[en] Achieving ubiquitous connectivity and radar sensing on the same platform with improved spectral/energy efficiency is a critical challenge for low Earth orbit (LEO) satellite systems. To mitigate severe radar echo loss at high altitudes, we put forth a bistatic integrated sensing and communication (ISAC) framework, where a ground-based radar receiver operates separately from the satellite. For robust and effective interference management, we employ rate-splitting multiple access (RSMA), which splits and encodes users' messages into private and common streams. Instead of relying on instantaneous communication channel state information (CSI), we exploit the geometric and statistical characteristics of the satellite channel while accounting for uncertainty in the geometric information. Based on this practical modeling, we optimize the robust dual-functional precoders to maximize the minimum user rate while satisfying Cramér-Rao bound (CRB) constraints. To achieve this, we develop an efficient optimization algorithm using multiple mathematical relaxation techniques for joint precoder design. Numerical results show that the proposed framework efficiently performs both communication and radar sensing, exhibiting strong interference mitigation even under geometric channel uncertainty. Furthermore, it is validated that the common stream plays three vital roles: i) beamforming towards the radar target, ii) interference management between communications and radar, and iii) interference management among communication users. By leveraging the multi-functionality of the common stream, efficient and robust joint operation of radar sensing and communication is achieved even without requiring a dedicated radar sequence.
Disciplines :
Electrical & electronics engineering
Author, co-author :
Park, Juha ; Korea University, School of Electrical Engineering, Seoul, South Korea
Seong, Jaehyup ; Korea University, School of Electrical Engineering, Seoul, South Korea
Mao, Yijie ; ShanghaiTech University, School of Information Science and Technology, Shanghai, China
Shin, Wonjae ; Korea University, School of Electrical Engineering, Seoul, South Korea
OTTERSTEN, Björn ; University of Luxembourg > Interdisciplinary Centre for Security, Reliability and Trust (SNT) > PI Ottersten
External co-authors :
yes
Language :
English
Title :
A Bistatic ISAC Framework for LEO Satellite Systems: A Rate-Splitting Approach
Publication date :
2025
Journal title :
IEEE Transactions on Aerospace and Electronic Systems
ISSN :
0018-9251
eISSN :
1557-9603
Publisher :
Institute of Electrical and Electronics Engineers Inc.
This work was supported in part by the National Research Foundation of Korea (NRF) grants (RS-2025-00562095), in part by the Institute of Information & Communications Technology Planning & Evaluation (IITP) grants (RS-2024-00359235, RS-2022-0-00704), and in part by the Luxembourg National Research Fund (FNR), grant reference INTER/MOBILITY/2023/IS/18014377/MCR. (Corresponding author: Wonjae Shin.) J. Park, J. Seong, and W. Shin are with the School of Electrical Engineering, Korea University, Seoul 02841, South Korea (e-mail: {juha, jaehyup, wjshin}@korea.ac.kr); Y. Mao is with the School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China (e-mail: maoyj@shanghaitech.edu.cn); B. Ottersten is with Interdisciplinary Centre for Security, Reliability and Trust (SnT), University of Luxembourg, L-1359 Luxembourg (e-mail: bjorn.ottersten@uni.lu).
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