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arXiv · 2509.08642

RIS-Assisted Near-Field ISAC for Multi-Target Indication in NLoS Scenarios

Hang Ruan·Homa Nikbakht·Ruizhi Zhang·Honglei Chen·Yonina C. Eldar
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Abstract

Enabling multi-target sensing in near-field integrated sensing and communication (ISAC) systems is a key challenge, particularly when line-of-sight paths are blocked. This paper proposes a beamforming framework that leverages a reconfigurable intelligent surface (RIS) to achieve multi-target indication. Our contribution is the extension of classic beampattern gain and inter-target cross-correlation metrics to the near-field, leveraging both angle and distance information to discriminate between multiple users and targets. We formulate a problem to maximize the worst-case sensing performance by jointly designing the beamforming at the base station and the phase shifts at the RIS, while guaranteeing communication rates. The non-convex problem is solved via an efficient alternating optimization (AO) algorithm that utilizes semidefinite relaxation (SDR). Simulations demonstrate that our RIS-assisted framework enables high-resolution sensing of co-angle targets in blocked scenarios.

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Hang Ruan, Homa Nikbakht, Ruizhi Zhang, Honglei Chen, Yonina C. Eldar. 2025-09-10. RIS-Assisted Near-Field ISAC for Multi-Target Indication in NLoS Scenarios. https://arxiv.org/abs/2509.08642

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