AF Cooperative Diversity MATLAB Code Needed

[David83]

AF Cooperative Diversity MATLAB Code

Hi,

I have trouble in programming AF cooperative diversity technique. I have the following MATLAB code, but the result does not match the theoretical results. I assumed that the power at the source is equal to the power at the relay.

clear all;
clc
N=10^6;%Number of bits
b=rand(1,N)>0.5;%Generate 0s and 1s
s=2.*b-1;%NRZ
SNRdB=0:2:24;%SNR in dB
for ii=1:length(SNRdB)
    d=s;
    
    h0=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%the channel gain of the direct path.
    h1=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%the channel gain of the first hop in the relay path.
    h2=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%the channel gain of the second hop in the relay path.
    n0=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%AWGN in direct path.
    n1=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%AWGN in the first hop.
    n2=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%AWGN in the second hop.
    
   B=1./abs(h1);%Amplification Gain
    
    y0=h0.*d+((10.^(-SNRdB(ii)/20))).*n0;%the received signal in the direct path.
    y1=h1.*d+((10.^(-SNRdB(ii)/20))).*n1;%the received signal in the first hop.
    yAmp=B.*y1;%Amplification of y1
    y2=h2.*yAmp+((10.^(-SNRdB(ii)/20))).*n2;%received signal in the second hop
    
    y=(conj(h0)./(10.^(-SNRdB(ii)/20))).*y0+((conj(h1).*conj(h2).*conj(B))./((abs(h2).^2+abs(B).^2+1).*(10.^(-SNRdB(ii)/20)))).*y2;
   
    bHat=real(y)>0.5;%The estimated bit sequence
    
    nErr(ii)=size(find(bHat-b),2);%Extract the number of erros between b and bHat
end
BER=nErr./N;%Average BER
semilogy(SNRdB,BER);

Any one knows where is my problem?

Thanks in advance

 

[aniket18]

Re: AF Cooperative Diversity MATLAB Code

hi,

i have question ...i am doing my project on cooperative communication in cdma..

and for power allocation algorithm i am using Amplify and forward protocol...here you have used the AF protocol with equal gain ...

i am confused if i want to use different gain for source to relay and relay to receiver...how to implement this...please guide me

Thanks In advance

 

[stupidity]

Re: AF Cooperative Diversity MATLAB Code

your problem seems about amplification gain. since there is an addition noise too at received signal at the relay; amplication gain should be
B=1./sqrt(No+abs(hsr).^2)

 

[barznjy]

Re: AF Cooperative Diversity MATLAB Code

Here is the correct code:

clear all; close all; clc;
N=10^6;%Number of bits
b=rand(1,N)>0.5;%Generate 0s and 1s
Tx=2.*b-1;%NRZ
SNRdB=0:2:30;%SNR in dB
snr = 10.^(0.1 .* SNRdB);
nErr = zeros(1,length(SNRdB));

for ii=1:length(SNRdB)

sd = sqrt(1/(snr(ii)));

h0=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%the channel gain of the direct path.
h1=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%the channel gain of the first hop in the relay path.
h2=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%the channel gain of the second hop in the relay path.
n0=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%AWGN in direct path.
n1=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%AWGN in the first hop.
n2=(1/(sqrt(2))).*(randn(1,N)+1i.*randn(1,N));%AWGN in the second hop.

% B=1./abs(h1);%Amplification Gain
B=sqrt(snr(ii) ./ ((snr(ii) .* abs(h1).^2) + 1));

y0=(h0.*Tx)+(sd).*n0;%the received signal in the direct path.
y1=(h1.*Tx)+(sd).*n1;%the received signal in the first hop.
yAmp=B.*y1;%Amplification of y1
y2=h2.*yAmp+(sd).*n2;%received signal in the second hop

y=(conj(h0)./(sd)).*y0+((conj(h1).*conj(h2).*conj(B))./((abs(h2).^2+abs(B).^2+1).*(sd))).*y2;

bHat=real>0.5;%The estimated bit sequence

nErr(ii)=size(find(bHat-b),2);%Extract the number of erros between b and bHat
end
BER=nErr./N;%Average BER
semilogy(SNRdB,BER);
grid on