Joint Beam-and-Probabilistic Shaping Scheme Based on Orbital Angular Momentum Mode for Indoor Optical Wireless Communications

In this article, we propose a novel beam-and-probabilistic shaping technique based on orbital angular momentum (OAM) modes for indoor optical wireless communications (OWC) to improve the system effective coverage. Our results show that both Huffman coding (HC) and sign inversion coding (SIC) based probabilistic shaping schemes can improve the effective coverage for 16QAM modulation format while only SIC based probabilistic shaping can improve the effective coverage for 64QAM modulation under different beam shaping schemes with different power ratios of different modes. Furthermore, it can be seen that more significant performance improvement can be obtained by employing both of the probabilistic shaping schemes by decreasing the power ratio of the fundamental mode to the higher-order OAM mode. Therefore, further increment of the effective coverage can be predicted with the probabilistic shaping schemes by decreasing the power ratio.