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Main Authors: Fang, Tianyu, Zhou, Xiaohua, Mao, Yijie
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2601.01834
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author Fang, Tianyu
Zhou, Xiaohua
Mao, Yijie
author_facet Fang, Tianyu
Zhou, Xiaohua
Mao, Yijie
contents Microwave linear analog computer (MiLAC)-aided beamforming, which processes the transmitted symbols fully in the analog domain, has recently emerged as a promising alternative to fully digital and hybrid beamforming architectures for multiple-input multiple-output (MIMO) systems. While prior studies have shown that lossless and reciprocal MiLAC can achieve the same capacity as digital beamforming in a single-user MIMO network, its performance in multi-user scenarios remains unknown. To answer this question, in this work, we establish a downlink multi-user multiple-input single-output (MU-MISO) network with a MiLAC-aided transmitter, and investigate its sum-rate performance. Based on the microwave network theory, we first prove that lossless and reciprocal MiLAC cannot achieve the same performance as digital beamforming in a general MU-MISO network. Then, we formulate a sum-rate maximization problem and develop an efficient optimization framework to jointly optimize the power allocation and the scattering matrix for MiLAC. Numerical results validate our theoretical analysis and demonstrate that MiLAC is a promising architecture for future extremely large-scale MIMO systems.
format Preprint
id arxiv_https___arxiv_org_abs_2601_01834
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the Performance of Lossless Reciprocal MiLAC Architectures in Multi-User Networks
Fang, Tianyu
Zhou, Xiaohua
Mao, Yijie
Signal Processing
Microwave linear analog computer (MiLAC)-aided beamforming, which processes the transmitted symbols fully in the analog domain, has recently emerged as a promising alternative to fully digital and hybrid beamforming architectures for multiple-input multiple-output (MIMO) systems. While prior studies have shown that lossless and reciprocal MiLAC can achieve the same capacity as digital beamforming in a single-user MIMO network, its performance in multi-user scenarios remains unknown. To answer this question, in this work, we establish a downlink multi-user multiple-input single-output (MU-MISO) network with a MiLAC-aided transmitter, and investigate its sum-rate performance. Based on the microwave network theory, we first prove that lossless and reciprocal MiLAC cannot achieve the same performance as digital beamforming in a general MU-MISO network. Then, we formulate a sum-rate maximization problem and develop an efficient optimization framework to jointly optimize the power allocation and the scattering matrix for MiLAC. Numerical results validate our theoretical analysis and demonstrate that MiLAC is a promising architecture for future extremely large-scale MIMO systems.
title On the Performance of Lossless Reciprocal MiLAC Architectures in Multi-User Networks
topic Signal Processing
url https://arxiv.org/abs/2601.01834