A 2-D FFT-Based Transceiver Architecture for OAM-OFDM Systems With UCA Antennas

Abstract

Radio orbital angular momentum (OAM) provides another perspective of spatial multiplexing to improve the spectrum efficiency. However, multipath induces severe intraand interchannel crosstalk. To solve the problem in a uniform circular array (UCA)-based OAM system, we first incorporate the effect of sign changing of OAM reflection in modeling the multipath OAM channel. Then, we propose a transceiver architecture for broadband OAM orthogonal frequency-division multiplexing (OFDM) wireless communication systems, which uses baseband digital 2-D fast Fourier transform (FFT) rather than existing radio frequency analog phase shifters to generate and receive the OAM-OFDM signal, thus reducing energy consumption and hardware cost. At last, a flexible 2-D FFT algorithm is developed. Analysis and simulation results show that compared with the traditional row-column FFT algorithm, the proposed 2-D FFT algorithm could reduce the multiplication complexity by 41MN log2 N, where N and Mare the number of UCA antenna elements and the number of subcarriers, respectively.