Wireless AP: single radio dual band vs dual radio dual band

[SAM MUNZANI]

Hi,

What is fundamental difference in functionality between an AP with single radio but dual band and dual radio dual band? Why would someone invest in dual radio AP? Someone had told me that in single radio once someone connects at one frequency, it brings the AP in that frequency which doesn't make any sense to me.

There has to be some difference but looking for a logical answer.

Thanks in advance.

[Leo Laohoo]

What is fundamental difference in functionality between an AP with single radio but dual band and dual radio dual band? Why would someone invest in dual radio AP?

I think this question is no longer relevant anymore since Cisco no longer sells "single band radio".  All APs (starting with the 1600/2600/3600) being marketed now are dual band.  

Single-band radio is only 802.11b.  Dual band radio adds 802.11a.  

[SAM MUNZANI]

It wasn't for purchasing an AP but more of understanding the concept. I found following on google search that makes sense.

http://eduncan911.com/blog/archives/the-truth-about-802-11n.html

Dual Radios vs Dual Channel vs Dual Mode vs Dual Band vs MIMO (The Marketing buzz-words)

Finally, the nit-n-gritty of this post.  I will say it loud and clear:

Stay away from dual channel devices and only get a two radio device!

What is dual-two-huh?  It is simple: To operate a device at a frequency of, say, 2.4Ghz, you need a RF radio to broadcast and receive at that frequency.  To operate at 5.8Ghz, you need a RF radio as well.  To operate at both frequencies (sometimes called Dual Channel or Dual Mode), your radio switches from 2.4Ghz to 5Ghz.  But the limiting factor here is a RF radio can only operate in one mode or the other.  Not both at the same time.  These dual channel/dual mode devices have a history of “cutting out” when mixed G and N devices are connected.  It is better to operate them at 2.4Ghz at all times.

How do you operate at both channels?  Simple, you have two radios: one at 2.4Ghz and the other at 5.8Ghz.

The biggest buzz is that 802.11n specifications allow it to operate at either 2.4Ghz or 5.8Ghz.  This allows you to run at 2.4Ghz and connect all of your 802.11g devices as well as 802.11n devices.