Beam Pattern Modulation Embedded Hybrid Transceiver Optimization for Integrated Sensing and Communication

TL;DR

This paper proposes a novel beam pattern modulation embedded hybrid transceiver design for integrated sensing and communication in mmWave systems, optimizing spectrum efficiency and sensing accuracy under hardware constraints.

Contribution

It introduces an optimized transceiver architecture that allocates RF chains for sensing and communication, employing index modulation and sequential optimization to improve ISAC performance.

Findings

Enhanced sensing accuracy demonstrated by lower MSE and CRB.

Improved spectrum efficiency through index modulation.

Theoretical analysis confirms asymptotic error probability improvements.

Abstract

Integrated sensing and communication (ISAC) emerges as a promising technology for B5G/6G, particularly in the millimeter-wave (mmWave) band. However, the widely utilized hybrid architecture in mmWave systems compromises multiplexing gain due to the constraints of limited radio frequency chains. Moreover, additional sensing functionalities exacerbate the impairment of spectrum efficiency (SE). In this paper, we present an optimized beam pattern modulation-embedded ISAC (BPM-ISAC) transceiver design, which spares one RF chain for sensing and the others for communication. To compensate for the reduced SE, index modulation across communication beams is applied. We formulate an optimization problem aimed at minimizing the mean squared error (MSE) of the sensing beampattern, subject to a symbol MSE constraint. This problem is then solved by sequentially optimizing the analog and digital parts. Both the multi-aperture structure (MAS) and the multi-beam structure (MBS) are considered for the design of the analog part. We conduct theoretical analysis on the asymptotic pairwise error probability (APEP) and the Cram\'er-Rao bound (CRB) of direction of arrival (DoA) estimation. Numerical simulations validate the overall enhanced ISAC performance over existing alternatives.