发表机构
Beihang University; State Key Laboratory of CNS/ATM; Queen’s University Belfast; Nanyang Technological University（北京航空航天大学; 空管中央控制国家重点实验室; 贝尔法斯特女王大学; 南洋理工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出多模夹持天线系统（PASS）的物理模型，揭示模间干扰问题并建立无干扰硬件条件，在ISAC场景中通过联合优化基带与夹持波束成形，实现优于单模PASS的性能。
AI 中文摘要
基于耦合模理论，提出了多模夹持天线系统（PASS）的物理模型。在所考虑的模型中，多个导模在同一波导中被同时激励，并作为独立的信号承载信道加以利用，从而为信号传输提供了额外的模态自由度。在夹持天线（PA）引入的局部电磁扰动下，明确研究了不期望的导模耦合，并揭示了由此产生的模间干扰（IMI）问题。进一步建立了实现无IMI状态的充分硬件设计条件，并通过全波电磁仿真验证了其实际可行性。然后，推导了在无IMI状态下运行的多模PASS的易处理信号模型。为展示所提出的多模PASS模型的优势，将集成感知与通信（ISAC）作为代表性应用场景进行研究，其中基站同时使用两个导模与一个通信用户通信并感知一个目标。在连续和离散PA激活情况下，以最小化目标定位的克拉美-罗界为目标，同时满足最小通信速率要求，提出了联合基带和夹持波束成形优化问题。开发了一种基于交替优化的算法来解决所提出的非凸问题。对于基带波束成形，采用了基于惩罚的逐次凸近似方法。对于夹持波束成形，分别针对连续和离散PA激活情况，提出了粒子群优化算法和双边匹配算法。在ISAC应用场景中获得的数值结果证明了所提出的多模PASS模型相对于单模PASS的优越性。
英文摘要
The physical model of multi-mode pinching-antenna systems (PASS) is proposed based on the coupled-mode theory. Within the considered model, multiple guided modes are simultaneously excited in a single waveguide and exploited as independent signal-bearing channels, thus providing additional modal degrees of freedom for signal transmission. Under the local electromagnetic perturbations introduced by PAs, the undesired guided-modes coupling is explicitly investigated, and the resulting inter-mode interference (IMI) issue is revealed. The sufficient hardware-design condition for achieving the IMI-free regime is further established, for which the practical feasibility is validated through full-wave electromagnetic simulations. Then, a tractable signal model is derived for multi-mode PASS operating over the IMI-free regime. To demonstrate the benefits of the proposed multi-mode PASS model, the integrated sensing and communications (ISAC) is studied as a representative application scenario, where the base station simultaneously communicates with a communication user and senses a target by using two guided modes. A joint baseband and pinching beamforming optimization problem is formulated for the minimization of the Cramer-Rao bound for target localization, subject to the minimum communication rate requirement, under both continuous and discrete PAs activation cases. An alternating optimization-based algorithm is developed to address the formulated non-convex problem. For the baseband beamforming, a penalty-based successive convex approximation method is invoked. For the pinching beamforming, a particle swarm optimization algorithm and a two-sided matching algorithm are proposed for the continuous and discrete PAs activation cases, respectively. Numerical results obtained in the ISAC application scenario demonstrate the superiority of the proposed multi-mode PASS model over the single-mode PASS.
