The Experts below are selected from a list of 20004 Experts worldwide ranked by ideXlab platform

Julian Spittka - One of the best experts on this subject based on the ideXlab platform.

  • Iterative source-Channel Decoder using extrinsic information from softbit-source decoding
    2001 IEEE International Conference on Acoustics Speech and Signal Processing. Proceedings (Cat. No.01CH37221), 2001
    Co-Authors: Marc Adrat, R. Vary, Julian Spittka
    Abstract:

    In digital mobile communications, efficient compression algorithms are needed to encode speech or audio signals. As the determined source parameters are highly sensitive to transmission errors, robust source and Channel decoding schemes are required. This contribution deals with an iterative source-Channel decoding approach where a simple Channel Decoder and a softbit-source Decoder are concatenated. We mainly focus on softbit-source decoding which can be considered as an error concealment technique. This technique utilizes residual redundancy remaining after source coding. We derive a new formula that shows how the residual redundancy transforms into extrinsic information utilizable for iterative decoding. The derived formula opens several starting points for optimizations, e.g. it helps to find a robust index assignment. Furthermore, it allows the conclusion that softbit-source decoding is the limiting factor if applied to iterative decoding processes. Therefore, no significant gain will be obtainable by more than two iterations. This will be demonstrated by simulation

  • ICASSP - Iterative source-Channel Decoder using extrinsic information from softbit-source decoding
    2001 IEEE International Conference on Acoustics Speech and Signal Processing. Proceedings (Cat. No.01CH37221), 1
    Co-Authors: Marc Adrat, Peter Vary, Julian Spittka
    Abstract:

    In digital mobile communications, efficient compression algorithms are needed to encode speech or audio signals. As the determined source parameters are highly sensitive to transmission errors, robust source and Channel decoding schemes are required. This contribution deals with an iterative source-Channel decoding approach where a simple Channel Decoder and a softbit-source Decoder are concatenated. We mainly focus on softbit-source decoding which can be considered as an error concealment technique. This technique utilizes residual redundancy remaining after source coding. We derive a new formula that shows how the residual redundancy transforms into extrinsic information utilizable for iterative decoding. The derived formula opens several starting points for optimizations, e.g. it helps to find a robust index assignment. Furthermore, it allows the conclusion that softbit-source decoding is the limiting factor if applied to iterative decoding processes. Therefore, no significant gain will be obtainable by more than two iterations. This will be demonstrated by simulation.

Marc Adrat - One of the best experts on this subject based on the ideXlab platform.

  • Turbo decodulation: iterative combined demodulation and source-Channel decoding
    IEEE Communications Letters, 2005
    Co-Authors: Thorsten Clevorn, Marc Adrat, Johannes Brauers, Peter Vary
    Abstract:

    We propose the combination of iterative demodulation and iterative source-Channel decoding as a multiple turbo process. The receiver structures of bit-interleaved coded modulation with iterative decoding (BICM-ID), iterative source-Channel decoding (ISCD), and iterative source coded modulation (ISCM) are merged to one novel turbo system, in which in two iterative loops reliability information is exchanged between the three single components, demodulator, Channel Decoder and (softbit) source Decoder. Simulations show quality improvements compared to the different previously known systems, which use iterative processing only for two components of the receiver.

  • Iterative source-Channel Decoder using extrinsic information from softbit-source decoding
    2001 IEEE International Conference on Acoustics Speech and Signal Processing. Proceedings (Cat. No.01CH37221), 2001
    Co-Authors: Marc Adrat, R. Vary, Julian Spittka
    Abstract:

    In digital mobile communications, efficient compression algorithms are needed to encode speech or audio signals. As the determined source parameters are highly sensitive to transmission errors, robust source and Channel decoding schemes are required. This contribution deals with an iterative source-Channel decoding approach where a simple Channel Decoder and a softbit-source Decoder are concatenated. We mainly focus on softbit-source decoding which can be considered as an error concealment technique. This technique utilizes residual redundancy remaining after source coding. We derive a new formula that shows how the residual redundancy transforms into extrinsic information utilizable for iterative decoding. The derived formula opens several starting points for optimizations, e.g. it helps to find a robust index assignment. Furthermore, it allows the conclusion that softbit-source decoding is the limiting factor if applied to iterative decoding processes. Therefore, no significant gain will be obtainable by more than two iterations. This will be demonstrated by simulation

