Re: [Discuss-gnuradio] GRC 3.6 / 802.11 a/g test signal

[Bastian Bloessl]

Please, stay on the list.

On 04 Oct 2014, at 18:20, Ernest Szczepaniak <address@hidden> wrote:

> Hi,
> 
> we are talking about 'frame.bin' signal right?

yes

> Becouse my decoder says:
> 
> Service: 'ok'
> Protocol_version: 'Supported'
> Type: 'Menagement'
> Subtype: 'Probe Request'
> To_DS: 'True'
> From_DS: 'False'
> More_fragments: 'No'
> Power_menagement: 'Power-Saving Mode'
> More_data: 'No'
> Protected: 'No'
> Order: 'Random'
> 
> and the initial state was 0b0101011. Furthermore, i cant see those "1", which 
> will indicate the broadcast adress thou:( So i think it is not working 
> correctly yet.

If you are still not convinced, you can very easily send the frame with a USRP 
and receive it with a WiFi card to inspect the MAC header with Wireshark. You 
can either use a simple GNU Radio flow graph (file source -> USRP sink) or use 
the tx_samples_from_file example that ships with UHD. At least my card agreed 
with my interpretation of the payload :-)

Best,
Bastian

> 
> W dniu 2014-10-04 19:56, Bastian Bloessl pisze:
>> Hi,
>> 
>> On 04 Oct 2014, at 15:50, Ernest Szczepaniak <address@hidden> wrote:
>> 
>>> Hello,
>>> 
>>> First of all, much love for your reply (it made my day).
>>> 
>>> So i started with sent frame [2]. And my receiver gives some nice results:
>>> 
>>> - found OFDM symbol
>>> - aquired time synchronization
>>> - Shmidl/Cox says that there is no frequency offset (so it is good for no 
>>> noise frame)
>>> - SIGNAL field is modulated with BPSK 6 Mbps (correct) and it says that:
>>>    - rest of the data is modulated with BPSK 6Mbps
>>>    - coderate is 1/2
>>>    - 1 bit per carrier
>>>    - 364 octets of data (is that correct?)
>>>    - reserved field, parity bit and tail bits seems to be fine.
>>> 
>>> Further MAC decoding says that:
>>> - descrambler initial state is [0 1 0 1 0 1 1] (correct?)
>>> - 16 zeros in SERVICE field (7 for desrcambler synchro and 9 reserved - 
>>> seems to be correct)
>>> - according to standard this is a PNC Selection (PNCS) frame type with 
>>> retry ([0 0 0 1] in frame type field) is that correct?
>> 
>> my decoder says:
>> 
>> new mac frame  (length 360)
>> =========================================
>> duration: 00 00
>> frame control: 00 08 (DATA)
>> Subtype: Data
>> seq nr: 0
>> mac 1: ff:ff:ff:ff:ff:ff
>> mac 2: 23:23:23:23:23:23
>> mac 3: ff:ff:ff:ff:ff:ff
>> Hello World!Hello World!Hello World!Hello World!Hello World!Hello 
>> World!Hello World!Hello World!Hello World!Hello World!Hello World!Hello 
>> World!Hello World!Hello World!Hello World!Hello World!Hello World!Hello 
>> World!Hello World!Hello World!Hello World!Hello World!Hello World!Hello 
>> World!Hello World!Hello World!Hello World!Hello World!
>> 
>> It does not contain a LLC, just a MAC header. It is BPSK 1/2 encoded. I 
>> guess the initial scrambler state was 0b0101010 (=42) and it is a data frame.
>> 
>> Best,
>> Bastian
>> 
>> 
>>> Best,
>>> 
>>> Ernest
>>> 
>>> 
>>> 
>>> W dniu 2014-10-04 11:16, Bastian Bloessl pisze:
>>>> Hi,
>>>> 
>>>> you can use gr-ieee802-11 [1] to generate WiFi frames. Just start the TX 
>>>> flow graph and pipe the output to a file.
