On the Impact of Optimal Modulation and FEC Overhead on Future Optical Networks

TL;DR

This paper investigates how optimal modulation and FEC overhead choices can significantly enhance throughput in future optical networks, revealing that strategic selection can yield substantial gains over standard practices.

Contribution

It provides an information theory-based analysis of optimal modulation and FEC overhead, demonstrating practical gains and simplified configurations for future optical networks.

Findings

Large throughput gains over QPSK with 7% OH.

HD-FEC reduces throughput by 12-20%.

Most gains achievable with one modulation and two OH levels.

Abstract

The potential of optimum selection of modulation and forward error correction (FEC) overhead (OH) in future transparent nonlinear optical mesh networks is studied from an information theory perspective. Different network topologies are studied as well as both ideal soft-decision (SD) and hard-decision (HD) FEC based on demap-and-decode (bit-wise) receivers. When compared to the de-facto QPSK with 7% OH, our results show large gains in network throughput. When compared to SD-FEC, HD-FEC is shown to cause network throughput losses of 12%, 15%, and 20% for a country, continental, and global network topology, respectively. Furthermore, it is shown that most of the theoretically possible gains can be achieved by using one modulation format and only two OHs. This is in contrast to the infinite number of OHs required in the ideal case. The obtained optimal OHs are between 5% and 80%, which highlights the potential advantage of using FEC with high OHs.