Signal Shaping and Modulation for Optical Wireless Communication
In this paper, a signal shaping framework for Optical Wireless Communication (OWC) is proposed. The framework is tailored to the single-carrier pulse modulation techniques, such as multi-level Pulse Position Modulation (-PPM) and multi-level Pulse Amplitude Modulation (-PAM), and to multi-carrier transmission realized through multi-level Quadrature Amplitude Modulation (-QAM) with Orthogonal Frequency Division Multiplexing (OFDM). Optical OFDM (O-OFDM) transmission is generally accomplished via Direct-Current-biased Optical OFDM (DCO-OFDM) or Asymmetrically Clipped Optical OFDM (ACO-OFDM). Through scaling and DC-biasing the transmitted signal is optimally conditioned in accord with the optical power constraints of the transmitter front-end, i.e., minimum, average and maximum radiated optical power.