Two-Timescale Transmission Design and RIS Optimization for Integrated Localization and Communications

TL;DR

This paper introduces a framework that integrates localization and communication by fixing RIS configurations over location coherence intervals, reducing overhead and enhancing performance through novel optimization and estimation methods.

Contribution

It proposes a new integrated design that fixes RIS configurations during location intervals and optimizes BS precoders, leveraging accurate location info and novel methods to improve communication.

Findings

Enhanced localization accuracy

Reduced pilot overhead for RIS control

Improved achievable communication rate

Abstract

Reconfigurable intelligent surfaces (RISs) have tremendous potential to boost communication performance, especially when the line-of-sight (LOS) path between the user equipment (UE) and base station (BS) is blocked. To control the RIS, channel state information (CSI) is needed, which entails significant pilot overhead. To reduce this overhead and the need for frequent RIS reconfiguration, we propose a novel framework for integrated localization and communications, where RIS configurations are fixed during location coherence intervals, while BS precoders are optimized every channel coherence interval. This framework leverages accurate location information obtained with the aid of several RISs as well as novel RIS optimization and channel estimation methods. Performance in terms of localization accuracy, channel estimation error, and achievable rate demonstrates the effectiveness of the proposed approach.