encoder and decoder design using ldpc

hi.....

i am trying to encode the data by using dvbs2ldpc , i am getting the error message "Inner matrix dimensions must agree." my sample code is given

M = 4; % QPSK signal constellatio
fft_size = 64; % have 128 data point
fspacing=15000;
fs=15000*64;
Ts = 1/fs; % Sampling period of channel
Fd = 0; % Max Doppler frequency shift
nsym = 100;
source_user_1 = randsrc(1, fft_size*(nsym-2), 0:M-1); %the data source
henc=dvbs2ldpc(1/2);
data_encoded=source_user_1*henc;

also how i do modify the size of the parity check matrix of an ldpc encoder and decoder by using dvbs2ldpc.

[Image Analyst]

What is the size of source_user_1 and henc? Evidently the number of columns in source_user_1 does not equal the number of rows in henc.

whos source_user_1
whos henc

Answer 1

[Walter Roberson]

You cannot modify the size of the matrix returned by that function.