CRB-Based Waveform Optimization for MIMO ISAC Systems With One-Bit ADCs

TL;DR

This paper develops CRB-based waveform optimization for low-cost, power-efficient MIMO ISAC systems with one-bit ADCs, balancing sensing accuracy and communication reliability.

Contribution

It introduces novel CRBs for quantized MIMO ISAC, formulates a nonconvex optimization problem, and proposes an ADMM-based solution for joint waveform design.

Findings

CRBs are tight for quantized estimation performance

Proposed methods outperform benchmark schemes

Trade-off between CRB and SEP achieved with ADMM

Abstract

This paper studies the transmit waveform optimization for a quantized multiple-input multiple-output (MIMO) integrated sensing and communication (ISAC) system, where one-bit analog-to-digital converters (ADCs) are employed to enable a low-cost and power-efficient hardware implementation. Focusing on the parameter estimation task, we propose two novel Cram\'er-Rao bounds (CRBs) for both point-like target (PT) and extended target (ET) to characterize the impact of quantization distortion on the estimation accuracy, where associated estimation methods are also developed to approach these theoretical CRBs. Moreover, with the goal of jointly enhancing the sensing and communication performances, we formulate the bi-criterion ISAC waveform optimization problem by minimizing the derived CRB objectives subject to a communication symbol error probability (SEP) constraint and a total power constraint, which, due to the high nonlinearity of the one-bit CRBs, are extremely nonconvex. To yield a high-quality suboptimal solution, we develop an efficient alternating direction method of multipliers (ADMM) framework which exploits the majorization-minimization (MM) technique to address the nonconvex issue. Simulation results verify that the one-bit CRBs are tight for characterizing the quantized estimation performance and the proposed estimation methods also show clear performance advantages over the existing benchmark schemes. Furthermore, a flexible trade-off between the CRB and the SEP performance can be achieved by the developed ADMM framework, demonstrating the effectiveness of the optimized ISAC waveform.