Multi-User ISAC with Heterogeneous Unknown Parameters: Optimal Beamforming based on Distribution Information

Fuente: arXiv
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Main Authors: Xu, Chan, Zhang, Shuowen
Format: Preprint
Published: 2026
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author Xu, Chan
Zhang, Shuowen
author_facet Xu, Chan
Zhang, Shuowen
contents This paper studies an integrated sensing and communication (ISAC) system where a multi-antenna base station (BS) communicates with multiple single-antenna users in the downlink and senses the unknown and random angle information of a target based on its prior distribution information and the received echo signals. We focus on a challenging scenario with heterogeneous unknown parameters where the target's reflection coefficient is also unknown with no prior information. We consider a general transmit beamforming structure with both communication beams and dedicated sensing beams, where the communication users can cancel the interference caused by the pre-determined sensing signals. By adopting the periodic posterior Cramer-Rao bound (PCRB) to quantify a lower bound of the mean-cyclic error (MCE) for sensing the periodic angle parameter, we optimize the transmit beamforming to minimize the periodic PCRB, subject to individual communication user rate constraints, which is a non-convex problem. By leveraging the semi-definite relaxation (SDR) technique and Lagrange duality theory, we derive the optimal solution and prove that at most one dedicated sensing beam is needed. Numerical results validate our analysis and effectiveness of the proposed beamforming design.
format Preprint
id arxiv_https___arxiv_org_abs_2604_22392
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Multi-User ISAC with Heterogeneous Unknown Parameters: Optimal Beamforming based on Distribution Information
Xu, Chan
Zhang, Shuowen
Information Theory
Signal Processing
This paper studies an integrated sensing and communication (ISAC) system where a multi-antenna base station (BS) communicates with multiple single-antenna users in the downlink and senses the unknown and random angle information of a target based on its prior distribution information and the received echo signals. We focus on a challenging scenario with heterogeneous unknown parameters where the target's reflection coefficient is also unknown with no prior information. We consider a general transmit beamforming structure with both communication beams and dedicated sensing beams, where the communication users can cancel the interference caused by the pre-determined sensing signals. By adopting the periodic posterior Cramer-Rao bound (PCRB) to quantify a lower bound of the mean-cyclic error (MCE) for sensing the periodic angle parameter, we optimize the transmit beamforming to minimize the periodic PCRB, subject to individual communication user rate constraints, which is a non-convex problem. By leveraging the semi-definite relaxation (SDR) technique and Lagrange duality theory, we derive the optimal solution and prove that at most one dedicated sensing beam is needed. Numerical results validate our analysis and effectiveness of the proposed beamforming design.
title Multi-User ISAC with Heterogeneous Unknown Parameters: Optimal Beamforming based on Distribution Information
topic Information Theory
Signal Processing
url https://arxiv.org/abs/2604.22392