Wireless Access

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Occasional Contributor II

Channel Width

Hi,

What is channel width ?

Super Contributor II

Re: Channel Width

The width of a channel is measured in mhz and you´ll usually see the options of 20, 40 or 80 mhz. It´s basically how much space you allow a channel to use and with it comes the extra throughput of that extra space.

 

On the 2,4ghz band I´d never use anything else than 20mhz. On 5ghz I´ll mostly use 40mhz channels even if I deploy 802.11ac access points because of the 80mhz channels taking up to much space and make channel re-use harder or impossible.

Christoffer Jacobsson | Aranya AB
Aruba Partner Ambassador
Aruba: ACMX #537 ACCP | CWNP: CWNA CWDP CWSP CWAP
New Contributor

Re: Channel Width

A channel width specifies how broad a channel is for transmitting data.  

A channel is comparable to a road and the channel width is comparable to the width of the road.  Wider the road more traffic it could carry.  Wider the channel more data it could carry.

 

The 2.4GHz band has 11 channels and each channel has a width of 20Mhz.  When you configure the 2.4GHz band to use 40Mhz width, it merges two 20Mhz channels into one.

 

The 5GHz band has 23 channels and the maximum width of the channel can go up to 160MHz.  This is the reason why 5GHz band can carry more traffic than the 2.4GHz band.

 

Channel width of 20MHz increases the signal reachability but reduces the speed of the data it carries.  40MHz channel width increases the speed of the data it carries but reduces the signal reachability.

 

The reason for this behavior is, when you increase the channel width there is a high possibility for collision and noise interference from channels used by other wireless devices in your neighbourhood.

As there are not many devices using the 5GHz band it is generally less congested.  

 

So it is highly recommended to use the 40MHz or higher for the routers using the 5GHz band to get the best wifi bandwidth.

 

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