On 2011-11-10 11:04 AM, Felix Fietkau wrote:
On 2011-11-10 10:44 AM, Rajkumar Manoharan wrote:
Retriving tx power for 2x2 and 3x3 chainmask is not handled
properly. While calculating tx power for 2x2, 3 dBm was reduced
and for 3x3, 5 dBm was reduced which should be added back when
retriving.
Cc: Paul Stewart<pstew@xxxxxxxxxx>
Signed-off-by: Rajkumar Manoharan<rmanohar@xxxxxxxxxxxxxxxx>
I think the tx power reduction for 2x2/3x3 needs to be revisited. In the
discussion that led to Walsh spatial spreading being disabled you
mentioned this:
In the FCC rulings, only transmissions that are completely non-coherent, are
allowed to waive the array gain contribution to EIRP for multi-transmit configurations.
The use of 2-stream with 2 transmit and use of 3-steam with 3 transmit qualifies
for this spatial multiplexing MIMO classification as long as the streams are
directly mapped to each radio (not Walsh spread prior to splitting to multiple radios)
So if I understand this issue correctly, Walsh spatial spreading was
disabled so that the tx power for 2x2 or 3x3 would not have to be
reduced by the array gain contribution - yet we're still doing that.
When Adrian pointed out that tx power is reduced based on the number of
chains, you mentioned this:
Those pwrdecrease fields are applicable for AR9280 chips not for AR9003.
According to this patch, this doesn't seem to match what the code does,
though I didn't notice it back then.
So before we merge this patch, let's decide whether we actually need
this tx power reduction or not.
I just spent some time reading up on the FCC's MIMO test procedures and
it appears that I just got mixed up in the terminology earlier. The
patch should be merged as-is.
- Felix
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
