cooperative_network2.m

Analyze a performance of cooperative networks over Rayleigh fading channels for different transmissi

clear all
%% Generate data and apply fading channel.
M = 2; % DBPSK modulation order
tx = randint(50000,1,M);  % Random bit stream


%Fading Channel %%direct path%%
chan1 = rayleighchan(1/10000,1000); %input symbol period, fd max
%%relayed path
chan2 = rayleighchan(1/50000,4); %input symbol period, fd max
chan3 = rayleighchan(1/10000,4);


% BPSK passed through the fading channel
%%direct path%%
dpskSig = dpskmod(tx,M);  % DPSK signal
fadedSig1 = filter(chan1,dpskSig); % Effect of direct channel

%%At relay
fadedSig2 = filter(chan2,dpskSig); % Effect of channel

SNR = 0:.2:20;
for n = 1:length(SNR)
rxSig2 = awgn(fadedSig2,SNR(n)); % Add Gaussian noise.
rx2 = dpskdemod(rxSig2,M); % Demodulate.
tx_r=rx2; 
%%After relay
dpskSig_r= dpskmod(tx_r,M);
fadedSig3 = filter(chan3,dpskSig_r); % Effect of channel
end

% Compute error rate for different values of SNR.
SNR = 0:.2:20; % Range of SNR values, in dB.
for n = 1:length(SNR)
   rxSig1 = awgn(fadedSig1,SNR(n)); % Add Gaussian noise.
   rxSig3 = awgn(fadedSig3,SNR(n)); % Add Gaussian noise.
   
   rx1 = dpskdemod(rxSig1,M); % Demodulate.
   rx2 = dpskdemod(rxSig3,M); % Demodulate.
   
  
 % Compute bit error rate ignoring first sample 
   [nErrors1, BER1(n)] = biterr(tx(2:end),rx1(2:end));
   [nErrors2, BER2(n)] = biterr(tx(2:end),rx2(2:end));

end

%%BER results.
semilogy(SNR,BER1,'b-',SNR,BER2,'r*');
legend(' BER d','BER R');
xlabel('SNR (dB)'); ylabel('BER');
title('Binary DPSK over Rayleigh Fading Channel');