5.5.3 The optimum detector The Optimum Detector: MAP: Max a posterior probability Note that f(rs,)is usually called likelihood funct ML Maximum-likelihood Min-Dist Minimum-distance Maximum-likelihood (ML):to select the s,that Max-Corr:Maximum Correlation Denoted by, s=arg max,f(rIs) Minimum-distance (Min-Dist):to select the s,that is nearest to r, that is s=arg min,D(r,s) and,D(r,s)=r-s We can say more,D(r,s)=-2rs+s Let E =s and C(r,s)=r.s-E/2 Maximum Correlation (Max-Corr):to select the s,that is most correlated with r,possibly compensated by some bias due to unequal energy,that is, s=arg max,C(r,s) UESTC-Digital transmission through the AWGN channel Prof李晓峰 14