Baseband and RF Hardware Impairments in Full-Duplex Wireless Systems: Experimental Characterisation and Suppression

TL;DR

This paper experimentally characterizes hardware impairments in full-duplex wireless systems, such as IQ imbalance and DAC non-linearities, and proposes a suppression method that significantly improves self-interference mitigation.

Contribution

It provides the first measurement-based analysis of hardware imperfections in full-duplex systems and develops a mathematical model for their suppression.

Findings

Up to 13 dB additional suppression achieved.

IQ imbalance and DAC non-linearities are major sources of residual interference.

Joint compensation of hardware impairments enhances full-duplex performance.

Abstract

Hardware imperfections can significantly reduce the performance of full-duplex wireless systems by introducing non-idealities and random effects that make it challenging to fully suppress self-interference. Previous research has mostly focused on analyzing the impact of hardware imperfections on full-duplex systems, based on simulations and theoretical models. In this paper, we follow a measurement-based approach to experimentally identify and isolate these hardware imperfections leading to residual self-interference in full-duplex nodes. Our measurements show the important role of images arising from in-phase and quadrature (IQ) imbalance in the mixers. We also observe base-band non-linearities in the digital-to-analog converters (DAC), which can introduce strong harmonic components that have not been previously considered. A corresponding general mathematical model to suppress these components of the self-interference signal arising from the hardware non-idealities is developed from the observations and measurements. Results from a 10 MHz bandwidth full-duplex OFDM system, operating at 2.48 GHz, show up to 13 dB additional suppression, relative to state-of-the-art implementations can be achieved by jointly compensating for IQ imbalance and DAC non-linearities.