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A variety of novel orbital angular momentum (OAM)-based communication or sensing systems have attracted much attention over the past decade, the superiority is brought about by nothing other than its orthogonality or vorticity. Plane spiral OAM (PSOAM) mode-group (MG) technique as a reconfigurable beamforming method can be used for building a multiple-in-multiple-out (MIMO) system to achieve the reduction in subchannel correlation, which benefits from the spiral phase distribution within the mainlobe. However, the demultiplexing process still depends on the MIMO algorithm, in which the receiver complexity is same as the conventional MIMO systems. In this article, a PSOAM MG orthogonal multiplexing communication link at the X-band using partial arc sampling receiving (PASR) scheme has been demonstrated experimentally. The MG channels have a good isolation of about 15 dB, and the existing performance can ensure the reliable 16-QAM wireless transmission. Besides, a real-time dual-channel video transmission experiment has been carried out to verify the channel isolation caused by MG’s orthogonality intuitively. More importantly, the demultiplexing procedure using the PASR scheme can be implemented by simple analog phase shifting operation with a lower receiver complexity compared with the conventional MIMO systems. [ABSTRACT FROM AUTHOR]

Spatial division multiplexing using conventional orbital angular momentum (OAM) has become a well-known physical layer transmission method over the past decade. The mode-group (MG) superposed by specific single-mode plane spiral OAM (PSOAM) waves has been proved to be a flexible beamforming method to achieve the azimuthal pattern diversity, which inherits the spiral phase distribution of conventional OAM wave. Thus, it possesses both beam directionality and vorticity. In this article, it is the first time to show and verify a novel PSOAM MG based multiple-in–multiple-out (MG-MIMO) communication link experimentally in a line-of-sight (LoS) scenario. A compact multimode PSOAM antenna is demonstrated experimentally to generate multiple-independent controllable PSOAM waves, which can be used for constructing MGs. After several proof-of-principle tests, it has been verified that the beam directionality gain of MG can improve the receiving signal-to-noise ratio (SNR) level in an actual system. Meanwhile, the vorticity can provide another degree of freedom (DoF) to reduce the spatial correlation of MIMO system. Furthermore, a tentative long-distance transmission experiment operated at 10.2 GHz has been performed successfully at a distance of 50 m with a single-way spectrum efficiency of 3.7 bits/s/Hz/stream. The proposed MG-MIMO may have potential in the long-distance LoS backhaul scenario. [ABSTRACT FROM AUTHOR]

Over the past decades, orbital angular momentum (OAM) has attracted great interest due to its helical phase characteristics. It has been proved that plane spiral OAM (PSOAM) waves have a potential in azimuthal pattern reconfiguration. PSOAM waves could be termed as a special form of OAM wave, which avoids the inconsistency of the divergent angles for different OAM waves. However, from a practical point of view, such a PSOAM-based pattern reconfiguration scheme badly needs a compact high-purity multimode PSOAM antenna. In this communication, a compact high-purity eight-mode PSOAM antenna consisting of a coaxial resonator group (CRG) and a rotating parabolic reflector (RPR) is fabricated and measured. The prototype is designed for $X$ -band operation with a bandwidth of 140 MHz, and the simulated efficiencies of the PSOAM modes ±1,±2,±3, and ±4 are 88.86%, 92.18%, 90.93%, and 91.25%, respectively. The constructed pattern may have the directivity, vorticity, and nondistortion azimuthal 360° scanning capability. This scheme realizes these pattern characteristics with a simpler algorithm and a lower system complexity compared with the phased array antenna-based pattern reconfiguration scheme. It will have potential in next-generation radar and wireless communication system. [ABSTRACT FROM AUTHOR]

A plane spiral orbital angular momentum (PSOAM) mode-group (MG) based multiple-in-multiple-out (MIMO) communication system is proposed, and the performance is numerically analyzed in line-of-sight (LoS) channel. The simulated results show that the proposed scheme can increase the channel capacity, which means that PSOAM MGs superposed by several PSOAM waves can not only improve the signal-to-noise ratio (SNR) of system but also decrease the spatial correlation of sub-channels. Besides, combined with partial arc sampling receiving (PASR) method, the data streams can be recovered orthogonally with low complexity. The capacity gain and bit-error rate (BER) performance of the proposed scheme are evaluated. This technique may have potential in higher wireless capacity communications. [ABSTRACT FROM AUTHOR]

In , the title of the article was incorrectly stated as “A Compact Pattern Reconfiguration Antenna Based on Multimode Plane Spiral OA. ” The correct title is: “A Compact Pattern Reconfiguration Antenna Based on Multimode Plane Spiral OAM. ” [ABSTRACT FROM AUTHOR]