arXiv subjects

Shoushuo Zhang

Publications and source records attributed to Shoushuo Zhang.

3 recordsLinked to original sources

arXiv2026

Cooperative OFDM-ISAC Networks: Performance Analysis and Resource Allocation

Cooperative integrated sensing and communication (ISAC) based on orthogonal frequency-division multiplexing (OFDM) enables network-wide sensing by exploiting the spatial diversity of multi-base-station (BS). This paper studies performance analysis and time-frequency resource allocation for a multi-BS cooperative OFDM-ISAC network with fine-grained resource-element (RE)-level orthogonal coordination. Two fusion architectures are considered: signal-level fusion (SLF), which forwards raw echoes to a fusion center, and parameter-level fusion (PLF), which reports only local delay/Doppler estimates and their uncertainty information. For SLF, we derive the Cramér--Rao bound (CRB) for joint target position and velocity estimation. For PLF, we develop a two-stage CRB-like metric by combining local delay/Doppler uncertainty characterization with first-order geometric error propagation, and show that only an oracle ML-based PLF benchmark can asymptotically attain the SLF CRB under restrictive conditions. Based on these results, we formulate a joint RE-selection and power-allocation problem under network-wide RE exclusivity, per-BS power budgets, a communication sum-rate constraint, and a sidelobe-amplitude constraint on the delay-Doppler ambiguity function. An efficient solution is developed via Schur-complement reformulations and penalty-based alternating optimization. Numerical results validate the analysis, demonstrate effective ambiguity-sidelobe suppression and consistent localization/velocity gains over representative baselines, while revealing geometry-dependent SLF-PLF performance gaps.

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arXiv2025

Target Detection in ISAC Systems with Active RISs: A Multi-Perspective Observation Approach

Integrated sensing and communication (ISAC) has emerged as a transformative technology for 6G networks, enabling the seamless integration of communication and sensing functionalities. Reconfigurable intelligent surfaces (RIS), with their capability to adaptively reconfigure the radio environment, have shown significant potential in enhancing communication quality and enabling advanced cooperative sensing. This paper investigates a multi-RIS-assisted ISAC system and introduces a novel multi-perspective observation framework that leverages the diversity of multiple observation paths, each exhibiting distinct spatial, delay, and Doppler characteristics for both target and clutter. The proposed framework integrates symbol-level precoding (SLP) and space-time adaptive processing (STAP) to fully exploit the benefits of multi-perspective observations, enabling superior target-clutter separation and significantly improving detection accuracy. The objective is to jointly design the transmit waveform, reflection coefficients of multiple active RISs, and spatial-temporal receive filters to maximize the radar output signal-to-clutter-plus-noise ratio (SCNR) for target detection, while ensuring the quality-of-service (QoS) requirements of communication users. To address the resulting non-convex optimization problem, an effective iterative algorithm is developed, combining fractional programming (FP), majorization-minimization (MM), and the alternating direction method of multipliers (ADMM). Extensive simulation results validate the effectiveness of the proposed multi-perspective observation strategy, demonstrating its advantages in improving target detection performance in challenging environments.

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arXiv2024

Multipath Exploitation for Fluctuating Target Detection in RIS-Assisted ISAC Systems

Integrated sensing and communication (ISAC) systems are typically deployed in multipath environments, which is usually deemed as a challenging issue for wireless communications. However, the multipath propagation can also provide extra illumination and observation perspectives for radar sensing, which offers spatial diversity gain for detecting targets with spatial radar cross-section (RCS) fluctuations. In this letter, we propose to utilize reconfigurable intelligent surfaces (RIS) in ISAC systems to provide high-quality and controllable multipath propagation for improving the performance of fluctuating target detection and simultaneously enhancing the quality of communication services. To effectively exploit the spatial diversity offered by RIS-empowered multipath, the dual-functional transmit beamforming and the RIS reflection beamforming are jointly designed to maximize the expectation of radar signal-to-noise ratio (SNR). To solve the resulting complex non-convex optimization problem, we develop an efficient alternating optimization algorithm that utilizes majorization-minimization (MM) and alternating direction method of multipliers (ADMM) algorithms. Simulation results illustrate the advantages of multipath exploitation and the proposed beamforming design algorithm for fluctuating target detection in RIS-assisted ISAC systems.

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