Integrated sensing and communications (ISAC) allows networks to perform sensing alongside data transmission. While most ISAC studies focus on single-target, multi-user scenarios, multi-target sensing is scarcely researched. This letter examines the monostatic sensing performance of a multi-target massive MIMO system, aiming to minimize the sum of Cram\'er-Rao lower bounds (CRLBs) for target direction-of-arrival estimates while meeting user equipment (UE) rate requirements. We propose several precoding schemes, comparing sensing performance and complexity, and find that sensing-focused precoding with power allocation for communication achieves near-optimal performance with 20 times less complexity than joint precoding. Additionally, time-sharing between communication and sensing outperforms simple time division, highlighting the benefits of resource-sharing for ISAC.
@article{arxiv.2410.22532,
title = {Multi-Target Integrated Sensing and Communications in Massive MIMO Systems},
author = {Ozan Alp Topal and Özlem Tuğfe Demir and Emil Björnson and Cicek Cavdar},
journal= {arXiv preprint arXiv:2410.22532},
year = {2024}
}