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IEEE TRANSACTIONS ON INFORMATION THEORY 2013年第1期59卷 51-63页

作者： Guenduez, Deniz Yener, Aylin Goldsmith, Andrea Poor, H. Vincent Univ London Imperial Coll Sci Technol & Med Dept Elect & Elect Engn London SW7 2AZ England Ctr Tecnol Telecomunicac Catalunya Castelldefels 08860 Spain Penn State Univ Dept Elect Engn University Pk PA 16802 USA Stanford Univ Dept Elect Engn Stanford CA 94305 USA Princeton Univ Dept Elect Engn Princeton NJ 08544 USA

The multiuser communication channel, in which multiple users exchange information with the help of a relay terminal, termed the multiway relay channel (mRC), is introduced. In this model, multiple interfering clusters of users communicate simultaneously, such that the users within the same cluster wish to exchange messages among themselves, i.e., each user multicasts its message to all the other users in its own cluster. It is assumed that the users cannot receive each other's signals directly. Hence, the relay terminal in this model is the enabler of communication. In particular, restricted encoders are considered, such that the encoding function of each user depends only on its own message and the received signal is used only for decoding the messages of the other users in the cluster. Achievable rate regions and an outer bound are characterized for the Gaussian mRC, and their comparison is presented in terms of the exchange rate, the symmetric rate point in the capacity region in a symmetric Gaussian mRC scenario. It is shown that the compress-and-forward (CF) protocol achieves exchange rates within a constant bit offset of the optimal exchange rate, independent of the power constraints of the terminals in the network. A finite bit gap between the exchange rates achieved by the CF and the amplify-and-forward protocols is also shown. The two special cases of the mRC, the full data exchange model, in which every user wants to receive messages of all other users, and the pairwise data exchange model which consists of multiple two-way relay channels, are investigated in detail. In particular for the pairwise data exchange model, in addition to the proposed random coding-based achievable schemes, a nested lattice coding-based scheme is also presented and is shown to achieve exchange rates within a constant bit gap of the exchange capacity.

关键词： Compress and forward (CF) joint source-channel coding lattice coding relay channel two-way relaying

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Spread Spectrum Visual Sensor Network Resource Management Using an End-to-End Cross-Layer Design

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IEEE TRANSACTIONS ON MULTIMEDIA 2011年第1期13卷 125-131页

作者： Bentley, Elizabeth S. Kondi, Lisimachos P. Matyjas, John D. Medley, Michael J. Suter, Bruce W. USAF Res Lab Rome NY 13441 USA Univ Ioannina Dept Comp Sci GR-45110 Ioannina Greece

In this paper, we propose an approach to manage network resources for a direct sequence code division multiple access (DS-CDMA) visual sensor network where nodes monitor scenes with varying levels of motion. It uses cross-layer optimization across the physical layer, the link layer, and the application layer. Our technique simultaneously assigns a source coding rate, a channel coding rate, and a power level to all nodes in the network based on one of two criteria that maximize the quality of video of the entire network as a whole, subject to a constraint on the total chip rate. One criterion results in the minimal average end-to-end distortion amongst all nodes, while the other criterion minimizes the maximum distortion of the network. Our experimental results demonstrate the effectiveness of the cross-layer optimization.

关键词： Code division multiple access (CDMA) convolutional codes cross-layer H.264 joint source-channel coding multimedia communications power control resource allocation spread spectrum visual sensor network

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Entropy-constrained index assignments for multiple description quantizers

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2004年第1期52卷 265-270页

作者： Cardinal, J Free Univ Brussels B-1050 Brussels Belgium

Multiple description coding has revealed itself highly useful for the transmission of digital signals over packet-switched networks or diversity systems. The index assignment problem is central in the theory and practice of multiple description quantizers. We propose a novel local optimization algorithm that produces index assignments for such quantizers. It locally minimizes the distortion due to description losses with constraints on the entropy of each description. It works in any vector dimension and is easily generalizable to various cases such as asymmetric descriptions or m-description systems. We present experimental comparisons with previously known index assignment methods in both scalar and vector cases and show that the proposed algorithm performs significantly better.

关键词： joint source-channel coding optimization methods quantization

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On the iterative approximation of optimal joint source-channel decoding

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2001年第9期19卷 1662-1670页

作者： Görtz, N Univ Kiel Fac Engn Inst Circuits & Syst Theory Kiel Germany

joint source-channel decoding is formulated as an estimation problem. The optimal solution is stated and it is shown that it is not feasible in many practical systems due to its complexity. Therefore, a novel iterative procedure for the approximation of the optimal solution is introduced, which is based on the principle of iterative decoding of turbo codes. New analytical expressions for different types of information in the optimal algorithm are used to derive the iterative approximation. A direct comparison of the performances of the optimal algorithm and its iterative approximation is given for a simple transmission system with "short" channel codewords. Furthermore, the performance of iterative joint source-channel decoding is investigated for a more realistic system.

