This paper focuses on investigating the effect of the receiver’s tilted angle on the channel capacity of an underwater wireless optical communication (UWOC) system, in which an avalanche photodiode (APD) detector is adopted as the receiver. Under the non-negativity, peak power, and average power constraints, the lower bounds on the capacity of UWOC are derived in detail according to different average-to-peak power ratios. With modeling achieving the maximum of the lower bounds of the capacity as an optimization object, we prove that the proposed optimization issue is in fact a simple convex optimization about the tilted angle of the APD receiver, and then present related theoretical solution for it. Both theoretical analysis and simulation results show that by appropriately tilting the receiver, we can significantly enhance the final capacity performance of the UWOC with APD receiver.

中文翻译：

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APD接收机倾角对水下无线光通信信道容量的影响

本文重点研究接收器倾斜角度对水下无线光通信（UWOC）系统信道容量的影响，其中采用雪崩光电二极管（APD）探测器作为接收器。在非负、峰值功率和平均功率约束下，根据不同的平均峰值功率比，详细推导出UWOC容量的下限。我们以实现容量下界最大值的建模为优化对象，证明所提出的优化问题实际上是关于APD接收机倾斜角的简单凸优化，然后给出了相关的理论解决方案。理论分析和仿真结果均表明，通过适当倾斜接收机，