Inter-mode Interference Suppression Method for OAM Multiplexing in the Presence of Ground Reflection and Beam Axis Misalignment

Inter-mode interference (IMI) in orbital angular momentum (OAM) multiplexing exhibits different mode ranges and dependences according to factors such as beam axis misalignment and ground reflection, which require countermeasures that consider their properties. In this study, we propose an IMI suppression method to improve the transmission performance of OAM multiplexing using mode limitation and an efficient IMI canceler at the transmitter and receiver, respectively, when both beam axis misalignment and ground reflection are present. Considering that the IMI caused by ground reflection becomes more severe at higher OAM modes, the proposed method focuses on transmitting the OAM during lower modes (which are less affected by such IMI). Later, the residual IMI is eliminated using an efficient IMI canceler at the receiver. The proposed method has demonstrated its superiority over the traditional one (which solely uses an efficient IMI canceler) via computer simulations.