OFDM BASED ORBITAL ANGULAR MOMENTUM SYSTEM AND METHOD

摘要

Disclosed herein is a method of implementing Orbital Angular Momentum (OAM) for radio communications in general and LTE in particular. Common prior art so far recreate said vorticity (axial rotation of the Poynting vector) by using ring-shaped antenna arrays. This application proposes to create said vorticity in signal processing without the need of any space diversity (ie work with a single antenna). In the present application, the main idea is to apply an Hilbert transform in frequency domain to the Fourier transform of the analytical representation of a band-limited OFDM signal. Said Hilbert transform is then approximated by a development in series into orthogonal twisted modes. This can be seen as an inverse Fourier transform of the complex analytical signal. Therefore an OAM IFFT based transmitter is proposed where parallel IFFTs are performed for each OAM mode and superimposed.