Question about WiFi channels

[m.maleki.m89]

Hi everyone.

I have few problems understanding WiFi channels. I'm talking about 2.5GHz channels. I'll be glad if someone can help me with these:

1) why we say channels 1, 6 and 11 are non-overlapping WiFi channels? Doesn't channel 6 overlaps with channel 5? If we are saying it because they don't overlap with each other, then should we also consider channels 2, 7 and 12 also non-overlapping channels?

2) I'm using channel 6 and my neighbor is also using channel 6, we will have interference, right?

3) I'm in a place where there are 2 other WiFi routers around me. One is using channel 3, the other is using channel 13. Should I use channel 8 to have the minimum overlap and interference while everyone are saying use channel 1, 6 or 11?

4) if the answer to question 3 is that I have to use channel 8, does it mean in a very crowded place, I have to use a channel that has less overall overlaps regardless of channel 1, 6 and 11?

Thank you in advance.

 

[bill001g]

Your problem is the standard confusion over what "channel" means. Not sure historically how they made such a mess of this.

On the 2.4g band the so called channels you see in the router are 5mhz wide. WiFi on the other hand uses 20mhz of bandwidth to represent a channel. This means that a WiFi broadcast takes up mulitple of the 5mhz "channels" To make it even more confusing the channels number represent the starting radio frequencies where as actual radio transmissions this is the center frequencies. It gets complex quickly but someone who is using channel 6 is actually using 4,5,6,7. If you were to pick channel 4 as your center you would still overlap channel 6.

Now the whole concept of 1,6,11 has been outdated for many years. There is a total of 60mhz of radio allowed to be used for wifi. Those numbers represented the best method to divide it into 20mhz parts. Now that 802.11n has been around you use 40mhz rather than 20. It is impossible to fix 2 40mhz singals into the 60mhz allowed.

This means that there is no possibility to select a channel configuration that does not overlap when you are using 40mhz channels.

Used to be the solution was to go to the 5g band where there is more bandwidth.....and to add to the confusion the channel numbers there represent 20mhz of bandwidth rather than 5mhz. This used to work good until 802.11ac came out and the bandwidth pigs with their tri-band routers. The newest routers use 2 80mhz 802.11ac signals but there is only a total of 180mhz so 1 person uses all the 5g bandwidth.

So we are now in the situation where a single person can use all the radio bandwidth on 2.4g and 5g with a single router and we have people putting multiple routers in their house making the overlap even worse.

Wifi is just like the freeways that were so nice when they first opened them. Now it is massive traffic jams and no way to really fix it.