Joint Communication and Radar Sensing with Reconfigurable Intelligent Surfaces

TL;DR

This paper introduces a RIS-assisted mmWave system that jointly enhances radar sensing and communication, using adaptive RIS partitioning and hierarchical codebooks to improve localization accuracy and spectral efficiency.

Contribution

It proposes a novel adaptive RIS partitioning method and a multi-stage hierarchical codebook for joint sensing and communication, reducing transmissions and improving efficiency.

Findings

Fewer transmissions needed for target localization compared to exhaustive search.

Spectral efficiency comparable to RIS-assisted MIMO systems without sensing.

Significantly better spectral efficiency than traditional MIMO systems without RIS.

Abstract

In this paper, we use a reconfigurable intelligent surface (RIS) to enhance the radar sensing and communication capabilities of a mmWave dual function radar communication system. To simultaneously localize the target and to serve the user, we propose to adaptively partition the RIS by reserving separate RIS elements for sensing and communication. We design a multi-stage hierarchical codebook to localize the target while ensuring a strong communication link to the user. We also present a method to choose the number of times to transmit the same beam in each stage to achieve a desired target localization probability of error. The proposed algorithm typically requires fewer transmissions than an exhaustive search scheme to achieve a desired target localization probability of error. Furthermore, the average spectral efficiency of the user with the proposed algorithm is found to be comparable to that of a RIS-assisted MIMO communication system without sensing capabilities and is much better than that of traditional MIMO systems without RIS.