relign4.m

基于卷积信号的MIMO系统盲信号估计

function [H_est_even,h_est]=relign4(N, F, h, real_channel, L_diff, delta)

%%%% Recover the time domain channel from the frequency domain estimates

L=length(h);
Le=L+L_diff;

h=[reshape(h,1,L),zeros(1,L_diff)];

d=abs(delta);

H=fft(h,N);

hh=zeros(1,N);
for i=0:d:d*(Le-1)
    hh(mod(i,N)+1)=h(i/d+1);
    %upsampled h by d
end

f=reshape(ifft(F(1:end),N), 1, N); %IDFT of eq. (26)

index=zeros(N,1);

for ii=0:N-1
    index(ii+1)= f* (hh( mod([0:N-1] - ii, N)+1))';    
end

[v,I]=max(abs(index));

tmp=f(mod(([0:N-1]+(I-1)),N)+1);

for ii=0:(Le-1)
    ff(ii+1)=tmp(mod(ii*d,N)+1);   %%%% down sampled by d
end

% if real_channel
%     ff=real(ff);
% end

ff=reshape(ff,1,Le);

scalar=h*ff'/(ff*ff');

h_est=ff*scalar;

if real_channel
    h_est=real(h_est);
end

scalar=h*h_est'/(h_est*h_est');

h_est=h_est*scalar;

H_est_even=fft(h_est,N);


if 0
    
    figure;

    stem(real(h),'*'); hold on; 

    %stem(abs(tmp),'r*'); stem(abs(hh),'g'); 

     stem(real(h_est),'ms');
 end