Every bad code has a good subcode: A local converse to the coding theorem
Every bad code has a good subcode: A local converse to the coding theorem
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每个坏代码都有一个好的子代码:编码定理的局部逆向
DOI:
10.1007/bf00535683
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发表时间:
1976
期刊:
影响因子:
--
通讯作者:
G. Dueck
中科院分区:
文献类型:
--
作者:
R. Ahlswede;G. Dueck
The Local Converse The transmission probabilities P of a discrete memoryless channel (DMC) with alphabets 5F and Y/are given by P(y"]x")= ~ w(ytlx,) (1) t=l n n where x" = (x 1 .... , x,) ~ 2F" = 1~ 5F, y" = (y~ ..... y,) ~ ~d" = I~ @', and where w is a IX[ x l~l-stochastic matrix, z 1 An (n, N, 2)-code for the DMC is a system of pairs {(u~, D~)[i= 1, ..., N} with ui~Y' and pairwise disjoint subsets D i of ~" (i= 1 .... , N), and with This result was stated (without proof) in [1] as Theorem 12. The inequality liminf n-1 log N(n, ' > /~)=C, 0<2<1 (4) noD oD (the coding theorem) was proved in [3] and in [5]. It was shown in [2] that (weak converse) inf limsup n-1 log N(n, 2)< C (5) 2>0 n-,oo and finally in [4] that the strong converse holds, i.e. limsup n-1 log N(n, 2) < C, 0 < 2 < 1.