Author_Institution :
Inst. Fresnel, Ecole Centrale Marseille, Marseille, France
Abstract :
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. Specifi- topics include advances in modulation, channel coding, spatial/cooperative diversity techniques, adaptive transmission, and hybrid RF/FSO systems.
Keywords :
MIMO communication; atmospheric turbulence; channel coding; cooperative communication; data communication; diversity reception; fading; local area networks; metropolitan area networks; modulation; next generation networks; optical communication; optical links; optical receivers; optical transmitters; telecommunication network reliability; FSO channel models; FSO communication systems; FSO links; FSO technology; IR bands; LAN-to-LAN connectivity; MAN extension; RF systems; UV bands; adaptive transmission; algorithmic-level system design; atmospheric turbulence-induced fading; channel coding; communication theory; data rates; disaster recovery; fiber back-up; free space optical communication; high definition TV; hybrid RF-FSO systems; infrared bands; link reliability; local area network; medical image; metropolitan area network; modulation; multiple-input multiple-output communication; next generation FSO systems; optical bandwidth; optical carriers; optical wireless communication; outdoor terrestrial OWC links; propagation media; quantum key distribution; radio requency; spatial-cooperative diversity techniques; transmitter-receiver structures; ultraviolet bands; video transmission; visible bands; wireless cellular networks; wireless video surveillance; Atmospheric modeling; Laser beams; Optical beams; Optical fiber communication; Radio frequency; Receivers; Wireless communication; Free-space optical (FSO) communication; adaptive transmission; channel capacity; channel coding; channel modeling; hybrid RF/FSO systems; optical modulation; optical wireless communication (OWC); relay-assisted networks; spatial diversity;
