Han Shuo, Yue Peng, Yi Xiang
J Opt Soc Am A Opt Image Sci Vis. 2022 Jun 1;39(6):1014-1024. doi: 10.1364/JOSAA.451074.
In an actual scene, underwater optical wireless communication (UOWC) transceivers may not be perfectly aligned from the start due to imprecise operation or disturbances such as water flow, and thus outdated pointing errors can no longer reliably reflect precise channel conditions. In this paper, for the first time, to our knowledge, we formulate a comprehensive misalignment errors model by taking into account both random jitter and initial misalignment errors. Furthermore, we deduce an effective receiving area due to the deflection of the receiver with three rotation angles in three-dimensional space. Moreover, we also apply the above findings to the composite fading channel model, which is more accurate and practical than the previous. Finally, we develop closed-form results for the bit error rate (BER) in terms of the Meijer G-function of UOWC systems. The performance is also analyzed by the multiplicative statistical channel model. Results demonstrate that comprehensive misalignment errors exacerbate performance degradation in terms of both average BER and outage probability, compared to pointing errors considering only random jitter. It indicates that the initial misalignment errors are not negligible, and analyzing scenes with comprehensive misalignment errors is of great importance in practice.
在实际场景中，由于操作不精确或水流等干扰因素，水下光无线通信（UOWC）收发器一开始可能无法完美对准，因此过时的指向误差无法再可靠地反映精确的信道条件。据我们所知，本文首次通过同时考虑随机抖动和初始对准误差，建立了一个全面的对准误差模型。此外，我们推导了在三维空间中接收器具有三个旋转角度时因接收器偏转而产生的有效接收区域。而且，我们还将上述研究结果应用于复合衰落信道模型，该模型比之前的模型更准确、更实用。最后，我们针对UOWC系统的误码率（BER），根据梅杰尔G函数得出了闭式结果。性能也通过乘法统计信道模型进行了分析。结果表明，与仅考虑随机抖动的指向误差相比，综合对准误差在平均误码率和中断概率方面都会加剧性能下降。这表明初始对准误差不可忽略，在实际中分析具有综合对准误差的场景非常重要。
