We address the connection between the multiple-description (MD) problem and Delta-Sigma quantization. The inherent redundancy due to oversampling in Delta-Sigma quantization, and the simple linear-additive noise model...
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We address the connection between the multiple-description (MD) problem and Delta-Sigma quantization. The inherent redundancy due to oversampling in Delta-Sigma quantization, and the simple linear-additive noise model resulting from dithered lattice quantization, allow us to construct a symmetric and time-invariant MD coding scheme. We show that the use of a noise-shaping filter makes it possible to trade off central distortion for side distortion. Asymptotically, as the dimension of the lattice vector quantizer and order of the noise-shaping filter approach infinity, the entropy rate of the dithered Delta-Sigma quantization scheme approaches the symmetric two-channel MD rate-distortion function for a memoryless Gaussian source and mean square error (MSE) fidelity criterion, at any side-to-central distortion ratio and any resolution. In the optimal scheme, the infinite-order noise-shaping filter must be minimum phase and have a piecewise flat power spectrum with a single jump discontinuity. An important advantage of the proposed design is that it is symmetric in rate and distortion by construction, so the coding rates of the descriptions are identical and there is therefore no need for source splitting.
In this paper, we consider real-time video coding and transmission over packet-switched wireless IP networks, such as WLAN, using RCPT codes and joint source-channel coding (JSCC) with concentration on a packet-by-pac...
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In this paper, we consider real-time video coding and transmission over packet-switched wireless IP networks, such as WLAN, using RCPT codes and joint source-channel coding (JSCC) with concentration on a packet-by-packet adaptive scheme. We present a systematic design methodology to enable the applicability of JSCC techniques. The performance of H.263+ video coding and transmission over wireless channel modeled as slow Rician fading channels using this approach is studied. Results indicate that a packet-by-packet adaptive RCPT-JSCC approach is of significant advantage for real-time video applications and leads to more acceptable video delivery quality over interference-limited and time-varying wireless networks.
作者:
Park, MoonseoKim, Seong-LyunAjou Univ
Div Elect & Comp Engn Commun Syst Lab Suwon 443749 South Korea Yonsei Univ
Sch Elect & Elect Engn Radio Resource Management & Optimizat Lab Seoul 120749 South Korea
In this letter, we consider the two-way relay channel (TWRC) employing network coding. In TWRC, a conventional relay first decodes symbols from each user and combines (network coding) them using, for example, the XOR ...
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In this letter, we consider the two-way relay channel (TWRC) employing network coding. In TWRC, a conventional relay first decodes symbols from each user and combines (network coding) them using, for example, the XOR (eXclusive OR) operation. However, it may be suboptimal for the relay to use this concatenated approach, when the channels are noisy and the cost criterion is source distortion. Instead, we propose a new relay scheme that generates network coded symbols by performing symbol estimation and network coding operation jointly, in order to minimize the source distortion at the users.
We consider layered transmission of a Gaussian source over a quasi-static fading channel. A broadcast strategy is used in which multiple layers of source data are superimposed, and each layer is allocated a different ...
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We consider layered transmission of a Gaussian source over a quasi-static fading channel. A broadcast strategy is used in which multiple layers of source data are superimposed, and each layer is allocated a different power and transmission rate. For a multiple-antenna system where either the transmitter or the receiver has a single antenna, we propose a low-complexity algorithm for minimizing the expected end-to-end distortion of the received signal. Numerical results for a Rayleigh fading channel are presented, and the performance gain over a time-sharing strategy is quantified. It is numerically shown that for a wide range of operating conditions, equal rate allocation is as good as unequal rate allocation.
A sensor networks in which two nodes communicate a remote measurement to an access point is investigated (CEO problem). The focus is on assessing the performance advantages of cooperative encoding strategies as enable...
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A sensor networks in which two nodes communicate a remote measurement to an access point is investigated (CEO problem). The focus is on assessing the performance advantages of cooperative encoding strategies as enabled by out-of-band and finite-capacity communication links between the sensors. The analysis assumes Gaussian source and observation noises, a quadratic (MSE) distortion metric and homogeneous sensors. With rate-constrained links between each sensor and the access point, an achievable rate-distortion trade-off is derived that reduces to known rate-distortion characterizations in the cases without and with perfect cooperation. This result is then extended to a Gaussian multiple access channel scenario by deriving achievable distortions with separate or joint source-channel coding. It is concluded that, for both scenarios, even modest values of the capacity of the inter-sensor links enable the optimal performance with full sensor cooperation to be approached.
The problem of lossy transmission of a Gaussian source over an AWGN bandwidth-mismatched broadcast channel with three receivers is addressed. The tradeoff between the distortion levels at the good and the bad receiver...
