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

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Gökçe Gökkoca
Gökçe Gökkoca on 28 Jan 2015
Commented: ali yasser on 26 Apr 2020
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,
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);
fprintf('Error rate = %1.2f\nNumber of errors = %d\n', ...
errorStats(1), errorStats(2))


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