jml_decode.m

alamouti 空频分组码---在时变信道下SFBC-OFDM

% Joint Maxima Likelihood Dectection
function X_receive = JML_decode(H11, H12, H21, H22, X_odd, X_even, Ncarr)

X_receive = [];                                 % receive/demodulate bits

% calculating the APP of symbol-pairs -- "for" can be avioded by using function
P(1,1,:) = abs(X_odd + H11.' + H21.').^2 + abs(X_even + H22.' - H12.').^2;
P(1,2,:) = abs(X_odd + H11.' - H21.').^2 + abs(X_even + H22.' + H12.').^2;
P(2,1,:) = abs(X_odd - H11.' + H21.').^2 + abs(X_even - H22.' - H12.').^2;
P(2,2,:) = abs(X_odd - H11.' - H21.').^2 + abs(X_even - H22.' + H12.').^2;

for i = 1:Ncarr/2
% find min element in APP    
    [min_val min_row] = min(P(:,:,i));
    [min_all min_col] = min(min_val.');

% link to recover the sent bits
    X_receive = [X_receive min_row(min_col)-1 min_col-1];
end