channel_estimation.m

程序是MIMO-OFDM系统下

function [H tx_data] =channel_estimation(Data,pilot_Data,Lh,ant_num,pilot_position,sub_num)
%Data ofdm data
%pilot_data pilot data
%N  sub_num
%Lh  time domain response length
%ant_num antenna number
%pilot_position
pilot_num=length(pilot_position);
F=zeros(sub_num,Lh);
f=zeros(pilot_num,Lh);
f_data=zeros(sub_num-pilot_num,Lh); 
tx_data=zeros(sub_num-pilot_num,1);
R=zeros(pilot_num,1);
X=zeros(pilot_num,pilot_num,ant_num);
%%%%%%%%%%%%%%%%
d=pilot_position(2)-pilot_position(1);
 temp_k=1;
 pilot_k=1;
for k=1:1:sub_num    
    for m=1:1:Lh
        F(k,m)=exp(-i*2*pi*(k-1)*(m-1)/sub_num);
        
    end
    if rem(k+d-1,d)==0
        f(pilot_k,:)=F(k,:); 
        R(pilot_k,1)=Data(k);  

        pilot_k=pilot_k+1;
    else
       f_data(temp_k,:)=F(k,:);
       tx_data(temp_k,1)=Data(k); 
       temp_k=temp_k+1;
    end
end




for am=1:1:ant_num
    for k=1:1:pilot_num
        X(k,k,am)=pilot_Data(am,k);
    end
end



if  ant_num==1
    G=X*f;
elseif ant_num==2
    G=[X(:,:,1)*f X(:,:,2)*f];
elseif ant_num==3
    G=[X(:,:,1)*f X(:,:,2)*f X(:,:,3)*f];
elseif ant_num==4
    G=[X(:,:,1)*f X(:,:,2)*f X(:,:,3)*f X(:,:,4)*f];
end

ht=inv(G'*G)*G'*R;
H=zeros(sub_num-pilot_num,ant_num);
for k=1:1:ant_num
    H(:,k)=f_data*ht(Lh*(k-1)+1:Lh*k,:);
end