Network Coding in Photonicland: Three Commandments for Future-proof Optical Core Networks

Abstract

The digital transformation has been underway, creating digital shadows of (almost) all physical entities and moving them to the Internet. The era of Internet of Everything has therefore started to come into play, giving rise to unprecedented traffic growths. In this context, optical core networks forming the backbone of Internet infrastructure have been under critical issues of reaching the capacity limit of conventional fibers, a phenomenon widely referred as capacity crunch. For many years, the many-fold increases in fiber capacity is thanks to exploiting physical dimensions for multiplexing optical signals such as wavelength, polarization, time and lately space-division multiplexing using multi-core and/or few-mode fibers and such route seems to come to an end as almost all known ways have been investigated. This necessitates for a departure from traditional approaches to use the fiber capacity more efficiently and thereby improve economics of scale. Indeed, recent leaps-and-bounds progresses in photonic signal processing is expected to pave the way for re-defining the optical networking realm by transforming the convention functions of intermediate nodes from simply regeneration and/or switching to incorporating photonic signal processing functions, notably encoding and decoding ones. To this end, this paper lays out a new perspective to integrate network coding (NC) functions into optical networks to achieve greater capacity efficiency in a pragmatic manner by upgrading intermediate nodes functionalities. In addition to the review of our recent proposals on creating new research problems enabled by NC operations in optical networks, we also report state-of-the-art findings in the literature in an effort to renew the interest of network coding in optical networks and discuss three critical points for pushing forward its applicability and practicality including <tex>$i$</tex>) network coding as a new dimension for multiplexing optical signals ii) algorithmic aspects of network coding-enabled optical networks design iii) network coding as an entirely fresh way for securing optical signals at physical layers.