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In 802.11n 2.4Ghz, the spectrum is varied from 2400Mhz to 2500Mhz and consists of 13 (or 14) channels, each channel having 20Mhz band width. When I search google for best channel, all websites say 1,6 and 11 are the best channels since they won't overlap. But from my study, i found the following.

channel 1 : 3 [2, 3, 4]
channel 2 : 4 [1, 3, 4, 5]
channel 3 : 5 [1, 2, 4, 5, 6]
channel 4 : 6 [1, 2, 3, 5, 6, 7]
channel 5 : 6 [2, 3, 4, 6, 7, 8]
channel 6 : 6 [3, 4, 5, 7, 8, 9]
channel 7 : 6 [4, 5, 6, 8, 9, 10]
channel 8 : 6 [5, 6, 7, 9, 10, 11]
channel 9 : 6 [6, 7, 8, 10, 11, 12]
channel 10 : 6 [7, 8, 9, 11, 12, 13]
channel 11 : 5 [8, 9, 10, 12, 13]
channel 12 : 4 [9, 10, 11, 13]
channel 13 : 3 [10, 11, 12]

Channel 1 overlaps with 3 channels, Channel 6 overlaps with 6 channels and finally channel 11 overlaps with 5 channels.

So from my study, I conclude that channel 1,2,3,11,12,13 have less overlap interference.

Am I correct?

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  • $\begingroup$ you can use 1,6 and 11 in the same area without overlapping each other, meaning you have 3 near interference free channels. $\endgroup$ – L Selter Jan 15 '18 at 8:45
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Q: "Why channel 1, 6 and 11 are best for WiFi ... ?"

The are three major sources of interference: Co-Channel, Adjacent-Channel, and non-WiFi.

  • Co-Channel interference is simply where other WiFi equipment is using the same channel. and you need to share timeYour equipment waits until the channel is clear before trying it's luck, if there's enough competition or a fault in the equipment you get a collision; meaning you must wait and try again.

When setting up your own equipment on different channels and seek to not interfere with yourself you would choose channels 1, 6, 11, and 14 (if it's available in your area).

2.4 GHz channel widths

Avoiding interference from other people's WiFi involves using a WiFi APP on your cellphone (or test equipment) to determine which channels are least congested. If you enable channel bonding you might double your transmission speed but you're more likely to double your collisions if anyone else is nearby.

  • Adjacent channel interference occurs when a nearby channel is used by either you or your neighbor. If you use channel 1 and everyone else uses channel 6 or higher then your in luck.

  • Interference can also occur from non-WiFi sources such as cordless phones or microwaves.

Sources of interference

Most people only use a single WiFi channel in their home. In that case you're not going to want to stick with 1,6,11 but instead survey the channels and attempt to find one that is least used (all of the time).

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  • $\begingroup$ Consider i am using channel 3 and everyone else use channels above 6, then i will not have adjacent channel interference right?. This indicates that my study is correct? since channel 3 interfere only with 1,2,3,4,5 and 6 . $\endgroup$ – mcv Jan 16 '18 at 11:03
  • $\begingroup$ If i have 3 access points in my home, in order to avoid the interference i can configure the 3 Aps in channel 1 , 6 and 11. right ? $\endgroup$ – mcv Jan 16 '18 at 11:06
  • $\begingroup$ @mc vishnu - Correct. $\endgroup$ – Rob Jan 16 '18 at 20:00
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All channels good but:

  1. National standards can control some parameters (gain, numbers of channels, gain in channel ...). Gain of Channel 1 can be less in some cases.
  2. I have 19 visible ssids in my workplace so channel is best if it only my and have no neighbors.
  3. often if no activity wifi routers choose channel 6, and it`ll be the most loaded.
  4. often all routers automatically select channels and can change it next time. So you can plan channels load only if you can set channels manually for all wifi routers.
  5. you can set come nonstandard frequency (if your router can) but client devices must understand it.

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Use 'auto' channel or use wifi-analyzer before setting number of channel manually.

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