# A Unified Beamforming and A/D Self-Interference Cancellation Design for Full Duplex MIMO Radios

## TL;DR

This paper presents a joint digital and analog self-interference cancellation method for full duplex MIMO radios that improves interference suppression and system performance with reduced complexity and practical impairments.

## Contribution

It introduces a unified design combining beamforming and A/D cancellation with a multi-tap analog canceller and pilot-assisted channel estimation, addressing practical impairments.

## Key findings

- Achieves higher self-interference cancellation with fewer analog taps.
- Improves achievable rate and bit error performance.
- Demonstrates effectiveness through Monte Carlo simulations.

## Abstract

In this paper, we focus on reduced complexity full duplex Multiple-Input Multiple-Output (MIMO) systems and present a joint design of digital transmit and receive beamforming with Analog and Digital (A/D) self-interference cancellation. We capitalize on a recently proposed multi-tap analog canceller architecture, whose number of taps does not scale with the number of transceiver antennas, and consider practical transmitter impairments for the full duplex operation. Particularly, transmitter IQ imbalance and nonlinear power amplification are assumed via relevant realistic models. Aiming at suppressing the residual linear and nonlinear self-interference signal below the noise floor, we propose a novel digital self-interference cancellation technique that is jointly designed with the configuration of the analog taps and digital beamformers. Differently from the state of the art, we design pilot-assisted estimation of all involved wireless channels. Our representative Monte Carlo simulation results demonstrate that our unified full duplex MIMO design exhibits higher self-interference cancellation capability with less analog taps compared to available techniques, which results in improved achievable rate and bit error performance.