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ISBN:
(纸本)9781479951864
The problem of lossy transmission of a Gaussian source over an AWGN bandwidth-mismatched broadcast channel with three receivers is addressed. The tradeoff between the distortion levels at the good and the bad receivers is tackled when the distortion at the median receiver is required to be optimal. The problem was proposed by Tian and Shamai [8], who subsequently found in [9] remarkable achievability results for bandwidth expansion ratios k which are integers or unit fractions, i.e., k = 2, 1/3, 1/5, etc. Their result is extended here to all k >= 2 and k <= 1/2 by generalizing the hybrid digital/analog (HDA) scheme of [10] to the case of bandwidth mismatch. Finally, novel schemes are proposed for 1/2 <= k < 1 and 1 < k <= 2 achieving nontrivial tradeoffs.
In this paper we describe a multi-layered video transport scheme for wireless channels capable of adapting to channel conditions in order to maximize end-to-end quality of service (QoS). This scheme combines a scalabl...
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ISBN:
(纸本)0780367251
In this paper we describe a multi-layered video transport scheme for wireless channels capable of adapting to channel conditions in order to maximize end-to-end quality of service (QoS). This scheme combines a scalable H.263+ video source coder with unequal error protection (UEP) ac-cross layers. The UEP is achieved by employing different channel codes together with a multiresolution modulation approach to transport the different priority layers. Adaptivity to channel conditions is provided through use of joint source-channel coding (JSCC) which attempts to jointly optimize the source and channelcoding rates together with the modulation parameters to obtain the maximum achievable end-to-end QoS for the prevailing channel conditions. Results indicate that this adaptive JSCC scheme employing scalable video encoding together with a multiresolution modulation/coding approach leads to significant improvement-, in delivered video quality for specified channel conditions. In particular, the approach results in considerably improved graceful degradation properties for decreasing channel SNR.
In this paper, we present an adaptive scheme for forward error protection of any video coding standard. The channelcoding rate changes according to the channel bit error rate (BER). The results are impressive. For in...
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ISBN:
(纸本)0780385233
In this paper, we present an adaptive scheme for forward error protection of any video coding standard. The channelcoding rate changes according to the channel bit error rate (BER). The results are impressive. For instance, a PSNR gain of about 16.7 dB is obtained at BER=10(-2) for "Foreman" video sequence, encoded either by H.263 or by MPEG-I and protected using the Common scheme in comparison to the unprotected case. Being however this scheme common to all standards, it provides some acceptable video quality degradation. We have evaluated the quality degradation of the Common solution in comparison to the optimal scheme of protection, which uses a finite number of channel codes. Additionally, we propose a protection solution tailored to H.263/MPEG-4 video coding with an average PSNR improvement of about 0.2 dB relatively to the above mentioned Common solution.
The distributed remote sourcecoding (the so-called CEO) problem is studied in the case where the underlying source, not necessarily Gaussian, has finite differential entropy and the observation noise is Gaussian. The...
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The distributed remote sourcecoding (the so-called CEO) problem is studied in the case where the underlying source, not necessarily Gaussian, has finite differential entropy and the observation noise is Gaussian. The main result is a new lower bound for the sum-rate-distortion function under arbitrary distortion measures. When specialized to the case of mean-squared error, it is shown that the bound exactly mirrors a corresponding upper bound, except that the upper bound has the source power (variance), whereas the lower bound has the source entropy power. Bounds exhibiting this pleasing duality of power and entropy power have been well known for direct and centralized sourcecoding since Shannon's work. While the bounds hold generally, their value is most pronounced when interpreted as a function of the number of agents in the CEO problem.
Motivated by error correction coding in multimedia applications, we study the problem of broadcasting a single common source to multiple receivers over heterogeneous erasure channels. Each receiver is required to part...
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Motivated by error correction coding in multimedia applications, we study the problem of broadcasting a single common source to multiple receivers over heterogeneous erasure channels. Each receiver is required to partially reconstruct the source sequence by decoding a certain fraction of the source symbols. We propose a coding scheme that requires only off-the-shelf erasure codes and can be easily adapted as users join and leave the network. Our scheme involves splitting the source sequence into multiple segments and applying a systematic erasure code to each such segment. We formulate the problem of minimizing the transmission latency at the server as a linear programming problem and explicitly characterize an optimal choice for the code rates and segment sizes. Through numerical comparisons, we demonstrate that our proposed scheme outperforms both separation-based coding schemes and degree-optimized rateless codes and performs close to a natural outer (lower) bound in certain cases. We further study individual user decoding delays for various orderings of segments in our scheme. We provide closed-form expressions for each individual user's excess latency when parity checks are successively transmitted in both increasing order and decreasing order of their segment's coded rate and also qualitatively discuss the merits of each order.
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