Close-Form Expression of One-Tap Normalized LMS Carrier Phase Recovery in Optical Communication Systems

TL;DR

This paper derives a closed-form expression for the one-tap normalized LMS carrier phase recovery algorithm in optical communication systems, accounting for laser phase noise and EEPN, validated by simulations.

Contribution

It provides the first analytical expression for the one-tap normalized LMS CPR that predicts BER floors considering both laser phase noise and EEPN.

Findings

The analytical expression matches traditional differential CPR in predicting BER floors.

The method effectively compensates for laser phase noise and EEPN.

Numerical simulations confirm the theoretical analysis.

Abstract

The performance of long-haul high speed coherent optical fiber communication systems is significantly degraded by the laser phase noise and the equalization enhanced phase noise (EEPN). In this paper, the analysis of the one-tap normalized least-mean-square (LMS) carrier phase recovery (CPR) is carried out and the close-form expression is investigated for quadrature phase shift keying (QPSK) coherent optical fiber communication systems, in compensating both laser phase noise and equalization enhanced phase noise. Numerical simulations have also been implemented to verify the theoretical analysis. It is found that the one-tap normalized least-mean-square algorithm gives the same analytical expression for predicting CPR bit-error-rate (BER) floors as the traditional differential carrier phase recovery, when both the laser phase noise and the equalization enhanced phase noise are taken into account.