Capacity Analysis of Orbital Angular Momentum Multiplexing Transmission System

Orbital Angular Momentum (OAM) multiplexing at radio has been proven as a potential way of enhancing channel capacity. In this paper, we analyze the spatial propagation characteristic of OAM beams and the channel capacity of different receiving antenna array configurations in OAM multiplexing transmission system. Simulation results reveal that an OAM beam becomes more and more divergent as the transmission distance and OAM mode order increases. Moreover, the capacity with one receiving Uniform Circular Array (UCA) outperforms the capacity with multiple receiving UCAs regardless of transmission distance and Transmit-Receive (TX-RX) lateral displacement distance, which provides a reference for receiving antenna design of OAM multiplexing transmission system. Furthermore, we verify that multiplexing more OAM modes can improve system robustness.