Rotatable antenna (RA) enhances wireless coverage through directional gain steering, yet suffers from performance degradation under physical blockages. Intelligent reflecting surface (IRS) establishes reflective paths to bypass obstacles, but suffers from angular mismatch when deployed in the side-lobe region of base station (BS) antennas. To address this issue, we propose a new RA-enabled IRS-assisted multi-user uplink system, in which the BS antennas are capable of flexibly adjusting their 3D orientations to align their boresights with the IRS. We formulate a sum rate maximization problem by jointly optimizing the antenna 3D rotations, receive beamforming and IRS phase shifts. To tackle this non-convex problem, we propose an efficient alternating optimization (AO) algorithm. Specifically, we iteratively update the antenna rotations via projected gradient ascent (PGA), compute the receive beamforming via a closed-form solution, and optimize the IRS phase shifts via fractional programming (FP). Numerical results demonstrate that the proposed system yields significant performance gains over conventional fixed-antenna systems, especially under large angular misalignments.

翻译：可旋转天线通过定向增益调控增强无线覆盖，但在物理遮挡下存在性能下降问题。智能反射面通过建立反射路径规避障碍物，但部署在基站天线旁瓣区域时面临角度失配问题。为解决该问题，本文提出一种新型可旋转天线赋能的智能反射面辅助多用户上行系统，其中基站天线能够灵活调整三维朝向以使其轴向对准智能反射面。我们通过联合优化天线三维旋转、接收波束赋形与智能反射面相移，构建了和速率最大化问题。针对这一非凸问题，我们提出一种高效交替优化算法：通过投影梯度上升法迭代更新天线旋转参数，采用闭式解计算接收波束赋形向量，并利用分式规划优化智能反射面相移。数值仿真结果表明，所提系统较传统固定天线系统具有显著性能增益，在大角度失配场景下尤为突出。