Multiple Wireless access points with same channel number

If you were configuring 10+ Wifi access points within range of each other and with the same network name would you put then on different channel numbers?

What would happen if all the channel numbers were the same?

If there were only going to be 1 or 2 concurrent users then no real issue. However, I guess you are talking about a hotel or office with a lot of connections. I would use different channel numbers.

If you have three WAPs in a straight line and users on all three then the centre one will suffer interference from both of the others.

I would use channels 1, 5, 9, 13 - a spacing of four is fine, the overlap is very minimal and will have negligible impact on performance. Try it with inSSIDer running and you will see the lack of overlap.

If there are a large number of other WAPs in teh vicinity then you may need to find channels in between theirs - for example if there are a lot on 1 & 6 which is quite usual you could choose 3, 8, 13 - yes there will be interference but less than if you went for 1, 6, 11

In reply to a post by Michael_Chare:

If you were configuring 10+ Wifi access points within range of each other and with the same network name would you put then on different channel numbers?

What would happen if all the channel numbers were the same?

Unless it was certain enterprise-grade kit that can works by using APs on the same channel, you would get significantly reduced performance.

It is a hotel. I have seen as many as 20 access points all on channel 6. they are presumably spread out due to the 'bungalow' nature of the establishment. Quite often the network has failed, though that may well be due to the onward connection or the way access permissions are granted.

I would do a rough sketch of the building and put each WAP location on it.

Then mark the midpoint between adjacent WAPs and then join the dots around each one so you have say 20 zones.

It is possible to colour any 2-dimensional map using just four colours, so do that to the zone map you have. Allocate four channel numbers, 1, 5, 9, 13 to the colours and then program each WAP accordingly. Give them all the same SSID and passcode (if used)

Being a hotel, individuals will tend to be in a room and not wandering about so there is little need for them to change WAP.

Michael

You may find this thread interesting, as it was/is two others with similar requirements-

http://forums.thinkbroadband.com/multiuser/f/4333339...

Wouldn't 1,6,11 be better for a Hotel or somewhere that's expected to get quite a lot of international visitors?

1,5,9,13 would give you the extra channel but potentially if it's in a hospitality environment you could get a number of devices that cannot "see" the AP's on channel 13 due to them being configured for the american market.

Edited by dragon2611 (Thu 19-Jun-14 00:18:38)

No. WAPs tend to have the channel restrictions built in not the interface cards in the PC. Does the card in your PC give you any control over which channel to use? No, it searches and looks for any WAP in the full band.

Firstly I would say using the same channel is a bad idea...

I to disagree with the advice here of using 1, 5, 9, 13 however. It's not terrible advice but most home routers will be on Auto and will default to 1, 6 and 11, so best to stick with this. Also a lot of devices sold in the UK will not work on channel 13 as they have a USA configuration, so this could mean those near to a 13 point end up getting poor reception as they are forced onto a router much further away not using 13.

Around 30% of devices I've used do not see channel 13 due to restrictions worldwide on this channel. So using this is a big no-no.

Using 1, 5, 9, 13

1 overlaps with 5, 5 overlaps with 9, 9 overlaps with 13. So that in itself could be problematic.
Then add home users into the mix (as it's likely in parts of the hotel a neighbours WiFi will be seen). These will be on 1, 6 or 11.

5 will overlap with 1 and 6.
9 will overlap with 6 and 11
13 will overlap with 11.

You are much better to just use 1, 6 and 11. As none of these channels overlap with one another. Also if a neighbour has a router on 1, 6 or 11 it's actually better to use the same channel as them than an overlapping one.

E.g. neighbour on channel 1, you are better to use channel 1 than channel 2. Having a router on 1 and another router on 2 will cause more collisions in the air and retransmitting of data than having both on channel 1.
Ideally you would use channel 6 as this doesn't overlap with channel 1 at all.
Hence 1, 6 and 11 are ideal as no collisions between the channels. This is why home equipment defaults to these channels.

To sum up virtually all businesses, hotels etc in the UK will use 1, 6 and 11.
Assuming a straight line you would put 1st router on 1, 2nd on 6, 3rd on 11. Then back to 1, 6 and 11. This way the crosstalk will be minimal. As the 1st router on channel 1 will be a whole 2 routers distance from the 2nd on 1. So they probably wont have any crosstalk at all.

The 2nd router on channel 6 will have no crosstalk with the 1st router on channel 1 or the third router on channel 11.

Having a setup like this 1, 5, 9, 13
The 1st router will have crosstalk with the 2nd router
The 2nd router will have crosstalk with the 1st router and the 3rd router
The 3rd router will have crosstalk with the 2nd router and the 4th router
The 4th router will have crosstalk with the 3rd router.

Do you see why 1, 6 and 11 MAY work better here. It reduces the crosstalk which may or may not cause issues.
Also it prevents issues with channel 13 where a large chunk of devices are unable to see this channel.

Having them all on 6 may work ok but speeds may be severely reduced or there could be too much interference and you may just be unable to connect at all.

Edited by ukhardy07 (Thu 19-Jun-14 02:12:54)

In reply to a post by MHC:

No. WAPs tend to have the channel restrictions built in not the interface cards in the PC. Does the card in your PC give you any control over which channel to use? No, it searches and looks for any WAP in the full band.

Some adapter drivers do. They don't normally ask the channels to limit but they can have a setting for "country" and it is that that restricts the channels available to use. I haven't tried it in recent years but in know some time back that we had issues when our laptops were set to the wrong country on the wireless card if we used channel 13 on the AP.