Photonics-assisted analog wideband self-interference cancellation for in-band full-duplex MIMO systems with adaptive digital amplitude and delay pre-matching

TL;DR

This paper introduces a photonics-assisted analog RF self-interference cancellation method for in-band full-duplex MIMO systems, utilizing adaptive digital pre-matching to effectively suppress interference and enable frequency downconversion.

Contribution

It presents a novel dual-parallel Mach-Zehnder modulator-based approach with adaptive digital amplitude and delay pre-matching for wideband SI cancellation in IBFD MIMO systems.

Findings

Achieved around 20 dB SI cancellation depth for 1-Gbaud 16-QAM OFDM signals.

Demonstrated effective SI suppression using combined genetic and least-squares algorithms.

Validated the approach with experiments involving two different SI signals.

Abstract

A photonics-assisted analog wideband RF self-interference (SI) cancellation and frequency downconversion approach for in-band full-duplex (IBFD) multiple-input multiple-output (MIMO) systems with adaptive digital amplitude and delay pre-matching is proposed based on a dual-parallel Mach-Zehnder modulator (DP-MZM). In each MIMO receiving antenna, the received signal, including different SI signals from different transmitting antennas and the signal of interest, is applied to one arm of the upper dual-drive Mach-ehnder modulator (DD-MZM) of the DP-MZM, the reference signal is applied to the other arm of the upper DD-MZM, and the local oscillator signal is applied to the lower DD-MZM. The SI signals are canceled in the optical domain in the upper DD-MZM and the frequency downconversion is achieved after photodetection. To cancel the SI signals, the reference signal is constructed in the digital domain, while the amplitude and delay of the constructed reference are adjusted digitally by upsampling with high accuracy. Experiments are performed when two different SI signals are employed. The genetic algorithm and least-squares algorithm are combined with segmented searching respectively for the SI signal reconstruction and amplitude and delay pre-matching. A cancellation depth of around 20 dB is achieved for the 1-Gbaud 16 quadrature-amplitude modulation orthogonal frequency-division multiplexing signal.