2002 Copyright EE Lab508
(5)ÓÉÉÏÃæ,d?1ʱÓëÊÔÑéÐŵÀÏà¶ÔÓ¦µÄD?1??d[PY]??D??d?d?D??1?d?D·´ÏòÊÔÑéµÄÐŵÀ¾ØÕóΪ:
8.14ÉèÀëÉ¢ÎÞ¼ÇÒäÐÅÔ´:
?U u1 u2 u3 ?[U?P]:?111
?P(U) 333?ÆäÊ§ÕæÊ§Õæ¶ÈΪººÃ÷Ê§Õæ¶È.
(1) ÊÔÇóDmin,R(Dmin),²¢Ð´³öÏàÓ¦ÊÔÑéÐŵÀµÄÐŵÀ¾ØÕó;
(2) ÊÔÇóDmax,R(Dmax), ²¢Ð´³öÏàÓ¦ÊÔÑéÐŵÀµÄÐŵÀ¾ØÕó;
(3) ÈôÔÊÐíÆ½¾ùÊ§Õæ¶ÈD=1/8,ÊÔÎÊÐÅÔ´[U¡¤P]µÄÿһ¸öÐÅÔ´·ûºÅƽ¾ù×îÉÙÓɼ¸¸ö¶þ½øÖÆÂë
·ûºÅ±íʾ? ½â:
3(1)×îСÔÊÐíÊ§Õæ¶È£ºÔòÂú×ã±£Õæ¶ÈD?DDminmin??i?1p(ui)?minjd(ui,bj)??p(u1)?0?p(u2)?0??p(u3)?0£½0?0µÄÐŵÀ¾ØÕó0100??0?1??Y,Ôò´ËʱH(U/Y)?0?1? [P]?0???0p(bj/ai)?0»òp(bj/ui)?1(i?1,2,3),ÉèÊä³ö·ûºÅ¼¯ºÏ?R(Dmin)?R(0)?min?I(U;Y)??min?H(U)?H(U/Y)??H(U)?log3?1.585bit/symble(2)Dmax?D?min?3??111?1?min??p(ai)d(ai,bj)??min{p(u1));p(u2);p(u3)}?min?;;??jjj?333?3?i?1?1´ËʱI(U;Y)?0?R(Dmax)?R()?03(3)ÀëÉ¢ÐÅÔ´ÔÚººÃ÷Ê§Õæ¶ÈÏÂ,R(D)?H(X)?H(D)?Dlog(r?1)?¶Ô´ËÐÅÔ´R(D)?H(U)?H(D)?Dlog2?log3?H(D)?D1?log3?H(D)?D 0?D???3¼´R(D)???0 D?1?3?D?1111ʱ,R()?log3?H()??0.9164bit/symble8888¾ù×îÉÙ¿ÉÒÔÓÃ0.9164¸ö¶þ½øÖÆÂë·ûºÅÀ´±íʾ.
ÔòÐÅÔ´µÄÿһ¸ö·ûºÅƽ8.15Éè¶þÔªÐÅÔ´XµÄÐÅÔ´¿Õ¼äΪ:
?U u1 u2 [U?P]:?
P(U) ? 1-??(¦Ø<1/2),ÆäÊ§Õæ¶ÈΪººÃ÷Ê§Õæ¶È.
?H.F.
2002 Copyright EE Lab508
ÈôÔÊÐíÆ½¾ùÊ§Õæ¶ÈD=¦Ø/2,ÊÔÎÊÿһ¸öÐÅÔ´·ûºÅƽ¾ù×îÉÙÐèÒª¼¸¸ö¶þ½øÖÆÂë·ûºÅ±íʾ? ½â:
ÀëÉ¢ÐÅÔ´ÔÚººÃ÷Ê§Õæ¶ÈÏÂ,R(D)?H(X)?H(D)?Dlog(r?1)?¶Ô´ËÐÅÔ´R(D)?H(U)?H(D)?H(?)?H(D)?H(?)?H(D) 0?D??¼´R(D)???0 D???D?12?ʱ11111R(?)?H(?)?H(?)???log??(1??)log(1??)?(2??)log(2??)?(3??)22222?ÿ¸öÐÅÔ´·ûºÅƽ¾ù×îÉÙ1ÐèÒªH(?)?H(?)¸ö¶þ½øÖÆÂë·ûºÅÀ´±íʾ2.
?H.F.
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