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coding for the Large-Alphabet Adversarial channel

IEEE TRANSACTIONS ON INFORMATION THEORY 2017年第10期63卷 6347-6363页

作者： Ahmed, Ebad Wagner, Aaron B. Cornell Univ Sch Elect & Comp Engn Ithaca NY 14853 USA LSI Corp San Jose CA USA Natera Inc San Carlos CA 94070 USA

We consider the problem of encoding an i.i.d. source into a set of symbols or messages that may be altered by an adversary while en route to the decoder. We focus in particular on the regime in which the number of messages is fixed while the blocklength of the source and the size of each message tend to infinity. For this fixed-blocklength, "large alphabet" channel, we show that combining an optimal rate-distortion code with an optimal error-correction code yields an optimal overall code for Gaussian sources with quadratic distortion and binary uniform sources with Hamming distortion but that it can be suboptimal by an arbitrarily large factor in general. We also consider the scenario in which the distortion constraint that the decoder must satisfy depends on the number of errors that occur. We show that the problem can be reduced operationally to one with erasures instead of errors in two special cases: one involving lossless reproduction of functions of the source and one in which the encoder and decoder share common randomness.

关键词： Adversarial channel coding lossy compression man-in-the-middle attack source-channel coding

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Vector quantization with transmission energy allocation for time-varying channels

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IEEE TRANSACTIONS ON COMMUNICATIONS 1999年第1期47卷 149-157页

作者： Gadkari, S Rose, K Univ Calif Santa Barbara Dept Elect & Comp Engn Santa Barbara CA 93106 USA

This work is concerned with the problem of designing robust, vector quantizer (VQ)-based communication systems for operation over time-varying Gaussian channels. Transmission energy allocation to VQ codeword bits, according to their error sensitivities, is a powerful tool for improving robustness to channel noise. The power of this technique can be further enhanced by appropriately combining it with index assignment methods. me pose the corresponding joint optimization problem and suggest a simple iterative algorithm for finding a locally optimal solution. The susceptibility of the solution to poor local minima is significantly reduced by an enhanced version of the algorithm which invokes the method of noisy channel relaxation whereby the VQ system is optimized while gradually decreasing the assumed level of channel noise, In a series of experiments, the resulting combined technique is shown to outperform standard pseudo-Gray coding by up to 3.5 dB and to exhibit graceful degradation at mismatched channel conditions. Finally, we extend these ideas to the case where both the transmitter and the receiver have information on the current state of a time-varying channel. The proposed method is based on switched encoding and adaptive decoding. Experimental results show that the proposed system achieves close to optimal performance.

关键词： index assignment modulation source-channel coding vector quantization

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Distortion Minimization in Gaussian Layered Broadcast coding With Successive Refinement

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IEEE TRANSACTIONS ON INFORMATION THEORY 2009年第11期55卷 5074-5086页

作者： Ng, Chris T. K. Guenduez, Deniz Goldsmith, Andrea J. Erkip, Elza Alcatel Lucent Bell Labs Holmdel NJ 07733 USA Stanford Univ Dept Elect Engn Stanford CA 94305 USA Princeton Univ Dept Elect Engn Princeton NJ 08544 USA NYU Dept Elect & Comp Engn Polytech Inst Brooklyn NY 11201 USA

A transmitter without channel state information wishes to send a delay-limited Gaussian source over a slowly fading channel. The source is coded in superimposed layers, with each layer successively refining the description in the previous one. The receiver decodes the layers that are supported by the channel realization and reconstructs the source up to a distortion. The expected distortion is minimized by optimally allocating the transmit power among the source layers. For two source layers, the allocation is optimal when power is first assigned to the higher layer up to a power ceiling that depends only on the channel fading distribution;all remaining power, if any, is allocated to the lower layer. For convex distortion cost functions with convex constraints, the minimization is formulated as a convex optimization problem. In the limit of a continuum of infinite layers, the minimum expected distortion is given by the solution to a set of linear differential equations in terms of the density of the fading distribution. As the number of channel uses per source symbol tends to zero, the power distribution that minimizes expected distortion converges to the one that maximizes expected capacity.

