Microwave Linear Analog Computer (MiLAC) for Simultaneous Active and Passive Beamforming

2026-05-29

AI Summary

This work addresses the challenge of jointly realizing efficient active and passive beamforming in the analog domain to enhance spectral and energy efficiency. It proposes a dual-functional Microwave Linear Analog Computer (MiLAC) architecture that, for the first time, unifies active beamforming—used for transmission and reception—and passive reflection—as a reconfigurable intelligent surface—on a single hardware platform. By introducing analog-domain precoding/combining and leveraging information-theoretic analysis, the study derives fundamental capacity region bounds and sum-rate limits for active-passive communication, and formulates an optimal reconfiguration strategy that characterizes the intrinsic rate trade-off between the two functionalities. These results theoretically and practically validate the feasibility and performance advantages of the proposed dual-functional architecture.

Abstract

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.

Problem

• Microwave Linear Analog Computer
• Active Beamforming
• Passive Beamforming
• Reconfigurable Intelligent Surface
• Rate Trade-off

Innovation

• Microwave Linear Analog Computer
• Dual-functionality
• Active Beamforming
• Passive Beamforming
• Reconfigurable Intelligent Surface