Photonic-based analog and digital RF self-interference cancellation with high spectral efficiency

Area of Science:

• Photonics
• Optical Communications
• Radio Frequency Engineering

Background:

• In-band full-duplex (FD) systems require effective self-interference cancellation (SIC) for base stations.
• Radio-over-fiber (RoF) systems offer high bandwidth and long-distance transmission capabilities.

Purpose of the Study:

• To propose and demonstrate a photonic-assisted analog and digital SIC approach for high spectral efficiency in RoF-based FD systems.
• To achieve significant self-interference suppression using a combination of optical and digital techniques.

Main Methods:

• Utilized a dual-polarization quadrature phase-shift keying (DP-QPSK) modulator biased as carrier-suppressed single-sideband modulators for optical domain SIC.
• Employed a recursive least-square (RLS) algorithm for digital domain residual self-interference suppression.
• Experimentally validated the system using two independent channels with QPSK-modulated self-interferences at various baud rates.

Main Results:

• Achieved analog cancellation depths of approximately 24 dB (200 Mbaud), 20 dB (500 Mbaud), and 20 dB (800 Mbaud).
• Attained total cancellation depths of around 29 dB, 28 dB, and 25 dB when both analog and digital SIC were applied.
• Demonstrated that fiber distribution had no significant impact on the SIC performance.

Conclusions:

• The proposed photonic-assisted analog and digital SIC method effectively suppresses self-interference in RoF-based FD systems.
• The approach achieves high spectral efficiency, crucial for advanced wireless communication base stations.
• The combined optical and digital cancellation strategy offers a robust solution for interference management in future communication networks.