A Simple OFDM Scheme for VLC Systems Based on $\mu $ -Law Mapping

A simple orthogonal frequency division multiplexing (OFDM) scheme termed μ-OFDM is proposed for visible light communication (VLC). In this scheme, the peak-to-average power ratio (PAPR) reduction technique, μ-law companding, is first introduced in VLC systems to achieve the required signal format for VLC transmission. Due to the inherent characteristics of the companding operation, low PAPR signals are obtained in the scheme. Compared with most of the unipolar optical OFDM schemes, such as asymmetrically clipped optical OFDM scheme, μ-OFDM doubles the spectral efficiency. Furthermore, this scheme shows significant energy advantages over direct-current biased optical OFDM scheme and polar OFDM scheme. To the best of our knowledge, this is the first design of a unipolar optical OFDM scheme, which is able to achieve both high spectrum and energy efficiency under a constraint of the dynamic range of the light-emitting diodes.