ml_decision_2x2.m

两发两收的空时分组编码OFDM系统 采用SUI5信道模型

function [Symbol_1,Symbol_2]=ML_decision_2x2(H11,H21,H12,H22,ComSymbol_1,ComSymbol_2,qam)
% Alamouti Maximum Likelihood Decision Rule

Factor=H11.*conj(H11)+H21.*conj(H21)+H12.*conj(H12)+H22.*conj(H22)-1;
IQvalue=get80216map(qam);

% Detect S1
Symbol_1=zeros(1,length(ComSymbol_1));
for loop=1:length(ComSymbol_1)
    Metric=Factor(loop)*(IQvalue.*conj(IQvalue))+(abs(ComSymbol_1(loop)-IQvalue)).^2;
    index=find(Metric==min(Metric));
    if length(index)>1
        index=index(1);
        disp('Uncertain');
    end
    Symbol_1(loop)=index-1;
end

% Detect S2
Symbol_2=zeros(1,length(ComSymbol_2));
for loop=1:length(ComSymbol_2)
    Metric=Factor(loop)*(IQvalue.*conj(IQvalue))+(abs(ComSymbol_2(loop)-IQvalue)).^2;
    index=find(Metric==min(Metric));
    if length(index)>1
        index=index(1);
        disp('Uncertain');
    end
    Symbol_2(loop)=index-1;
end