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[<bogus@does.not.exist.com>]

* If your RX chainmask has >1 radio enabled, you'll always be doing
receive-side "diversity" (which is really "combining" (MRC) if I
understand the technology correctly on multi-radio atheros 11n cards);
* If your TX chainmask has >1 radio enabled and the TX descriptor has
the relevant chainmask bits set, you should be transmitting on both
antennas regardless of the rate. I honestly haven't verified it (I've
only verified that behaviour for transmitting legacy rates out of the
11n chips);

* For rates < MCS8 (and legacy rates) there's further TX-side trickery
that can be going on which I'm not too up-to-date on. For example,
some (all?) of the 11n chips allow you to optionally transmit MCS0-7
using STBC. But iirc, STBC is only enabled for 1-stream TX.

In short, if you've got all the radios enabled  for RX and ath9k is
enabling both/all radio chains when TX'ing, I think the answer is
"yes" for you. :)



Adrian

On 16 February 2011 22:47, Baldomero Coll <baldo.ath9k@gmail.com> wrote:
> I'm not sure, but I've read somewhere that by default the two antennas are
> used.
> It is true that I'm not interested in selecting the number of antennas, what
> I really want is that the MIMO capability is exploited if I'm using 802.11n
> HT IBSS operation mode.
> Can someone confirm that by default the two antennas (spatial diversity) are
> being used when we create the HT IBSS network?
>
> 2011/2/16 Mohammed Shafi <shafi.ath9k@gmail.com>
>>
>> On Tue, Feb 15, 2011 at 2:35 PM, Baldomero Coll <baldo.ath9k@gmail.com>
>> wrote:
>> > Hello,
>> >
>> > Can you please tell me how do you select one o two antennas?
>>
>> I don't know why you should do that. I guess changing the tx/rx
>> chainmask will do after it was read from eeprom.
>>
>> >
>> > I'm using a similar setting than you:
>> > Linux kernel: 2.6.32-28-generic-pae.
>> > Driver: compat-wireless-2011-01-17 and iw-0.9.21 with the patch
>> > suggested by
>> > Alex.
>> > Radio card: Ubiquiti SR71x
>> >
>> > Thanks in advance,
>> > Baldomero
>> >>
>> >> Hi all,
>> >>
>> >> I would like to confirm my findings. My test platform configurations
>> >> are
>> >> follow.
>> >> Board: pcengine alix3d2
>> >> Linux kernel: 2.6.35 from linux-wireless git
>> >> Driver: compat-wireless-2011-01-17 and iw-0.9.21 with the patch
>> >> suggested by Alex.
>> >> Radio card: Ubiqiti SR71a on channel 36 with HT40+
>> >> Measurement tool and settings: Iperf, UDP, 100Mb offered load
>> >>
>> >> Recored throughput: 50-54Mbps (one antenna); 78-80Mbps (two or three
>> >> antennas).
>> >
>> >
>> > _______________________________________________
>> > ath9k-devel mailing list
>> > ath9k-devel at lists.ath9k.org
>> > https://lists.ath9k.org/mailman/listinfo/ath9k-devel
>> >
>> >
>
>
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