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Iterative source-channel decoding with Markov random field source models

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2006年第10期54卷 3688-3701页

作者： Kliewer, Jorg Goertz, Norbert Mertins, Alfred Univ Notre Dame Dept Elect Engn Notre Dame IN 46556 USA Univ Edinburgh Inst Digital Commun Joint Res Inst Signal & Image Proc Edinburgh EH9 3JL Midlothian Scotland Carl von Ossietzky Univ Oldenburg Dept Phys D-26111 Oldenburg Germany

We propose a joint source-channel decoding approach for multidimensional correlated source signals. A Markov random field (MRF) source model is used which exemplarily considers the residual spatial correlations in an image signal after source encoding. Furthermore, the MRF parameters are selected via an analysis based on extrinsic information transfer charts. Due to the link between MPFs and the Gibbs distribution, the resulting soft-input soft-output (SISO) source decoder can be implemented with very low complexity. We prove that the inclusion of a high-rate block code after the quantization stage allows the MRF-based decoder to yield the maximum average extrinsic information. When channel codes are used for additional error protection the MRF-based SISO source decoder can be used as the outer constituent decoder in an iterative source-channel decoding scheme. Considering an example of a simple image transmission system we show that iterative decoding can be successfully employed for recovering the image data, especially when the channel is heavily corrupted.

关键词： EXIT charts iterative source-channel decoding joint source-channel coding Markov random fields

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Distortion bounds for broadcasting with bandwidth expansion

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IEEE TRANSACTIONS ON INFORMATION THEORY 2006年第8期52卷 3778-3788页

作者： Reznic, Zvi Feder, Meir Zamir, Ram Tel Aviv Univ Dept Elect Engn Syst IL-69978 Ramat Aviv Israel

We consider the problem of broadcasting a single Gaussian source to two listeners over a Gaussian, broadcast channel, with rho channel uses per source sample, where rho > 1. A distortion pair (D-1, D-2) is said to be achievable if one can simultaneously achieve a mean-squared error (MSE) D-1 at receiver 1 and D-2 at receiver 2. The main result of this correspondence is an outer bound for the set of all achievable distortion pairs. That is, we find necessary conditions under which (D, 1 D2) is achievable. We then apply this result to the problem of point-to-point transmission over a Gaussian channel with unknown signal-to-noise ratio (SNR) and rho > 1. We show that if a system must be optimal at a certain SNRmin, then, asymptotically, the system distortion cannot decay faster than O(1/SNR). As for achievability, we show that a previously reported scheme, due to Mittal and Phamdo (2002), is optimal at high SNR. We introduce two new schemes for broadcasting with bandwidth expansion, combining digital and analog transmissions. We finally show how a system with a partial feedback, returning from the bad receiver to the transmitter and to the good receiver, achieves a distortion pair that lies on the outer bound derived here.

关键词： distortion region joint source-channel coding lossy broadcasting

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Progressive video delivery over wideband wireless channels using space-time differentially coded OFDM systems

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2006年第4期5卷 303-316页

作者： Zhao, SJ Xiong, ZX Wang, XD Hua, JP Lucent Technol Bell Labs Wireless Innovat Open Labs Adv Wireless Syst Technol & Algorithms Grp Whippany NJ 07981 USA Texas A&M Univ Dept Elect & Comp Engn College Stn TX 77843 USA Columbia Univ Dept Elect Engn New York NY 10027 USA Translat Gen Res Inst Phoenix AZ 85004 USA

Progressive video delivery over wireless networks is very challenging due to the time-varying nature of wireless channels and limited power in the mobile devices. This paper proposes an end-to-end architecture for multilayer progressive video delivery over space-time differentially coded orthogonal frequency division multiplexing (STDC-OFDM) systems. An input video sequence is compressed by 3D-ESCOT into a layered bitstream. We input multiple layers of the bitstream in series to a STDC-OFDM channel. Different video source layers are protected by different error protection schemes in order to achieve unequal error protection. In progressive transmission, the reconstruction quality is important not only at the target transmission rate but also at the intermediate rates. So, the error protection strategy needs to optimize the average performance over the set of intermediate rates. We propose to use progressive joint source-channel coding to generate operational transmission distortion-rate (TD-R) functions and operational transmission distortion-power (TD-P) functions for multiple layers before forming the operational transmission distortion-power-rate (TD-PR) surfaces. Lagrange multipliers are then employed on the fly to obtain the optimal power allocation and optimal rate allocation among multiple layers, subject to constraints on the total transmission rate and the total power level. Progressive joint source-channel coding offers the scalability feature to handle bandwidth variations and changes in channel conditions. By extending the rate-distortion function in source coding to the TD-PR surface in joint source-channel coding, our work can use the "equal slope" argument to effectively solve the transmission rate allocation problem as well as the transmission power allocation problem for multilayer video transmission. Experiments show that our scheme achieves significant improvement over a nonoptimal system with the same total power level and total transmission rate

