Modulation Classification Using Received Signal's Amplitude Distribution for Coherent Receivers

TL;DR

This paper introduces a modulation classification method for coherent optical receivers that uses the amplitude distribution's CDF, achieving accurate results without carrier recovery across various modulation formats.

Contribution

The paper presents a novel amplitude distribution-based modulation classification algorithm that does not require carrier recovery, suitable for coherent optical systems.

Findings

Accurate classification at relevant optical SNR levels

No need for carrier recovery in the classification process

Effective across multiple modulation formats

Abstract

In this letter, we propose a modulation classification algorithm which is based on the received signal's amplitude for coherent optical receivers. The proposed algorithm classifies the modulation format from several possible candidates by differentiating the cumulative distribution function (CDF) curves of their normalized amplitudes. The candidate with the most similar CDF to the received signal is selected. The measure of similarity is the minimum average distance between these CDFs. Five commonly used quadrature amplitude modulation formats in digital coherent optical systems are employed. Optical back-to-back experiments and extended simulations are carried out to investigate the performance of the proposed algorithm. Results show that the proposed algorithm achieves accurate classification at optical signal-to-noise ratios of interest. Furthermore, it does not require carrier recovery.