面向到达方向估计的目标导向波计算
Goal-Oriented Wave Computing for Direction-of-Arrival Estimation
- Faculty of Engineering and Natural Sciences, Sabancı University（萨班奇大学工程与自然科学学院）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究提出目标导向训练可编程超表面进行到达方向估计，无需预设算子，使浅层或稀疏连接表面达到复杂设计性能，且优势在量化控制下保持。
AI中文摘要：
可编程超表面——其电磁响应可电子调谐的元件阵列——可以在波传播穿过或反射时处理信号，这一范式被称为波域模拟计算。其设计策略通常是间接的：将表面适配到预定的线性算子（如离散傅里叶变换），并从输出功率测量中读取结果。以到达方向（DoA）估计作为典型基准，我们研究了这种间接性在模拟计算拓扑中的代价，即反射式可重构智能表面（RIS）、超越对角RIS（BD-RIS）和堆叠智能超表面（SIM）。我们首先推导了完整物理估计链的Cramér–Rao界，包括一个考虑仅测量强度的输出探测器的界。然后，我们提出了一种目标导向的替代方案，其中表面直接通过部署的读出进行训练，无需算子目标。我们观察到，目标导向训练使稀疏连接或较浅的表面达到其更复杂的算子适配对应物的任务性能——尽管Fisher信息几乎相同——并且这种优势在粗量化（1–3位）控制下仍然存在。从16到64个元件，深度节省持续存在，而超越对角RIS所需的连接性随孔径增长。在调谐器和逐层损耗下，目标导向设计保持其优势。
英文摘要：
Programmable metasurfaces---arrays of elements whose electromagnetic response can be tuned electronically---can process signals as a wave propagates through or reflects off them, a paradigm known as wave-domain analog computing. The design strategy is typically indirect: the surface is fitted to a prescribed linear operator, such as a discrete Fourier transform, and the result is read from output power measurements. Using direction-of-arrival (DoA) estimation as a canonical benchmark, we study what this indirection costs across analog computing topologies, namely reflective reconfigurable intelligent surfaces (RIS), beyond-diagonal RIS (BD-RIS), and stacked intelligent metasurfaces (SIM). We first derive Cramér--Rao bounds for the complete physical estimation chain, including one that accounts for output detectors measuring only intensity. We then formulate a goal-oriented alternative where the surfaces are trained directly through the deployed readout, with no operator target. We observe that goal-oriented training lets sparsely connected or shallower surfaces reach the task performance of their more complex operator-fitted counterparts---despite nearly identical Fisher information---and that the advantage persists under coarsely quantized (1--3 bit) control. From 16 to 64 elements, the depth saving persists, while the connectivity a beyond-diagonal RIS needs grows with the aperture. Under tuner and per-layer loss, the goal-oriented designs keep their advantage.
