PAPR reduction and non-linearity alleviation using hybrid of precoding and companding in a visible light communication (VLC) system

摘要

In this paper, a hybrid technique using a precoder and a μ law compander is proposed to alleviate light emitting diode (LED) nonlinearity as well as peak-to-average power ratio (PAPR) reduction in a VLC system. A μ law compander is used to compress the peak valued signal and enhances small amplitudes to lower the PAPR. The work attains optimal PAPR and improves bit error rate (BER) of the system at low signal to noise ratio values. The nonlinear characteristic of a LED used as the transmitter in a VLC system leads to damaging effects while using OFDM in an optical system. The combination scheme improves LED nonlinearity for low input back off (IBO) power. In the work, nonlinearity is characterized using error vector magnitude (EVM) in percentage. The proposed method shows a 5% EVM improvement for 0 dB IBO. The paper provides a choice for a trade-off among PAPR reduction, BER and reduced nonlinearity.