The Experts below are selected from a list of 323202 Experts worldwide ranked by ideXlab platform

Murat Uysal - One of the best experts on this subject based on the ideXlab platform.

  • Survey on Free Space Optical Communication: A Communication Theory Perspective
    IEEE Communications Surveys Tutorials, 2014
    Co-Authors: Mohammad Ali Khalighi, Murat Uysal
    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.

Mohammad Ali Khalighi - One of the best experts on this subject based on the ideXlab platform.

  • Survey on Free Space Optical Communication: A Communication Theory Perspective
    IEEE Communications Surveys Tutorials, 2014
    Co-Authors: Mohammad Ali Khalighi, Murat Uysal
    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.

Nir Sochen - One of the best experts on this subject based on the ideXlab platform.

Timothy W Coombs - One of the best experts on this subject based on the ideXlab platform.

  • impact of past crises on current crisis Communication insights from situational crisis Communication Theory
    Journal of Business Communication, 2004
    Co-Authors: Timothy W Coombs
    Abstract:

    Previous research based on Situational Crisis Communication Theory (SCCT) suggests that an organization’s past crises history affects the reputational threat posed by a current crisis when that cri...

  • helping crisis managers protect reputational assets initial tests of the situational crisis Communication Theory
    Management Communication Quarterly, 2002
    Co-Authors: Timothy W Coombs, Sherry J Holladay
    Abstract:

    A situational crisis Communication Theory (SCCT), which articulates the variables, assumptions, and relationships that should be considered in selecting crisis response strategies to protect an organization’s reputation, is advanced. Although various studies taking a situational approach have touched on certain of the Theory’s variables and relationships, this study represents the first attempt to articulate and begin to test a situational Theory of crisis Communication. SCCT is premised on matching the crisis response to the level of crisis responsibility attributed to a crisis. The study explores one of the basic assumptions of SCCT by assessing whether the predicted correlational relationship between crisis responsibility and organizational reputation occurs across a range of crisis types. Results support the Theory’s predictions and suggest ways to refine the Theory.

B L Hughes - One of the best experts on this subject based on the ideXlab platform.

  • front end design for compact mimo receivers a Communication Theory perspective
    IEEE Transactions on Communications, 2012
    Co-Authors: C P Domizioli, B L Hughes
    Abstract:

    The front-end is a crucial component in modern wireless Communication systems. For SISO systems minimizing the front-end noise factor is optimal, and this also applies to MIMO systems with i.i.d. noise. However, for compact MIMO receivers that may exhibit spatially correlated noise, e.g., through antenna mutual coupling, the optimal design procedure is not clear. In this paper we develop MIMO low-noise design principles from a Communication Theory perspective by deriving generalizations of SNR and noise factor from various MIMO Communication schemes. As one result, we are able to derive optimal matching networks for a bank of uncoupled amplifiers.