Free-Space Optical Communications with Channel Shortening Filter and Viterbi Equalizer



This paper is about signal processing techniques for airborne free-space optical (FSO) wireless communications through clouds. FSO channel is known to be accompanied by multi-scattering, which causes severe intersymbol interference. Unlike traditional FSO systems relying on optical signal processing devices, this research paper investigates the feasibility of digital signal processing schemes applied to FSO. By having a channel shortening equalizer (CSE or TEQ for time equalization) at the transmitter and a Viterbi equalizer at the receiver, reliable communication at low-to-mid level optical thickness values is shown to be feasible. We also propose how existing TEQ algorithms can be modified to fit into TEQ-in-transmitter configurations. Performance is evaluated in BER, and compared with conventional equalizations.


Free-space optical communications Channel shortening Viterbi Scattering 



A DARPA Grant sponsored by the U.S. Air Force Research Laboratory/Wright-Patterson AFB Contract-FA8650-04-C-7114 and The Pennsylvania State University CICTR have supported this research.


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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Samsung ElectronicsSuwon-cityKorea
  2. 2.Department of Electrical EngineeringThe Pennsylvania State University, The Center for Information and Communications Technology Research (CICTR)University ParkUSA

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