Watermarking-based self-embedding schemes designed to combat the kind of malicious tampering in which a portion of the image is replaced with the fake content are mostly developed for the uncompressed images;and thus,...
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Watermarking-based self-embedding schemes designed to combat the kind of malicious tampering in which a portion of the image is replaced with the fake content are mostly developed for the uncompressed images;and thus, are vulnerable against image processing attacks such as noise addition and image compression. This drawback makes them impractical especially when applied to the popular JPEG domain. Based on modeling the tampering as a source-channel coding problem, a self-embedding scheme for digital images in JPEG domain is proposed in this paper. A compressed version of the original image protected against tampering with the help of proper channelcoding approach forms the watermark of our proposed method. sourcecoding is applied to recover the lost content, while channelcoding helps the watermarked image to tolerate tampering. Since the proposed method is designed based on the JPEG model, it can be efficiently integrated into the JPEG standard. Experimental results show that the proposed method offers robustness against attacks such as noise addition and recompression, which is the shortcoming of available existing uncompressed-domain image self-embedding schemes. Moreover, satisfactory performance of the proposed method is stated in comparison with the major existing JPEG domain self-embedding schemes in terms of better robustness and image quality. (C) 2018 Elsevier B.V. All rights reserved.
A new universal coding/decoding scheme for random access with collision detection is given in case of two senders. The result is used to give achievable joint source-channel coding error exponents for multiple access ...
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A new universal coding/decoding scheme for random access with collision detection is given in case of two senders. The result is used to give achievable joint source-channel coding error exponents for multiple access channel and independent sources. In a modified model admitting zero rate communication between the senders, an improved exponent is derived, of form similar to Csiszar's joint source-channel exponent for the one-sender case.
An approach to hybrid digital-analog (HDA) source-channel coding for the communication of analog sources over memoryless Gaussian channels is introduced. The HDA system, which exploits the advantages of both digital a...
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An approach to hybrid digital-analog (HDA) source-channel coding for the communication of analog sources over memoryless Gaussian channels is introduced. The HDA system, which exploits the advantages of both digital and analog systems, generalizes a scheme previously presented by the authors, and can operate for any bandwidth ratio (bandwidth compression and expansion). It is based on vector quantization and features turbo coding in its digital component and linear/nonlinear processing in its analog part. Simulations illustrate that, under both bandwidth compression and expansion modes of operation, the HDA system provides a robust and graceful performance with good reproduction fidelity for a wide range of channel conditions.
We consider wireless sensor networks deployed to observe arbitrary random, fields., The requirement is to reconstruct an estimate of the random field at a certain collector node. This creates a many-to-one data gather...
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We consider wireless sensor networks deployed to observe arbitrary random, fields., The requirement is to reconstruct an estimate of the random field at a certain collector node. This creates a many-to-one data gathering, wireless channel. One of the main challenges in this scenario is that the source/channel separation theorem, proved by Shannon for point-to-point links, does not hold anymore. In this, paper, we construct novel cooperative source-channel coding schemes that exploit the wireless channel and the correlation between the sources. In particular, we differentiate between two distinct cases. The first case assumes that the sensor nodes are equipped with receivers and, hence, every node,can exploit the wireless link to distribute its information to its neighbors. We then devise an efficient, deterministic cooperation strategy where the neighboring nodes act as virtual antennas in a beamforming configuration. The second, and more challenging, scenario restricts the capability of sensor nodes to transmit only. In this case, we argue that statistical cooperative source-channel coding techniques still yield significant performance gains in certain relevant scenarios. Specifically, we propose a low complexity cooperative source-channel coding scheme based on the proper use of low-density generator matrix codes. This scheme is shown to outperform the recently proposed joint source-channel coding scheme (Garcia-Frias et al., 2002) in the case of highly correlated sources. In both the. deterministic and statistical cooperation scenarios, we develop analytical results that guide the optimization of the proposed schemes and validate the performance gains observed in simulations.
We study energy management policies for the compression and transmission of source data collected by an energy-harvesting sensor node with a finite energy buffer (e.g., rechargeable battery) and a finite data buffer (...
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We study energy management policies for the compression and transmission of source data collected by an energy-harvesting sensor node with a finite energy buffer (e.g., rechargeable battery) and a finite data buffer (memory) between source encoder and channel encoder. The sensor node can adapt the source and channelcoding rates depending on the observation and channel states. In such a system, the absence of precise information about the amount of energy available in the future is a key challenge. We provide analytical bounds and scaling laws for the average distortion that depend on the size of the energy and data buffers. We furthermore design a resource allocation policy that achieves almost optimal distortion scaling. Our results demonstrate that the energy leakage of state of art energy management policies can be avoided by jointly controlling the source and channelcoding rates.
The development of 'Beyond 3G'-B3G-or '4G' networks and applications, with all-IP based ubiquitous and seamless service provisioning across heterogeneous infrastructures, presents a number of challenge...
