发表机构
Hainan University; Fujian Agriculture and Forestry University; Sanming University; Tsinghua University（海南大学; 福建农林大学; 三明大学; 清华大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出采用混合固定与可旋转天线阵列的中继网络，结合可重构智能表面，通过DSAC-T算法优化，实现低空网络保密速率提升、功率与天线节省及多用户服务。
AI 中文摘要
本文提出一种采用混合固定位置与可旋转天线阵列的中继网络，旨在为低空经济应用提供更安全的通信，考虑在传统中继网络中部署可旋转阵列。具体而言，基站与中继站均配备固定位置天线阵列和可旋转阵列，分别服务地面用户与空中用户。为应对多用户干扰挑战，采用低成本可重构智能表面作为候选路径。在发射功率、用户服务质量、可旋转范围及路径选择的约束下，目标是通过联合波束成形、功率分配与可旋转天线方向设计，最大化最坏情况下的保密速率（SR）。首先研究单用户场景下的SR性能，提出一种基于逐步骤泄漏的方案；随后分析一般多用户场景，提出支持混合离散与连续动作的改进型分布软演员-评论家算法（DSAC-T）学习方案，以最大化最坏情况SR。仿真结果验证了所提方案的有效性：与各向同性天线相比，所提方案的SR性能提升约两倍，系统实现约71.4%的功率节省、55%的天线节省，且可服务更多用户。
英文摘要
In this paper, a relay network with hybrid fixed-position and rotatable antenna arrays is proposed. The deployment of rotatable arrays in conventional relay networks is considered to provide more secure communications for low-altitude economy applications. Specifically, both the base station and the relay station are equipped with fixed-position antenna arrays and rotatable arrays to serve ground users and aerial users, respectively. To address the challenge of multi-user interference, a low-cost reconfigurable intelligent surface is exploited as a candidate path. Accordingly, under constraints on transmit power, user quality of service, rotatable range, and path selection, the objective is to maximize the worst-case secrecy rate (SR) through joint beamforming, power allocation, and rotatable antenna orientation design. First, the SR performance in the \textcolor{black}{single ground-aerial user pair scenario} is investigated, and a step-by-step leakage-based scheme is proposed. Then, the general multi-user scenario is studied, and a Distributional Soft Actor-Critic with Three refinements (DSAC-T)-based learning scheme, which supports hybrid discrete and continuous actions, is proposed to maximize the worst-case SR. Simulation results validate the effectiveness of the proposed schemes. The proposed schemes achieve approximately a twofold improvement in SR performance compared to isotropic antennas. \textcolor{black}{The proposed system can achieve approximately 99.7\% power saving, 55\% antenna saving, and can serve more users.}
