AP mode simultaneous dualband with one USB dongle

[Arend van Spriel]

On 11/22/2013 02:59 AM, Ben Greear wrote:
> On 11/21/2013 03:47 PM, Drasko DRASKOVIC wrote:
>> Hi Arend,
>>
>> On Thu, Nov 21, 2013 at 8:21 PM, Arend van Spriel <arend at broadcom.com> wrote:
>>> In my Conexant days early 2000 a marketing guy came up with the concept of a
>>> time-slicing AP. Since that time everytime a similar idea pops up I get
>>> allergic reactions. It's a pandora's box unless as others mentions you have
>>> two independent radio chains/basebands.
>>
>> Does this Pandora's box has some reference/doc/example that I can
>> google and see where the limitation exactly come from and on which
>> layer?
>
> A (normal?) radio can only listen to one channel at a time, so even if you manage to quickly change from one
> band to another when transmitting, anything else trying to talk to you on other than the current
> operating channel cannot actually communicate.

I think CTS-to-self was used as a trick to signal that. And an AP needs 
to transmit a beacon on every TBTT and transmit broadcast/multicast 
traffic every DTIM interval. That requires pretty accurate timing so you 
definitely need help from hardware to service two channels 'virtually 
simultaneous'. P2P GO can be concurrent, but I think it is primarily 
intended in combination with STA operation.

Gr. AvS