The saddlepoint approximation: Unified random coding asymptotics for fixed and varying rates
The saddlepoint approximation: Unified random coding asymptotics for fixed and varying rates
复制标题
鞍点近似：固定和变化速率的统一随机编码渐近
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
A. G. Fàbregas
中科院分区：
文献类型：
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作者：
J. Scarlett;Alfonso Martinez;A. G. Fàbregas
本文提出了Polyanskiy等人的随机编码结构的鞍点近似。对于I.I.D.通过离散的无内存通道进行随机编码。近似值是单个字母，因此可以有效地计算。此外，对于固定率和变化的速率，它在误差指数，二阶编码率和中等偏差的情况下统一了现有的可实现性会导致现有可实现性均匀地紧密。对于固定速率，新颖的精确质子表达式被指定为在乘法1+O（1）项之内。提供了一个数值示例，即使在短块长度下，近似值也非常准确。
This paper presents a saddlepoint approximation of the random-coding union bound of Polyanskiy et al. for i.i.d. random coding over discrete memoryless channels. The approximation is single-letter, and can thus be computed efficiently. Moreover, it is shown to be asymptotically tight for both fixed and varying rates, unifying existing achievability results in the regimes of error exponents, second-order coding rates, and moderate deviations. For fixed rates, novel exact-asymptotics expressions are specified to within a multiplicative 1+o(1) term. A numerical example is provided for which the approximation is remarkably accurate even at short block lengths.