Track-After-Scan Based ISAC System with Detection, Tracking, and Communications

This paper proposes a two-stage integrated sensing and communication system. A multi-antenna base station performs multi-target detection in Stage I and tracks these targets in Stage II, while maintaining downlink communication with a single user throughout both stages. The independent track-after-scan (I-TAS) and collaborative TAS (C-TAS) schemes are proposed, flexibly allocating time between the two stages and power within each stage to meet communication, detection, and tracking requirements. An optimization problem is formulated to balance the communication rate, detection signal-to-noise ratio, and tracking Cramér-Rao bound. Through analysis of the maximum rate and sector partition in Stage I, combined with variable substitution and affine transformation, a global optimal solution is obtained. Simulations verify that I-TAS and C-TAS extend the performance dimensions and boundaries of the baselines, yielding superior operational flexibility.