>>>> I uploaded a frame (IQ data, no noise) [2] for you that you can use to get 
>>>> started.
>>>> 
>>>> I don’t use Matlab, so i don’t know how to import the data, but you can 
>>>> display the IQ samples with
>>>> 
>>>> od -fw8 frame.bin
>>>> 
>>>> There is also a GNU Radio script [3] that might be helpful.
>>>> 
>>>> Hope it helps,
>>>> Bastian
>>>> 
>>>> 
>>>> [1] https://github.com/bastibl/gr-ieee802-11
>>>> [2] https://www.ccs-labs.org/~bloessl/frame.bin
>>>> [3] 
>>>> https://github.com/gnuradio/gnuradio/blob/master/gr-utils/octave/read_complex_binary.m
>>>> 
>>>> 
>>>> 
>>>> On 02 Oct 2014, at 17:25, Ernest Szczepaniak <address@hidden> wrote:
>>>> 
>>>>> Greetings engi's!
>>>>> 
>>>>> I'm currently working on my masters (802.11 wlan receiver with
>>>>> MATLAB/USRPN210). After creating all the important stuff ie:
>>>>> 
>>>>> -symbol finder
>>>>> -time synchronization
>>>>> -coarse and fine frequency compensation
>>>>> -symbol demodulator
>>>>> -deinterleaver
>>>>> -Viterbi decoder
>>>>> -descrambler etc.
>>>>> -MAC layer decoding
>>>>> 
>>>>> i'm looking for any tested 802.11 a/g IQ signal for further research
>>>>> becouse live samples captured by USRP seem to have incorrect result's
>>>>> (wrong frame type MAC field, random MAC adress, CRC, parity bits etc).
>>>>> 
>>>>> And here comes my 1st question.
>>>>> 
>>>>> Is there any place where i can get some real, tested IQ wlan signal i
>>>>> a/g standard and full description (rate, coded data, adresses, included
>>>>> MAC fields)? Tried with Agilent Signal Studio but files are saved in
>>>>> .wfm encrypted format :(
>>>>> 
>>>>> I also found GRC beacon frames transmitter, written in GRC
>>>>> 
>>>>> http://rrsg.ee.uct.ac.za/members/jwamicha/gr-wlan.tar.gz
>>>>> 
>>>>> but due to having GRC 3.7 (where 'gnuradio-core' was repleaced with
>>>>> 'gnurdaio-runtime') i can't simply compile this file becouse of an
>>>>> error:
>>>>> 
>>>>> ---------------------------------------------------------------------------
>>>>> 
>>>>> checking for GNURADIO_CORE... configure: error: Package requirements
>>>>> (gnuradio-core >= 3) were not met:
>>>>> 
>>>>> No package 'gnuradio-core' found
>>>>> 
>>>>> Consider adjusting the PKG_CONFIG_PATH environment variable if you
>>>>> installed software in a non-standard prefix.
>>>>> 
>>>>> Alternatively, you may set the environment variables
>>>>> GNURADIO_CORE_CFLAGS
>>>>> and GNURADIO_CORE_LIBS to avoid the need to call pkg-config.
>>>>> 
>>>>> ---------------------------------------------------------------------------
>>>>> It seems that those binaries arent compatible with my GRC version :(
>>>>> 
>>>>> Any helpful guy to install this library and send me IQ signal of this
>>>>> beacon frame? (in any MATLAB readable format - simple file sink in GRC).
>>>>> 
>>>>> Looking forward for any reply.
>>>>> 
>>>>> Thanks
>>>>> 
>>>>> 
>>>>> _______________________________________________
>>>>> Discuss-gnuradio mailing list
>>>>> address@hidden
>>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>>>> 
>>>> --
>>>> Dipl.-Inform. Bastian Bloessl
>>>> Distributed Embedded Systems Group
>>>> University of Paderborn, Germany
>>>> http://www.ccs-labs.org/~bloessl/
>>>> 
>>