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arXiv 1104.5546cs.ITmath.IT
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小删除概率下删除信道的最优编码

Optimal coding for the deletion channel with small deletion probability

Yashodhan Kanoria, Andrea Montanari

摘要:

删除通道是对缺乏同步进行建模的最简单的点对点通信通道。输入比特以概率d独立地被删除,并且当它们不被删除时,它们不受信道的影响。尽管付出了巨大的努力,很少有人知道这个信道的容量,甚至更少的最佳编码方案。在本文中,我们开发了一个新的系统的方法来解决这个问题,通过证明,容量可以计算在一系列的扩展为小删除概率。我们计算这种扩展的三个前导项,并找到一个输入分布,达到这个顺序的容量。这构成删除信道的第一最佳编码结果。采用的关键思想如下:我们完全理解删除概率d=0的删除通道。它的容量为1,最优输入分布为i.i.d.。Bernoulli(1/2).很自然地期望具有小删除概率的信道具有随d平滑变化的容量,并且通过平滑地扰动i.i.d. Bernoulli(1/2)过程。我们的研究结果表明,情况确实如此。我们认为,这种一般策略在许多容量计算中是有用的。

英文摘要:

The deletion channel is the simplest point-to-point communication channel that models lack of synchronization. Input bits are deleted independently with probability d, and when they are not deleted, they are not affected by the channel. Despite significant effort, little is known about the capacity of this channel, and even less about optimal coding schemes. In this paper we develop a new systematic approach to this problem, by demonstrating that capacity can be computed in a series expansion for small deletion probability. We compute three leading terms of this expansion, and find an input distribution that achieves capacity up to this order. This constitutes the first optimal coding result for the deletion channel. The key idea employed is the following: We understand perfectly the deletion channel with deletion probability d=0. It has capacity 1 and the optimal input distribution is i.i.d. Bernoulli(1/2). It is natural to expect that the channel with small deletion probabilities has a capacity that varies smoothly with d, and that the optimal input distribution is obtained by smoothly perturbing the i.i.d. Bernoulli(1/2) process. Our results show that this is indeed the case. We think that this general strategy can be useful in a number of capacity calculations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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