clear all; 
an=[1,0.3,-0.8,0.5,-0.4,0.2];tn=[0,1,2,3,4,5;0,0.1,0.2,0.3,0.4,0.5]; 
 
signal=[0, zeros(1,0),ones(1,501),zeros(1,1000)];  % transmitted signal 
 
for k=1:2;   %for two cases 
for i=1:6; 
ray(i,:)=an(i)*[0, zeros(1,(100*tn(k,i))),ones(1,501),zeros(1,(1000-100*tn(k,i)))]; 
end 
y(k,:)=sum(ray(:,1:end)); 
end 
 
t=((1:1:length(y(1,:)))-1)*10^(-2); 
 
subplot(2,2,1);plot(t,signal); 
ylabel('transmitted signal s(t)'); 
title('case 1 & case 2') 
axis([ 0 20 -0.5 1.5]) 
 
subplot(2,2,2);plot(t,y(1,:)); 
ylabel('received signal y(t)'); 
title('case 1: large delay spread') 
 
subplot(2,2,4); 
plot(t,y(2,:)); 
xlabel('Time(us)'); 
ylabel('received signal y(t)'); 
title('case 2: small delay spread')