Space-Time Coding for Optical MIMO Channels

光MIMO信道的空时编码[j]。摘要：自由空间光链路是一种新兴的宽带接入技术，因为它提供了巨大的带宽潜力。室外大气通道受到由于视距路径中的颗粒散射、晴空湍流或仅仅是静态折射率不均匀性造成的信号衰落效应的阻碍。同样，室内红外系统也面临着由固有多径环境引起的衰落。提高无线通信系统性能的一种有效方法是通过使用发射和接收天线，创建所谓的多输入/多输出（MIMO）信道。MIMO信道模型是由发射和接收天线阵列提供的，在过去的五年中，由于比特/秒/赫兹的潜在吞吐量非常大，并且与单天线设计相关的抗衰落保护增强，MIMO信道模型引起了射频无线系统的极大关注。本研究针对无线光通信环境中可应用于MIMO信道的空时码进行设计与性能分析。研究重点集中在这一问题的几个方面：—开发室外视距光通道的相关MIMO模型，特别关注源和探测器物理建模；-检查该通道的信息论潜力，特别是在不断增长的阵列大小的背景下，以及对错误概率的边界技术的分析，以帮助开发代码设计规则；-制定和评估在信道容量意义上有效的光学自由空间体制的空时编码方法；——块编码、网格编码和连接方法。讨论了空时码在室内无线红外信道中的应用及其性能检验。

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.