5Ghz channel separation using Router and AP, both with wifi

Forums › LAN (ethernet/Wifi/routers/Bluetooth) › 5Ghz channel separation using Router and AP, both with wifi

steve2222

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#218003 21-Jul-2017 20:42

I have read various posts and guides about setting up a router with wifi and a separate AP also with wifi that is connected to the router by LAN cable.

Most of these posts say to ensure that the wifi broadcasting from router and the wifi from the AP are on different channels that do not overlap - often they quote selecting from channel 1, 6 or 11.

But these are the 2.4Ghz channels, does the same advice apply to the 5Ghz channels? If so which channels do not overlap? Or is it that with 5Ghz I just need to ensure they are on different channels but it could be 2 channels next to each other?

Thanks

sbiddle

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#1826825 21-Jul-2017 20:44

20Mhz channels don't overlap.

Since you haven't said whether you're running at 20/40/80 it's not really possible to answer your question.

steve2222

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#1826830 21-Jul-2017 20:53

sbiddle: 20Mhz channels don't overlap.

Since you haven't said whether you're running at 20/40/80 it's not really possible to answer your question.

Okay so for 5Ghz:

Router is on 80 (with other possible options of 20 or 20/40)

AP is on 20/40 (with only other option being 20)

What are the pros and cons of the different options? Should it be that both router and AP should be on the same?

richms

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#1826837 21-Jul-2017 21:50

Most devices let you choose a 20MHz channel, and when enabling 40 or 80MHz will just widen it up to the extent of the larger channel that the 20MHz one is inside of. Some older devices would just let you choose up or down and take the next 20MHz channel for a total of 40MHz. This seemed to be taken away with most AC devices, which would force it into the correct 40 or 80MHz channel that the 20 is part of.

I would just stick one in the 36-40 range and the other in the top end of the range if nothing else is nearby, and ensure that they are spaced a couple of meters apart from each other.

Richard rich.ms

raytaylor

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#1831911 27-Jul-2017 00:17

Channel width
20mhz is standard. 40mhz was the first expansion option. It uses an ultra-wide channel to push more data through but you loose half your signal sensitivity or "strength". In theory, going from 20mhz to 40mhz will double your throughput but lower your range.

80mhz is the latest in widening channels to get more speed and is part of the 802.11ac standard. Again it will double the throughput of a 40mhz channel but again lower your range.

Another problem with 40/80mhz channels is by using more of the spectrum, you become more exposed to potential interference. Eg. Another router could come along and sit on a 20mhz wide channel right in the middle of your 80mhz wide channel.

Speed, Range, Reliability - With wifi you can only pick two.

This picture shows the channels - You will notice the 20mhz channels have numbering that does not run 1,2,3,4 but instead jumps in numbers. This is because the routers are designed to land only on specific channels that dont overlap.

In 2.4ghz, a router can pick 1,2,3,4,5,6,7,8,9,10,11 but in reality only 1,6,11 dont overlap at 20mhz. This is because before wifi as we know it was standardised, there were older formats before 802.11b that used channel widths smaller than 20mhz.
Anyhow, imagine if the router manufacturers decided that 1,6,11 were the only selectable channels in 2.4ghz. There would be no chance that a neighbouring router could land on auto channel 4 and interfere with you on 1 and another neighbour on 6.

Well thats what they did with 5ghz at 20mhz - most routers only allow you to select a non-overlapping channel.

However that all went out the window the moment 40mhz and 80mhz channels came about.

Ray Taylor

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Jase2985

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#1831922 27-Jul-2017 04:54

have a read of this from the Radio Spectrum Management NZ

https://www.rsm.govt.nz/consumers/pdf-and-documents-library/Wi-Fi%20Devices%20using%20the%205%20GHz%20Band.pdf

i run channels 100 and 136 (this is the first channel number so 106 and 138 on the RSM PDF)

i tried 149 but my laptop didnt like it and kept dropping to 2.4ghz.

hio77

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#1832229 27-Jul-2017 13:30

Jase2985:

have a read of this from the Radio Spectrum Management NZ

https://www.rsm.govt.nz/consumers/pdf-and-documents-library/Wi-Fi%20Devices%20using%20the%205%20GHz%20Band.pdf

i run channels 100 and 136 (this is the first channel number so 106 and 138 on the RSM PDF)

i tried 149 but my laptop didnt like it and kept dropping to 2.4ghz.

device compatibility is a funny one...

my old phone would only connect at decent 5ghz speeds on channel 36.. Any other channel and i'd be better off with mimo 2x2 2.4ghz! (okay rural case so exception is there for which is actually faster to use)

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Jase2985

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#1832383 27-Jul-2017 16:42

yea i dont know what it was. spent ages faffing around with the laptop and drivers.