clc
close all
clear all
SNR=0:1:10; %信噪比变化范围
SNR1=0.5*(10.^(SNR/10)); %将信噪比转化成直角坐标
N=1000000; %仿真点数
X=4; %进制数
x=randi([0,1],1,N); %产生随机信号
R=raylrnd(0.5,1,N); %产生瑞丽信号
h=pskmod(x,X); %调用matlab自带的psk调制函数
hR=h.*R;
for i=1:length(SNR);
SNR(i)
yAn=awgn(h,SNR(i),'measured');
yA=pskdemod(yAn,X); %QPSK=4PSK
[bit_A,l]=biterr(x,yA);
QPSK_s_AWGN(i)=bit_A/N;
yRn=awgn(hR,SNR(i),'measured');
yR=pskdemod(yRn,X); %调用matlab自带的psk解调函数
[bit_R,ll]=biterr(x,yR);
QPSK_s_Ray(i)=bit_R/N;
end
QPSK_t_AWGN=1/2*erfc(sqrt(10.^(SNR/10)/2)); %AWGN信道下QPSK理论误码率
QPSK_t_Ray= -(1/4)*(1-sqrt(SNR1./(SNR1+1))).^2+(1-sqrt(SNR1./(SNR1+1)));
%Rayleigh信道下QPSK理论误码率
%绘制图形
figure
semilogy(SNR,QPSK_s_AWGN,'r-*');hold on;
%semilogy(SNR,QPSK_t_AWGN,'y-o');hold on;
semilogy(SNR,QPSK_s_Ray,'b-*');hold on
%semilogy(SNR,QPSK_t_Ray,'g-o'); grid on;
legend('AWGN仿真','Rayleigh仿真');
title('QPSK误码性能分析');
xlabel('信噪比（dB）');ylabel('BER');
grid on;
