with - the only real advantage they have is that they bypass data caps[0]. [0] Oh, and they make it trivial for the city to track your whereabouts at all times.
DiabloD3 10y ago
Actually, we sort of already solved it. Wifi was never meant to go insanely long distances, and now spamming APs inside of even a smaller home is a cheap and effective way of dealing with signal problems. 60ghz (Added by 802.11ad) can't penetrate sheetrock effectively, let alone bother your neighbors, a much smaller distance than 5ghz (which has half-solved the dense urban environment issue on it's own, but not completely; the article overplays issues significantly). I support abandoning 2.4ghz for Wifi and anything else that is high bandwidth. The good news is, the 802.11 Working Group and the major Wifi impl manufs agree with me, which is why 802.11ac is 5ghz only, and 802.11ad is 60ghz first, both of them removing 2.4ghz for anything but 802.11 b/g/n legacy connectivity. Also, as a side note, I want the FCC to ban the LTE-over-5ghz plan. 5ghz is ours; they can have 2.4ghz, we're done with it.
- pimlottc 10y ago
  But then how I am going to leech free wifi off the coffee shop without going inside?
  - DiabloD3 10y ago
    I know you meant that as a joke, but when has "free Wifi" ever resulted in something better 1-2 mbit? I live in an extremely bad cell phone signal area, and not a single "free Wifi" area around here is usable, and I'd still rather use my cell phone signal for data given how bad the "free Wifi" is.
    - profmonocle 10y ago
      There are plenty of free hotspots in my city that are 20+ Mbps. It probably has more to do with the cost of Internet access in your area than the Wi-Fi connections themselves.
    - ClassyJacket 10y ago
      The free wifi at Telstra stores is pretty fast, often over 100Mbps. But then you're standing awkwardly outside a Telstra store with a laptop looking suspicious.

specialist 10y ago

Should I stop hoping that we'll get consumer grade ultra-wide band devices, mooting the whole frequency licensing issue? "Did the NSA help kill UWB?" http://www.cringely.com/2014/05/15/nsa-help-kill-uwb/

jrockway 10y ago

Wifi stations only interfere when they're transmitting at the same time, and other stations can hear it. Channels are a very simplistic way of understanding WiFi sharing, time and space are also important dimensions. If Station A and Client A want to communicate, they will not interfere with Station B and Client B if they pick different times to talk, or cannot "hear" each other at all. There is some good work going on to improve this. Faster WiFi speeds mean that less time is needed to transmit the same number of bytes, meaning that stations are less likely to interfere. (This is why everyone hates your 802.11b-only client that can do a maximum of 11Mbps. It ties up the entire channel for no good reason.) The default rate control built into most APs is awful, and makes things worse than they need to be. For example, let's say sending at 100Mbps, there's a 50% chance that the message won't be decodable, and sending at 1Mbps, there's a 99.999% chance that the message will get through. APs will try sending at the high rate, notice an error, and then go to the low rate. But that's wrong: it doesn't minimize the use of airtime. Sending 100Mb at 100Mbps twice is much more time-efficient than sending it at 1Mbps once. Some work is under way to improve this algorithm and get it in consumer routers. There is also work to make APs transmit to stations at a transmit power tuned to be as low as possible. If a station is close, the AP only needs a small amount of power to send a decipherable message to the station. And, because the power is low, it interferes with less space. I believe this is now working under Linux with ath9k chipsets. Anyway, "channels" is a terrible way to understand WiFi performance, because space and time are the other critical dimensions. Unfortunately, most "WiFi analyzers" only show which channels have APs, which is a meaningless metric. Here's an interesting talk about how this all works in the real world: http://apenwarr.ca/diary/wifi-data-apenwarr-201602.pdf http://apenwarr.ca/diary/wifi-data-apenwarr-201602.pdf

chrisfosterelli 10y ago
Could WiFi analyzers effectively determine information about space from a single location? Time is obviously possible, but isn't it inherently providing information about space by providing power readings from a single point?
- jrockway 10y ago
  Which WiFi analyzer actually looks for traffic? Most of the ones I've seen (a popular Android app) just show you beacons. Seeing beacons != seeing traffic.

ryao 10y ago

For those who are unaware, these are the channels that caused the FCC to effectively ban OSS firmware in wifi routers. As far as I know, Ubiquiti and Mikrotik could be configured to use them unconditionally, which caused problems with radar.