Compressed Sensing Inspired User Acquisition for Downlink Integrated Sensing and Communication Transmissions

TL;DR

This paper introduces a radar-assisted user acquisition method for downlink MIMO-OFDM systems, combining MUSIC and LASSO algorithms to improve accuracy and efficiency in identifying users based on delay and beamspace responses.

Contribution

It proposes a novel two-stage user acquisition approach using MUSIC for delay estimation and LASSO for beamspace response, with performance analysis and beam probing strategies.

Findings

Simultaneous multi-beam probing outperforms single-beam focusing under power constraints.

The rank and eigenvalues of the beamspace difference matrix influence acquisition performance.

Numerical results validate the effectiveness of the proposed method.

Abstract

This paper investigates radar-assisted user acquisition for downlink multi-user multiple-input multiple-output (MIMO) transmission using Orthogonal Frequency Division Multiplexing (OFDM) signals. Specifically, we formulate a concise mathematical model for the user acquisition problem, where each user is characterized by its delay and beamspace response. Therefore, we propose a two-stage method for user acquisition, where the Multiple Signal Classification (MUSIC) algorithm is adopted for delay estimation, and then a least absolute shrinkage and selection operator (LASSO) is applied for estimating the user response in the beamspace. Furthermore, we also provide a comprehensive performance analysis of the considered problem based on the pair-wise error probability (PEP). Particularly, we show that the rank and the geometric mean of non-zero eigenvalues of the squared beamspace difference matrix determines the user acquisition performance. More importantly, we reveal that simultaneously probing multiple beams outperforms concentrating power on a specific beam direction in each time slot under the power constraint, when only limited OFDM symbols are transmitted. Our numerical results confirm our conclusions and also demonstrate a promising acquisition performance of the proposed two-stage method.