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In this other SuperUser question, the consensus was to stick with WiFi channels 1, 6, or 11.

But what if two of those channels (channels 1 and 6, for example) are both very crowded, but the other channel (channel 11, in this example) is much less crowded, yet has a very strong competing signal?

In that case, is it better to use channel 1 (or 6) or channel 11?

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  • I dont get what u mean…If 1 6 is crowded than use 11 is fine
    – Bilo
    Jun 29, 2016 at 6:51
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    @Bilo he's asking about the choice between a channel with several weak competing hotspots or a channel with a single strong competing WiFi hotspot. Which do you choose.
    – Mokubai
    Jun 29, 2016 at 7:00
  • Have a look at the answer to this question .. tl;dr: yes, it's best to do the channel with least activity ..
    – txtechhelp
    Jun 29, 2016 at 7:23
  • @txtechhelp By activity you mean the least amount of signal strength? That's what I got out of the link you posted. And that made me think of this Which would you rather fight: one horse-sized duck, or 100 duck-sized horses? Jun 29, 2016 at 19:49
  • @BigElittles, no not signal strength but radio activity. See the answer Spiff left; it's a good explanation/expansion on that.
    – txtechhelp
    Jun 30, 2016 at 1:41

1 Answer 1

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You know how many APs are on each of those channels, but you don't know how much traffic each one is sending/receiving (an idle AP doesn't use much airtime), and you don't know what non-802.11 interference might be on those channels.

If the powerful AP is idle, and the less powerful APs on the other channels are really busy, then it would be be better to be on the channel of the powerful AP. But if one or more of those channels is being blown away by Bluetooth, Wiimotes, 2.4GHz cordless phones or baby monitors or other non-802.11 2.4GHz technologies, then those channels would be poor ones to choose and you'd never know from a Wi-Fi scan.

The truth is, you can't figure out the best channel to use based on scans of nearby Wi-Fi networks. You have to test it out yourself.

Put your AP on each channel (1, 6, and 11) in turn, and run iperf between two of your devices while on each channel.

Don't be surprised if your results change at different times of day (neighbor starts wirelessly streaming Netflix in the evenings, or microwaving popcorn, or making a long phone call on the cordless phone, or switching on the baby monitor overnight).

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  • I would also wonder if the networks are all private or business. If that strong signal belongs to a nearby college, for ecample, it's very likely to be way more active.
    – Nich Del
    Jun 30, 2016 at 18:44
  • Thanks Spiff. Excellent points. Very useful answer. I especially appreciate your point about an idle AP vs. an active AP. A simple WiFi scan does not indicate that important aspect. Is there any simple way to know how much traffic an AP is actually transmitting/receiving? Perhaps even a little hardware device that just measures the activity level on the frequency? Jun 30, 2016 at 20:25
  • @RockPaperLizard You've got to drop your Wi-Fi-centric notions. The 2.4GHz band is crowded with lots of non-Wi-Fi usage. It's better to look at all of the RF energy on the band, not just Wi-Fi signals. For that you need a spectrum analyzer, like a Metageek Wi-Spy (despite the name, it's not Wi-Fi-specific). They're not cheap, however.
    – Spiff
    Jul 1, 2016 at 0:30
  • You're absolutely right. I should have broken that into two separate requests: (1) Something to measure WiFi activity on a given frequency, and (2) Something to measure all RF activity on a given frequency. The Metageek devices look interesting, but as you noted, they're not cheap. Jul 1, 2016 at 3:43
  • @RockPaperLizard To see all Wi-Fi traffic on a given channel, get a state-of-the-art Wi-Fi card that supports 802.11 Monitor Mode, and run Wireshark or another 802.11 Monitor Mode capable packet sniffer on it. I say "state-of-the-art" because if you don't have a card capable of doing every possible combination of modulation schemes, channel widths, spatial streams, and guard intervals, you won't be able to see all the 802.11 traffic. For 2.4GHz, you can probably get away with an "N450" card: 802.11n, 3 spatial streams, 40MHz-wide channels, Short Guard Intervals.
    – Spiff
    Jul 1, 2016 at 8:39

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