Analogue self-interference cancellation in full-duplex radios

Active analogue self-interference cancellation (AASIC) techniques are used to prevent the saturation of the receiver chain in full-duplex (FD) radios. This is done by cancelling the self-interference (SI) signal before it enters the receiver chain. AASIC techniques are usually implemented together with passive and active digital self-interference cancellation (SIC) techniques.
In this study, an analogue radio frequency (RF) SI canceller that cancels the SI signal before it enters the receiver chain is proposed. The canceller uses an analogue RF circuit with tuneable attenuation, delay, and phase. The analogue RF circuit is implemented together with an RF circulator. The circulator isolates the transmitter chain from the receiver chain. The proposed design aims to reduce the form factor and complexity of the canceller.
The canceller is modelled and simulated in MATLAB/Simulink. The results show that the canceller cancels the SI signal. It achieves 52 dB of SIC using a 20 dBm SI test signal over a bandwidth of 20 MHz. The results also show that the canceller does not affect the signal of interest (SOI).
Keywords: Full-duplex, self-interference, analogue self-interference cancellation.