Precoded DCO-OFDM for Intensity-Modulated Direct-Detection Optical Wireless Systems

As the operating frequency of wireless communication systems moves further up in the electromagnetic spectrum, as these systems move away from the radiofrequency (RF) communication realm into the optical communication realm. This paper proposes a novel multi-carrier scheme for optical communication that relies on direct current (dc) biasing and precoding to convert a classic RF orthogonal frequency division multiplexing (OFDM) signal into a real nonnegative (unipolar) signal suitable for intensity-modulated/direct-detection based optical communication. It lays the design principle of our novel scheme, namely precoded dc-biased optical (pDCO)-OFDM, and benchmarks its performance in terms of spectral efficiency (SE), bit-error rate (BER), peak-to-average power ratio (PAPR) and computational complexity against comparable existing optical OFDM (O-OFDM) schemes. It turns out that our pDCO-OFDM scheme provides a better trade-off between the aforementioned metrics than for instance the well-researched layered asymmetrically clipped O-OFDM (LACO-OFDM) scheme. Our scheme achieves similar SE and BER performances than LACO-OFDM, but with a substantial reduction in both PAPR (i.e, > 2 dB) and computational complexity (i.e. one order of magnitude), due to its reliance on dc biasing and its much simpler transceiver structure, respectively.