Mode Combination in an Ideal Wireless OAM-MIMO Multiplexing System

In this letter, we present the mode combinations needed to achieve orthogonal sub-channels in an ideal wireless orbital angular momentum based multiple-input multiple-output (OAM-MIMO) multiplexing system with N OAM transmitters and M receive antennas. The results show that, orthogonality is achieved if the absolute difference between any two transmitted modes vertical bar v(k)vertical bar mod M not equal 0. The modes are considered equivalent if their absolute difference is a multiple of M. Orthogonal OAM-MIMO multiplexing systems can be used to enhance spectral efficiency in wireless backhaul networks.