%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%LMS自适应滤波器性能分析

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

clear

clc

close all

%%%%%%%%%%%%%%参数设置%%%%%%%%%%%%%%%%%%%%%%%

w=3;

% step_len=0.075;%步长

step_len=0.05;%步长

variance_v=0.01;%方差

repeat_times=20;%重复次数

iteration_times=500;%迭代次数

filt_len=2;%滤波器长度

delay=fix(filt_len/2)-1;

delay1=1;

%%%%%%%%%%%%%%%%%%%%变量及数组初始化%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Chan_factor=(1+cos(2*pi*([1:1:3]-2)/w))/2

Square_err=zeros(repeat_times,iteration_times);

% Chan_factor1=[-0.195 0.95]

Chan_factor1=[-0.195 0.95]

X=zeros(filt_len,1);

W1=[];

W2=[];

Wm1=[repeat_times,iteration_times];

Wm2=[repeat_times,iteration_times];

%%%%%%%%%%%%%外循环，重复做repeat_timws次实验，平均值%%%%%%%%%%%%%%%%

for loop1=1:repeat_times%循环次数

%%%%%%%%%%%%%%内循环变量及数组初始化%%%%%%%%%%%%%%%%%%%%%%%%

Source=zeros(iteration_times,1);

W=zeros(filt_len,1);

%%%%%%%%%%%%%内循环，做iteration_times次迭代%%%%%%%%%%%%%%%%%%%%%%%%%%%%

for i=1:iteration_times

%%%%%%%%%%%%%%信源，产生等概率分布的正负1%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if rand<0.5

Source(i)=-1;

else

Source(i)=1;

end

end

%%%%%%%%%%%%%%信道，滤波和加噪声%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Revdata=filter(Chan_factor1,1,Source)+randn(iteration_times,1)*sqrt(variance_v);

%  Revdata=filter(Chan_factor,1,Source)+randn(iteration_times,1)*sqrt(variance_v);

%    Revdata=filter(Chan_factor1,1,Source);

% RT=filter(Chan_factor1,1,Source);

%%%%%%%%%%%%%%均衡器，基于LMS算法%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

for loop2=1:iteration_times-filt_len+1

%         U=Revdata(loop2:loop2+filt_len-1);

%          y(n)=W'*U=W'*x(n),U=x(n)=输入

%          d为输出

U=Source(loop2:loop2+filt_len-1);

d=Revdata(loop2+1);

%         d=Source(loop2+delay);

%         X= x(3)=v(3)-a1*x(2)-a2*x(1);

%           d=RT(loop2+delay1);

%         Y(loop2)=W'*U;

e=d-W'*U;

%         e=d-W'*U;

W=W+step_len*U*e;

Wm1(loop2,loop1)=W(1);

Wm2(loop2,loop1)=W(2);

%         W1(loop2)=W(1);

%         W2(loop2)=W(2);

Square_err(loop1,loop2)=e.^2;

end

end

%%%%%%%%%%%%%%作图，显示结果%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Square_err_mean=sum(Square_err(:,:))/repeat_times;

% Wm2

W1=Wm1(:,repeat_times);

W2=Wm2(:,repeat_times);

meanW1=mean(Wm1');

meanW2=mean(Wm2');

Square_err;

%semilogy(Square_err_mean);

figure(1);

plot(Square_err_mean);

hold on;

plot(Square_err(1,:),'r');

legend('20次重复试验平均误差','单次误差');

xlabel('迭代次数');

ylabel('均方误差');

title('步长为0.075，500次迭代均方误差变化曲线');

grid on;

hold on;

figure(2);

plot(W1);

hold on;

plot(W2,'r');

hold on;

plot(meanW1,'k');

hold on;

plot(meanW2,'--k');

legend('W1','W2','20次重复试验W1','20次重复试验W2');

xlabel('迭代次数');

ylabel('抽头权值');

title('步长为0.075，500次迭代权值学习曲线');

grid on;