Survey on Free Space Optical Communication: A Communication Theory Perspective
Survey on Free Space Optical Communication: A Communication Theory Perspective
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DOI：
10.1109/comst.2014.2329501
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发表时间：
2014-01-01
影响因子：
35.6
通讯作者：
Uysal, Murat
中科院分区：
文献类型：
--
作者：
Khalighi, Mohammad Ali;Uysal, Murat
光无线通信（OWC）是指通过使用光载体，即可见光、红外（IR）和紫外（UV）波段，在无制导传播介质中进行传输。在这项调查中，我们关注的是在近红外波段工作的室外地面OWC链路。这些在文献中被广泛地称为自由空间光学（FSO）通信。FSO系统用于距离长达数公里的两个固定点之间的高速通信。与射频（RF）对应物相比，FSO链路具有非常高的可用光带宽，允许更高的数据速率。它们具有广泛的应用需求，如城域网（MAN）扩展、局域网（LAN）到局域网（LAN）连接、光纤备份、无线蜂窝网络回程、灾难恢复、高清电视和医疗图像/视频传输、无线视频监视/监控、量子密钥分发等。尽管FSO技术的主要优点和其应用领域的多样性，但由于大气湍流引起的衰落和对天气条件的敏感性，其链路可靠性令人失望，特别是在远距离时，其广泛使用受到阻碍。在过去五年左右的时间里，人们对FSO研究的兴趣激增，以解决这些主要的技术挑战。几个创新的物理层概念，最初是在射频系统的背景下引入的，如多输入多输出通信，合作分集和自适应传输，最近被探索用于下一代FSO系统的设计。在本文中，我们介绍了FSO通信系统的最新研究进展。第一部分描述了FSO信道模型和发送/接收结构。在第二部分中，我们详细介绍了FSO信道的信息理论极限以及接近这些极限的算法级系统设计研究活动。具体主题包括调制、信道编码、空间/合作分集技术、自适应传输和混合射频/无线通信系统的进展。
Optical wireless communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, infrared (IR), and ultraviolet (UV) bands. In this survey, we focus on outdoor terrestrial OWC links which operate in near IR band. These are widely referred to as free space optical (FSO) communication in the literature. FSO systems are used for high rate communication between two fixed points over distances up to several kilometers. In comparison to radio-frequency (RF) counterparts, FSO links have a very high optical bandwidth available, allowing much higher data rates. They are appealing for a wide range of applications such as metropolitan area network (MAN) extension, local area network (LAN)-to-LAN connectivity, fiber back-up, backhaul for wireless cellular networks, disaster recovery, high definition TV and medical image/video transmission, wireless video surveillance/monitoring, and quantum key distribution among others. Despite the major advantages of FSO technology and variety of its application areas, its widespread use has been hampered by its rather disappointing link reliability particularly in long ranges due to atmospheric turbulence-induced fading and sensitivity to weather conditions. In the last five years or so, there has been a surge of interest in FSO research to address these major technical challenges. Several innovative physical layer concepts, originally introduced in the context of RF systems, such as multiple-input multiple-output communication, cooperative diversity, and adaptive transmission have been recently explored for the design of next generation FSO systems. In this paper, we present an up-to-date survey on FSO communication systems. The first part describes FSO channel models and transmitter/receiver structures. In the second part, we provide details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits. Specific topics include advances in modulation, channel coding, spatial/cooperative diversity techniques, adaptive transmission, and hybrid RF/FSO systems.