RIS-Assisted Self-Interference Mitigation for In-Band Full-Duplex Transceivers

TL;DR

This paper proposes a RIS-assisted approach to mitigate self-interference in in-band full-duplex transceivers, enhancing capacity by configuring the wireless channel to reduce interference, considering quantization noise effects.

Contribution

It introduces a joint design of precoding and RIS coefficients for IBFD systems, accounting for quantization noise and finite RIS phase resolution.

Findings

RIS effectively mitigates self-interference in IBFD systems.

Joint optimization improves uplink and downlink rates.

Simulation confirms robustness with finite RIS phase resolution.

Abstract

The wireless in-band full-duplex (IBFD) technology can in theory double the system capacity over the conventional frequency division duplex (FDD) or time-division duplex (TDD) alternatives. But the strong self-interference of the IBFD can cause excessive quantization noise in the analog-to-digital converters (ADC), which represents the hurdle for its real implementation. In this paper, we consider employing a reconfigurable intelligent surface (RIS) for IBFD communications. While the BS transmits and receives the signals to and from the users simultaneously on the same frequency band, it can adjust the reflection coefficients of the RIS to configure the wireless channel so that the self-interference of the BS is sufficiently mitigated in the propagation domain. Taking the impact of the quantization noise into account, we propose to jointly design the downlink (DL) precoding matrix and the RIS coefficients to maximize the sum of uplink (UL) and DL rates. The effectiveness of the proposed RIS-assisted in-band full-duplex (RAIBFD) system is verified by simulation studies, even taking into considerations that the phases of the RIS have only finite resolution.