This letter investigates the issue of secure beamforming for non-orthogonal multiple access (NOMA)-assisted integrated sensing and communication (ISAC), where some targets acquiring group-oriented information from the base station (BS) of the ISAC system are cooperative. To secure the privacy of served users from malicious targets, artificial noise (AN) carrying no information is often transmitted in conventional security schemes. In this letter, we propose to employ multicast signals to convey group-oriented information to cooperative targets, disrupt malicious targets, and simultaneously sense all targets. Meanwhile, unicast signals are transmitted for privacy information of the served users. We formulate a robust secure beamforming problem that deals with imperfect channel state information (CSI) and the uncertainty regarding the angles of malicious targets. To solve this problem, we propose a penalty-based iterative algorithm by transforming the non-convex optimization problem into a convex one with semidefinite relaxation (SDR) and examining the relationship between the trace, the largest eigenvalue and the rank of a positive semidefinite matrix. Numerical results are provided to demonstrate that, with lower computational complexity, the proposed scheme delivers superior performance, compared to state-of-the-art schemes.

中文翻译：

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用于 NOMA-ISAC 的安全波束成形，具有组播和单播通信


本文研究了非正交多址 （NOMA） 辅助集成传感和通信 （ISAC） 的安全波束成形问题，其中一些从 ISAC 系统的基站 （BS） 获取面向群的信息的目标是合作的。为了保护所服务用户的隐私免受恶意目标的侵害，在传统的安全方案中，通常传输不携带信息的人工噪声 （AN）。在本文中，我们建议使用组播信号将面向组的信息传达给合作目标，破坏恶意目标，并同时感知所有目标。同时，传输单播信号以获取被服务用户的隐私信息。我们制定了一个健壮的安全波束成形问题，用于处理不完美的信道状态信息 （CSI） 和恶意目标角度的不确定性。为了解决这个问题，我们提出了一种基于罚的迭代算法，将非凸优化问题转换为具有半定松弛 （SDR） 的凸优化问题，并检查迹线、最大特征值和正半定矩阵的秩之间的关系。提供的数值结果表明，与最先进的方案相比，所提出的方案具有较低的计算复杂度，具有卓越的性能。