关键词： joint source-channel coding scalable video coding progressive transmission STDC-OFDM systems rate allocation power allocation

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A turbo-coded multiple-description system for multiple antennas

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IEEE TRANSACTIONS ON COMMUNICATIONS 2006年第2期54卷 187-191页

作者： Bahçeci, I Altunbasak, Y Duman, TM Univ Waterloo Dept Elect Engn Waterloo ON N2L 3G1 Canada Georgia Inst Technol Sch Elect & Comp Engn Atlanta GA 30332 USA Arizona State Univ Dept Elect Engn Tempe AZ 85287 USA

We propose a joint source-channel coding scheme for wireless communication systems with multiple transmit and receive antennas. The source coder is realized by a multiple description encoder that generates multiple bit streams. Each description is then separately turbo coded and transmitted using multiple antennas. For the receiver, we describe a suitable iterative joint source-channel decoding technique that exploits the correlations between the descriptions. We present several examples that illustrate the performance of the proposed system, and compare it with other approaches.

关键词： iterative decoding joint source-channel coding multiple antennas turbo-coded modulation (TCM) wireless communications

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Adaptive joint source-channel rate allocation policies for delay sensitive applications over fading channels

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IEEE TRANSACTIONS ON INFORMATION THEORY 2006年第12期52卷 5587-5598页

作者： Thejaswi P S, Chandrashekhar Sharma, Vinod Honeywell Technol Solut Lab Res & Technol Div Bangalore Karnataka India Indian Inst Sci Dept Elect Commun Engn Bangalore 560012 Karnataka India

In this correspondence, we consider a problem of optimal source, channel coding rate pair allocation over a wireless link based on the channel fading state and the queue length of the transmitter. The source is delay sensitive. Therefore, our objective is to minimize the mean delay under given mean power and distortion constraints. We show that by jointly optimizing the source and channel rates, one can gain substantially in performance as compared to only source or channel rate optimization, as is usually considered in the literature. This is shown for single user, single-input-single-output (SISO), multiple-input-multiple-output (MIMO), and multiuser systems. The methods used are from Markov decision theory.

关键词： joint source-channel coding Markov decision theory mean distortion constraint multiple-input-multiple-output (MIMO) systems multiple-access channel wireless link

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Progressive image transmission over differentially space-time coded OFDM systems

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WIRELESS COMMUNICATIONS & MOBILE COMPUTING 2006年第8期6卷 1057-1075页

作者： Sun, Yong Xiong, Zixiang Wang, Xiaodong Texas A&M Univ Dept Elect Engn College Stn TX 77843 USA Columbia Univ Dept Elect Engn New York NY 10027 USA

In this paper, we consider progressive image transmission over differentially space-time coded orthogonal frequency-division multiplexing (OFDM) systems and treat the problem as one of optimal joint source-channel coding (JSCC) in the form of unequal error protection (UEP), as necessitated by embedded source coding (e.g., SPIHT and JPEG 2000). We adopt a product channel code structure that is proven to provide powerful error protection and employ low-complexity decision-feedback decoding for differentially space-time coded OFDM without assuming channel state information. For a given SNR, the BER performance of the differentially spacetime coded OFDM system is treated as the channel condition in the JSCC/UEP design via a fast product code optimization algorithm so that the end-to-end quality of reconstructed images is optimized in the average minimum MSE sense. Extensive image transmission experiments show that SNR/BER improvements can be translated into quality gains in reconstructed images. Moreover, compared to another non-coherent detection algorithm, i.e., the iterative receiver based on expectation-maximization algorithm for the space-time coded OFDM systems, differentially space-time coded OFDM systems suffer some quality loss in reconstructed images. With the efficiency and simplicity of decision-feedback differential decoding, differentially space-time coded OFDM is thus a feasible modulation scheme for applications such as wireless image over mobile devices (e.g., cell phones). Copyright (C) 2006 John Wiley & Sons, Ltd.

