IF Phase Compensation and Demutiplexing for Distributed OAM Radio Receiving System

The enhancement of the transmission range in orbital angular momentum (OAM) multiplexing systems is anticipated to benefit significantly from the implementation of a distributed receiving strategy. This approach entails the strategic placement of multiple receiving antennas in a discrete and independent manner across a spiral phase plane, which is oriented perpendicularly to the direction of transmission. Given the lack of synchronization among the receiving antennas, a prerequisite for the de-multiplexing process is the execution of phase compensation on all incoming signals. To mitigate the expenses associated with Radio Frequency (RF) processing, this study introduces an innovative Intermediate Frequency (IF) phase compensation algorithm, accompanied by a uniquely structured data frame. By aligning the phases of signals received by the distributed antennas at the intermediate frequency level, the process facilitates the subsequent de-multiplexing to segregate each OAM channel. Through both simulation and empirical experimentation, it has been demonstrated that this methodology substantially diminishes the crosstalk prevalent among multiplexed OAM channels, thereby promoting a consistent and stable transmission rate within the system. This advancement underscores the potential of distributed receiving schemes in enhancing the efficacy and reliability of OAM multiplexing systems.