AI 中文总结
本文针对上行链路捏合天线系统，推导了频率选择性信道模型，提出感知频率选择性的捏合天线部署方法，可大幅提升大带宽、大波导孔径场景下的可达速率。
AI 中文摘要
本文研究了上行链路捏合天线系统（PASS），该系统采用分段介质波导为多个用户提供服务，且每个分段上激活一个捏合天线（PA）。大规模波导部署降低了用户到PA的路径损耗，但也在覆盖大波导孔径的PA辅助路径之间产生了差分传播延迟。本文保留了这些延迟，并推导了托普利茨块模型以表征由此产生的频率选择性（FS）信道。对于无限块长传输，本文表征了联合解码和并行解码下的可达单用户速率与多用户总速率；对于载波相位对齐的单用户PA部署，结果表明平坦频率（FF）模型会高估精确的FS速率。FF信道模型计算的速率与精确FS信道模型计算的速率之差被称为FF速率高估，本文表征了其对波导孔径诱导延迟扩展的依赖性：当延迟扩展较小时，FF速率高估随延迟扩展近似呈二次增长；而推导得到的下界表明，在大孔径状态下，高估随波导孔径（或等效为延迟扩展）至少呈双对数增长。对于有限块长传输，本文在实用的循环前缀单载波频域均衡框架下推导了可达速率，并开发了一种逐元素算法以在两种传输状态下优化感知FS的PA部署。分析结果表明，大规模部署的波导产生的差分延迟会引发显著的频率选择性，且所提出的感知FS的PA部署方法相比基于FF近似的部署，能大幅提升可达速率，尤其在大带宽和大孔径场景下效果显著。
英文摘要
An uplink pinching-antenna system (PASS) is considered, where a segmented dielectric waveguide is employed to serve multiple users and one pinching antenna (PA) is activated on each segment. Extensive waveguide deployment reduces user-to-PA path loss but also creates differential propagation delays among the PA-assisted paths spanning the large waveguide aperture. These delays are retained, and a Toeplitz block model is derived to characterize the resulting frequency-selective (FS) channel. For infinite-blocklength transmission, the achievable single-user rate and the multiuser sum-rates under joint and parallel decoding are characterized. For carrier-phase-aligned single-user PA placement, the frequency-flat (FF) model is shown to overestimate the exact FS rate. The difference between the rates computed under the FF channel model and the exact FS channel model is referred to as the FF rate overestimation, and its dependence on the waveguide-aperture-induced delay spread is characterized. For small delay spreads, the FF rate overestimation is shown to increase approximately quadratically with the delay spread, whereas a derived lower bound reveals that the overestimation grows at least double logarithmically with the waveguide aperture, or equivalently with the delay spread, in the large-aperture regime. For finite-blocklength transmission, achievable rates are derived under a practical cyclic-prefix single-carrier frequency-domain equalization framework. An element-wise algorithm is developed to optimize FS-aware PA placement in both transmission regimes. The analytical findings demonstrate that differential delays across the extensively deployed waveguide can cause significant frequency selectivity and that the proposed FS-aware PA placement method substantially improves the achievable rate over placement based on the FF approximation, especially for large bandwidths and apertures.
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