% 編一個如瑞利多徑的信道函數；
function y=Rayleigh_DuoJing(x,sigma,num_path,ray_factor,time_delay,p_path)

y=zeros(num_path,size(x,2));
for i=1:num_path
    % 即使瑞利衰落因子是一樣的，
    % 對于每一行的衰落系數也要分別產生；
    ray_number=raylrnd(ray_factor,size(x));
    y(i,:)=sqrt(10^(p_path(i)/10))*(ray_number.*x);
    temp=y(i,:);
    y(i,:)=[zeros(1,time_delay(i)),temp(1:end-time_delay(i))];
    randn('state',0);
    y(i,:)=y(i,:)+sigma*randn(size(x));
end;
    y=sum(y,1);