Endogenous Self-Interference Cancellation Within Pseudo-Doppler Aided Full-Duplex Communications

Abstract

The performance of full-duplex (FD) communications relying on antenna isolation, spatial beamforming, and/or self-interference (SI) reconstruction and subtraction, is limited by residual SI. For degrading the residual SI, we propose a novel FD transceiver design for SI cancellation (SIC), based on the mathematical modelling of pseudo-Doppler shift systems. Our pseudo-Doppler aided transceiver design manifests itself as an endogenous SIC mechanism, which removes SI from the center frequency of a transceiver’s desired signal. A low-pass filter can then be applied to pass on the clean desired signal. Since our design is essentially different from conventional SIC approaches, the SIC capability is defined as the improvement in the output signal-to-SI-plus-noise power ratio, which is taken as a metric for evaluating the intrinsic SIC performance. In terms of the SIC capability and operational complexity, our design outperforms conventional FD systems, even if the latter have managed very high SI suppression factors. To promote the practical application of our design in cellular networking, four main challenges are addressed, including the impact of synchronisation errors, the equivalence of SI suppression, the principles of resource allocation, and the investigation of diversity gain.