How Stuff Works – 802.11n and Channel Bonding

We already discussed how MIMO works.  Let’s look at another technical improvement currently utilized in 802.11n – channel bonding:

channel-bonding

The graphic is fairly self explanatory – traditional 802.11 channels are either 20 MHz wide (OFDM) or 22 MHz wide (DSSS).  Channel bonding combines two adjacent channels, which effectively doubles the amount of available bandwidth.

One footnote to channel bonding is that it works best in the 5GHz frequency band, as there is only space for three traditional, non-overlapping channels in the 2.4GHz frequency band.   Therefore, there is only enough space for one bonded channel in that portion of the RF spectrum.

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6 comments so far

  1. Janet on

    Can you please explain how 2.4 GHz RF spectrum would have only single pair for channel bonding at a time?

    http://en.wikipedia.org/wiki/File:2.4_GHz_Wi-Fi_channels_(802.11b,g_WLAN).svg

    From the above diagram, channel # 1, 6 and 11 are non-overlapping but are apart to and not adjacent to each other.

    Are you saying only channel # 11 & 14 could bond?

  2. Paul on

    In terms of usage, channels 1 and 6, and channels 6 and 11 are considered adjacent because they are the closest non-interfering channels to each other in the 2.4 GHz spectrum. Bonding channels 1 and 6 would give you the entire bandwidth from 2.401GHz to 2.448GHz, and bonding channels 6 and 11 would be from 2.426GHz up to 2.473GHz. Channel 14 is not used in North America where I live, so I have no experience with bonding 14.

    Please note that you can only bond one pair of channels in a Wi-fi environment using 2.4GHz.

    Paul

  3. نادر المنسي on

    thanks very much

  4. Tom Carpenter on

    You would actually bond channels 1 and 5 or channels 6 and 10 or channels 7 and 11. I know this is late, but thought I’d add it 🙂

  5. dfgallegosDiana Gallegos on

    Thank you for taking the time to make wireless simple, clear, and easy to understand. I am very glad I found your site!

  6. Zhe Wen on

    Hello Master Jedi! I am working on bonding channel width, too (wireless-compat driver hacking).

    In my problem, there is one STA and one AP (hostapd). If they both start using 20MHZ bw (HT20), AP switching channel width to 40MHZ bw (HT40+) will cause loss of connection. But bw change won’t cause any problem if both STA and AP start with 40MHZ bw. Could you think of any reason for this difference for me youngling?

    Thanks in advance!


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