Transmitter pre-emphasis is one of the techniques proposed to improve the relatively poor frequency responses of light-emitting diodes (LEDs) used in visible light communications (VLC) as light sources. However, according to the communications theory in linear channels, pre-emphasis may only be as good as the not particularly efficient feed-forward equalizer (FFE). Given the increase in peak-to-average power ratio (PAPR) caused by pre-emphasis, its use in place of receiver equalization can be considered counterproductive. In this study, we show that the performance of the transmitter pre-emphasis is indeed equivalent to the FFE at low input powers, where the LED is a linear system. However, at higher modulation voltages, the transmitter pre-emphasis has a clear advantage over FFE, as it mitigates the nonlinear distortion of the LED. This mechanism is for the first time to our knowledge explained in both theory and experiment.

中文翻译：

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线性预加重能否减轻发光二极管的非线性失真？

发射机预加重是为改善可见光通信 (VLC) 中用作光源的发光二极管 (LED) 相对较差的频率响应而提出的技术之一。然而，根据线性信道中的通信理论，预加重可能只能与效率不高的前馈均衡器 (FFE) 一样好。鉴于预加重导致峰均功率比 (PAPR) 增加，使用它代替接收器均衡可能会适得其反。在本研究中，我们表明发射器预加重的性能确实相当于低输入功率下的 FFE，其中 LED 是线性系统。然而，在较高的调制电压下，发送器预加重比 FFE 具有明显的优势，因为它可以减轻 LED 的非线性失真。据我们所知，这种机制首次在理论和实验中得到解释。