ABSTRACT
This chapter explores the performance of different modulation schemes under the constraints of noise and interferences. In addition to the AWGN, periodic and deterministic form of noise due to the artificial light sources also exists in indoor optical wireless channels, and they all combine to degrade the link performance severely. Fluorescent lamps emit light strongly at a spectral band of 780–950 nm overlapping with cheap optical transceiver components. Electronic ballast-driven fluorescent lamps have electrical spectrum contents that range up to megahertz making such lamps to be of potentially serious impairment to IR links [1–3]. The diffuse indoor links suffer from the multipath-induced ISI, thus limiting the maximum achievable data rates, for example, 260 Mbps for a typical indoor OWC system [4]. ISI also results in an additional power penalty that increases exponentially with the data rate [1]. The performance of the OOK, PPM and DPIM in the presence of FLI and ISI is investigated in this chapter. To improve the link performance possible mitigation techniques using high-pass filtering, equalization, wavelet transform and the neural network are also outlined in this chapter.
