Time-Domain Blind ICI Compensation in Coherent Optical FBMC/OQAM System.

Area of Science:

• Optical Communications
• Signal Processing
• Digital Modulation Techniques

Background:

• Coherent optical offset-quadrature amplitude modulation (CO-FBMC/OQAM) systems face inter-carrier-interference (ICI) due to phase noise.
• Traditional blind phase noise compensation (PNC) primarily addresses common phase error (CPE), often neglecting residual ICI.

Purpose of the Study:

• To propose and evaluate a blind discrete-cosine-transform-based phase noise compensation (BD-PNC) method for CO-FBMC/OQAM systems.
• To mitigate ICI and improve the overall bit error rate (BER) performance.

Main Methods:

• Developed a time-domain compensation model utilizing discrete cosine transform (DCT) approximations of phase noise.
• Implemented a partial pre-decision strategy on compensated signals to estimate transmitted signals for DCT coefficient calculation.
• Reduced computational complexity and decision errors by selectively pre-deciding signals with low error probability.

Main Results:

• The proposed BD-PNC scheme significantly improved BER performance by over one order of magnitude in a 30 GBaud CO-FBMC/OQAM system.
• Demonstrated effective mitigation of ICI, outperforming traditional blind PNC methods that only compensate for CPE.
• Achieved comparable performance to full pre-decision methods with reduced complexity.

Conclusions:

• The BD-PNC method offers a computationally efficient and high-performance solution for phase noise compensation in CO-FBMC/OQAM systems.
• This technique substantially enhances spectral efficiency and transmission reliability in optical communication systems.
• The findings highlight the potential of DCT-based signal processing for advanced optical communication challenges.