This study considers a novel full-duplex (FD) massive multiple-input multiple-output (mMIMO) system using hybrid beamforming (HBF) architecture, which allows for simultaneous uplink (UL) and downlink (DL) transmission over the same frequency band. Particularly, our objective is to mitigate the strong self-interference (SI) solely on the design of UL and DL RF beamforming stages jointly with sub-array selection (SAS) for transmit (Tx) and receive (Rx) sub-arrays at base station (BS). Based on the measured SI channel in an anechoic chamber, we propose a min-SI beamforming scheme with SAS, which applies perturbations to the beam directivity to enhance SI suppression in UL and DL beam directions. To solve this challenging nonconvex optimization problem, we propose a swarm intelligence-based algorithmic solution to find the optimal perturbations as well as the Tx and Rx sub-arrays to minimize SI subject to the directivity degradation constraints for the UL and DL beams. The results show that the proposed min-SI BF scheme can achieve SI suppression as high as 78 dB in FD mMIMO systems.

翻译：本研究考虑一种采用混合波束成形（HBF）架构的新型全双工（FD）大规模多输入多输出（mMIMO）系统，该系统允许在同一频段上同时进行上行链路（UL）和下行链路（DL）传输。特别地，我们的目标是仅通过设计上行和下行射频波束成形阶段，并结合基站（BS）处发射（Tx）和接收（Rx）子阵列选择（SAS），来抑制强自干扰（SI）。基于在消声室中测量的SI信道，我们提出了一种带有SAS的最小SI波束成形方案，该方案对波束方向性施加扰动，以增强上行和下行波束方向上的SI抑制。为了解决这一具有挑战性的非凸优化问题，我们提出了一种基于群体智能的算法解决方案，用于寻找最佳扰动以及Tx和Rx子阵列，以在满足上行和下行波束方向性退化约束的条件下最小化SI。结果表明，所提出的最小SI波束成形方案在FD mMIMO系统中可实现高达78 dB的SI抑制。