The vortex electromagnetic wave carried by multiple orthogonal orbital angular momentum (OAM) modes in the same frequency band can be applied to the field of wireless communications, which greatly increases the spectrum efficiency. The uniform circular array (UCA) is the classical structure to generate and receive vortex electromagnetic waves with multiple OAM-modes. However, when the transmit and receive UCAs are misaligned, there will be interference among the OAM-modes and the signal cannot be recovered at the receiver. In order to solve this problem, we propose movable antenna (MA) assisted OAM wireless communications scheme. We estimate the rotation angle between transmit and receive UCAs and feed it back to the transmitter. Then, the MA at the transmitter adjusts the rotation angle to achieve alignment of the UCA at both the receiver and transmitter. Simulation results show that our scheme can significantly improve the spectrum efficiency.

翻译：携带多个正交轨道角动量(OAM)模式的涡旋电磁波可在同一频段内应用于无线通信领域，从而大幅提升频谱效率。均匀圆形阵列(UCA)是产生和接收多OAM模式涡旋电磁波的经典结构。然而，当发射与接收UCA存在非对准时，OAM模式间会产生干扰，导致接收端无法恢复信号。为解决该问题，本文提出一种可移动天线(MA)辅助的OAM无线通信方案。我们估计发射与接收UCA之间的旋转角度并将其反馈至发射端，随后发射端通过MA调整旋转角度，实现接收端与发射端UCA的对准。仿真结果表明，该方案能显著提升频谱效率。