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

TL;DR

This paper investigates the optimization of pilot-to-data power ratio (PDPR) in RIS-assisted multiantenna networks, demonstrating significant benefits in channel estimation accuracy especially with many RIS elements and high channel coherence.

Contribution

It introduces a closed-form solution for optimizing PDPR in RIS-assisted networks based on channel statistics, a novel focus compared to prior cellular network studies.

Findings

Optimizing PDPR improves channel estimation accuracy.

Benefits increase with more RIS elements and higher channel coherence.

Closed-form solution enables practical implementation.

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.