Two hostap access points in the same computer

Jim Thompson jim at
Thu Dec 9 18:00:41 EST 2004

Right, it works if you're close-by, somewhat.

but try this:

turn-up card #1, on, say, channel 1, as an AP
go to range (farthest you can reach) with a notebook.   Run a  
throughput test.
turn-up card #1, on, say, channel 6 or even channel 11
go to range with a second notebook
run simultaneous throughput tests

explain why you don't get 2X the single notebook test.

For your second assignment, go read up on "clear channel assessment"  
and then figure out if the signal level of the first radio
is setting CCA on the second.   For the purposes of this exercise, you  
may assume a 1m separation between the antennas (so 40dB of path loss),
2.2dBi antennas, an ACR of 41dB, with perhaps 20dBm more while  
operating on 1 and 11, rather than 1 and 6 or 6 and 11.

here are some links to get you started: 

Or hell, just read this. or  


On Dec 9, 2004, at 12:45 PM, David Goodenough wrote:

> Odd that it should be impossible, I have lots of systems with two  
> wireless
> cards and a few with three (although I am in the UK so I have more
> available channels).  I do put a copper tape between the heads of the
> pcmcia cards, but nothing more.  All channels seems to work as you
> would expect.
> Still, doing six impossible things before breakfast always was fun.
> David
> On Thursday 09 December 2004 21:28, Jim Thompson wrote:
>> of course, the problem is that there are no "non-overlapping channels"
>> in 2.4GHz.
>> And please don't cite that tired old "1, 6, 11" transmit mask argument
>> unless you're
>> ready to talk about the selectivity of the receivers.
>> Short answer:  no, it doesn't work unless you're prepared to add a lot
>> more cost/engineering.
>> Jim
>> On Dec 9, 2004, at 5:43 AM, Dan Searle wrote:
>>> Hi,
>>> The radio cards appear as different interfaces: wlan0 wlan1 etc... so
>>> you can have many in one host at any one time.
>>> Hardware considerations are power consumption (if it's a low power
>>> host), and RF interferrance. If you're using 2.4GHz (802.11b/g) then
>>> be careful to choose channels which don't overlap, otherwise you'll
>>> have both radios fighting for the bandwidth, or interfering with each
>>> other.
>>> Dan...
>>> Thursday, December 9, 2004, 3:34:58 PM, you wrote:
>>>> Is it possible to put one pcmcia card and one pci card to the same
>>>> pc, so that they
>>>> both acts like an access point? The pci card uses external antenna
>>>> which would be
>>>> 10m apart from the pc (outside of the building). The pcmcia card
>>>> would use its own
>>>> inbuilt antenna.
>>>> How this kind of setup would work? What things should be taken into
>>>> consideration ?
>>> --
>>> Dan Searle
>>> Adelix Ltd
>>> dan.searle at web:
>>> tel: 0845 230 9590 / fax: 0845 230 9591 / support: 0845 230 9592
>>> snail: The Old Post Office, Bristol Rd, Hambrook, Bristol BS16 1RY.  
>>> UK.
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