Study of an underwater accurate channel model considering comprehensive misalignment errors

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may not be perfectly aligned from the start due to imprecise operation or disturbances such as water flow, and thus outdated pointing errors can no longer reliably reflect precise channel conditions.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.