Per-Antenna Self-Interference Cancellation Beamforming Design for Digital Phased Array

Abstract

Almost all current beamforming-based designs of self-interference cancellation (SIC) for digital phased array systems neglect the practical issue of the limited dynamic range of analog-to-digital converters (ADCs) and, thus, lack restriction for self-interference (SI) that is incident at each receiving antenna. Other than beamforming, these methods usually require additional SIC techniques to provide a part of isolation, which brings higher system complexity. In this letter, a SIC method is proposed to overcome these issues. By developing a transmit SIC beamformer design that minimizes the power of SI on a per-antenna basis, we can obtain more isolation before the ADCs in each receiving channel and better prevent them all from being saturated. Then, the residual SI can be further suppressed by adaptive receive beamformers to achieve high total isolation performance. The proposed method reduces the need for other SIC techniques than beamforming technology in phased array systems and, thus, facilitates lower system complexity. Numerical results demonstrate the effectiveness of the proposed method.