Self-Interference Cancellation Techniques in Radio-Frequency Systems

Self-interference cancellation (SIC) constitutes a critical enabler for in-band full-duplex radio-frequency communications, whereby a transceiver simultaneously transmits and receives on the same frequency channel. In conventional half-duplex systems, capacity is inherently constrained by the need to separate uplink and downlink channels in time or frequency. SIC techniques aim to suppress the strong echo of the transmitted signal that leaks into the receiver path and masks the desired incoming signal. A broad spectrum of approaches has been developed, ranging from purely analogue methods—using tuned circuits, phase shifters, delay lines and attenuators—to digital algorithms that estimate the interference channel and subtract an adaptive replica in the baseband. More recently, hybrid analogue–digital schemes have become prevalent, combining coarse interference suppression in the radio-frequency front end with fine cancellation in digital signal processing. Optical-domain SIC, employing modulators, delay elements and balanced photodetectors, has also demonstrated ultrawideband operation and immunity to electronic nonlinearity. Machine-learning and reinforcement-learning algorithms have been introduced to automate parameter tuning and adapt to dynamic channel conditions. Collectively, these advances have driven improvements in cancellation depth, bandwidth and convergence speed, fostering practical implementations in 5G and beyond, defence and satellite communications, and radio-over-fibre networks. Global efforts continue to optimise system complexity, energy consumption and stability, ensuring that SIC remains a cornerstone for the next generation of spectral-efficient, high-capacity wireless systems.

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Self-Interference Cancellation Techniques in Radio-Frequency Systems publication trend

The graph below shows the total number of articles in self-interference cancellation techniques in radio-frequency systems across all publications each year (not limited to Nature Index journals).

Technical terms

Self-interference cancellation: Techniques to suppress or remove a transmitter’s own leakage signal from a co-located receiver path, enabling simultaneous transmission and reception on the same frequency.

Full-duplex communication: A mode of operation in which a device transmits and receives signals concurrently over the same frequency channel.

Mach–Zehnder modulator (MZM): An electro-optic device used to impose intensity or phase modulation on an optical carrier, often employed in photonic-domain cancellation schemes.

Variable optical delay line (VODL): A reconfigurable photonic component that introduces controllable time delays, facilitating phase alignment between interference paths.

Orthogonal frequency division multiplexing (OFDM): A multicarrier modulation technique that divides a wideband channel into orthogonal subcarriers, commonly used in modern wireless standards.

References

1. Optical Multipath RF Self-Interference Cancellation Based on Phase Modulation for Full-Duplex Communication. IEEE Photonics Journal (2020).
2. Photonic-Enabled Image Rejection Mixer with Simultaneous Wideband Self-Interference Cancellation for In-Band Full-Duplex System. Photonics (2023).
3. Real-time adaptive optical self-interference cancellation for in-band full-duplex transmission using SARSA(λ) reinforcement learning.. Optics Express (2023).