QPSK理论误码率与实际误码率MATLAB仿真程序

%%QPSK clc;

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0,1 qpsk_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; end end

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_receive2(k) = 0; 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; end

Pe_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;