Simple sampling clock synchronisation scheme for reduced-guard-interval coherent optical OFDM systems

TL;DR

This paper introduces a simple data-aided sampling clock synchronization scheme for reduced-guard-interval coherent optical OFDM systems, utilizing existing training symbols to estimate and compensate for clock offsets without additional overhead.

Contribution

It proposes a novel, low-overhead synchronization method that leverages training symbols for clock offset estimation and resampling for compensation in RGI-CO-OFDM systems.

Findings

Effective SCO estimation using training symbols

No extra training overhead required

Validated through numerical simulations at 32-Gbaud 16-QAM

Abstract

A simple data-aided scheme for sampling clock synchronisation in reduced-guard-interval coherent optical orthogonal frequency division multiplexing (RGI-CO-OFDM) systems is proposed. In the proposed scheme, the sampling clock offset (SCO) is estimated by using the training symbols reserved for channel estimation, thus avoiding extra training overhead. The SCO is then compensated by resampling, using a time-domain interpolation filter. The feasibility of the proposed scheme is demonstrated by means of numerical simulations in a 32-Gbaud 16-QAM dual-polarisation RGI-CO-OFDM system.