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


From: Bastian Bloessl
Subject: Re: [Discuss-gnuradio] GRC 3.6 / 802.11 a/g test signal
Date: Wed, 08 Oct 2014 12:04:21 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.2

On 10/08/2014 11:54 AM, Ernest Szczepaniak wrote:
Ok. After couple of days trying to decode your frame i decided to check my
receiver with real samples.
Could it be possible that after demodulation (de-interleaving,
de-convolutional, de-scrambling) im getting over 40x0's in correct positions
(9 reserved bits, 16x0s in duration, correct pads) and still cant work out
your frames? Such amount of correct data couldnt be a coincidence :(


As I already mentioned, it is very hard to help you without the code...

That test frame from Annex L is fully coded (scrambled, interleaved and conv
coded)?


Yes, it is. And it's clearly stated. But for your convenience I can copy paste from the standard.

The encoding illustration goes through the following stages:
a) Generating the short training sequence section of the preamble;
b) Generating the long preamble sequence section of the preamble;
c) Generating the SIGNAL field bits;
d) Coding and interleaving the SIGNAL field bits;
e) Mapping the SIGNAL field into frequency domain;
f) Pilot insertion;
g) Transforming into time domain;
h) Delineating the data octet stream into a bit stream;
i) Prepending the SERVICE field and adding the pad bits, thus forming the DATA;
j) Scrambling and zeroing the tail bits;
k) Encoding the DATA with a convolutional encoder and puncturing;
l) Mapping into complex 16-QAM symbols;
m) Pilot insertion;
n) Transforming from frequency to time and adding a circular prefix;
o) Concatenating the OFDM symbols into a single, time-domain signal.

Bastian



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