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The development of 'Beyond 3G'-B3G-or '4G' networks and applications, with all-IP based ubiquitous and seamless service provisioning across heterogeneous infrastructures, presents a number of challenges beyond existing capabilities conceived so far by the IETF for Mobile IP and by the ITU for Third Generation networks. Management, signaling and transport functions must evolve from different link layer technologies, uniformly and end-to-end, to the packet switched IP-network layer. Global mobility throughout all network types requires capability for seamless handover between different administrative and technology domains, extending at the same time the present edge mobility concept to ad-hoc networks and to mobile networks. Having at least identified, if not solved, these important problems, the technical key challenge for this B3G or '4G' world remains to provide IP-based audio and video communications at the same or at least comparable 'carrier class' and bandwidth efficiency as the corresponding circuit-switched subsystems of 3G and 2G. In the IETF, some elements to achieve this goal have been identified and are under discussion: situated between link and IP layers, the Robust Header Compression (ROHC) framework addresses the problems of spectrum and bandwidth scarcity and of bit errors characterizing wireless links. The fact that, for some applications, erroneous packet payloads can be valuable and better to cope with than lost ones, has inspired the introduction of the UDP-lite transport protocol. Assuming ROHC, UDP-lite and an appropriate inter- or cross-layer signaling mechanism in action, this paper is going to elaborate and incorporate the joint source and channelcoding-JSCC-paradigm into a complete QoS framework for 4G mobile wireless multimedia communications. (C) 2004 Elsevier B.V. All rights reserved.
This paper studies an almost-lossless source-channel coding scheme in which source messages are assigned to different classes and encoded with a channel code that depends on the class index. The code performance is an...
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This paper studies an almost-lossless source-channel coding scheme in which source messages are assigned to different classes and encoded with a channel code that depends on the class index. The code performance is analyzed by means of random-coding error exponents and validated by simulation of a low-complexity implementation using existing source and channel codes. While each class code can be seen as a concatenation of a source code and a channel code, the overall performance improves on that of separate source-channel coding and approaches that of joint source-channel coding when the number of classes increases.
We present a general scheme for the lossy transmission of a source with arbitrary statistics through a noisy channel under the mean-square error fidelity criterion. Our approach is based on transform coding, scalar qu...
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We present a general scheme for the lossy transmission of a source with arbitrary statistics through a noisy channel under the mean-square error fidelity criterion. Our approach is based on transform coding, scalar quantization of the transform coefficients and linear encoding of the quantization indices. Entropy coding and channelcoding are merged into a single linear encoding function, such that the "catastrophic" behavior of conventional entropy coding is avoided and the full power of modern coding techniques and iterative "Belief-Propagation" decoding can be exploited. We show that this approach is asymptotically optimal in the limit of large block length, for arbitrary source statistics and binary-input output-symmetric channel. In the practical regime of finite block length and low decoding complexity, we show, through the explicit construction of codes for the lossy transmission of digital images over a binary symmetric channel, that our approach yields significant improvements with respect to previously proposed channel-optimized quantization schemes and also with respect to the conventional concatenation of state-of-the art image coding with state-of-the art channelcoding. Although our constructive example focuses on a special case, the approach is general and can be applied to other classes of sources of practical interest.
Multimedia applications operating in today's Internet have to employ some form of error resilience to cope with losses. For interactive applications with strict delay constraints the latency introduced by these sc...
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Multimedia applications operating in today's Internet have to employ some form of error resilience to cope with losses. For interactive applications with strict delay constraints the latency introduced by these schemes has to be low as well. Furthermore the parameters of the applied scheme have to be set based on measurements in a possibly rapidly changing environment. In this paper we propose a robust method, called min-max-alpha, for optimal source-channel code rate allocation to deal with time-varying packet channels and channel state estimation errors. We evaluate its performance when used with forward error correction and multiple description coding in both stationary and non-stationary environments. We show that on a stationary channel robust rate allocation is suboptimal in terms of mean distortion, but it achieves a lower variance, while on a non-stationary channel it prevents severe degradation of the quality. We apply the proposed rate allocation method to motion compensated video and show that it performs better on a non-stationary channel than minimization of the mean distortion proposed earlier.
In this dissertation, we studied two seemingly uncorrelated, but conceptuallyrelated problems in terms of source-channel coding: 1) wireless image transmissionand 2) Costa ("dirty-paper") code design.In the ...
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In this dissertation, we studied two seemingly uncorrelated, but conceptually
related problems in terms of source-channel coding: 1) wireless image transmission
and 2) Costa ("dirty-paper") code design.
In the first part of the dissertation, we consider progressive image transmission
over a wireless system employing space-time coded OFDM. The space-time coded
OFDM system based on a newly built broadband MIMO fading model is theoretically
evaluated by assuming perfect channel state information (CSI) at the receiver for
coherent detection. Then an adaptive modulation scheme is proposed to pick the
constellation size that offers the best reconstructed image quality for each average
signal-to-noise ratio (SNR).
A more practical scenario is also considered without the assumption of perfect
CSI. We employ low-complexity decision-feedback decoding for differentially space-
time coded OFDM systems to exploit transmitter diversity. For JSCC, we adopt a
product channel code structure that is proven to provide powerful error protection and
bursty error correction. To further improve the system performance, we also apply
the powerful iterative (turbo) coding techniques and propose the iterative decoding
of differentially space-time coded multiple descriptions of images.
The second part of the dissertation deals with practical dirty-paper code designs. We first invoke an information-theoretical interpretation of algebraic binning and
motivate the code design guidelines in terms of source-channel coding. Then two
dirty-paper code designs are proposed. The first is a nested turbo construction based
on soft-output trellis-coded quantization (SOTCQ) for sourcecoding and turbo trellis-
coded modulation (TTCM) for channelcoding. A novel procedure is devised to
balance the dimensionalities of the equivalent lattice codes corresponding to SOTCQ
and TTCM. The second dirty-paper code design employs TCQ and IRA codes for
near-capacity performance. This is done by synergistically combinin
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