Ultimate Capacity Analysis of Orbital Angular Momentum Channels

Abstract

Orbital angular momentum (OAM) multiplexing has recently been proposed as a solution to the ultimate goal of increasing the channel capacity of wireless communication links because of the existence of infinite orthogonal modes. It can be combined with the existing conventional multiplexing techniques to boost up the data rate multiple times for future wireless communication systems. We analyze the fundamental behavior of the channel capacity of OAM channels based on two concepts for the most common Laguerre-Gaussian OAM beams: paraxiality and orthogonality. We also confirm our general theory by applying the proposed method to the evanescing OAM beams, circular transverse electric beams. Our study is based on calculating the paraxial estimator of these OAM beams and relating it as a parameter that limits the degree of freedom in OAM channels. In particular, we investigate the dependency on physical parameters, such as transmitter and receiver sizes, in our calculation to define the capacity of OAM channels.