The use of optical free-space emissions to provide indoor wireless communications
has been studied extensively since the pioneering work of Gfeller
and Bapst in 1979 [1]. These studies have been invariably interdisciplinary involving
such far flung areas such as optics design‚ indoor propagation studies‚
electronics design‚ communications systems design among others. The focus
of this text is on the design of communications systems for indoor wireless
optical channels. Signalling techniques developed for wired fibre optic networks
are seldom efficient since they do not consider the bandwidth restricted
nature of the wireless optical channel. Additionally‚ the elegant design methodologies
developed for electrical channels are not directly applicable due to the
amplitude constraints of the optical intensity channel. This text is devoted to
presenting optical intensity signalling techniques which are spectrally efficient‚
i.e.‚ techniques which exploit careful pulse design or spatial degrees of freedom
to improve data rates on wireless optical channels.