Modified MMSE-OSIC Detection for Arbitrary-Order Orbital Angular Momentum Multiplexing System

Arbitrary-order orbital angular momentum multiplexing (AOAMM) systems can increase the capacities of optical communications. In this paper, the symmetry of the mode transmission matrices of AOAMM systems is proven. According to this feature, a modified algorithm that performs bidirectional interference cancellations for AOAMM systems is proposed. The results show that the proposed algorithm outperforms the standard minimum mean squared error (MMSE) with ordered successive interference cancellation (OSIC) algorithm and approaches to the bit error rate of the MMSE-based sorted QR decomposition with M-algorithm, when the topological charge intervals are small in the region of low to moderate signal-to-noise ratios. The proposed algorithm makes the AOAMM systems available in practice.