OAM-based reconfigurable doppler shifts enable PAPR reduction for multi-carrier doppler diversity

Orbital Angular Momentum (OAM) transmission is expected to be implemented for large capacity communication. However, the conical beam and the coaxial all-phase reception brings painful difficulties. As a promising solution to overcome this difficulty, an OAM multiplexing transmission method is proposed for use in a satellite formation relay scheme in this paper. Specifically, the channel model of the OAM wave from the base station to the relay satellites and then forwarded by relays to the central receiver is established and analyzed. In order to explore the feasibility of the scheme and its influencing factors, we analyze the influence of orbit distribution and random jitter on channel capacity based on the orbit parameters of actual satellite formations. The simulation results show that the uniform and evenly spaced satellite formation has the highest multiplexed channel capacity and anti-interference performance.

For the application of electromagnetic (EM) wave with orbital angular momentum (OAM), which is also called the vortex beam, it is essential to determine the real OAM mode of the transmit antenna, i.e., accurately measure the OAM mode of the manufactured antenna with systematic error. In this paper, an accurate OAM measurement of EM wave based on rotational antenna is proposed. Specifically, the EM beam with helical phase fronts can be well measured via frequency shift detection by rotating the OAM wave at the transmitter. At the same rotation speed, different OAM beams will produce significantly different frequency shifts. The simulation results show that the rotational detection method allows the Root-Mean-Square Error (RMSE) to drop rapidly with no error floor. In addition, this method will not be affected by the different installation environments in practical applications, and has higher detection accuracy and robustness.