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    Adaptive Wiener-Turbo System and adaptive Wiener-Turbo Systems with JPEG & bit plane compressions
    (Istanbul Univ, Fac Engineering, 2007) Büyükatak, Kenan; Uçan, Osman Nuri; Göse, Ersin; Osman, Onur; Kent, Sedef
    In order to improve unequal error protection and compression ratio of 2-D colored images over wireless environment, we propose two new schemes denoted as ''Adaptive Wiener-Turbo System (AW-TS) and Adaptive Wiener-Turbo Systems with JPEG & Bit Plane Compressions (AW-TSwJBC)''. In AW-TS, there is a feedback link between Wiener filtering and Turbo decoder and process iteratively. The scheme employs a pixel-wise adaptive Wiener-based Turbo decoder and uses statistics (mean and standard deviation of local image) of estimated values of local neighborhood of each pixel. It has extra-ordinary satisfactory results of both bit error rate (BER) and image enhancement performance for less than 2 dB Signal-to-Noise Ratio (SNR) values, compared to separately application of traditional turbo coding scheme and 2-D filtering. In AW-TSwJBC scheme, 2-D colored image is passed through a color & bit planes� slicer block. In this block, each pixel of the input image is partitioned up to three main color planes as R,G,B and each pixel of the color planes is sliced up to N binary bit planes, which corresponds to binary representation of pixels. Thus depending on importance of information knowledge of the input image, pixels of each color plane can be represented by fewer number of bit planes. Then they are compressed by JPEG prior to turbo encoder. Hence, two consecutive compressions are achieved regarding the input image. In 2-D images, information is mainly carried by neighbors of pixels. Here, we benefit of neighborhood relation of pixels for each color plane by using a new iterative block, named as ''Adaptive Wiener-Turbo'' scheme, which employs Turbo decoder, JPEG encoder/decoders and Adaptive Wiener Filtering.
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    Channel equalization and noise reduction based on turbo codes
    (Institute of Electrical and Electronics Engineers Inc., 2003) Büyükatak, Kenan; Göse, Ersin; Uçan, Osman N.; Kent, Sedef; Osman, Onur
    A new class of error control coding with binary parallel concatenated recursive systematic convolution codes turbo codes- And its an application over SAR (Synthetic Aperture Radar) image transmitting is presented in this paper. The remarkable coding gains achieved by turbo code have a great influence in various area of digital communication, including cellular mobile, deep space communications and satellite communication. The basic idea is that two or more a posteriori probability decoders exchange soft information [I]. One of the decoders calculates the a posteriori probability distribution of the information sequence and passes that information to the next decoder. The new decoder uses this information and computes its own version of the probability distribution. This exchange of information is called an iteration. After a certain number of iterations, a decision is made at the second decoder. For each iteration, the probability that we decode in favor of the correct decision will improve. At the last iteration, the hard decision is made using the soft decision of the last decoder [5]. © 2003 IEEE.