通信原理课程设计—实现Qpsk调制解调

% QPSK 2 clear all, close all N = 1000; iter = 100; expSymErrs = 10; EbNo = 0:1:10; bitsnrdB = EbNo; bitsnrlin = 10.^(bitsnrdB/10); theo_berr = 0.5*erfc(sqrt(bitsnrlin)); theo_serr = 1 - (1 - theo_berr).^2; semilogy(bitsnrdB,theo_berr,'m', bitsnrdB,theo_serr,'g'); axis([0 max(EbNo) 1e-6 1]); grid on hold on drawnow for t = 1:length(EbNo) idx = 1; errSym = 0; while ((idx <= iter) || (sum(errSym) <= expSymErrs)) s = 1/sqrt(2)*(randsrc(N,1) + j*randsrc(N,1)); % Compute EsNo EsNo = EbNo(t) + 10*log10(2); EsNolin = 10.^(EsNo/10); No = 1/EsNolin; % Assuming Es = 1 var = No; % n = sqrt(var/2)*(randn(N,1) + j*randn(N,1)); x = s + n; % Detection follows alph = [1+j, 1-j, -1+j, -1-j]/sqrt(2); detx = zeros(N,1); for tt = 1:N [val,id] = min(abs(x(tt) - alph)); detx(tt) = alph(id); end errSym(idx) = length(find(s ~= detx)); idx = idx + 1; end pe(t) = mean(errSym)/N; semilogy(EbNo(t),pe(t),'-ob') drawnow end