Orthogonal Basis Expansion-Based Phase Noise Estimation and Suppression for CO-OFDM Systems

In coherent optical orthogonal frequency- division-multiplexing systems, the laser phase noise which induces common phase error (CPE) and intercarrier interference (ICI) is a major impairment to the system's performance. In this letter, we propose an orthogonal basis expansion-based phase noise suppression algorithm which can mitigate CPE as well as ICI effectively. The proposal can significantly reduce the bit-error-rate floor caused by ICI.

I. Introduction

Intersymbol interference (isi) caused by chromatic dispersion (CD) and polarization-mode dispersion (PMD) becomes severe for optical fiber communications as the transmission rate reaches several tens of gigabits per second. Sophisticated equalization techniques were shown to be able to mitigate CD and PMD-induced ISI [1], [2]. As a more efficient option to combat ISI, coherent optical orthogonal frequency-division multiplexing (CO-OFDM) has attracted wide interest recently since ISI can be fully avoided in CO-OFDM systems if the guard interval is sufficiently large [3]. However, as is known, CO-OFDM is very sensitive to the laser phase noise which induces not only common phase error (CPE) but also intercarrier interference (ICI). To realize phase noise suppression, Jansen proposed an RF-aided scheme [4], Yi proposed pilot-aided and data-aided methods [5], [6], and Shieh proposed a maximum-likelihood (ML) method [7].