Multi-Static Cell-Free Massive MIMO ISAC: Performance Analysis and Power Allocation

TL;DR

This paper analyzes the performance of a cell-free massive MIMO ISAC system, deriving closed-form expressions for communication and sensing metrics, and proposes an optimized power allocation scheme to enhance system efficiency.

Contribution

It provides the first closed-form expressions for achievable rate and CRLB in multistatic cell-free MIMO-ISAC, and introduces an optimized power allocation method.

Findings

Closed-form expressions for communication rate and CRLB.

Optimized power allocation improves system performance.

Numerical results validate theoretical analysis and proposed scheme.

Abstract

In this work, we consider a cell-free massive multiple-input multiple-output (MIMO) integarted sensing and communications (ISAC) system with maximum-ratio transmission schemes combined with multistatic radar-type sensing. Our focus lies on deriving closed-form expressions for the achievable communications rate and the Cram\'er-Rao lower bound (CRLB), which serve as performance metrics for communications and sensing operations, respectively. The expressions enable us to investigate important operational characteristics of multistatic cell-free massive MIMO-ISAC, including the mutual effects of communications and sensing as well as the advantages stemming from using numerous distributed antenna arrays for each functionality. Furthermore, we optimize the power allocation among the access points to maximize the communications rate while guaranteeing the CRLB constraints and total transmit power budget. Extensive numerical results are presented to validate our theoretical findings and demonstrate the efficiency of the proposed power allocation approach.