# A Comprehensive Self-interference Model for Single-antenna Full-duplex Communication Systems

## TL;DR

This paper develops a detailed self-interference model for single-antenna full-duplex systems, accounting for nonlinearities and imperfections, and proposes an improved digital cancellation method that significantly enhances interference suppression.

## Contribution

It introduces a comprehensive SI model considering RF nonlinearities, IQ imbalance, phase noise, and receiver noise, along with a QR-based digital cancellation approach.

## Key findings

- Achieves 20 dB more cancellation than existing methods
- Validates the model through circuit-level waveform simulation
- Enhances digital SI cancellation effectiveness

## Abstract

Single-antenna full-duplex communication technology has the potential to substantially increase spectral efficiency. However, limited propagation domain cancellation of single-antenna system results in a higher impact of receiver chain nonlinearities on the residual self-interference (SI) signal. In this paper, we offer a comprehensive SI model for single-antenna full-duplex systems based on direct-conversion transceiver structure considering nonlinearities of all the transceiver radio frequency (RF) components, in-phase/quadrature (IQ) imbalances, phase noise effect, and receiver noise figure. To validate our model, we also propose a more appropriate digital SI cancellation approach considering receiver chain RF and baseband nonlinearities. The proposed technique employs orthogonalization of the design matrix using QR decomposition to alleviate the estimation and cancellation error. Finally, through circuit-level waveform simulation, the performance of the digital cancellation strategy is investigated, which achieves 20 dB more cancellation compared to existing methods.