Robust Beam Codebooks for mmWave/THz Systems: Toward a Stochastic RL Approach

Fuente: arXiv
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Auteurs principaux: Nechi, Anouar, Buchty, Rainer, Berekovic, Mladen, Mulhem, Saleh
Format: Preprint
Publié: 2026
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author Nechi, Anouar
Buchty, Rainer
Berekovic, Mladen
Mulhem, Saleh
author_facet Nechi, Anouar
Buchty, Rainer
Berekovic, Mladen
Mulhem, Saleh
contents Millimeter-wave (mmWave) and terahertz (THz) massive MIMO systems often rely on predefined beamforming codebooks, which are usually suboptimal in Non-Line-of-Sight (NLoS) conditions and for hardware-limited transceivers. Reinforcement Learning (RL) enables adaptive, data-driven codebook design without explicit Channel State Information (CSI), but the robustness of such algorithms in practical conditions is underexplored. This paper introduces a robust multi-agent RL framework that learns beam codebooks directly from environmental feedback, eliminating the need for prior channel knowledge. Our method is well-suited for real-world deployments facing unpredictable propagation and hardware constraints. We conduct a comprehensive analysis of three off-policy algorithms, Deep Deterministic Policy Gradient (DDPG), Twin Delayed DDPG (TD3), and Soft Actor-Critic (SAC), evaluating their resilience to hardware impairments and feedback noise. Simulations show that SAC consistently outperforms deterministic methods, achieving superior beamforming gains and stability in NLoS scenarios, even under severe impairments. These results demonstrate the promise of RL-based codebook design for robust mmWave/THz massive MIMO systems.
format Preprint
id arxiv_https___arxiv_org_abs_2603_19930
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Robust Beam Codebooks for mmWave/THz Systems: Toward a Stochastic RL Approach
Nechi, Anouar
Buchty, Rainer
Berekovic, Mladen
Mulhem, Saleh
Information Theory
Networking and Internet Architecture
Millimeter-wave (mmWave) and terahertz (THz) massive MIMO systems often rely on predefined beamforming codebooks, which are usually suboptimal in Non-Line-of-Sight (NLoS) conditions and for hardware-limited transceivers. Reinforcement Learning (RL) enables adaptive, data-driven codebook design without explicit Channel State Information (CSI), but the robustness of such algorithms in practical conditions is underexplored. This paper introduces a robust multi-agent RL framework that learns beam codebooks directly from environmental feedback, eliminating the need for prior channel knowledge. Our method is well-suited for real-world deployments facing unpredictable propagation and hardware constraints. We conduct a comprehensive analysis of three off-policy algorithms, Deep Deterministic Policy Gradient (DDPG), Twin Delayed DDPG (TD3), and Soft Actor-Critic (SAC), evaluating their resilience to hardware impairments and feedback noise. Simulations show that SAC consistently outperforms deterministic methods, achieving superior beamforming gains and stability in NLoS scenarios, even under severe impairments. These results demonstrate the promise of RL-based codebook design for robust mmWave/THz massive MIMO systems.
title Robust Beam Codebooks for mmWave/THz Systems: Toward a Stochastic RL Approach
topic Information Theory
Networking and Internet Architecture
url https://arxiv.org/abs/2603.19930