关键词： Broadcast convex optimization distortion fading channels power allocation source-channel coding successive refinement superposition

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Progressive transmission of images over memoryless noisy channels

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2000年第6期18卷 850-860页

作者： Chande, V Farvardin, N Univ Maryland Dept Elect & Comp Engn College Pk MD 20742 USA Univ Maryland Syst Res Inst College Pk MD 20742 USA

An embedded source code allows the decoder to reconstruct the source progressively from the prefixes of a single bit stream. It is desirable to design joint source-channel coding schemes which retain the capability of progressive reconstruction in the presence of channel noise or packet loss. Here, we address the problem of joint source-channel coding of images for progressive transmission over memoryless bit error or packet erasure channels. We develop a framework for encoding based on embedded source codes and embedded error correcting and error detecting channel codes. For a target transmission rate, we provide solutions and an algorithm for the design of optimal unequal error/erasure protection. Three performance measures are considered: the average distortion, the average peak signal-to-noise ratio, and the average useful source coding rate. Under the assumption of rate compatibility of the underlying channel codes, we provide necessary conditions for progressive transmission of joint source-channel codes. We also show that the unequal error/erasure protection policies that maximize the average useful source coding rate allow progressive transmission with optimal unequal protection at a number of intermediate rates.

关键词： error resilience image transmission progressive coding source-channel coding

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The Generalized Stochastic Likelihood Decoder: Random coding and Expurgated Bounds

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IEEE TRANSACTIONS ON INFORMATION THEORY 2017年第8期63卷 5039-5051页

作者： Merhav, Neri Technion Israel Inst Technol Dept Elect Engn IL-32000 Haifa Israel

The likelihood decoder is a stochastic decoder that selects the decoded message at random, using the posterior distribution of the true underlying message given the channel output. In this paper, we study a generalized version of this decoder, where the posterior is proportional to a general function that depends only on the joint empirical distribution of the output vector and the code word. This framework allows both mismatched versions and universal versions of the likelihood decoder, as well as the corresponding ordinary deterministic decoders, among many others. We provide a direct analysis method that yields the exact random coding exponent (as opposed to separate upper bounds and lower bounds that turn out to be compatible, which were derived earlier by Scarlett et al.). We also extend the result from pure channel coding to combined source and channel coding (random binning followed by random channel coding) with side information available to the decoder. Finally, returning to pure channel coding, we derive also an expurgated exponent for the stochastic likelihood decoder, which turns out to be at least as tight (and in some cases, strictly so) as the classical expurgated exponent of the maximum likelihood decoder, even though the stochastic likelihood decoder is suboptimal.

关键词： Stochastic decoder likelihood decoder random coding exponent expurgated exponent random binning source-channel coding

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Rate Optimization to Minimize Distortion for source-channel Coded H-BLAST with SIC Decoding

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IEEE COMMUNICATIONS LETTERS 2009年第2期13卷 115-117页

作者： Choi, Jinho Ha, Jeongseok Swansea Univ Inst Adv Telecommun Swansea SA2 8PP W Glam Wales Informat & Commun Univ Sch Engn Taejon 305732 South Korea

As joint source and channel coding schemes, layered transmission schemes for a successive refinable source (SRS) are recently studied over quasi-static fading channels. In this letter, we consider spatial layered transmission for a SRS with successive interference cancellation (SIC) decoder over quasistatic multi-input multi-output (MIMO) fading channels. We show that if the distortion function can be factorized, the minimum average distortion can be obtained by individual rate optimization for each layer when zero-forcing (ZF) SIC receiver is employed over Rayleigh fading channels.

关键词： source-channel coding fading channels successive refinement

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Robust vector quantizer design by noisy channel relaxation

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IEEE TRANSACTIONS ON COMMUNICATIONS 1999年第8期47卷 1113-1116页

作者： Gadkari, S Rose, K Conexant Syst Inc Newport Beach CA 92658 USA Univ Calif Santa Barbara Dept Elect & Comp Engn Santa Barbara CA 93106 USA

This letter proposes a method to design a vector quantizer (VQ) for robust performance under noisy channel conditions. By re-optimizing the quantizer at progressively lower levels of assumed channel noise, the design is less susceptible to poor local optima. The method is applied to: 1) channel-optimized VQ design;and 2) index assignment for a source-optimized VQ, For both problems, me demonstrate substantial performance improvements over commonly used techniques.

