sml_decode.m

alamouti 空频分组码---在时变信道下SFBC-OFDM

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

% prepare for normalization
H1 = abs(H11).^2 + abs(H22).^2;                    % h1 = h11*conj(h11)+h22*conj(h22)
H2 = abs(H12).^2 + abs(H21).^2;                    % h2 = h12*conj(h12)+h21*conj(h21)

% linear combining
X_est1 = (conj(H11).*X_odd.' + H22.*X_even')./H1;  % conj(h11)*R1 + h22*conj(R2) = (|h11|^2 + |h22|.^2)*X1
X_est2 = (conj(H21).*X_odd.' - H12.*X_even')./H2;  % conj(h21)*R1 - h12*conj(R2) = (|h21|^2 + |h12|.^2)*X2

% equlization in frequence domain
X_receive(1:2:Ncarr) = X_est1;                     % the received symbols
X_receive(2:2:Ncarr) = X_est2;