MATLAB: Encoder and decoder design using ldpc

communicationCommunications Toolboxsignal processing

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.

Best Answer

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

Related Solutions

MATLAB: How to use erasure information to do Reed Solomon decoding with the Communications Toolbox 4.1 (R2008a)

This change has been incorporated into the documentation in Release 2009a (R2009a). For previous releases, read below for any additional information.

The ability to use erasure information with the RSDEC function is not available in Communications Toolbox.

To work around this limitation, you can use the FEC.RSDEC decoder object from the Communications Toolbox, instead of the RSDEC function. The following example demonstrates how this object can be used with erasure information, with m = 3, k = 5, n = 7:

          %%Code parameters
          n = 7; k = 5;
          %%Construct encoder
          coder = fec.rsenc(n,k);
          %%Message to encode
          msg = [0 1 2 3 4]'
          %%Perform Coding
          code = encode(coder,msg)
          %%Construct decoder from encoder
          decoder = fec.rsdec(coder);
          %%Introduce 2 errors in the codeword
          code(end) = 1;
          code(end-1) = 0;
          %%Generate a vector of erasures-- 0 marks a good symbol, 1 marks an error location
          erasures = [0 0 0 0 0 1 1]';
          %%Decode the code without supplying the erasures

          %  Note that the decoded message is incorrect, because the number
          %  of errors (2) exceeds the correction capability (n-k)/2 = 1
          [decoded,cnumerr,ccode] = decode(decoder,code);
          decoded
          %%Decode the code without supplying the erasures
          %  Note that the decoded message is correct now
          [decoded_with_erasures,cnumerr,ccode] = decode(decoder,code,erasures);
          decoded_with_erasures

More details on the FEC.RSDEC object are available at the following link:

 <http://www.mathworks.com/access/helpdesk/help/toolbox/comm/ref/fec.rsdec.html>

Furthermore, if you have the Communications Blockset (a Simulink block library), you can also perform Reed Solomon decoding with erasure information in the Simulink environment. Examples are provided at the following documentation link:

 <http://www.mathworks.com/access/helpdesk/help/toolbox/commblks/ug/fp74297.html#brb6prx>

MATLAB: How should we know the functionality of built in functions

doc rsenc
help rsenc

Best Answer

Related Solutions

MATLAB: How to use erasure information to do Reed Solomon decoding with the Communications Toolbox 4.1 (R2008a)

MATLAB: How should we know the functionality of built in functions

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