  • ICASSP - Iterative source-Channel Decoder using extrinsic information from softbit-source decoding
    2001 IEEE International Conference on Acoustics Speech and Signal Processing. Proceedings (Cat. No.01CH37221), 1
    Co-Authors: Marc Adrat, Peter Vary, Julian Spittka
    Abstract:

    In digital mobile communications, efficient compression algorithms are needed to encode speech or audio signals. As the determined source parameters are highly sensitive to transmission errors, robust source and Channel decoding schemes are required. This contribution deals with an iterative source-Channel decoding approach where a simple Channel Decoder and a softbit-source Decoder are concatenated. We mainly focus on softbit-source decoding which can be considered as an error concealment technique. This technique utilizes residual redundancy remaining after source coding. We derive a new formula that shows how the residual redundancy transforms into extrinsic information utilizable for iterative decoding. The derived formula opens several starting points for optimizations, e.g. it helps to find a robust index assignment. Furthermore, it allows the conclusion that softbit-source decoding is the limiting factor if applied to iterative decoding processes. Therefore, no significant gain will be obtainable by more than two iterations. This will be demonstrated by simulation.

Norbert Gortz - One of the best experts on this subject based on the ideXlab platform.

  • ICASSP - Iterative source-Channel decoding for robust image transmission
    IEEE International Conference on Acoustics Speech and Signal Processing, 2002
    Co-Authors: Jorg Kliewer, Norbert Gortz
    Abstract:

    In this paper we discuss the application of a joint source-Channel decoding approach to image transmission over wireless Channels. In addition to Channel codes, also the implicit residual redundancy after source encoding in both horizontal and vertical direction is utilized for error protection. At the Decoder we use an iterative (“turbo”) source-Channel Decoder which can be obtained in the same manner as for serially concatenated Channel codes. As a new result we show that this iterative decoding scheme in combination with a novel simplified joint source and Channel coding rate allocation at the encoder can be successfully employed for protecting the image data, especially when the Channel is highly corrupted. Furthermore, when the source correlations are approximated with a large training set at the Decoder, only a small loss in performance is observed.

  • EUSIPCO - Joint source-Channel decoding with iterative algorithms
    2000
    Co-Authors: Norbert Gortz, Ulrich Heute
    Abstract:

    Ideas from iterative decoding of concatenated Channel codes are adopted for joint source-Channel decoding. Extrinsic information from a soft-in/soft-out Channel Decoder is used as a-priori information for the new soft-in/soft-out source Decoder. The source Decoder processes soft Channel outputs, extrinsic information from the Channel Decoder, and source-statistics and it computes extrinsic information for the data-bits that again is used as a-priori information for the Channel Decoder. In this novel iterative approach to joint source-Channel decoding the redundancies within the data-bits of the source encoder are used as an additional source of information in contrast to iterative Channel decoding, where further information on the data-bits is drawn from the redundancy-bits of some additional, independent Channel-coding scheme.

  • Iterative source-Channel decoding using soft-in/soft-out Decoders
    2000 IEEE International Symposium on Information Theory (Cat. No.00CH37060), 1
    Co-Authors: Norbert Gortz
    Abstract:

    The concept of iterative decoding of concatenated Channel codes is applied to joint source-Channel decoding (JSCD). Extrinsic information from the soft-in/soft-out Channel Decoder is used as a priori information for the new soft-in/soft-out source Decoder and vice versa. In this novel iterative approach the redundancies within the data-bits and the Channel codewords are alternately exploited in order to approximate the highly complex optimal JSCD.

Pierre Duhamel - One of the best experts on this subject based on the ideXlab platform.

