Digital Adaptive Carrier Phase Estimation in Multi-Level Phase Shift Keying Coherent Optical Communication Systems

TL;DR

This paper investigates adaptive carrier phase estimation in high-speed multi-level phase shift keying optical systems using a normalized LMS algorithm, deriving formulas and analyzing performance limitations.

Contribution

It provides closed-form expressions for carrier phase and BER floor in n-PSK systems, highlighting the algorithm's effectiveness and limitations with increasing modulation levels.

Findings

Normalized LMS performs well in phase estimation.

Performance degrades with higher modulation levels.

BER floor expressions are derived.

Abstract

The analysis of adaptive carrier phase estimation is investigated in long-haul high speed n-level phase shift keying (n-PSK) optical fiber communication systems based on the one-tap normalized least-mean-square (LMS) algorithm. The close-form expressions for the estimated carrier phase and the bit-error-rate floor have been derived in the n-PSK coherent optical transmission systems. The results show that the one-tap normalized LMS algorithm performs pretty well in the carrier phase estimation, but will be less effective with the increment of modulation levels, in the compensation of both intrinsic laser phase noise and equalization enhanced phase noise.