In this paper, we investigate simultaneous lightwave information and power transfer (SLIPT) for underwater visible light communication systems. We consider three SLIPT methods namely time switching (TS), power splitting (PS) and time switching-power splitting (TS-PS) where the splitting/switching factors are defined as optimization parameters. For each of these methods, we derive closed-form expressions for the average harvested energy, bit error rate and spectral efficiency in the presence of underwater turbulence modeled by lognormal statistics. Using these expressions, we determine the optimal splitting factors to maximize the harvested energy while satisfying a given bit error rate value and a given threshold spectral efficiency value. Our results reveal that, if not optimized, SLIPT methods under consideration are outperformed by the simple AC-DC separation (ADS) method which provides the largest harvested energy versus spectral efficiency (HE-SE) region. Optimization of splitting/switching factors extends the HE-SE regions; hence, optimized versions of TS, PS and TS-PS methods are able to significantly outperform ADS for most cases. We further investigate the effect of various channel and system parameters such as water type, turbulence level, beam divergence, receiver aperture size on the harvested energy and quantify the improvements in battery lifetime through the use of SLIPT methods.

中文翻译：

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用于水下可见光通信的 SLIPT：性能分析和优化

在本文中，我们研究了水下可见光通信系统的同步光波信息和功率传输 (SLIPT)。我们考虑三种 SLIPT 方法，即时间切换 (TS)、功率分配 (PS) 和时间切换功率分配 (TS-PS)，其中将分离/切换因子定义为优化参数。对于这些方法中的每一种，我们推导出在存在由对数正态统计建模的水下湍流的情况下平均收集能量、误码率和频谱效率的封闭形式表达式。使用这些表达式，我们确定了在满足给定误码率值和给定阈值频谱效率值的同时最大化收集能量的最佳分裂因子。我们的结果表明，如果不进行优化，正在考虑的 SLIPT 方法优于简单的 AC-DC 分离 (ADS) 方法，该方法提供最大的收集能量与频谱效率 (HE-SE) 区域。分裂/切换因子的优化扩展了 HE-SE 区域；因此，在大多数情况下，TS、PS 和 TS-PS 方法的优化版本能够显着优于 ADS。我们进一步研究了各种通道和系统参数（如水类型、湍流水平、光束发散度、接收器孔径大小）对收集能量的影响，并通过使用 SLIPT 方法量化电池寿命的改进。在大多数情况下，PS 和 TS-PS 方法能够显着优于 ADS。我们进一步研究了各种通道和系统参数（如水类型、湍流水平、光束发散度、接收器孔径大小）对收集能量的影响，并通过使用 SLIPT 方法量化电池寿命的改进。在大多数情况下，PS 和 TS-PS 方法能够显着优于 ADS。我们进一步研究了各种通道和系统参数（如水类型、湍流水平、光束发散度、接收器孔径大小）对收集能量的影响，并通过使用 SLIPT 方法量化电池寿命的改进。