基于均匀圆形阵列的轨道角动量复用通信中有效自由度的限制

The Limits of Effective Degrees of Freedom in UCA based Orbital Angular Momentum Multiplexed Communications.

作者信息

Li Zhipeng, Qu Fengzhong, Wei Yan, Yang Guowei, Xu Wen, Xu Jing

机构信息

Ocean College, Zhejiang University, Zhoushan, Zhejiang, 316021, China.

School of Communication Engineering, Hangzhou Dianzi University, Hangzhou, Zhejiang, 310000, China.

出版信息

Sci Rep. 2020 Mar 23;10(1):5216. doi: 10.1038/s41598-020-61329-z.

DOI:10.1038/s41598-020-61329-z

PMID:32251300

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC7090009/

Abstract

Orbital angular momentum (OAM) multiplexing technique has recently emerged and generated widespread interests since the OAM was discovered as a property of electromagnetic wave and acoustic wave. It was widely acknowledged that OAM multiplexing can achieve very high effective degrees of freedom (EDOF) and improve the spectral efficiency in optical, radio and acoustic communications. However, in the field of free-space optical (FSO) communications, it was demonstrated that OAM multiplexing is not the optimal multiplexing technique and the spatial bandwidth product (SBP) limits the EDOF. Is there any EDOF limits of OAM multiplexing in radio and acoustic communications? Could OAM multiplexing be safely scaled to far field? Here, we discover that the azimuthal resolution of OAM mode generator in OAM multiplexing limits its EDOF. Furthermore, we also verify that the OAM multiplexing in radio and acoustic communication fails to enable a long distance transmission and high EDOF simultaneously incurred by the inherently imperfect OAM mode generator.

摘要

自从轨道角动量（OAM）作为电磁波和声波的一种属性被发现以来，OAM复用技术最近应运而生并引起了广泛关注。人们普遍认为，OAM复用可以实现非常高的有效自由度（EDOF），并提高光通信、无线电通信和声学通信中的频谱效率。然而，在自由空间光（FSO）通信领域，研究表明OAM复用并非最优复用技术，空间带宽积（SBP）限制了有效自由度。在无线电通信和声学通信中，OAM复用是否存在有效自由度限制？OAM复用能否安全地扩展到远场？在此，我们发现OAM复用中OAM模式发生器的方位角分辨率限制了其有效自由度。此外，我们还验证了，由于OAM模式发生器本身存在缺陷，无线电通信和声学通信中的OAM复用无法同时实现长距离传输和高有效自由度。