From: LAMBA Jaideep
Sent: Friday, 15 January 2010
Subject: RE: [Madwifi-devel] Long
distance link with madwifi
Well Brett the makes atleast two of us
interested and committed for XR feature.
Also Does that mean at this moment ath9K
and other open source drivers cannot use Atheros XR feature as well ?
>> It was hilltop to hilltop, using XR2 @ 400mW.
>> I am pretty sure that getting XR working requires knowledge of some
more hardware registers than are already known to the open source HAL. I have
done quite a bit of hacking into the open source
>> HAL to try and get this functionality working but have had
>> Basically, my approach was just to start of by trying to get a
radio to transmit at one of the XR rates and have another module receive the
frame, since really XR is nothing more fancy than just
>> some lower data rate OFDM frames. To do that I made
some hacks to ar5212_phy.c to add ar5212_xr_table (which I got from openwrt
madwifi). Everything was setup correctly as far as I could tell
>> to get the radio transmitting at an XR data rate –
I even debugged ath_tx_start() to ensure that the frames were being sent with
what is supposed to be an XR rate. However I was never able to receive
>> this frame.
>> My feeling is that the ratecode must either be wrong or there is
some other hardware setting required that we don’t know about. I would be
willing to assist in any efforts to get this functionality working,
>> but don’t know where to go next. It would be really,
really, helpful if someone (from Atheros?) could give us the correct settings
to apply to the hardware to make these rates work.
Thanks for your reply. What height and
what radios are you using ?
All: Everything else being equal can the
range change if we are using infrastructure or adhoc mode ?
I would be interested in plugging madwifi
to get XR feature but would need some direction.
>> Hi Jaideep,
>>I comfortably got 10km using infrastructure mode, 18dB yagis at
each end of pt-pt link with signal of -74dBm and iperf throughput of about
7Mbps (urban environment). So in theory if all the stars align, >>with extra 12dB gain should get 4 times this distance with similar
>>I had to extend the max distance setting (use athctrl or distance
proc entry), and also found that I got better performance with interference
mitigation (aka ANI) turned off.
>>I too would love to have XR support, but it does not work in trunk
as far as I can determine.
>>Hope this helps
I am doing some madwifi testing with XR2 radios and madwifi trunk. I
would appreciate if you can share your comments on the questions below.
- What distance can I expect with good line of
sight, respectable height, 29Db gain grid antennas and XR2 (high power)
radios using madwifi trunk ?
- Does it change if I am in adhoc mode instead of
infrastructure mode ?
- What parameters do I need to tweak to get the max
- Do we support UBNT XR features in madwifi trunk ?