Transmit Optimization for Multi-functional MIMO Systems Integrating Sensing, Communication, and Powering

TL;DR

This paper investigates a multi-functional MIMO system that simultaneously performs sensing, communication, and power transfer, revealing fundamental tradeoffs and optimizing transmit strategies to balance these functions effectively.

Contribution

It introduces a unified framework for multi-functional MIMO systems integrating sensing, communication, and powering, and derives optimal transmit strategies to maximize performance tradeoffs.

Findings

Optimal transmit covariance solutions are derived.

The proposed design outperforms time switching benchmarks.

The achievable C-R-E region boundary is characterized.

Abstract

This paper unifies integrated sensing and communication (ISAC) and simultaneous wireless information and power transfer (SWIPT), by investigating a new multi-functional multiple-input multiple-output (MIMO) system integrating wireless sensing, communication, and powering. In this system, one multi-antenna hybrid access point (H-AP) transmits wireless signals to communicate with one multi-antenna information decoding (ID) receiver, wirelessly charge one multi-antenna energy harvesting (EH) receiver, and perform radar sensing for a point target based on the echo signal at the same time. Under this setup, we aim to reveal the fundamental performance tradeoff limits of sensing, communication, and powering, in terms of the estimation Cram{\'e}r-Rao bound (CRB), achievable communication rate, and harvested energy level, respectively. Towards this end, we define the achievable CRB-rate-energy (C-R-E) region and characterize its Pareto boundary by maximizing the achievable rate at the ID receiver, subject to the estimation CRB requirement for target sensing, the harvested energy requirement at the EH receiver, and the maximum transmit power constraint at the H-AP. We obtain the semi-closed-form optimal transmit covariance solution to the formulated problem by applying advanced convex optimization techniques. Numerical results show the optimal C-R-E region boundary achieved by our proposed design, as compared to the benchmark scheme based on time switching.