Virtual-Array Implementation for High Performance Multi-Target Angular Sensing in UAV-ISAC Systems.

UAV-enabled Integrated Sensing and Communication (ISAC) systems simultaneously support target sensing and communication and, combined with their abilities in autonomy and control situations, they have the potential to be deployed for search and rescue tasks that were, previously, challenging or impossible. However, the limited apertures of UAV-mounted physical arrays restrict angular resolution and multi-target sensing capability. This work proposes a method for implementing virtual arrays in UAV-assisted MIMO-OFDM ISAC systems to enhance the multi-target sensing capability. With a range of possibilities including transmit-receive channel pairings and two virtual-array configurations, Virtual-7 and Virtual-10 are developed to form greater effective apertures out of a 4×4 ISAC transceiver. A sensing model based on virtual arrays and the corresponding signal-processing procedure are established for angle estimation and for sensing-performance investigation. Simulation results show that ISAC systems with virtual arrays perform better in terms of multi-target detection. The proposed method for virtual-array establishment can, potentially, be applied in UAV-ISACs for high-resolution sensing with a low-profile configuration requirement.