精选优质文档-倾情为你奉上%QPSKclc;clear all;close all;nsymbol = 50000;%每种信噪比下符号数的发送符号数data = randi(0,1,1,nsymbol*2); %产生1行，nsymbol列均匀分布的随机数0,1qpsk_mod1 = zeros(1,nsymbol);qpsk_mod2 = zeros(1,nsymbol);data_receive1 = zeros(1,nsymbol);data_receive2 = zeros(1,nsymbol);data_receive = zeros(1,nsymbol*2);Wrongnumber = 0;SymbolWrongnumber = 0;for i=1:nsymbol %调制 symbol1 = data(2*i-1); symbol2 = data(2*i); if symbol1 = 0 & symbol2 = 0 qpsk_mod1(i) = 1; qpsk_mod2(i) = 0; elseif symbol1 = 0 & symbol2 = 1 qpsk_mod1(i) = 0; qpsk_mod2(i) = 1; elseif symbol1 = 1 & symbol2 = 1 qpsk_mod1(i) = -1; qpsk_mod2(i) = 0; elseif symbol1 = 1 & symbol2 = 0 qpsk_mod1(i) = 0; qpsk_mod2(i) = -1; endend SNR_dB = 1:10;%信噪比dB形式 SNR = 10.(SNR_dB/10);%信噪比转化为线性值 for loop= 1:10 sigma = sqrt(1/(2*SNR(loop);%根据符号功率求噪声功率 qpsk_receive1 = qpsk_mod1 + sigma * randn(1,nsymbol); qpsk_receive2 = qpsk_mod2 + sigma * randn(1,nsymbol); %添加复高斯白噪声 for k=1:nsymbol if qpsk_receive2(k) qpsk_receive1(k) data_receive2(k) = 1; end if qpsk_receive2(k) -qpsk_receive1(k) data_receive1(k) = 0; end if qpsk_receive2(k) -qpsk_receive1(k) data_receive1(k) = 1; end data_receive(2*k-1) = data_receive1(k); data_receive(2*k) = data_receive2(k); end for p=1:(nsymbol*2) if data_receive(p) = data(p) Wrongnumber = Wrongnumber + 1; end end for l=1:nsymbol if data_receive1(l)=data(2*l-1); SymbolWrongnumber = SymbolWrongnumber + 1; elseif data_receive2(l) = data(2*l); SymbolWrongnumber = SymbolWrongnumber + 1; end end Pe(loop)=SymbolWrongnumber/nsymbol; Pb(loop)=Wrongnumber/(nsymbol*2); Wrongnumber = 0 ; SymbolWrongnumber = 0; endPe_theory = 1-(1-qfunc(sqrt(SNR).2;Pb_theory = 0.5* erfc(sqrt(SNR/2);semilogy(SNR_dB,Pb,-k*,SNR_dB,Pb_theory,-bo,SNR_dB,Pe,-r,SNR_dB,Pe_theory,g)title(QPSK信号在AWGN信道下的性能);xlabel(信噪比/dB);ylabel(误码率);legend(误比特率,理论误比特率,误码率,理论误码率);grid on; 专心-专注-专业