Optimal User and Target Scheduling, User-Target Pairing, and Low-Resolution Phase-Only Beamforming for ISAC Systems

TL;DR

This paper develops an optimal joint scheduling, pairing, and low-resolution beamforming strategy for ISAC systems, demonstrating significant performance improvements over heuristic methods.

Contribution

It introduces a globally optimal solution for the complex resource allocation problem in ISAC, combining mixed-integer linear programming with low-resolution phase-only beamforming.

Findings

Optimal joint design outperforms heuristic approaches.

Reformulation to MILP enables global optimality.

Low-resolution beamforming is effective for ISAC.

Abstract

We investigate the joint user and target scheduling, user-target pairing, and low-resolution phase-only beamforming design for integrated sensing and communications (ISAC). Scheduling determines which users and targets are served, while pairing specifies which users and targets are grouped into pairs. Additionally, the beamformers are designed using few-bit constant-modulus phase shifts. This resource allocation problem is a nonconvex mixed-integer nonlinear program (MINLP) and challenging to solve. To address it, we propose an exact mixed-integer linear program (MILP) reformulation, which leads to a globally optimal solution. Our results demonstrate the superiority of an optimal joint design compared to heuristic stage-wise approaches, which are highly sensitive to scenario characteristics.