关键词： concatenated codes iterative decoding joint source-channel coding MAP algorithm soft-in/soft-out decoding turbo (de)coding

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Error resilient LZ'77 data compression: Algorithms, analysis, and experiments

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IEEE TRANSACTIONS ON INFORMATION THEORY 2007年第5期53卷 1799-1813页

作者： Lonardi, Stefano Szpankowski, Wojciech Ward, Mark Daniel Univ Calif Riverside Dept Comp Sci & Engn Riverside CA 92521 USA Purdue Univ Dept Comp Sci W Lafayette IN 47907 USA Univ Penn Dept Math Philadelphia PA 19104 USA

We propose a joint source-channel coding algorithm capable of correcting some errors in the popular Lempel-Ziv'77 (LZ'77)scheme without introducing any measurable degradation in the compression performance. This can be achieved because the LZ'77 encoder does not completely eliminate the redundancy present in the input sequence. One source of redundancy can be observed when an LZ'77 phrase has multiple matches. In this case, LZ'77 can issue a pointer to any of those matches, and a particular choice carries some additional bits of information. We call a scheme with embedded redundant information the LZS'77 algorithm. We analyze the number of longest matches in such a scheme and prove that it follows the logarithmic series distribution with mean 1/h (plus some fluctuations), where h is the source entropy. Thus, the distribution associated with the number of redundant bits is well concentrated around its mean, a highly desirable property for error correction. These analytic results are proved by a combination of combinatorial, probabilistic, and analytic methods (e.g., Mellin transform, depoissonization, combinatorics on words). In fact, we analyze LZRS'77 by studying the multiplicity matching parameter in a suffix tree, which in turn is analyzed via comparison to its independent version, called trie. Finally, we present an algorithm in which a channel coder (e.g., Reed-Solomon (RS) coder) succinctly uses the inherent additional redundancy left by the LZS'77 encoder to detect and correct a limited number of errors. We call such a scheme the LZS'77 algorithm. LZRS'77 is perfectly backward-compatible with LZ'77, that is, a file compressed with our error-resistant LZRS'77 can still be decompressed by a generic LZ'77 decoder.

关键词： autocorrelation polynomial combinatorics on words depoissonization joint source-channel coding Lempel-Ziv'77 (LZ'77) scheme Mellin transform multiple matches pattern matching Reed-Solomon (RS) code suffix trees tries

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On finite-state vector quantization for noisy channels

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IEEE TRANSACTIONS ON COMMUNICATIONS 2004年第12期52卷 2125-2133页

作者： Yahampath, P Pawlak, M Univ Manitoba Dept Elect & Comp Engn Winnipeg MB R3T 5V6 Canada

Finite-state vector quantization (FSVQ) over a noisy channel is studied. A major drawback of a finite-state decoder is its inability to track the encoder in the presence of channel noise. In order to overcome this problem, we propose a nontracking decoder which directly estimates the code vectors used by a finite-state encoder. The design of channel-matched finite-state vector quantizers for noisy channels, using an iterative scheme resembling the generalized Lloyd algorithm, is also investigated. Simulation results based on encoding a Gauss-Markov source over a memoryless Gaussian channel show that the proposed decoder exhibits graceful degradation of performance with increasing channel noise, as compared with a finite-state decoder. Also, the channel-matched finite-state vector quantizers are shown to outperform channel-optimized vector quantizers having the same vector dimension and rate. However, the nontracking decoder used in the channel-matched finite-state quantizer has a higher computational complexity, compared with a channel-optimized vector-quantizer decoder. Thus, if they are allowed to have the same overall complexity (encoding and decoding), the channel-optimized vector quantizer can use a longer encoding delay and achieve similar or better performance. Finally, an example of using the channel-matched finite-state quantizer as a backward-adaptive quantizer for nonstationary signals is also presented.

关键词： channel-optimized vector quantization finite-state vector quantization (FSVQ) joint source-channel coding noisy channels optimal estimation

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Reconstruction of predictively encoded signals over noisy channels using a sequence MMSE decoder

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IEEE TRANSACTIONS ON COMMUNICATIONS 2004年第8期52卷 1292-1301页

作者： Lahouti, F Khandani, AK Univ Waterloo Dept Elect & Comp Engn Waterloo ON N2L 3G1 Canada

In this paper, we consider the problem of decoding a predictively encoded signal over a noisy channel when there is a residual redundancy (captured by a gamma-order Markov model) in the sequence of transmitted data. Our objective is to minimize the mean-squared error (MSE) in the reconstruction of the original signal (input to the predictive source coder). The problem is formulated and solved through minimum mean-squared error (MMSE) decoding of a sequence of samples over a memoryless noisy channel. The related previous works include several maximum a posteriori (MAP) and MMSE-based decoders. The MAP-based approaches are suboptimal when the performance criterion is the MSE. On the other hand, the previously known MMSE-based approaches are suboptimal, since they are designed to efficiently reconstruct the data samples received (the prediction residues) rather than the original signal. The proposed scheme is set up by modeling the source-coder-produced symbols and their redundancy with a trellis structure. Methods are presented to optimize the solutions in terms of complexity. Numerical results and comparisons are provided, which demonstrate the effectiveness of the proposed techniques.

