Sequence Scrambling for Non-Hollow-OAM Based Wireless Communications

摘要

Orbital angular momentum (OAM), which is inherently possessed by the electromagnetic (EM) beams, bridges a new way for multiple access using multiple orthogonal OAM-modes in wireless communications. Uniform circular array (UCA), as a convenient antenna structure for supporting the transmission and reception of OAM based signals, has been paid much attention in recent years. However, the OAM beams generated by the UCAs are centrally hollow and divergent, limiting the efficient reception as well as the long-distance transmission for OAM based signals. To solve this problem, in this paper we propose the Zadoff-Chu (ZC) sequence based scrambling scheme to generate the non-hollow OAM beams while maintaining the orthogonality among different OAM-modes. Then, based on the properties of applying discrete Fourier transform (DFT) for circulant matrices and zero-free sequences, we develop the scrambling-tolerant detection scheme to efficiently obtain the transmit symbols. Performance evaluations show the non-hollow irregular OAM beams and validate that our developed ZC sequence based scrambling scheme works well for long-distance transmission in OAM based wireless communications.