.. question: are the regulatory limits programmed into the cards taking this spreading into effect? Adrian On 5 August 2011 17:48, Felix Fietkau <nbd@xxxxxxxxxxx> wrote: > On 2011-08-05 10:36 AM, Rajkumar Manoharan wrote: >> >> On Fri, Aug 05, 2011 at 08:24:53AM +0530, Rajkumar Manoharan wrote: >>> >>> On Thu, Aug 04, 2011 at 08:23:28PM +0200, Felix Fietkau wrote: >>> > On 2011-08-04 7:54 PM, Rajkumar Manoharan wrote: >>> > >The Walsh bit is disabled for regulatory consideration. >>> > > >>> > >As per 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) >>> > I think ath9k does not waive the array gain contribution. I haven't >>> > checked AR9003, but on AR9002 and older, it explicitly includes the >>> > array gain contribution in the tx power limit calculation. I'm not >>> > sure that unconditionally disabling spatial spreading is the right >>> > way to deal with this. >>> > >>> We might violate the FCC rule with 2x2 config(3dB higher at 2-stream) >>> if this bit is enabled. Based on chainmask we can disable Walsh bit. >> >> This change does not affect 3x3, since we don't use 2-chain for 2-stream. >> And Walsh mode would follow INI setting for 2x2 or 3x3 config. > > The thing is, on many channels the the card is allowed to transmit at up to > 27 dBm, and often the hardware does not even get close to that. Why limit tx > power by disabling this bit in cases where it's not even close to going over > the limit. > How about disabling it only if the combined txpower is within x dBm of the > regulatory limit, or simply adding the same kind of multi-chain limit > calculation that is being used on AR9280? > > - 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 > -- 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
