Implications of information theory in optical fibre communications

Abstract

Recent decades have witnessed steady improvements in our ability to harness the information-carrying capability of optical fibres. Will this process continue, or will progress eventually stall? Information theory predicts that all channels have a limited capacity depending on the available transmission resources, and thus it is inevitable that the pace of improvements will slow. However, information theory also provides insights into how transmission resources should, in principle, best be exploited, and thus may serve as a guide for where to look for better ways to squeeze more out of a precious resource. This tutorial paper reviews the basic concepts of information theory and their application in fibre-optic communications.

Performance limits in optical communications due to fiber nonlinearity

“…Table 1 therefore lists a selection of alternative models which the reader will find useful in these circumstances. It is useful to note at this point that if memory is included in a formal calculation of the maximum information spectral density, then performance slightly above the optimum predicted by equations 30 and 32 may be possible using, for example, Satellite [180] or Ripple [136] constellations respectively, provided any additional assumptions are satisfied. In addition accurate channel modelling can be used as a basis for advanced methods of nonlinearity mitigation [192][193][194].…”

Achievable Information Rates for Fiber Optics: Applications and Computations

“…In particular, if q Y |X is the true channel law f Y |X , (48) holds with equality. Clearly, the more "close" q Y |X is to f Y |X , the tighter the bound in (48). A common choice for q Y |X is a circularly symmetric Gaussian PDF with variance σ 2 z .…”

Nonlinear Fourier transform for optical data processing and transmission: advances and perspectives

“…There is currently a widespread belief that the nonlinear optical channel capacity is still largely unknown: As discussed in [146], [147], exact channel capacity results for fibre optical systems are scarce, and many aspects related to this problem remain open. The transmission methods employing on-off-keying (OOK) fundamental solitons have been almost abandoned, mostly due to the low SE ≈ 0.2 bits/s/Hz of OOK soliton systems limited by the celebrated Gordon-Haus jitter phenomena [148], and, in addition, due to the problems with inter-soliton interaction between the WDM soliton channels [27].…”