A Novel Precoding Technique to Reduce PAPR of UCA-OAM Systems

Orbital angular momentum (OAM) multiplexing, which improves channel capacity without requiring additional spectrum resources, is a key technology for future communication systems. However, a uniform circular array (UCA)-based OAM transmission system, which uses an inverse discrete Fourier transform and a discrete Fourier transform to realize OAM mode multiplexing and demultiplexing, has a high peak average power ratio (PAPR) problem. This letter proposes a precoding scheme based on the conjugate symmetric discrete orthogonal transform that reduces the PAPR of UCA-OAM systems with misaligned transceivers. Simulation results indicate that the proposed scheme greatly reduces the PAPR of the system without losing the bit error rate (BER) performance in misaligned transceivers.