Gaussian basis expansion phase noise suppression method for CO-OFDM systems

Area of Science:

• Optical Communications
• Signal Processing

Background:

• Phase noise is a significant impairment in coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems, degrading performance.
• Existing phase noise suppression methods like common phase compensation (CPE), orthogonal basis expansion (OBE), and eigenvector basis expansion (EBE) have limitations.

Purpose of the Study:

• To propose and evaluate a novel phase noise suppression method based on Gaussian basis expansion (GBE) for CO-OFDM systems.
• To demonstrate the effectiveness of GBE in improving system performance under various transmission conditions.

Main Methods:

• Analysis of the GBE principle for phase noise suppression.
• Experimental validation in Quadrature Phase Shift Keying (QPSK) and 16-Quadrature Amplitude Modulation (16-QAM) CO-OFDM systems.
• Simulation to assess performance with varying laser linewidth and transmission distances.

Main Results:

• GBE shows better phase noise fitting ability than CPE and OBE with similar computational complexity.
• Experimental results demonstrate Q-factor improvements of 1.7 dB (vs. CPE) and 0.5 dB (vs. OBE) in a QPSK system after 160 km.
• Bit error rate (BER) in a 16-QAM system improved from 8.21×10⁻⁴ to 2.36×10⁻⁴ using GBE.
• Simulations indicate GBE extends transmission distance by 420 km (from 1120 km to 1540 km) for a 2-MHz linewidth at a BER of 10⁻⁴.

Conclusions:

• The proposed GBE method effectively suppresses phase noise in CO-OFDM systems.
• GBE offers a promising alternative for enhancing the performance and transmission capabilities of CO-OFDM systems.
• GBE provides increased tolerance to laser linewidth, enabling longer transmission distances.