A Review of Orbital Angular Momentum Vortex Waves for the Next Generation Wireless Communications

Abstract

The next-generation wireless technology that can fulfill such a demand, namely the fifthgeneration (5G) technology, should provide 1000 times larger capacity. Moreover, sixth-generation (6G) communication, which represents a significant upgrade from the fifth-generation (5G) network and is anticipated to operate from 100 GHz to 3 THz band, will be required in the years after 2030 due to newly developed data-hungry applications and the greatly expanded wireless network. To meet the ever-growing demands of wireless carriers, an efficient wireless access method that can improve wireless area throughput without expanding bandwidth or cell size is required. Radio Frequency (RF) Orbital Angular Momentum vortex waves (which is now on referred to as OAM waves) to address the concerns mentioned above have attracted much attention in recent years. Due to their orthogonality, different OAM waves of different modes can be multiplexed in the same frequency channel, which can greatly increase the channel capacity. Using the orthogonal modes, a new type of multiple access scheme known as Mode Domain Multiple Access (MDMA) can be used by multiple users using the same frequency channel without additional resources such as frequency and time. As a result, the channel capacity for the next generation wireless communication systems can be enhanced as well as the overall spectrum efficiency can be improved. This review paper begins with an overview of the next generation communication such as 5G communication technology and beyond. This paper first briefly discusses the theory of OAM waves and several methods to generate OAM waves. Various different designs have also been analyzed for their ability to generate OAM waves and discussion on several restrictions and solutions to resolve. Open concerns and development trends are discussed for possible future RF OAM antenna upgrades. This study also proposes that for next generation wireless communication employing OAM, the typically used Uniform Circular Array (UCA) could be paired with the Multiple-Input-Multiple-Output (MIMO) system to improve performance in dense or urban areas for multiusers. In addition, the purity of OAM-modes needs to be considered for efficient utilization of the OAM system for future communications at the radio domain.INDEX TERMS Orbital angular momentum (OAM) waves, uniform circular array antenna, 5G communication systems, antenna review paper, future wireless communication survey. I. INTRODUCTIONAdvances in mobile communications have significantly impacted economic and social growth over the past few decades. There have been noteworthy improvements with every generation of communication technology in terms of data rate, channel capacity, advanced applications such as video call, real-time health monitoring and so on. Based on the survey [1], it all started in the 1980s with the first generation (1G) technology, which mainly employed analog signals for voice services. The data rate was up to 2.4 Kbps.

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“…OAM can unleash its potential in achieving high spectrum efficiency [176], [177]. Consequently, 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 [175], [178]- [181]. It can also be combined with the existing conventional multiplexing techniques to boost up the data rate multiple times for future wireless communication systems [176], [181].…”

Evolution properties of partially coherent electromagnetic elliptical vortex beam propagating through atmospheric turbulence

“…al have proposed that vortex beam can carry a spiral phase factor exp(in j) (n is the topological charge and j denotes the azimuthal angle) and each photon in the beam has an orbital angular momentum (OAM) of n,  where  is the reduced Planck constant. Meanwhile, vortex beam can improve the channel capacity of communication system by OAM coding or OAM multiplexing [12,13]; and can resist affects caused by turbulent atmosphere [5,[14][15][16][17][18][19][20] due to characteristics of itself. Moreover, elliptical beam also is a special beam, characterized by having elliptical intensity distribution [21][22][23][24].…”

Broadband spin-decoupled metasurface for independent wavefront manipulations of orthogonal circularly-polarized waves

“…In brief, the research of spin-independent manipulation methods has achieved good results, but metasurfaces with wider operating bandwidths and higher working performance still remain challenging. Furthermore, vortex wave has been of great importance for its exceptional advantages in efficiently expanding channel capacity in communication fields [44]. The vortex wave generation using metasurfaces have been extensively studied [45][46][47], but the bandwidth, efficiency and multiplexing of these metasurfaces need to be optimized and improved.…”