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Unformatted text preview: 收到第三个数字也为0 时,又增加多少关于M 的信息? 4 解: 1) q("0" ) p( Mi ) p(0|Mi ) 1[2(1 )2 ] 1 4 2 i 1 p ( 0|M1 ) 1 互信息I ( M 1 ; "0" ) log log log[2(1 )] q ("0") 1/ 2 单符号离散信道 单符号离散信道 4 2) q("00" ) i1 1 p(Mi ) p(00|Mi ) [ p(0|0) p(0|0) p(0|0) p(0|1) p(0|1) p(0|0) p(0|1) p(0|1)] 4 1 1 2 2 [(1 ) 2 (1 ) ] 4 4 p ( 00|M1 ) (1 ) 2 互信息I ( M 1 ; "00" ) log log 2 log[2 (1 )] q ("00") 1/ 4 附加信息 2 log[2 (1 )] log[2 (1 )] log[2 (1 )] 4 3) q("000" ) i 1 1 2 1 3 2 p( Mi ) p(000Mi ) [(1 ) 3(1 ) ] (1 )(4 2 1) | 4 4 p ( 000|M1 ) 2 互信息I ( M 1 ; "000" ) log 2 log[2(1 )] log(4 2 1) q ("000") 又增加的信息 log( 4 2 2 1) 1.3 信道容量的定义 信道容量的定义 ★ 平稳离散无记忆信道的容量C定义为输入与 输出平均互信息I(X;Y)的最大值: 输出平均互信息I(X;Y)的最大值: C max I ( X ; Y ) p( x ) 1)单位为: 比特/信道符号(奈特/信道符号) 比特 2)当信道给定后,p(y|x)就固定...
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This document was uploaded on 02/10/2014.

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