摘要
轨道角动量(OAM)是电磁波的固有物理量,与电场强度的物理量纲线性无关,可构成无线传输中的新维度。从电磁波资源利用和发展的历史出发,分析了电磁波轨道角动量的物理特征,明确了只有电磁波量子携带内禀OAM的涡旋电磁波传输系统才可以获得MIMO传输以外的无线传输新维度;统计态OAM涡旋波束中的电磁波量子形成的外部OAM与空域维度相耦合,无法构成MIMO传输以外的新维度,但在直射视距(Lo S)信道时可获得额外自由度和较低的复杂度。依据信道容量的不同,将典型涡旋电磁波OAM传输系统划分为4个不同区域,并着重指出量子态OAM涡旋电磁波传输可以形成超越传统MIMO容量界的含有OAM维度的新MIMO容量界。
Orbital angular momentum(OAM) is a physical quantity in the electro-magnetic(EM) wave which has the physical dimension linearly independent with that of the electric field strength, so that the OAM can constitute the new dimension in the wireless transmission. With tracing back to the history of EM wave utilization and development, the physical characteristics of OAM were analyzed, and the fact that only the vortex wave transmission system with EM wave photon carrying intrinsic OAM could obtain the new dimension besides MIMO transmission was clarified. Compared with the MIMO transmission, the extrinsic OAM formed by the plane microwaves in the statistical OAM beam was coupled with the space domain and could not provide the additional new dimension. However, in the line of sight(LoS)channel, the additional degrees of freedom and lower complexity could be achieved compared with MIMO transmission.Moreover, the typical vortex EM wave OAM transmission systems could be divided into four different regions based on the different channel capacities. Taking the microwave band as an example, it is pointed out that the quantum OAM transmission based on vortex microwave photon can form the new MIMO bound with the OAM dimension, which is beyond the traditional MIMO bound.
作者
张超
王元赫
ZHANG Chao;WANG Yuanhe(Labs of Avionics,School of Aerospace Engineering,Tsinghua University,Beijing 100084,China)
出处
《通信学报》
EI
CSCD
北大核心
2022年第6期211-222,共12页
Journal on Communications
基金
国家自然科学基金资助项目(No.61731011)。
关键词
轨道角动量
无线通信
涡旋微波量子
涡旋电磁波
内禀轨道角动量
外部轨道角动量
orbital angular momentum
wireless communication
vortex microwave photon
vortex electro-magnetic wave
intrinsic OAM
extrinsic OAM
