%%dpsk格雷码矩形
%%等效基带调制
clc;
clear all;
close all;%%关闭所有窗口，比如之前画的图
nsymbol = 1e6;%%每种信噪比下符号数的发送符号数，10^6个数errornumber = zeros(1,10);
errorratio = zeros(1,10);
dataa = randi([0,1],1,2*nsymbol);%%产生1行，2*nsymbol列均匀分布的随机数datab = zeros(1,2*nsymbol);
data_mod1 = zeros(1,nsymbol);%%各参量初始化
data_mod2 = zeros(1,nsymbol);
data_demod1 = zeros(1,nsymbol);
data_demod2 = zeros(1,nsymbol);
s_receive1 = zeros(1,nsymbol);
s_receive2 = zeros(1,nsymbol);
datab_receive = zeros(1,2*nsymbol);
dataa_receive = zeros(1,2*nsymbol);
datab(1) = xor(0,dataa(1));%%给定初始相位
for l = 2:(2*nsymbol)%%逻辑运算
datab(l) = xor(dataa(l),datab(l-1));
end
for i = 1:nsymbol %%格雷码调制到星座图的映射
if datab(2*i-1)==0 && datab(2*i)==0
data_mod1(i) = 1;
data_mod2(i) = 1;
elseif datab(2*i-1)==0 && datab(2*i)==1
data_mod1(i) = -1;
data_mod2(i) = 1;
elseif datab(2*i-1)==1 && datab(2*i)==1
data_mod1(i) = -1;
data_mod2(i) = -1;
elseif datab(2*i-1)==1 && datab(2*i)==0
data_mod1(i) = 1;
data_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/SNR(loop));%%%根据符号功率求噪声功率
s_receive1 = data_mod1+sigma * randn(1,length(data_mod1));
s_receive2 = data_mod2+sigma * randn(1,length(data_mod2));%%添加复高斯白噪声
for k = 1:nsymbol%%反映射
if s_receive1(k)>0 && s_receive2(k)>0
data_demod1(k) = 0;
data_demod2(k) = 0;
elseif s_receive1(k)<0 && s_receive2(k)>0
data_demod1(k) = 0;
data_demod2(k) = 1;
elseif s_receive1(k)<0 && s_receive2(k)<0
data_demod1(k) = 1;
data_demod2(k) = 1;
elseif s_receive1(k)>0 && s_receive2(k)<0
data_demod1(k) = 1;
data_demod2(k) = 0;
end
datab_receive(2*k-1) = data_demod1(k);
datab_receive(2*k) = data_demod2(k);
end
dataa_receive(1) = xor(0,datab_receive(1));
for n = 2:(2*nsymbol)
dataa_receive(n) = xor(datab_receive(n),datab_receive(n-1));
end
for m = 1:nsymbol
if (dataa_receive(2*m-1) ~= dataa(2*m-1))||(dataa_receive(2*m) ~= dataa_receive(2*m))%%统计误码个数
errornumber(loop) = errornumber(loop)+1;
end
end
errorratio(loop) = errornumber(loop)/nsymbol; %%计算误码率
end
ser_theory = 1-(1-qfunc(sqrt(SNR))).^2;%理论误码率，注意Q函数和误差函数的对应关系semilogy(SNR_dB,errorratio,'-k*',SNR_dB,ser_theory,'-ro');
title('DPSK信号在AWGN信道下的性能（格雷码）');
xlabel('信噪比/dB');ylabel('误码率');
legend('误码率','理论误码率');
grid on;%%坐标线