Linear programming for tone reservation based IM/DD optical OFDM communications

This paper investigates the use of tone reservation for optical orthogonal frequency-division multiplexing (OFDM) systems in a short-range intensity-modulated, direct-detected (IM/DD) channel. In order to avoid any asymmetric clipping of the bipolar OFDM signal and associated nonlinear distortion, some of the tones/subchannels are reserved to produce a negative peak cancellation (NPC) signal. This approach guarantees a unipolar output and hence eliminates all in-band and out-of-band distortion. With an arbitrary reserved set, a linear programming (LP) problem can be formulated to optimally solve the frequency-domain signal design problem. Simulation results suggest that this method offers greater flexibility and a better trade-off between power and spectral efficiency for a given link budget.