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Proceedings ArticleDOI

Implementation Issues In Map Joint Source/channel Coding

01 Jan 1988-Vol. 1, pp 102-106
TL;DR: A MAP approach to joint source/channel coding has been proposed which uses a MAP decoder and a modification of the source coder to provide error correction and results for an image coding application are provided.
Abstract: One of Shannon's many fundamental contributions was his result that source coding and channel coding can be implemented separately without any loss of optimality. However, the assumption underlying this result may at times be violated in practice. Various joint source/channel coding approaches have been developed for handling such situations. A MAP approach to joint source/channel coding has been proposed which uses a MAP decoder and a modification of the source coder to provide error correction. We present various implementation strategies for this approach and provide results for an image coding application.
Citations
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01 Dec 1978
TL;DR: In this paper, a combined source-channel coding approach is described for the encoding, transmission and remote reconstruction of image data, where the source encoder employs two-dimensional (2-D) differential pulse code modulation (DPCM).
Abstract: A combined source-channel coding approach is described for the encoding, transmission and remote reconstruction of image data. The source encoder employs two-dimensional (2-D) differential pulse code modulation (DPCM). This is a relatively efficient encoding scheme in the absence of channel errors. In the presence of channel errors, however, the performance degrades rapidly. By providing error control protection to those encoded bits which contribute most significantly to image reconstruction, it is possible to minimize this degradation without sacrificing transmission bandwidth. The result is a relatively robust design which is reasonably insensitive to channel errors and yet provides performance approaching the rate-distortion bound. Analytical results are provided for assumed 2-D autoregressive image models while simulation results are described for real-world images.

167 citations

Journal ArticleDOI
TL;DR: This joint source/channel coder design provides significant packet loss recovery with minimal rate overhead, and compares favorably with conventional schemes.
Abstract: Reserving space fur a symbol that is not in the source alphabet has been shown to provide excellent error detection. In this paper, we show how to exploit this capability using two sequential decoder structures to provide powerful error correction capability. This joint source/channel coder design provides significant packet loss recovery with minimal rate overhead, and compares favorably with conventional schemes.

72 citations


Cites methods from "Implementation Issues In Map Joint ..."

  • ...In terms of joint source channel coding where source and source coder characteristics are used to provide error protection, one of the earliest works that incorporated variable-length codes was that of Sayood et al. [ 7 ]....

    [...]

Book
14 Jan 2010
TL;DR: This paper shows how to use this capability using a sequential decoder structure to provide powerful error correction capability, and provides significant packet loss recovery with minimal overhead.
Abstract: Reserving space for a symbol that is not in the source alphabet has been shown to provide excellent error detection. In this paper we show how to use this capability using a sequential decoder structure to provide powerful error correction capability. This joint source/channel coder design provides significant packet loss recovery with minimal overhead.

47 citations

Journal ArticleDOI
TL;DR: A new maximum a posteriori (MAP) detector is proposed, without the need for explicit channel coding, to lessen the impact of communication channel errors on compressed image sources and the robustness of the proposed MAP detector's performance to estimation errors is studied.
Abstract: We propose a new maximum a posteriori (MAP) detector, without the need for explicit channel coding, to lessen the impact of communication channel errors on compressed image sources. The MAP detector exploits the spatial correlation in the compressed bitstream as well as the temporal memory in the channel to correct channel errors. We first present a technique for computing the residual redundancy inherent in a compressed grayscale image (compressed using VQ). The performance of the proposed MAP detector is compared to that of a memoryless MAP detector. We also investigate the dependence of the performance on memory characteristics of the Gilbert-Elliott channel as well as average channel error rate. Finally, we study the robustness of the proposed MAP detector's performance to estimation errors.

23 citations

Patent
24 Mar 2001
TL;DR: In this article, a system and method for joint source-channel encoding, symbol decoding and error correction is presented, utilizing an arithmetic encoder with operational error detection space; and a combination sequential, and arithmetic encoded symbol decoder structure.
Abstract: Disclosed is aA system and method for joint source-channel encoding, symbol decoding and error correction, preferably utilizing an arithmetic encoder with operational error detection space; and a combination sequential, and arithmetic, encoded symbol decoder structure.

