Deep Reinforcement Learning-Based Precoding for Multi-RIS-Aided Multiuser Downlink Systems with Practical Phase Shift

Fuente: arXiv
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Main Authors: Chou, Po-Heng, Zheng, Bo-Ren, Huang, Wan-Jen, Saad, Walid, Tsao, Yu, Chang, Ronald Y.
Format: Preprint
Published: 2025
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author Chou, Po-Heng
Zheng, Bo-Ren
Huang, Wan-Jen
Saad, Walid
Tsao, Yu
Chang, Ronald Y.
author_facet Chou, Po-Heng
Zheng, Bo-Ren
Huang, Wan-Jen
Saad, Walid
Tsao, Yu
Chang, Ronald Y.
contents This study considers multiple reconfigurable intelligent surfaces (RISs)-aided multiuser downlink systems with the goal of jointly optimizing the transmitter precoding and RIS phase shift matrix to maximize spectrum efficiency. Unlike prior work that assumed ideal RIS reflectivity, a practical coupling effect is considered between reflecting amplitude and phase shift for the RIS elements. This makes the optimization problem non-convex. To address this challenge, we propose a deep deterministic policy gradient (DDPG)-based deep reinforcement learning (DRL) framework. The proposed model is evaluated under both fixed and random numbers of users in practical mmWave channel settings. Simulation results demonstrate that, despite its complexity, the proposed DDPG approach significantly outperforms optimization-based algorithms and double deep Q-learning, particularly in scenarios with random user distributions.
format Preprint
id arxiv_https___arxiv_org_abs_2509_25661
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Deep Reinforcement Learning-Based Precoding for Multi-RIS-Aided Multiuser Downlink Systems with Practical Phase Shift
Chou, Po-Heng
Zheng, Bo-Ren
Huang, Wan-Jen
Saad, Walid
Tsao, Yu
Chang, Ronald Y.
Information Theory
Artificial Intelligence
Machine Learning
Networking and Internet Architecture
Signal Processing
68T07, 68T05, 90C26, 94A05
C.2.1; C.2.2; C.4; I.2.6; G.1.6
This study considers multiple reconfigurable intelligent surfaces (RISs)-aided multiuser downlink systems with the goal of jointly optimizing the transmitter precoding and RIS phase shift matrix to maximize spectrum efficiency. Unlike prior work that assumed ideal RIS reflectivity, a practical coupling effect is considered between reflecting amplitude and phase shift for the RIS elements. This makes the optimization problem non-convex. To address this challenge, we propose a deep deterministic policy gradient (DDPG)-based deep reinforcement learning (DRL) framework. The proposed model is evaluated under both fixed and random numbers of users in practical mmWave channel settings. Simulation results demonstrate that, despite its complexity, the proposed DDPG approach significantly outperforms optimization-based algorithms and double deep Q-learning, particularly in scenarios with random user distributions.
title Deep Reinforcement Learning-Based Precoding for Multi-RIS-Aided Multiuser Downlink Systems with Practical Phase Shift
topic Information Theory
Artificial Intelligence
Machine Learning
Networking and Internet Architecture
Signal Processing
68T07, 68T05, 90C26, 94A05
C.2.1; C.2.2; C.4; I.2.6; G.1.6
url https://arxiv.org/abs/2509.25661