Question: ath10k and tcpdump antenna noise information missing

Tue Nov 3 02:54:10 PST 2015

Hi Tomasz,

Thank you for you reply and suggestions.

Indeed, I modified the script as follows, and now it scans quite fast:

ifconfig wlan0 down
iwconfig wlan0 mode managed
ifconfig wlan0 up
iw wlan0 set channel 1
while [ 1 ]
do
  iw wlan0 scan trigger freq 2412 2417 2422 2427 2432 2437 2442 2447 2452 2457 2462
  reset
  iw wlan0 survey dump | grep "noise"
  #  sleep 1
done

I also included the few interface initialization lines missing from my previous post.

My concern here still is whether this noise information is similar to the antenna noise
reported by the tcpdump (should the ath10k driver provide the antenna noise to the tcpdump).

If I have understood it correctly, the antenna noise info should be provided to the radiotap
by the ath10k driver per frame basis, and the radiotap would then provide this infomation
to the tcpdump or any other similar utility.

Best regards,
Tomi Saarnio

________________________________________
From: Tomasz Skapski <tomasz.skapski at tieto.com>
Sent: Tuesday, November 3, 2015 9:43 AM
To: Tomi Saarnio
Cc: ath10k at lists.infradead.org
Subject: Re: Question: ath10k and tcpdump antenna noise information missing

Hi Tomi,

you can scan only on given frequencies using iw:

iw dev <devname> scan [-u] [freq <freq>*] [ies <hex as 00:11:..>]
[ssid <ssid>*|passive]
Scan on the given frequencies and probe for the given SSIDs
(or wildcard if not given) unless passive scanning is requested.
If -u is specified print unknown data in the scan results.
Specified (vendor) IEs must be well-formed.

It should speed up your script.

Regards,
Tomasz Skąpski

On 3 November 2015 at 07:45, Tomi Saarnio <Tomi.Saarnio at ekahau.com> wrote:
> Hi all,
>
> More information on this. When I run the following bash script, the iw survey dump returns channel noise value,
> but I have no idea whether this value would be identical to the "antenna noise" that the tcpdump should return.
>
> while [ 1 ]
> do
>   iwlist wlan0 scan > /dev/null
>   reset
>   iw wlan0 survey dump | grep "noise"
> done
>
> And, running the iwlist scan + iw survey dump is v-e-r-y s-l-o-w as it scans all the channels supported, where as
> the tcpdump will return the antenna noise only on the specific channel we are monitoring.
>
> Any suggestions?
>
> Best regards,
> Tomi Saarnio
>
> ________________________________________
> From: ath10k <ath10k-bounces at lists.infradead.org> on behalf of Tomi Saarnio <Tomi.Saarnio at ekahau.com>
> Sent: Monday, November 2, 2015 1:27 PM
> To: ath10k at lists.infradead.org
> Subject: Question: ath10k and tcpdump antenna noise information missing
>
> Hi,
>
> I have been trying to figure out how to get the antenna noise information from the tcpdump.
> So far, no luck.
>
> The purpose is to estimate the channel noise level and quality using the antenna signal level
> (which is available in the tcpdump already) and the antenna noise level (the missing piece of
> the puzzle).
>
> For example:
>
> # tcpdump -ni wlan0 -c 10 2> /dev/null
>
>  [63933.453161] device wlan0 entered promiscuous mode
> 15:22:43.038447 1.0 Mb/s 2412 MHz[63934.205367] device wlan0 left promiscuous mode
>  11b -60dB signal antenna 0 Beacon (NM-WLAN2) [1.0* 2.0* 5.5* 11.0* 9.0 18.0 36.0 54.0 Mbit] ESS CH: 1, PRIVACY
> 15:22:43.038853 11.0 Mb/s 2412 MHz 11b -31dB signal antenna 0 Probe Response (aaaa) [9.0 11.0* 12.0 18.0 24.0 36.0 48.0 54.0 Mbit] CH: 1, PRIVACY
> 15:22:43.039077 5421223us tsft 11.0 Mb/s 2412 MHz 11b -38dB signal antenna 0 Acknowledgment RA:00:19:07:c5:58:11
> 15:22:43.039469 11.0 Mb/s 2412 MHz 11b -31dB signal antenna 0 Probe Response (bbbb) [9.0 11.0* 12.0 18.0 24.0 36.0 48.0 54.0 Mbit] CH: 1, PRIVACY
> 15:22:43.039694 5421839us tsft 11.0 Mb/s 2412 MHz 11b -39dB signal antenna 0 Acknowledgment RA:00:19:07:c5:58:1e
> 15:22:43.040062 11.0 Mb/s 2412 MHz 11b -31dB signal antenna 0 Beacon (cccc) [9.0 11.0* 12.0 18.0 24.0 36.0 48.0 54.0 Mbit] ESS CH: 1, PRIVACY
> 15:22:43.040298 5422447us tsft 11.0 Mb/s 2412 MHz 11b -31dB signal antenna 0 Clear-To-Send RA:00:19:07:c5:58:1e
> 15:22:43.040580 5421593us tsft 11.0 Mb/s 2412 MHz 11b -31dB signal antenna 0 CF +QoS Data IV:4d23 Pad 20 KeyID 0
> 15:22:43.040659 5422747us tsft 5.5 Mb/s 2412 MHz 11b -38dB signal antenna 0 Acknowledgment RA:00:19:07:c5:58:1e
> 15:22:43.043266 5425416us tsft 11.0 Mb/s 2412 MHz 11b -28dB signal antenna 0 Clear-To-Send RA:00:19:07:c5:58:1e
>
> (Note: it seems that the board didn't enter the promiscous mode, but apparently the tcpdump
> captures data successfully.)
>
> The platform is Gateworks Ventana board with the latest kernel 4 build and WLE600VX Ath10k miniPCIe board.
> "Linux OpenWrt 4.1.6 #2 SMP Thu Oct 29 15:18:59 EET 2015 armv7l GNU/Linux"
>  The ath10k firmware version is firmware-2.bin_10.1.467.2-1, but I have also tried firmware-5.bin_10.2.4.70.10-2.
>
> Questions:
>
> - Does the current athk10k firmware and/or driver support the antenna noise information?
> - If the current driver doesn't support the feature yet, any plans when it would be available?
> - If the current driver does provide the missing information, how can I get it to the tcpdump capture?
> - Is there any other ways of obtaining the same information by not using tcpdump?
>
> Any pointers and suggestions greatly appreciated.
>
> Best regards,
> Tomi Saarnio
>
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