General configuration MIMO system with arbitrary OAM

Abstract

ABSTRACT As the traditional resources (such as frequency, time, and space) are efficiently utilized, it becomes more and more challenging to satisfy the ever-lasting, capacity-growing, and users-boosting demand for wireless networks. Recently, the orthogonal Orbital Angular Momentum (OAM) modes of electromagnetic waves were exploited to achieve high spectral efficiency in radio and microwave transmission. This research discusses the challenges in OAM signal generation, OAM beam divergence, and OAM signal reception misalignment through a new proposed method. A transmission array with arbitrary shape is used to synthesize the desired OAM waveform at a receiver. The receiver, usually in the form of a ring, could have arbitrary size and location in space and therefore the perfect alignment condition, as required between the transmitter and receiver planes, is relaxed. It is also shown that a notable save in the size of the transmission array is gained against other conventionally used OAM generation methods. This could be of great utility in massive Multiple-Input-Multiple-Output (MIMO) systems. Such reduction in the transmitter size along with the flexibility in choosing the receiver size are all exploited to handle the OAM beam divergence problem. The results are shown using mathematical formulas and are checked by comparing them to numerical simulations.