I am trying to simulate BER performance for turbo code. The original code is written by copyright Nov. 1998 Yufei Wu, MPRG lab, Virginia Tech for academic use only . I am trying to incorparate Rayleigh fading instead of AWGN but performance is very poor. The following is a segment of code. Any suggestions will be highly appreciated.
"%%%%%% " encoder" %%%%
en_output = encoderm( x, g, alpha, puncture ) ; % encoder output (+1/-1)
a=sqrt(0.5)*(randn(1,1)+1i*randn(1,1));
%%%%%%%%%%%%%%%%%%% Channel %%%%%%%%%%%%%%%%%%%
en = 10^(EbN0db(nEN)/10); % convert Eb/N0 from unit db to normal numbers
Lc = 4*conj(a)*en*rate; % reliability value of the channel
sigma = 1/sqrt(2*rate*en); % standard deviation of AWGN noise
noise=sigma.*(randn(1,L_total*(2+puncture))+1j*randn(1,L_total*(2+puncture)));
%%%%%%%%%%%%%%%%%%%%%%%%% Receiver %%%%%%%%%%%%%%%%%%%%%%%%%%
r = en_output.*a+noise; % received bits
% Scale the received bits:
rec_ss = 0.5*(Lc.*r);"
Hi!
There are two things:
1) First apply Raleigh channel (h) and then add noise (n), i.e. y =hx+n.
2) Secondly, you need to assume perfect channel estimation at the receiver to nullify the impact of Rayleigh fading, i.e. y/h.
The following link might also help you :
http://www.dsplog.com/2008/08/10/ber-bpsk-rayleigh-channel/
Thanks in first place. I also tried this yet no improvement. As per my observation it is Lc "the channel reliability " this is not adjusted properly thus i do not see any improvements from iteration to iteration.
Still looking for another solution.
Thanks @Maharshi Rindani . actually i found the problem the problem was not in simulations it was in my understanding of the results. For a quasi-static channel you should expect worst gains when you are moving from AWGN scenarios.
Hello Saqib,
I am working on turbo code for bpsk symbols in rayleigh fading.
As the received symbols will be complex value. My problem is how Match filtering is performed. As books use this match filter output to write pdf. Can u help me out how u have performed match filtering.
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