Моделирование в Matlab

% Create Rayleigh fading channel obj e c t .
chan = rayleighchan (1/10000, 100);
% Generate data and apply fading channel .
M = 2 ; % DBPSK modulation orde r
hMod = comm.DBPSKModulator ; % Create a DPSK modulator
hDemod = comm.DBPSKDemodulator ; % Create a DPSK demodulator
tx = randi([0 M-1],50000,1); % Generate a random bit stream
dpskSig = step (hMod, tx) ; % DPSK modulate the signal
fadedSig = filter (chan, dpskSig) ; % Apply the channel effects
% Compute error rate for different values of SNR.
SNR = 0:2:20 ; % Range of SNR values , in dB.
numSNR = length (SNR) ;
berVec = zeros (3, numSNR) ;
% Create an AWGNChannel and Er rorRate calculator System object
hChan = comm.AWGNChannel('NoiseMethod','Signal to noise ratio (SNR)');
hErrorCalc = comm.ErrorRate ;
 
for n = 1 :numSNR
hChan.SNR = SNR(n) ;
rxSig = step (hChan , fadedSig ) ; % Add Gaussian no i s e
rx = step (hDemod , rxSig ) ; % Demodulate
reset ( hErrorCalc )
% Compute errorrate .
berVec (:, n) = step ( hErrorCalc , tx , rx ) ;
end
BER = berVec ( 1 , : ) ;
% Compute theoretical performance results , for comparison .
BERtheory = berfading (SNR,'dpsk',M,1) ;
% Plot BER results .
semilogy (SNR, BERtheory , 'b-' ,SNR,BER, ' r+ ' ) ;
legend ( ' Theoretical BER' , 'Empirical BER' ) ;
xlabel ( 'SNR (dB) ' ) ; ylabel ( 'BER' ) ;
title ( ' Binary DPSK over Rayleigh Fading Channel ' ) ;

% Create Rayleigh fading channel obj e c t .
chan = rayleighchan (1/10000, 100);
% Generate data and apply fading channel .
M = 4 ; % DQPSK modulation orde r
hMod = comm.DQPSKModulator ; % Create a DPSK modulator
hDemod = comm.DQPSKDemodulator ; % Create a DPSK demodulator
tx = randi([0 M-1],50000,1); % Generate a random bit stream
dpskSig = step (hMod, tx) ; % DPSK modulate the signal
fadedSig = filter (chan, dpskSig) ; % Apply the channel effects
% Compute error rate for different values of SNR.
SNR = 0:2:20 ; % Range of SNR values , in dB.
numSNR = length (SNR) ;
berVec = zeros (3, numSNR) ;
% Create an AWGNChannel and Er rorRate calculator System object
hChan = comm.AWGNChannel('NoiseMethod','Signal to noise ratio (SNR)');
hErrorCalc = comm.ErrorRate ;
 
for n = 1 :numSNR
hChan.SNR = SNR(n) ;
rxSig = step (hChan , fadedSig ) ; % Add Gaussian no i s e
rx = step (hDemod , rxSig ) ; % Demodulate
reset ( hErrorCalc )
% Compute errorrate .
berVec (:, n) = step ( hErrorCalc , tx , rx ) ;
end
BER = berVec ( 1 , : ) ;
% Compute theoretical performance results , for comparison .
BERtheory = berfading (SNR,'dpsk',M,1) ;
% Plot BER results .
semilogy (SNR, BERtheory , 'b-' ,SNR,BER, ' r+ ' ) ;
legend ( ' Theoretical BER' , 'Empirical BER' ) ;
xlabel ( 'SNR (dB) ' ) ; ylabel ( 'BER' ) ;
title ( ' Binary DPSK over Rayleigh Fading Channel ' ) ;