MATLAB实现QPSK调制与误码率仿真详解

ns = 1000; %number of data for one loop
loop = 100000; %we will simulate 10000 times to generate 'enough' errors 
ebn0 = 0:1:10; %the parameter of Eb/N0
h1 = modem.pskmod('M',4,'SymbolOrder','Gray','InputType','Bit'); %to make it simple ,wo use build-in function to accomplish this task
h2 = modem.pskdemod('M',4,'SymbolOrder','Gray','OutputType','Bit');
h11 = modem.pskmod('M',4,'InputType','Bit'); 
h22 = modem.pskdemod('M',4,'OutputType','Bit');
tic  % start the counter of time
for i = 1:length(ebn0)  %outer loop for --each value of Eb/N0
 error = 0;  % for each Eb/N0,first,set number of errors to be ZERO.
 for iii=1:loop %inner loop : for each Eb/N0,we do simulation for <loop> times,ie--10000
     data = randint(1,ns)'; %generate the source data
     tx1 = modulate(h1,data); %modulate by using build-in function
     %To simulate Rayleigh Channel
     x=randn(1,ns);
     y=randn(1,ns);
     r=sqrt(0.5*(x.^2+y.^2));%r is a Rayleigh distribution
     %go through fading channel
     %tx = tx1.*r;
     %------------
     %Es/N0 = Eb/N0 + 10log10(k),k is the number of useful information bits
     %  per symbol
     %Es/N0 = snr + 10log10(m),m is the ratio between the period of symbol
     %  and the sampling
     %------------
     %for QPSK ,we set m=1 and we know that k is 2
     snr = ebn0(i) +10*log10(2); 
     ynoisy = awgn(tx1,snr,'measured');% for 'awgn' function,we shoule use the SNR parameter
     yrx = ynoisy;%contaminated signal
     zsym = demodulate(h2,yrx);%demodulate