• An Analysis on the Coverage Distance of LDPC-Coded Free-Space Optical Links

      Borah, Deva K.; Luna, Ricardo; Tapse, Hrishikesh; New Mexico State University (International Foundation for Telemetering, 2008-10)
      We design irregular Low-Density Parity-Check (LDPC) codes for free-space optical (FSO) channels for different transmitter-receiver link distances and analyze the error performance for different atmospheric conditions. The design considers atmospheric absorption, laser beam divergence, and random intensity fluctuations due to atmospheric turbulence. It is found that, for the same transmit power, a system using the designed codes works over much longer link distances than a system that employs regular LDPC codes. Our analysis is particularly useful for portable optical transceivers and mobile links.
    • Joint JPEG2000/LDPC Code System Design for Image Telemetry

      Ryan, William E.; Marcellin, Michael W.; Bilgin, Ali; Jagiello, Kristin; Aydin, Mahmut Zafer; Ng, Wei-Ren; University of Arizona (International Foundation for Telemetering, 2008-10)
      This paper considers the joint selection of the source code rate and channel code rate in an image telemetry system. Specifically considered is the JPEG2000 image coder and an LDPC code family. The goal is to determine the optimum apportioning of bits between the source and channel codes for a given channel signal-to-noise ratio and total bit rate, R(total). Optimality is in the sense of maximum peak image SNR and the tradeoff is between the JPEG2000 bit rate R(source) and the LDPC code rate R(channel). For comparison, results are included for the industry standard rate-1/2, memory-6 convolutional code.