DRL-Based Joint Beamforming and Surface Shape Optimization for Flexible Intelligent Metasurface-Aided ISAC Systems

2026-07-01

AI Summary

This work addresses the joint optimization of beamforming and surface geometry in reconfigurable intelligent metasurface-assisted integrated sensing and communication (ISAC) systems, aiming to minimize the Cramér-Rao bound while satisfying communication quality-of-service constraints. Tackling this non-convex optimization challenge, the study pioneers the incorporation of deformable surface geometry into the ISAC design framework and proposes a deep reinforcement learning approach based on Deep Deterministic Policy Gradient (DDPG). A constraint-aware reward mechanism is introduced to balance sensing accuracy and communication performance. Simulation results demonstrate that the proposed method significantly reduces the Cramér-Rao bound compared to conventional rigid arrays, while effectively maintaining required communication quality-of-service levels.

Abstract

Integrated sensing and communication (ISAC) unifies high-precision sensing and wireless data transmission. In this paper, we investigate the design of ISAC systems enabled by flexible intelligent metasurface (FIM) and aim to minimize the Cramér-Rao bound (CRB) with quality of service (QoS) constraints using deep reinforcement learning (DRL). Specifically, we formulate the joint design of beamforming matrix and FIMs surface shape to reduce the CRB subject to transmit power, QoS and the FIMs surface shape constraints. However, the non-convex formulation makes optimization problem difficult to solve. To tackle this issue, we develop a deep deterministic policy gradient (DDPG) actor critic DRL scheme for the joint design, guided by a constraint aware reward to progressively improve sensing performance. Numerical results demonstrate that jointly optimizing the beamforming matrix and the FIMs surface shape substantially decreases CRB while ensuring communication quality compared with existing rigid arrays.

Problem

• Intelligent Metasurface
• Integrated Sensing and Communication
• Beamforming
• Cramér-Rao Bound
• Surface Shape Optimization

Innovation

• Deep Reinforcement Learning
• Intelligent Metasurface
• ISAC
• Beamforming Optimization
• Cramér-Rao Bound