ABSTRACT
This chapter describes the wavelength multiplexing and the multi-user access technologies in near-infrared high-speed indoor Optical Wireless Communication (OWC) systems. In indoor OWC systems, the data-carrying optical signal propagates via the free space for wireless communications. Inside the OWC transmitter, multiple light sources are used for transmitting different data streams. The frequency domain, the code domain and the time domain can be explored, leading to the frequency-division-multi-access, code-division-multi-access and time-division-multi-access techniques. The modulated light signals are multiplexed using a wavelength multiplexer and then launched into the OWC channel with the same free-space interface. In the WMD-based indoor OWC systems, the total data rate is increased by transmitting multiple data streams using different wavelengths simultaneously. In the subcarrier multiplexing-based indoor OWC systems, the power spectrum needs to be evenly distributed across both baseband and subcarrier bands to use the available optical power efficiently and to provide fair service connections to multiple users.
