We present a demonstration of two error-correction coding schemes that can successfully operate on a free-space optical (FSO) communication channel subject to atmospheric turbulence. The codes (a puntured Low-density parity-check code and a Raptor code) operate by continuously adapting the information rate to accommodate the varying channel conditions. Because these coding schemes require the use of a feedback channel, we evaluate the bandwidth cost incurred. The evaluation of the codes is performed offline and uses experimental optical signals recorded from an FSO link.We analyze the temporal characteristics of the experimental channels and compare the performance of the codes for different bit rates to asses the effect of temporal correlation and imperfect channel state information. Index Terms-Atmospheric turbulence, error-correction coding, free-space optical (FSO) communication, laser applications, optical communication, rateless coding, soft decoding, time-varying channels.
Bibliographical noteFunding Information:
Manuscript received October 02, 2009; revised November 29, 2009. First published January 15, 2010; current version published March 05, 2010. This work was supported in part by the Chilean Science and Technology Commission under Grant Fondecyt 1090709. J. A. Anguita is with the College of Engineering and Applied Sciences, University of the Andes, Santiago 7620001, Chile (e-mail: email@example.com). M. A. Neifeld is with the Department of Electrical and Computer Engineering and the College of Optical Sciences, University of Arizona, Tucson, AZ 85719 USA. B. Hildner and B. Vasic are with the Electrical and Computer Engineering Department, University of Arizona, Tucson, AZ 85719 USA. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/JLT.2010.2040136