Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET, UK.
Nat Commun. 2014 May 20;5:3861. doi: 10.1038/ncomms4861.
Since Shannon derived the seminal formula for the capacity of the additive linear white Gaussian noise channel, it has commonly been interpreted as the ultimate limit of error-free information transmission rate. However, the capacity above the corresponding linear channel limit can be achieved when noise is suppressed using nonlinear elements; that is, the regenerative function not available in linear systems. Regeneration is a fundamental concept that extends from biology to optical communications. All-optical regeneration of coherent signal has attracted particular attention. Surprisingly, the quantitative impact of regeneration on the Shannon capacity has remained unstudied. Here we propose a new method of designing regenerative transmission systems with capacity that is higher than the corresponding linear channel, and illustrate it by proposing application of the Fourier transform for efficient regeneration of multilevel multidimensional signals. The regenerative Shannon limit--the upper bound of regeneration efficiency--is derived.
自从 Shannon 推导出加性线性白高斯噪声信道容量的基本公式以来，它通常被解释为无差错信息传输率的极限。然而，当使用非线性元件抑制噪声时，可以在相应的线性信道限制之上实现容量；也就是说，可以实现线性系统中不可用的再生功能。再生是一个从生物学到光通信的基本概念。相干信号的全光再生引起了特别关注。令人惊讶的是，再生对 Shannon 容量的定量影响仍未得到研究。在这里，我们提出了一种新的设计具有高于相应线性信道容量的再生传输系统的方法，并通过提出使用傅里叶变换来有效地再生多级多维信号来说明该方法。推导出了再生 Shannon 极限——再生效率的上限。
