发表机构
National Key Laboratory of Wireless Communications, University of Electronic Science and Technology of China; School of Electrical and Electronic Engineering, Nanyang Technological University; Institute for Fundamental and Frontier Sciences, University of Electronic Science and Technology of China（电子科技大学无线通信重点实验室; 南洋理工大学电气与电子工程学院; 电子科技大学前沿交叉科学研究院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文针对RIS赋能SR系统，提出极化感知RA设计，联合优化多参数并开发低复杂度RA方案，可显著降低发射功率且性能接近基准方案。
AI 中文摘要
本文研究了一种配备可旋转天线（RA）的双极化可重构智能反射面（DP-RIS）赋能共生无线电（SR）系统。通过重配置天线方向，RA可将其辐射方向图导向期望方向，从而有效缓解RIS辅助级联链路中的双重衰落效应。然而，天线旋转不仅改变辐射方向，还会改变局部极化基，可能导致极化失配并降低可实现增益。这促使了一种联合空间-极化设计，同时利用定向辐射增益和极化匹配。具体而言，我们构建了一个发射功率最小化问题，该问题需联合优化数字波束成形、RA旋转、收发器极化状态及DP-RIS相移，约束条件为非SR用户的主、次速率要求及干扰温度约束。为求解该非凸问题，我们开发了一种交替优化算法，集成了半定规划、凸差规划及黎曼共轭梯度方法。此外，为降低实际部署的硬件和计算复杂度，我们提出了两种低复杂度RA设计，即子阵共享旋转设计和离散旋转码本设计。仿真结果表明，与固定方向和极化不感知的基准方案相比，所提极化感知RA设计显著降低了所需发射功率。此外，两种所提低复杂度RA设计在降低旋转复杂度的同时实现了相当的性能。
英文摘要
This paper investigates a dual-polarized reconfigurable intelligent surface (DP-RIS)-empowered symbiotic radio (SR) system with rotatable antennas (RAs). By reconfiguring antenna orientations, RAs can steer their radiation patterns toward desired directions, thereby effectively mitigating the double-fading effect in RIS-assisted cascaded links. However, antenna rotation not only changes the radiation direction but also alters the local polarization bases, which may result in polarization mismatch and degrade the achievable gain. This motivates a joint spatial-polarization design that simultaneously exploits directional radiation gain and polarization matching. Specifically, we formulate a transmit power minimization problem that jointly optimizes digital beamforming, RA rotations, transceiver polarization states, and DP-RIS phase shifts, subject to the primary and secondary rate requirements as well as interference temperature constraints for non-SR users. To solve this non-convex problem, we develop an alternating optimization algorithm that integrates semidefinite programming, difference-of-convex programming, and Riemannian conjugate gradient methods. Moreover, to reduce hardware and computational complexity for practical deployment, we propose two low-complexity RA designs, namely a subarray-wise shared rotation design and a discrete rotation codebook design. Simulation results show that the proposed polarization-aware RA design significantly reduces the required transmit power compared with fixed-orientation and polarization-unaware benchmark schemes. Moreover, both the proposed low-complexity RA designs achieve comparable performance with reduced rotation complexity.
