Differences between 20mhz, 40mhz, 80mhz and 160mhz channels?

[bhupenderrawat79]

Hello,

Can someone explain in lame terms what is the differences and advantages of using 20, 40, 80 and 160mhz channels and how each can improve speed performance and how is able to do this?, are all of these frequencies fully supported by clients? if not how do you know if a laptop or a wireless card can support 20,40,80, or 160mhz?

Also what is the expected behaviour from a client/laptop that cannot support 160mhz and the wifi is configured to use 160mhz? Thanks in advance!

[balaji.bandi]

20Mhz

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20MHz is the most common Wi-Fi bandwidth as most users still opt to use 2.4GHz radios.

40Mhz

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In an environment with less congestion where a higher data throughput is required, using the 40MHz channel can be a good idea as it still offers 12 non-overlapping channels on 5GHz

80Mhz

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80MHz is available on many 802.11ac routers.

80MHz channels are therefore best off used on a best-effort basis but only when the entire channel range is clear.

160Mhz

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160MHz is a wide channel available in the 5GHz band. (802.11 AC).

you need to check what end device offers with built in Wifi chip set.

[bhupenderrawat79]

Balaji,

Thanks for the response! question is it worth using 5ghz with 20mhz channels width?. 

And In reference to 40mhz and 5GHz what are the 12 non-overlapping channels? Thanks in advance

[Leo Laohoo]

Currently, 20- and 40 Mhz are still in use. 80 Mhz simply ruins the amount of channels 5.0 Ghz can use. 160 Mhz is just for marketing talk.

[bhupenderrawat79]

Leo, Thanks for your response. So in your opinion it will be better or best practice to use 40MHz channels with 5GHz only correct? and now lets say my clients laptop can support 2x2 MU-MIMO which means if i am understanding correctly the theorical speed that my client could get, would be 433mbps, is this a correct statement and of course assuming 40dBm signal to the AP. ? also if you were using 40MHz channels on 5GHZ, which channels would you use? thanks again for your time!

[Leo Laohoo]

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@bhupenderrawat79 wrote:
So in your opinion it will be better or best practice to use 40MHz channels with 5GHz only correct? 

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I would prioritize 40 Mhz channel width, HOWEVER, this will depend on the worst wireless client.  If there is a wireless client that won't talk in 40 Mhz then crank down to 20 Mhz.  

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@bhupenderrawat79 wrote:
and now lets say my clients laptop can support 2x2 MU-MIMO which means if i am understanding correctly the theorical speed that my client could get, would be 433mbps

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I would say 300 Mbps half duplex or 150 in a single direction.  

[bhupenderrawat79]

Leo,

Thanks for your time in answering my questions. You are definetely an expert! Quick question what is the best way on how to find out if a client or wireless card can do 20,40,80 or 160Mhz ? so that we can properly configure or set our channels width? Thanks!

[Scott Fella]

The best way is to search on the manufacturer site the wireless NIC specifications.
What channel width to use is not determined by what your clients support but how much channel overlap you have which also relates to how dense you have your AP’s. Channel width increase for 20-40 reduces the number of overlapping channels by half. So every increase in channel width will reduce your available non overlapping channels. Best to stick with 40MHz and in very high density environments, use 20MHz.

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-Scott

[bhupenderrawat79]

Scott,

thanks for your your time to respond. What do you consider to be a high density environment? 

Thanks!

[Scott Fella]

High density would be if you have AP’s within probably 30’, this varies depending if it’s office, walls and or open area. If for example you can see more than 3 AP’s at a signal of -67dbm or better on the 5GHz, it’s probably high density. Take a look at the Cisco Wireless HDX Design Guide. Depending on country also, you have different allowed channels, so if your in a country that only allows 3-4 channels on the 5GHz, why would you use 40 or higher? 40MHz bonds two 20MHz channels. 80MHz bonds four 20MHz channels. You want AP’s to be on different channels or else you have overlapping channels and that will eventually cause you issues. Stick with 20 or 40.