Joint timing and frequency synchronization based on weighted CAZAC sequences for reduced-guard-interval CO-OFDM systems

TL;DR

This paper introduces a joint timing and frequency synchronization algorithm for RGI-CO-OFDM systems using weighted CAZAC sequences, improving synchronization accuracy with a novel training symbol structure.

Contribution

It proposes a new joint synchronization method based on weighted CAZAC sequences and a unique training symbol design for RGI-CO-OFDM systems.

Findings

Achieves accurate timing and CFO estimation in high-speed optical systems.

Demonstrates robustness through numerical simulations at 115.8 Gb/s.

Improves synchronization with reduced guard intervals.

Abstract

A novel joint symbol timing and carrier frequency offset (CFO) estimation algorithm is proposed for reduced-guard-interval coherent optical orthogonal frequency-division multiplexing (RGI-CO-OFDM) systems. The proposed algorithm is based on a constant amplitude zero autocorrelation (CAZAC) sequence weighted by a pseudo-random noise (PN) sequence. The symbol timing is accomplished by using only one training symbol of two identical halves, with the weighting applied to the second half. The special structure of the training symbol is also utilized in estimating the CFO. The performance of the proposed algorithm is demonstrated by means of numerical simulations in a 115.8-Gb/s 16-QAM RGI-CO-OFDM system.