关键词： progressive image transmission differentially space-time coding OFDM joint source-channel coding SPIHT JPEG 2000

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Robust transmission of progressive image bitstreams based on DCT over broadband wireless channels

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Journal of Harbin Institute of Technology(New Series) 2006年第2期13卷 219-225页

作者：王东华周源华马曾栋 Institute of Image Communication & Information Processing Shanghai Jiaotong University Shanghai 200030 China Research Institute of Communication Technology Harbin Institute of Technology Harbin 150001 China

A robust progressive image transmission scheme over broadband wireless fading channels is developed for 4th generation wireless communication systems （4G） in this paper. The proposed scheme is based on space-time block coded orthogonal frequency-division multiplexing （OFDM） with 4 transmit antennas and 2 receive antennas and uses a simplified minimum mean square error （MMSE） detector instead of maximum likelihood （ML） detectors. Considering DCT is simpler and more widely applied in the industry than wavelet transforms, a progressive image compression method based on DCT called mean-subtract embedded DCT （MSEDCT） is developed, with a simple mean-subtract method for the redundancy of reorganized DC blocks in addition to a structure similar to the embedded zerotree wavelet coding （EZW） method. Then after analyzing and testing bit importance of the progressive MSEDCT bitstreams, the layered unequal error protection method of joint source-channels coding based on Reed-Solomon （RS） codes is used to protect different parts of bitstreams, providing different QoS assurances and good flexibility. Simulation experiments show our proposed scheme can effectively degrade fading effects and obtain better image transmission effects with 10 -20 dB average peak-sig- nal-noise-ratio （PSNR） gains at the median Eb/No than those schemes without space-time coded OFDM or equal error protections with space-time coded OFDM.

关键词： broadband communication embedded source coding image transmission joint source-channel coding

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A low complexity progressive bitstream transmission system for hybrid channels with correlated loss

A low complexity progressive bitstream transmission system f...

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IEEE International Conference on Image Processing (ICIP 2006)

作者： Etemadi, Farzad Jafarkhani, Hamid Univ Calif Irvine Dept Elect Engn & Comp Sci Irvine CA 92697 USA

ISBN: (纸本)9781424404810

We propose a simple, low-complexity coding scheme for the transmission of a packetized progressive bitstream. We consider tandem channels introducing correlated bit errors and packet erasures. We show that our proposed technique transforms the hybrid channel into a channel with a single impairment for which various optimization techniques exists. Numerical results show that our proposed scheme outperforms existing solutions over the useful operating regions of the channel.

关键词： joint source-channel coding progressive transmission rate allocation product codes

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Combined error protection and compression with turbo codes for image transmission using a JPEG2000-like architecture

Combined error protection and compression with turbo codes f...

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IEEE International Conference on Image Processing (ICIP 2006)

作者： Fresia, Maria Caire, Giuseppe Univ Genoa DIST Genoa Italy Univ Southern Calif Los Angeles CA USA

ISBN: (纸本)9781424404810

In this paper, a joint source channel coding scheme for error resilient image transmission is proposed. Instead of compressing the image using the classical entropy coder, the redundancy of the image is exploited by using turbo codes for both data compression and error protection. At the decoder, the bit-planes are reconstructed in sequence by a multistage decoder. By properly choosing rate and puncturing, the system is able to approach the limit theoretically attainable and to outperform the separated approach of a JPEG2000 compressed image and the best turbo codes for the same overall length.

关键词： joint source-channel coding linear codes

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Enhancement of video quality for energy constrained cellular applications

Enhancement of video quality for energy constrained cellular...

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IEEE International Conference on Image Processing (ICIP 2006)

作者： Farshchian, Masoud Pearlman, William A. Sakalli, Mustafa Rensselaer Polytech Inst 110 Eighth St Troy NY 12180 USA

ISBN: (纸本)9781424404810

In this paper we consider the problem of faded wireless image and video transmission schemes under energy transmission constraints. An example of such a constrained system experiencing Rayleigh fading is Code Division Multiple Access (CDMA) where power control is used. We imposed on the average energy transmitted per an image or image sequence. A computationally inexpensive analytic mean square error (MSE) distortion rate (D-R) estimator for progressive wavelet coders which generates an exact distortion rate (D-R) function for 2-D and 3-D SPIHT algorithm is utilized from our previous research. Using the D-R function, the expected mean square error(MSE) at the receiver is minimized by optimally assigning the energy and parity allocation per each transmission block among the packets. A gain of 1.09 dB relative to optimal equal error protection (EEP) is obtained by varying both energy and parity among the transmission blocks. The results can be used to to increase image and video quality in CDMA systems.

关键词： 2-D and 3-D SPIHT joint source-channel coding energy constrained transmission

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