  • Semi-Orthogonal MARC with half duplex relaying: A Backward Compatible Cooperative Network with Interference Channels
    2016
    Co-Authors: Mohieddine El Soussi, Pierre Duhamel, Nguyen Hong Nhat, Florence Alberge, Luc Vandendorpe
    Abstract:

    This paper proposes a full-rate cooperative scheme adapted to the slow fading semi-orthogonal multiple access relay Channel (MARC). It is assumed that the sources transmit on orthogonal Channels and the relay is half duplex transmitting on the same Channels as the one of the sources. The sources employ LDPC to encode their messages before transmitting them, while the relay uses a simple demodulate-and-forward strategy to transmit the combination of the received codewords. The presence of the relay does not affect the time-scheduling of the sources. Therefore, this scheme is backward compatible to existing non-cooperative systems. In order to cancel the interference at the destination, we propose a joint network-Channel Decoder that uses maximum a posteriori (MAP) detection and Channel decoding. Through numerical results, we show the benefits of joint network-Channel Decoder. We also show that the proposed scheme significantly outperforms, in terms of BER, the non-cooperative system as well as the classical relay-assisted orthogonal Channel network and that it achieves the maximum code diversity.

  • ICASSP - Robust transmission of html files : Iterative joint source-Channel decoding of Lempel Ziv-77 codes
    2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008
    Co-Authors: Z. Jaoua, A. Zergainoh-mokraoui, Pierre Duhamel
    Abstract:

    This paper concerns the error correction of corrupted compressed HTML pages during their transmission via a noisy mobile Channel. The proposed receiver is based on an iterative joint source Channel decoding approach similar to the turbo decoding of two serial concatenated codes. We propose a soft-input soft-output Lempel-Ziv inner Decoder based on the modified version of the traditional sequential decoding M-algorithm. This new algorithm exploits the specific grammatical rules of the Lempel-Ziv-77 codes which are combined to the syntax of the HTML language. This source Decoder is combined to a Soft-Input Soft-Output Channel Decoder of convolutional codes. Simulation results, over an additive white Gaussian noise Channel, show that the proposed method drastically reduces the number of files in error compared to any conventional Channel decoding.

  • An equalizer including a soft Channel Decoder
    First IEEE Signal Processing Workshop on Signal Processing Advances in Wireless Communications, 1
    Co-Authors: S. Perreau, L.b. White, Pierre Duhamel
    Abstract:

    This paper deals with the presentation of a joint equalizer/Channel Decoder for the transmission of a digital modulation, with a convolutional encoder, on a dispersive Channel with additive white Gaussian noise. This equalizer directly produces the detection of the emitted sequence of information bits rather than the ones after Channel coding, as classically done, i.e., the novelty of this blind equalizer is to include the decoding step directly in the equalizer's structure.

  • ICASSP - Joint source-Channel coding using structured oversampled filters banks applied to image transmission
    2001 IEEE International Conference on Acoustics Speech and Signal Processing. Proceedings (Cat. No.01CH37221), 1
    Co-Authors: A. Gabay, Olivier Rioul, Pierre Duhamel
    Abstract:

    This paper proposes a new joint source and Channel coder based on real-valued BCH codes, in which the signal protection (analogous to a signal interpolation) is performed before compression. This allows a better tradeoff in high accuracy compression, since part of the distortion introduced by the compression can be corrected by the "Channel Decoder". Furthermore, we propose an optimal code allocation procedure, which also allows a good robustness to be obtained when the errors introduced by the Channel increase. The resulting rate/distortion curves outperform those obtained by a separate system on the whole range of operation. Although presented in the context of image transmission through a binary symmetric Channel, the resulting codes may be employed on a wide range of transmission schemes with significant performance benefits.

Ran Yan - One of the best experts on this subject based on the ideXlab platform.

  • ICASSP - Low complexity source controlled Channel decoding in a GSM system
    1999 IEEE International Conference on Acoustics Speech and Signal Processing. Proceedings. ICASSP99 (Cat. No.99CH36258), 1999
    Co-Authors: P. Strauch, C. Luschi, M. Sandell, Ran Yan
    Abstract:

    In this paper we investigate source controlled Channel decoding with a hard output Channel Decoder. Various methods have been devised in the past for source controlled Channel decoding, but most of them assume that a soft output Channel Decoder is used. Most receivers in mobile wireless communications have a standard Viterbi Channel Decoder which produces only hard outputs. It is shown that a simple sliding histogram is capable of improving the speech quality significantly. The ideas and methods in this paper are applied for the full-rate and enhanced full-rate speech codecs in the GSM system.