5.6.4QAM {人，an} {,an,} QAM (Amp/phs) s (t) r(0)= Recv s (t)+n(t) 1,2M1 The signals: 2πm Prob of err is computed by, The Pe of QAM depends on its specific constellation. =Amcg()cos2πf1-Ang)sin2πfl The distance between pairs of points and the The basis:cos2 average energy are two key paras. %,0=&，0sn2 Rectangular QAM constellations have distinct advantages of being equivalent to 2 PAMs.Though not the best,it is only slightly poorer than the best, so it is frequently used in practical. o.om) UESTC-Digital transmission through the AWGN channel Prof李晓峰 13