function out=decode22(H,r,M)
for m=1:M
    s(m)=qammod(m-1,M);
end
r1=r(:,1);
r2=r(:,2);
  z1=r1(1).*conj(H(1,1))+conj(r2(1))*H(1,2)+r1(2).*conj(H(2,1))+conj(r2(2))*H(2,2);
  z2=r1(1).*conj(H(1,2))-conj(r2(1))*H(1,1)+r1(2).*conj(H(2,2))-conj(r2(2))*H(2,1);
  for m=1:4
 d1(m,1)=(abs(H(1,1))^2+abs(H(1,2))^2+abs(H(2,1))^2+abs(H(2,2))^2-1)*abs(s(m))^2+(abs(z1-s(m)))^2;
 d2(m,1)=(abs(H(1,1))^2+abs(H(1,2))^2+abs(H(2,1))^2+abs(H(2,2))^2-1)*abs(s(m))^2+(abs(z2-s(m)))^2;
  end
    [v1 p1]=min(d1);
     s1d=s(p1);
      [v2 p2]=min(d2);
   s2d=s(p2);
    Xd=[s1d ;s2d];
     out=qamdemod(Xd,M);