Spectral and Energy Efficiency of DCO-OFDM in Visible Light Communication Systems With Finite-Alphabet Inputs

The bound of the information transmission rate direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) for visible light communication (VLC) with finite-alphabet inputs is yet unknown, where corresponding spectral efficiency (SE) and energy (EE) stems out as open research problems. In this paper, we derive exact achievable DCO-OFDM system first time. Furthermore, investigate SE maximization problems subject to both electrical power constraints. By exploiting relationship between mutual minimum mean-squared error, propose a multi-level mercury-water-filling allocation scheme achieve maximum SE. Moreover, EE are studied, Dinkelbach-type developed EE. Numerical results verify effectiveness proposed theories schemes.