Wireless Optical Communication Systems (Electronic book text, 2005 ed.)

Wireless optical channels offer an exciting medium to offer high-speed, inexpensive communications in indoor environments. Wireless Optical Communication Systems treats the problem of designing efficient signaling for these channels and provides a link between the rich area of communications theory and modem design for the amplitude constrained linear optical intensity channel. It presents a historical perspective on the design of signaling for optical intensity channels through an extensive reference list. The unique nature of the indoor wireless optical channel is discussed along with the channel impairments, amplitude constraints and the characteristics of popular optoelectronic components. A variety of wireless optical channel topologies are presented along with a survey and analysis of present day signalling techniques employed for these channels. Wireless Optical Communication Systems presents a unifying framework for signalling design on such channels which allows the channel constraints to be represented geometrically and permits the use of modem design principles from electrical channels on optical intensity channels. Modulation schemes are designed for the channels, using the formalism of lattice codes, and the design process for signalling sets on this channel is specified. An information theoretic exploration bounds the channel capacity of optical intensity signalling sets and gives general insight into the factors which produce an efficient optical intensity signalling system. The use of multiple-input/multiple-output (MIMO) wireless optical channels to improve the spectral efficiency of links is explored. The basic spatio-temporal modem design problem is specified and aspatial multiplexing gain is quantified. New spatial discrete multitone modulation is proposed and the unique features are discussed. Based on measurements on an experimental prototype, a channel model is formulated and a realizable spatio-temporal coding scheme is simulated to quantify performance gains. It presents insights and practical guidelines for the design of signalling sets for these channels and proposes new multiple-input/multiple-output signalling strategies which exploit spatial dimensions to improve data rates. This book is targeted at professional and academic readers engaged in modem design for wireless optical intensity channels. Significant background material is presented on both the properties of wireless optical intensity channels as well as on fundamental communications principles. As a result, Wireless Optical Communication Systems can be used by physicists and experimentalists as an introduction to signalling design and communication systems designers who wish to develop signaling for optical intensity channels.