gusucode.com > ​多天线系统的各种信号检测算法matlab源码程序 > MIMO_detection/MLD_detection.m

    function [MLD_det_bit]=MLD_detection(y,H,Tx,Modu_bit)
%使|y-Hs|^2最小的s
%considering Tx=4, and QPSK

OneBySqrt2=0.7071067812;
if Tx==4 & Modu_bit==2
    %constitute all candidates for each antenna
    tmp=[-1,1];
    cand=zeros(4,1);
    for a=1:2
        for b=1:2
            index=b+(a-1)*2;
            cand(index)=tmp(a)+j*tmp(b)
            cand(index)=cand(index)*OneBySqrt2;
        end
    end
    
    %initial
    s1_index_optimal=0;s2_index_optimal=0;s3_index_optimal=0;s4_index_optimal=0;
    min_err=9999999;
    
    for s1_index=1:4
        s1_index;
        z1=y-H(:,1)*cand(s1_index);
        for s2_index=1:4
            z2=z1-H(:,2)*cand(s2_index);
            for s3_index=1:4
                z3=z2-H(:,3)*cand(s3_index);
                for s4_index=1:4
                    z4=z3-H(:,4)*cand(s4_index);
                    err=z4'*z4;%向量模的平方等于各分量模的平方的和，而复数的模的平方等于该复数乘以它的共轭复数
                    if err<min_err
                        min_err=err;
                        s1_index_optimal=s1_index;s2_index_optimal=s2_index;
                        s3_index_optimal=s3_index;s4_index_optimal=s4_index;
                    end
                end
            end
            
        end
    end
    
    MLD_det_bit(1,:)=component_wise(cand(s1_index_optimal),Modu_bit);
    MLD_det_bit(2,:)=component_wise(cand(s2_index_optimal),Modu_bit);
    MLD_det_bit(3,:)=component_wise(cand(s3_index_optimal),Modu_bit);
    MLD_det_bit(4,:)=component_wise(cand(s4_index_optimal),Modu_bit);
    
end %if Tx==4



%considering Tx=4, and 64QAM

OneBySqrt42=0.1543033499;
if Tx==4 & Modu_bit==6
    %constitute all candidates for each antenna
    tmp=[-7,-5,-3,-1,1,3,5,7];
    cand=zeros(64,1);
    for a=1:8
        for b=1:8
            index=b+(a-1)*8;
            cand(index)=tmp(a)+j*tmp(b);
            cand(index)=cand(index)*OneBySqrt42;
        end
    end
    
    %initial
    s1_index_optimal=0;s2_index_optimal=0;s3_index_optimal=0;s4_index_optimal=0;
    min_err=9999999;
    
    for s1_index=1:64
        s1_index;
        z1=y-H(:,1)*cand(s1_index);
        for s2_index=1:64
            z2=z1-H(:,2)*cand(s2_index);
            for s3_index=1:64
                z3=z2-H(:,3)*cand(s3_index);
                for s4_index=1:64
                    z4=z3-H(:,4)*cand(s4_index);
                    err=z4'*z4; 
                    if err<min_err
                        min_err=err;
                        s1_index_optimal=s1_index;s2_index_optimal=s2_index;
                        s3_index_optimal=s3_index;s4_index_optimal=s4_index;
                    end
                end
            end
            
        end
    end
    
    MLD_det_bit(1,:)=component_wise(cand(s1_index_optimal),Modu_bit);
    MLD_det_bit(2,:)=component_wise(cand(s2_index_optimal),Modu_bit);
    MLD_det_bit(3,:)=component_wise(cand(s3_index_optimal),Modu_bit);
    MLD_det_bit(4,:)=component_wise(cand(s4_index_optimal),Modu_bit);
    
end %if Tx==4

return;