Symbol constellation predistortion for DCO-OFDM visible light communications system linearization

Visible Light Communication (VLC) systems face significant challenges due to the inherent nonlinear characteristics of light emitting diodes (LEDs), which cause distortion in the transmitted DCO-OFDM signals. This signal quality degradation can be lower forcing a large input power back-off (IBO), but leading to an inefficient use of the LEDs. In this work, we propose a predistortion technique, referred to as constellation predistorter (CPD), based on a novel frequency-domain algorithm for the linearization of OFDM signals in VLC systems. The CPD operates on the signal constellation and is based on applying a Bayesian pursuit to obtain a sparse memory polynomial (MP) model matrix. For comparison purposes, this method has been compared to the MP-based time-domain digital predistorter (DPD). The linearization performance of the CPD is measured in terms of the error vector magnitude (EVM) and illumination-to-communication conversion efficiency (ICE) parameters. With the proposed predistorter, we achieve a significant IBO reduction as large as 7.6 dB, enhancing the efficiency of VLC systems, or a nearly 62% decrease in the EVM for a fixed IBO, which represents a substantial reduction in signal distortion and an improvement in ICE. • Novel predistortion technique to mitigate the inherent nonlinearity of LEDs in DCO-OFDM visible light communications (VLC) systems. • Implementation of the new predistortion method in the frequency domain, operating on the signal constellation and applying a Bayesian pursuit to obtain a sparse memory polynomial model matrix. • Substantial decrease in signal distortion, improving overall communication performance, measured in terms of error vector magnitude (EVM) for a fixed input back-off (IBO) value. • Improvement of signal quality and enhanced efficiency in VLC systems by significantly reducing the IBO of the signal. • The proposed predistorter enhances the efficiency of VLC systems in terms of the lumination-to-communication conversion efficiency (ICE) parameter.