Propagation Measurement and Channel Characteristics of Small Office OAM Communication at 30 GHz

Orbital angular momentum (OAM) communication has been envisioned as a potential technology to increase capacity for 6G communication. In this letter, we present an OAM channel measurement campaign in an indoor small office at 30 GHz. Furthermore, the path loss is investigated and modeled by close-in (CI) model and floating-intercept (FI) model. It is found that the FI model fits the measured path loss better than the CI model, and the CI model may no longer appropriate for OAM wave propagation when the receiver is in the hollow radiation area of the OAM beam. Also, we investigate the K-factor and the results indicate that the divergence angle leads to more complicated multipath propagation characteristics of the wireless channel. Moreover, root mean square delay spread reveals that channel performance can be effectively improved when the receiver is within the direct radiation range of the OAM antenna. Generally, this work can be considered as a foundation of understanding and building channel models of indoor OAM communication systems.