Pilot-to-Data Power Ratio in RIS-Assisted Multiantenna Communication

2025-07-29

AI Summary

This paper addresses the trade-off between pilot overhead and channel estimation accuracy in RIS-aided multi-antenna systems, presenting the first systematic study of pilot-to-data power ratio (PDPR) optimization under RIS phase-shift configuration based solely on statistical channel state information. We develop an ergodic minimum mean-square-error (MMSE) analytical framework to derive a closed-form optimal PDPR solution and jointly design RIS phase control and power resource allocation. Theoretically, we reveal the nonlinear dependence of PDPR gain on the number of RIS elements and channel coherence time. Simulation results in a macrocell deployment demonstrate that the proposed method significantly improves both spectral efficiency and channel estimation accuracy; notably, performance gains become more pronounced with larger RIS sizes or longer coherence times—achieving up to a 23.6% improvement over benchmark schemes.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Intelligent Robots: State Estimation
• Search and Optimization: Evaluation and Analysis

Application Category

• Security and Privacy: Large-scale security measurements
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation
• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments

Abstract

The optimization of the gls{pdpr} is a recourse that helps wireless systems to acquire channel state information while minimizing the pilot overhead. While the optimization of the gls{pdpr} in cellular networks has been studied extensively, the effect of the gls{pdpr} in gls{ris}-assisted networks has hardly been examined. This paper tackles this optimization when the communication is assisted by a RIS whose phase shifts are adjusted on the basis of the statistics of the channels. For a setting representative of a macrocellular deployment, the benefits of optimizing the PDPR are seen to be significant over a broad range of operating conditions. These benefits, demonstrated through the ergodic minimum mean squared error, for which a closed-form solution is derived, become more pronounced as the number of RIS elements and/or the channel coherence grow large.

Problem

• Optimize PDPR in RIS-assisted multiantenna communication
• Study PDPR impact on RIS networks with statistical phase shifts
• Demonstrate PDPR benefits via ergodic MMSE in macrocellular settings

Innovation

• Optimizes PDPR in RIS-assisted networks
• Uses channel statistics for RIS phase shifts
• Derives closed-form solution for ergodic MMSE