On the Discrete-Input Continuous-Output Memoryless Channel Capacity of Layered ACO-OFDM

Layered Asymmetrically Clipped Optical Orthogonal Frequency Division Multiplexing (LACO-OFDM) has been proposed for optical communications and has attracted much attention, thanks to its flexibility in terms of power vs. spectral efficiency. In this article, we propose algorithms for optimizing the Discrete-input Continuous-output Memoryless Channel (DCMC) capacity of LACO-OFDM. Then, an algorithm is proposed for maximizing the capacity for twin-layer LACO-OFDM by optimizing the power sharing between the layers. This is followed by the conception of a more general algorithm applicable to LACO-OFDM having an arbitrary number of layers. Numerical results are provided for quantifying the capacity improvement attained by the proposed algorithm. Moreover, an adaptive scheme is proposed for adjusting the number of layers to be used for maximizing the capacity at different SNRs.