Intelligent Reflecting Surface Enabled Multi-Target Sensing

Besides improving communication performance, intelligent reflecting surfaces (IRSs) are also promising enablers for achieving larger sensing coverage and enhanced quality. Nevertheless, in the absence of a direct path between base station (BS) targets, multi-target is generally very difficult, since IRSs incapable proactively transmitting beams or analyzing target information. Moreover, echoes different targets reflected via IRS-assisted virtual links arrive at BS from same direction. In this paper, we study wireless system comprising multi-antenna an IRS sensing, where beamforming vector phase shifts jointly optimized to improve performance. To meet requirements, such as minimum received power frequency, propose three novel schemes: Time division (TD) signature sequence (SS) hybrid TD-SS sensing. For TD tasks performed over time. contrast, SS scheme senses all simultaneously establishes relationship directions SSs. strike flexible balance beam pattern gain efficiency, general with grouping, belonging group sensed while groups assigned orthogonal time slots. By controlling number groups, can provide more frequency. two-layer penalty-based algorithm solve challenging non-convex optimization problem joint design beamformers, shifts, grouping. Simulation results demonstrate effectiveness proposed trade-off Our reveal that leakage unintended tighter interference constraints.