In this paper, spectral efficiency of free-space optical (FSO) communication is enhanced by the utilization of advanced schemes of optical spatial modulation (OSM). Optical generalized spatial modulation (OGSM), optical enhanced spatial modulation (OESM), and optical improved quadrature spatial modulation (OIQSM) are proposed for performance improvement of FSO systems over Gamma-Gamma (G-G) channel incorporating pointing errors and path loss effect. These methods are investigated in terms of bit error rate (BER) and the analytical BER upper bound results are corroborated by Monte Carlo simulations. Both spatial domain and symbol domain errors are considered while calculating BER upper bounds. The specifications required to implement the schemes are also presented. The proposed methods offer benefits of reduced cost and power consumption, and BER performance improvement over OSM for higher spectral efficiencies. The upper bounds of BER are tight for all values of transmit power for various configurations of the proposed schemes.

中文翻译：

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用于 FSO 通信的高级光空间调制技术

在本文中，自由空间光 (FSO) 通信的频谱效率通过利用先进的光空间调制 (OSM) 方案来提高。提出了光学广义空间调制 (OGSM)、光学增强空间调制 (OESM) 和光学改进正交空间调制 (OIQSM) 以提高 FSO 系统在 Gamma-Gamma (GG) 信道上的性能，包括指向误差和路径损耗效应。这些方法在误码率 (BER) 方面进行了研究，并且分析 BER 上限结果由蒙特卡罗模拟证实。在计算 BER 上限时同时考虑空间域和符号域误差。还介绍了实施这些方案所需的规范。所提出的方法具有降低成本和功耗的好处，和 BER 性能优于 OSM，以获得更高的频谱效率。对于建议方案的各种配置的所有发射功率值，BER 的上限都很严格。