关键词： differential pulse code modulation (DPCM) forward-backward recursion joint source-channel coding Markov sources maximum a posteriori (MAP) detection minimum mean-squared error (MMSE) estimation predictive quantization residual redundancies source decoding

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MAP Decoding for Multi-Antenna Systems with Non-Uniform sources: Exact Pairwise Error Probability and Applications

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IEEE TRANSACTIONS ON COMMUNICATIONS 2009年第1期57卷 242-254页

作者： Behnamfar, Firouz Alajaji, Fady Linder, Tamas Nortel Networks Ottawa ON K2H 8E9 Canada Queens Univ Dept Math & Stat Kingston ON K7L 3N6 Canada Queens Univ Dept Elect & Comp Engn Kingston ON K7L 3N6 Canada Hungarian Acad Sci Comp & Automat Res Inst H-1111 Budapest Hungary

We study the maximum a posteriori (MAP) decoding of memoryless non-uniform sources over multiple-antenna channels. Our model is general enough to include space-time coding, BLAST architectures, and single-transmit multi-receive antenna systems which employ any type of channel coding. We derive a closed-form expression for the codeword pairwise error probability (PEP) of general multi-antenna codes using moment generating function and Laplace transform arguments. We then consider space-time orthogonal block (STOB) coding and prove that, similar to the maximum likelihood (ML) decoding case, detection of symbols is decoupled in MAP decoding. We also derive the symbol PEP in closed-form for STOB codes. We apply these results in several scenarios. First, we design a binary antipodal signaling scheme which minimizes the system bit error rate (BER) under STOB coding. At a BER of 10(-6), this constellation has a channel signal-to-noise ratio (CSNR) gain of 4.7 dB over conventional BPSK signaling for a binary non-uniform source with p(0) (sic) P(0) = 0.9. We next design space-time linear dispersion (LD) codes which are optimized for the source distribution under the criterion of minimizing the union upper bound on the frame error rate (FER). Two codes are given here: one outperforms V-BLAST by 3.5 dB and Alamouti's code by 12.3 dB at an FER of 10(-2) for a binary source with p(0) = 0.9, and the other outperforms V-BLAST by 4.2 dB at an FER of 10(-3) for a uniform source. These codes also outperform the LD codes of [13] constructed under a different criteria. Finally, the problem of bit-to-signal mapping is studied. It is shown that for a binary source with p(0) = 0.9, 64-QAM signaling, and SER = 10(-3), a gain of 3.7 dB can be achieved using a better-than-Gray mapping. For a system with one transmit and two receive antennas that uses trellis coding with 16-QAM signaling, a 1.8 dB gain over quasi-Gray mapping and ML decoding is observed when MAP decoding is used for binary so

关键词： joint source-channel coding space-time coding MAP decoding pairwise error probability statistical redundancy convolutional codes trellis coding maximum-ratio combining multi-antenna fading channels diversity wireless communications

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source CORRELATION IN A K-OUT-OF-M MULTIPLE-ACCESS channel

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IEEE TRANSACTIONS ON INFORMATION THEORY 1995年第2期41卷 540-546页

作者： SALEHI, M Department of Electrical and Computer Engineering Northeastern University Boston MA USA

A K-out-of-M multiple-access channel is a mathematical model for transmission of information between a large number of potential transmitters and one receiver, where at any transmission interval only a (usually small) number of transmitters are active transmitting their messages. La this work we study the problem of matching between correlated information sources and a K-out-of-M multiple-access channel. We show that by employing the correlation between the information sources and using a two-step coding scheme better results can be achieved compared to separate source and channel coding. A coding and decoding scheme is described and sufficient conditions for reliable transmission of the correlated information sources via the K-out-of-M multiple-access channel, based on this scheme are obtained.

关键词： MULTIUSER INFORMATION THEORY MULTIPLE-ACCESS channelS joint source-channel coding CORRELATED INFORMATION sourceS source-channel MATCHING

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Parity-check matrix calculation for paraunitary oversampled DFT filter banks

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2008年第10期56卷 5277-5283页

作者： Karp, Tanja Kieffer, Michel Duhamel, Pierre Texas Tech Univ Dept Elect & Comp Engn Lubbock TX 79409 USA Univ Paris 11 CNRS SUPELEC Lab Signaux & Syst F-91192 Gif Sur Yvette France

joint source-channel coding schemes based on oversampled filter banks were recently proposed. Oversampled filter banks are considered as error-correcting codes, extending the notion of code subspace, parity-check matrix, and syndrome to the domain of real and complex numbers. We here present an efficient calculation and implementation of the parity-check polynomial matrices for oversampled discrete Fourier transform (DFT) filter banks. If desired, the calculation of the parity-check polynomials can be performed as part of the prototype filter design procedure. We compare our method to those previously presented in the literature.

关键词： joint source-channel coding oversampled discrete Fourier transform (DFT) filter banks parity-check matrix

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