I have a problem with LDPC decoding with communication tool. I believe the problem is clear but I could not solve it.

Question

Gökçe Gökkoca 2015-1-28

1
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https://ww2.mathworks.cn/matlabcentral/answers/172859-i-have-a-problem-with-ldpc-decoding-with-communication-tool-i-believe-the-problem-is-clear-but-i-co

评论： ali yasser 2020-4-26

I use Matlab2014a and I run a simple code and everything seems to be okay until the LDPC decoding command. With SNR=100, I get an error rate of 91% which is unrealistic. I believe this problem is caused by LDPC decoding step but I couldn't solve it. I will be glad if anybody can help me with this. Here is the code,

clc

clear all

close all

H = dvbs2ldpc(1/2);

henc = comm.LDPCEncoder(H);

hMod = comm.QPSKModulator('BitInput',true);

hChan = comm.AWGNChannel(... 'NoiseMethod','Signal to noise ratio (SNR)','SNR',100);

hDemod = comm.QPSKDemodulator('BitOutput',true);

hdec = comm.LDPCDecoder(H);

hError = comm.ErrorRate;

    for counter = 1:10
      data = logical(randi([0 1], 32400, 1));
      encodedData    = step(henc, data);
      modSignal      = step(hMod, encodedData);
      receivedSignal = step(hChan, modSignal);
      demodSignal    = step(hDemod, receivedSignal);
      receivedBits   = step(hdec, demodSignal);
      errorStats     = step(hError, data, receivedBits);
   end
    fprintf('Error rate       = %1.2f\nNumber of errors = %d\n', ...
      errorStats(1), errorStats(2))