Microwave Linear Analog Computer (MiLAC) for Simultaneous Active and Passive Beamforming
This work addresses the problem of enhancing the versatility and efficiency of MiLAC-aided transceivers for wireless communication systems by enabling simultaneous active and passive beamforming, which is an incremental improvement for system designers.
This paper introduces a dual-functionality framework for Microwave Linear Analog Computers (MiLACs), enabling them to perform both active beamforming for transmission/reception and passive beamforming by acting as a reconfigurable intelligent surface (RIS). The authors provide an optimal reconfiguration strategy and characterize the fundamental limits on the trade-off between active and passive rates, including capacity region bounds and sum-rate capacity.
Microwave linear analog computers (MiLACs) have recently emerged to enable high-performance and efficient beamforming in the analog domain. In this paper, we introduce a dual-functionality framework for MiLAC-aided transceivers. Beyond analog-domain precoding/combining (active beamforming), a MiLAC and its antenna array can simultaneously act as a reconfigurable intelligent surface (RIS) (passive beamforming). This allows the MiLAC to execute beamforming for transmission/reception while reflecting external incident signals. We provide an optimal reconfiguration strategy for this dual-functional MiLAC, and characterize the fundamental limits on the trade-off between active and passive rate, namely the capacity region bounds and the sum-rate capacity.