关键词： index assignment source-channel coding vector quantizer

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Image recovery from noisy transmission using soft bits and Markov random field models

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OPTICAL ENGINEERING 2003年第10期42卷 2893-2899页

作者： Mertins, A Carl von Ossietzky Univ Oldenburg Sch Math & Nat Sci Inst Phys D-26111 Oldenburg Germany

A new method for robust image recovery from noisy transmission based on soft bits and Markov random field modeling is proposed. The method aims to exploit the residual redundancy present in the symbols produced by a source encoder together with knowledge about the statistical properties of natural images. The soft-bit information required for reconstruction can be extracted either directly at the output of a noisy communication channel or at the output of a soft channel decoder (if channel codes are used). In the latter case, the proposed algorithm can also be used in conjunction with iterative channel decoding, resulting in joint source-channel turbo decoding. Examples are presented for the case where no channel codes are employed. The results obtained indicate that the proposed method yields very good performance even under extremely noisy conditions. (C) 2003 Society of Photo-Optical Instrumentation Engineers.

关键词： soft decoding Markov random fields image transmission bit reliability error concealment source-channel coding

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On Cooperative source Transmission with Partial Rate and Power Control

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2008年第8期26卷 1408-1418页

作者： Kim, Tung T. Skoglund, Mikael Caire, Giuseppe Royal Inst Technol Sch Elect Engn S-10044 Stockholm Sweden Royal Inst Technol ACCESS Linnaeus Ctr S-10044 Stockholm Sweden Univ So Calif Dept Elect Engn Los Angeles CA 90089 USA

The problem of transmitting a Gaussian source over a half-duplex fading relay channel with limited channel state feedback is studied. It is shown that under a short-term power constraint, combining a simple feedback scheme with separate source and channel coding outperforms the best known no-feedback strategies even with only a few bits of feedback information. Partial power control is shown to be instrumental in achieving a very fast decaying average distortion, especially in the regime of high bandwidth ratios. Performance limitation due to the lack of full channel state information at the destination is also investigated, where the degradation in terms of the distortion exponent is shown to be significant. However, even in such restrictive scenarios, using partial feedback still yields distortion exponents superior to any no-feedback schemes.

关键词： Cooperative communications diversity-multiplexing tradeoff limited feedback source-channel coding power control

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Rate-Distortion-Based Physical Layer Secrecy with Applications to Multimode Fiber

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IEEE TRANSACTIONS ON COMMUNICATIONS 2014年第3期62卷 1080-1090页

作者： Song, Eva C. Soljanin, Emina Cuff, Paul Poor, H. Vincent Guan, Kyle Princeton Univ Dept Elect Engn Princeton NJ 08544 USA Alcatel Lucent Bell Labs Murray Hill NJ 07974 USA

Optical networks are vulnerable to physical layer attacks;wiretappers can improperly receive messages intended for legitimate recipients. Multimode fiber (MMF) transmission can be modeled via a broadcast channel in which both the legitimate receiver's and wiretapper's channels are multiple-input- multiple-output complex Gaussian channels. This work considers the theoretical aspects of this security problem in the domain of a broadcast channel. source-channel coding analyses based on the use of distortion as the metric for secrecy are developed. Alice has a source sequence to be encoded and transmitted over this broadcast channel so that the legitimate user Bob can reliably decode it while forcing the distortion of the wiretapper, or eavesdropper, Eve's estimate to be as high as possible. Tradeoffs between transmission rate and distortion under two extreme scenarios are examined: the best case where Eve has only her channel output and the worst case where she also knows the past realization of the source. It is shown that under the best case, an operationally separate source-channel coding scheme guarantees maximum distortion at the same rate as needed for reliable transmission. Theoretical bounds are given, and particularized for MMF. Numerical results showing the rate distortion tradeoff are presented and compared with corresponding results for the perfect secrecy case.

关键词： Terms-rate-distortion MIMO optical fiber communication source-channel coding secrecy SDM MMF

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