Rotatable antenna (RA) technology can harness additional spatial degrees of freedom by enabling the dynamic three-dimensional orientation control of each antenna. Unfortunately, the hardware cost and control complexity of traditional RA systems is proportional to the number of RAs. To address the issue, we consider a cross-linked (CL) RA structure, which enables the coordinated rotation of multiple antennas, thereby offering a cost-effective solution. To evaluate the performance of the CL-RA array, we investigate a CL-RA-aided uplink system. Specifically, we first establish system models for both antenna element-level and antenna panel-level rotation. Then, we formulate a sum rate maximization problem by jointly optimizing the receive beamforming at the base station and the rotation angles. For the antenna element-level rotation, we derive the optimal solution of the CL-RA array under the single-user case. Subsequently, for two rotation schemes, we propose an alternating optimization algorithm to solve the formulated problem in the multi-user case, where the receive beamforming and the antenna rotation angles are obtained by applying the minimum mean square error method and feasible direction method, respectively. In addition, considering the hardware limitations, we apply the genetic algorithm to address the discrete rotation angles selection problem. Simulation results show that by carefully designing the row-column partition scheme, the performance of the CL-RA architecture is quite close to that of the flexible antenna orientation scheme. Moreover, the CL antenna element-level scheme surpasses the CL antenna panel-level scheme by 25% and delivers a 128% performance improvement over conventional fixed-direction antennas.

翻译：可旋转天线技术通过实现每个天线动态三维方向控制，能够利用额外的空间自由度。然而，传统可旋转天线系统的硬件成本与控制复杂度与天线数量成正比。为解决此问题，本文提出一种交叉连接可旋转天线结构，该结构可实现多个天线的协同旋转，从而提供经济高效的解决方案。为评估交叉连接可旋转天线阵列的性能，我们研究了一种交叉连接可旋转天线辅助的上行链路系统。具体而言，我们首先建立了天线单元级和天线面板级旋转的系统模型。随后，通过联合优化基站的接收波束成形与旋转角度，构建了和速率最大化问题。针对天线单元级旋转，我们推导了单用户场景下交叉连接可旋转天线阵列的最优解。接着，针对两种旋转方案，提出一种交替优化算法以求解多用户场景下的规划问题，其中接收波束成形和天线旋转角度分别通过应用最小均方误差方法和可行方向法获得。此外，考虑到硬件限制，我们采用遗传算法处理离散旋转角度选择问题。仿真结果表明，通过精心设计行列分区方案，交叉连接可旋转天线架构的性能与灵活天线定向方案十分接近。更重要的是，交叉连接天线单元级方案相比天线面板级方案性能提升25%，较传统固定方向天线实现128%的性能增益。