Space-Time Coding for Optical MIMO Channels

University Of Virginia Main Campus, Charlottesville VA

Investigators

Abstract

Space-Time Coding for Optical MIMO ChannelsStephen G. Wilson and Maite Brandt-PearceDept. of Electrical and Computer EngineeringUniversity of Virginia, Charlottesville, VA 22906Phone: (434) 924-6091, (sgw,mb-p)@virginia.eduAbstract: Free-space optical links are an emerging technology for wideband access to networks because of the tremendous bandwidth potential they offer. Outdoor atmospheric channels are hampered by signal fading effects due to particulate scattering in a line-of-sight path, clear-air turbulence, or merely static index-of-refraction inhomogeneities. Similarly, indoor IR systems are faced with fading arising from the intrinsic multipath environment. One powerful method of improving the performance of wireless communication systems is through the use of transmit and receive antennas, creating a so-called multiple-input/multiple-output (MIMO) channel. MIMO channel models, provided by transmit and receive antenna arrays, have attracted enormous attention for RF wireless systems in the past five years, owing to the very large potential throughput in bits/second/Hertz and increased protection against fading associated with single antenna designs. This research addresses the design and performance analysis of space-time codes that can be applied to MIMO channels for application to the wireless optical communications environment. The research focuses on several aspects of this problem: --development of relevant MIMO models for outdoor line-of-sight optical channels, with particular attention to modeling of source and detector physics; --examination of the information-theoretic potential of this channel, particularly in the context of growing array size, and the analysis of bounding techniques on error probability to aid in the development of code design rules; --formulation and evaluation of space-time coding approaches for the optical free-space regime that are efficient in the channel capacity sense; --block-coded, trellis-coded, and concatenated approaches. Also, the application of space-time codes to the indoor wireless infrared channel and the examination of their performance are addressed.