Simulate a simple multipath channel for OFDM Modulation test. MATLAB Hi I need to simulate a simple multipath channel in matlab through which I can send my OFDM transmission signal, I want to test my OFDM receiver design.
So far I have:

%% Passing through Channel
nIFFT = 4096;

% Create channel
channel = randn(1,nIFFT) + sqrt(-1)*randn(1,nIFFT);

% cext_data is the signal to be transmitted
after_channel = filter(channel, 1, cext_data); 
wavwrite(after_channel,'ofdm_tx8khz.wav');


I get a warning when I run the transmitter:


  Warning: Data clipped during write to file:ofdm_tx8khz.wav


and when I run the receiver I get: 


  Index exceeds matrix dimensions.
  
  Error in ofdm_rx (line 26)
  
  chunk2 = signal((s+nIFFT):(s+nIFFT+nCyclic-1));


I was really hoping someone could help me simulate a multipath channel for my OFDM program.
Wav files expect values from -1 to +1.  You are probably exceeding those limits when you filter the signal through the channel model.  After the channel filter add the following:

after_channel = after_channel / max(abs(after_channel)); 

I suspect, though, that you will still have a problem.  I believe that wavwrite ignores the imaginary part of complex data, so you will be losing that part of the signal.