23 citations

References
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Journal ArticleDOI
TL;DR: This final installment of the paper considers the case where the signals or the messages or both are continuously variable, in contrast with the discrete nature assumed until now.
Abstract: In this final installment of the paper we consider the case where the signals or the messages or both are continuously variable, in contrast with the discrete nature assumed until now. To a considerable extent the continuous case can be obtained through a limiting process from the discrete case by dividing the continuum of messages and signals into a large but finite number of small regions and calculating the various parameters involved on a discrete basis. As the size of the regions is decreased these parameters in general approach as limits the proper values for the continuous case. There are, however, a few new effects that appear and also a general change of emphasis in the direction of specialization of the general results to particular cases.

65,425 citations

Journal ArticleDOI
TL;DR: It is concluded that the channel-optimized vector quantizer design algorithm, if used carefully, can result in a fairly robust system with no additional delay.
Abstract: Several issues related to vector quantization for noisy channels are discussed. An algorithm based on simulated annealing is developed for assigning binary codewords to the vector quantizer code-vectors. It is shown that this algorithm could result in dramatic performance improvements as compared to randomly selected codewords. A modification of the simulated annealing algorithm for binary codeword assignment is developed for the case where the bits in the codeword are subjected to unequal error probabilities (resulting from unequal levels of error protection). An algorithm for the design of an optimal vector quantizer for a noisy channel is briefly discussed, and its robustness under channel mismatch conditions is studied. Numerical results for a stationary first-order Gauss-Markov source and a binary symmetric channel are provided. It is concluded that the channel-optimized vector quantizer design algorithm, if used carefully, can result in a fairly robust system with no additional delay. The case in which the communication channel is nonstationary (as in mobile radio channels) is studied, and some preliminary ideas for quantizer design are presented. >

509 citations

Journal ArticleDOI
TL;DR: It is shown that this optimal design of the zero-memory quantization of memoryless sources could result in substantial performance improvements, more noticeable at high bit rates and for broad-tailed densities.
Abstract: We present an analysis of the zero-memory quantization of memoryless sources when the quantizer output is to be encoded and transmitted across a noisy channel. Necessary conditions for the joint optimization of the quantizer and the encoder/decoder pair are presented, and an iterative algorithm for obtaining a locally optimum system is developed. The performance of this locally optimal system, obtained for the class of generalized Gaussian distributions and the binary symmetric channel, is compared against the optimum performance theoretically attainable (using rate-distortion theoretic arguments), as well as against the performance of Lloyd-Max quantizers encoded using the natural binary code and the folded binary code. It is shown that this optimal design could result in substantial performance improvements. The performance improvements are more noticeable at high bit rates and for broad-tailed densities.

359 citations

Journal ArticleDOI
TL;DR: The generalized Lloyd algorithm is applied to the design of joint source and channel trellis waveform coders to encode discrete-time continuous-amplitude stationary and ergodic sources operating over discrete memoryless noisy channels and it is observed that the jointly optimized codes achieve performance close to or better than that of separately optimized tandem codes of the same constraint length.
Abstract: The generalized Lloyd algorithm is applied to the design of joint source and channel trellis waveform coders to encode discrete-time continuous-amplitude stationary and ergodic sources operating over discrete memoryless noisy channels. Experimental results are provided for independent and autoregressive Gaussian sources, binary symmetric channels, and absolute error and squared error distortion measures. Performance of the joint codes is compared with the tandem combination of a trellis source code and a trellis channel code on the independent Gaussian source using the squared error distortion measure operating over an additive white Gaussian noise channel. It is observed that the jointly optimized codes achieve performance close to or better than that of separately optimized tandem codes of the same constraint length. Performance improvement via a predictive joint source and channel trellis code is demonstrated for the autoregressive Gaussian source using the squared error distortion measure.

193 citations

01 Dec 1978
TL;DR: In this paper, a combined source-channel coding approach is described for the encoding, transmission and remote reconstruction of image data, where the source encoder employs two-dimensional (2-D) differential pulse code modulation (DPCM).
Abstract: A combined source-channel coding approach is described for the encoding, transmission and remote reconstruction of image data. The source encoder employs two-dimensional (2-D) differential pulse code modulation (DPCM). This is a relatively efficient encoding scheme in the absence of channel errors. In the presence of channel errors, however, the performance degrades rapidly. By providing error control protection to those encoded bits which contribute most significantly to image reconstruction, it is possible to minimize this degradation without sacrificing transmission bandwidth. The result is a relatively robust design which is reasonably insensitive to channel errors and yet provides performance approaching the rate-distortion bound. Analytical results are provided for assumed 2-D autoregressive image models while simulation results are described for real-world images.

167 citations