用于最大化OAM信道容量的混合机械和电子波束控制
Hybrid Mechanical and Electronic Beam Steering for Maximizing OAM Channel Capacity
摘要：
射频-轨道角动量调制（RF-OAM）是一种在同一频率信道上复用一组正交模式以实现高频谱效率的新方法。由于OAM要求发射天线和接收天线精确对准，因此针对基于均匀圆阵（Uniform Circular Array，UCA）的OAM通信系统，提出了电子波束控制方法，以避免实际环境中天线对准误差引起的系统性能下降。然而，在大角度失准的情况下，OAM信道容量不能仅通过电子波束转向来有效补偿。针对这一问题，提出了一种机械和电子相结合的波束控制方案，利用脉宽调制（PWM）信号控制的机械旋转装置作为执行单元，消除大的失准角，而电子波束控制则负责剩余的微小扰动引起的失准角。此外，由于干涉测量，接收信噪比（SNR）在接收UCA的元件处是不均匀的。为此，提出了一种可旋转UCA结构的OAM接收机，首先采用模拟退火算法获得最优旋转角度，然后伺服系统进行机械旋转，最后调整电子束转向，以最大化信道容量。数学分析和仿真结果均表明，所提出的机械电子混合波束控制方案能够有效地消除实际OAM信道中各种失调误差的影响，最大化OAM信道容量。
英文摘要：
Radio frequency-orbital angular momentum (RF-OAM) is a novel approach of multiplexing a set of orthogonal modes on the same frequency channel to achieve high spectrum efficiencies. Since OAM requires precise alignment of the transmit and the receive antennas, the electronic beam steering approach has been proposed for the uniform circular array (UCA)-based OAM communication system to circumvent large performance degradation induced by small antenna misalignment in practical environment. However, in the case of large-angle misalignment, the OAM channel capacity can not be effectively compensated only by the electronic beam steering. To solve this problem, we propose a hybrid mechanical and electronic beam steering scheme, in which mechanical rotating devices controlled by pulse width modulation (PWM) signals as the execution unit are utilized to eliminate the large misalignment angle, while electronic beam steering is in charge of the remaining small misalignment angle caused by perturbations. Furthermore, due to the interferometry, the receive signal-to-noise ratios (SNRs) are not uniform at the elements of the receive UCA. Therefore, a rotatable UCA structure is proposed for the OAM receiver to maximize the channel capacity, in which the simulated annealing algorithm is adopted to obtain the optimal rotation angle at first, then the servo system performs mechanical rotation, at last the electronic beam steering is adjusted accordingly. Both mathematical analysis and simulation results validate that the proposed hybrid mechanical and electronic beam steering scheme can effectively eliminate the effect of diverse misalignment errors of any practical OAM channel and maximize the OAM channel capacity.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
