clear all;
close all;
clc;
tic
Nt=4; %发射天线数
Nr=4; %接收天线数
L=10000; %仿真次数 共L组
EbNo=0:2:20; %信噪比dB 区间
M=4; %映射星座点个数
x=round(rand(Nt,L)*(M-1)); %均匀分布(并行数据) 4*10000 一次取一列4*1发送
s=qammod(x,M);% 4QAM调制
s=s/sqrt(2); %信号功率归一化
%%%%%
for index=1:length(EbNo);
x1=[];
x2=[];
x3=[];
x4=[];
x5=[];
for index1=1:L
h=randn(Nr,Nt)+1i*randn(Nr,Nt); % 瑞利衰落信道4*4
h=h./sqrt(2); %信道系数归一化
sigma=sqrt(1/(10.^(EbNo(index)/10))); %每根接收天线的噪声标准差
n=sigma/sqrt(2)*(randn(Nr,1)+1i*randn(Nr,1)); %Nr个接收天线的高斯白噪声4*1
%每根接收天线的噪声功率都是sigma^2
%%%%%ZF和MMSE滤波矩阵%%%%%
w_zf=inv(h'*h)*h'; %%%%%%%%%%%%%%%%ZF%%%%%%%%%%%%%%%%%%
w_mmse=h'*inv(h*h'+sigma.^2*diag(ones(1,Nt)));%%%MMSE%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
y=h*s(:,index1)+n; %信号经过信道 一列4*1
yy=y;
%%%信号检测%%%
y1=w_zf*yy; %4*1
y2=w_mmse*yy; %4*1
y3=osic_zf(yy,h); %4*1 OSIC
y4=osic_mmse(yy,h,sigma); %4*1 MMSE
y5=ML_algorithm(yy,h,M);
%%%%%%%%%%%%%
temp1=qamdemod(y1,M);
temp2=qamdemod(y2,M);
temp3=y3; %4*1
temp4=y4; %4*1
temp5=qamdemod(y5,M); %4*1
x1=[x1;temp1']; %10000*4
xx1=x1';
x2=[x2;temp2'];
xx2=x2';
x3=[x3;temp3'];
xx3=x3';
x4=[x4;temp4'];
xx4=x4';
x5=[x5;temp5'];
xx5=x5';
end
%求误码率
[~,ber1(index)]=biterr(x,xx1,log2(M));
[~,ber2(index)]=biterr(x,xx2,log2(M));
[~,ber3(index)]=biterr(x,xx3,log2(M));
[~,ber4(index)]=biterr(x,xx4,log2(M));
[~,ber5(index)]=biterr(x,xx5,log2(M));
end
semilogy(EbNo,ber1,'*-k',EbNo,ber2,'o-r',EbNo,ber3,'d-b',EbNo,ber4,'+-m',EbNo,ber5,'x-g');
legend('ZF','MMSE','OSICZF','OSICMMSE','ML');
xlabel('SNR(dB)');
ylabel('BER');
grid on;
toc
