Yes some of the terminology sounds similar but refers to different things.
Double channel width (dual channel) refer to using a 40MHz wide instead of 20MHz standard channel.
This would be like if a radio station was spread across more of the frequency dial when tuning in.
Dual band refers to operation in the 2.4GHz band or 5GHz band (or both simultaneously)
This would be like a radio station could transmit on MW or LW (or both simultaneously).
There is room for double channel widths on the 5Gz band because there are more legal channels.
Whereas on 2.4GHz band there are only 13 channels which overlap,
so using the analogy running 40MHz wide is like a radio station that takes up half
of the dial even when configured in the least selfish way, and worse if not positioned at the "left or right edge of the dial".
With that in mind, the diagrams on List of WLAN channels
should make more sense.
So, other things being equal it is better to have something that uses multiple antennas (spatial streams) to achieve higher throughput, rather than relying on double channel width, especially in the more common 2.4GHz band (b/g/n).
In other words MIMO does not require use of 40MHz wide channels in this band and 20MHz is more compatible (in the senses of both older devices and neighbouring wireless networks).
prompt $P - Invalid drive specification - Abort, Retry, Fail? $G
prlzx on n e w n e t: ADSL2+ / 21CN at 2.5Mbps / 800k
Edited by prlzx (Wed 07-Mar-12 10:58:40)