A Light-Emitting Diode (LED) has a nonlinear characteristic, and it contains fundamental

limitations for the performance of Visible Light Communication (VLC) systems in indoor environments

when using intensity modulation with Orthogonal Frequency Division Multiplexing (OFDM).

In this paper, we investigate this nonlinear characteristic with analysis and proposal. At first, we

identified the LED nonlinear characteristics in terms of bit-error performances. After analysis, we

propose initial predistortion schemes to mitigate the nonlinearity matters. In the predistortion

schemes, the nonlinear distortion compensation model contains predistortion features with the LED

inverse characteristics. Considering a Direct-Current-biased Optical OFDM (DCO-OFDM) system,

we compared the Bit-Error Rate (BER) performances with and without compensation via simulations.

The performance on the LED with the compensation showed LED nonlinearity could significantly

improve the bit-error performance. In addition, with consideration that the predistortion model is insufficient

to represent LED distortion, we investigated possible opportunities of distortion correction

using Bidirectional Long Short-Term Memory (BLSTM), one of the leading deep learning approaches.

Its result showed promising improvement of the distortion compensation as well.