We consider the problem of side-information scalable (SI-scalable) sourcecoding, where the encoder constructs a two-layer description, such that the receiver with high quality side information will be able to use onl...
详细信息
We consider the problem of side-information scalable (SI-scalable) sourcecoding, where the encoder constructs a two-layer description, such that the receiver with high quality side information will be able to use only the first layer to reconstruct the source in a lossy manner, while the receiver with low quality side information will have to receive both layers in order to decode. We provide inner and outer bounds to the rate-distortion (R-D) region for general discrete memoryless sources. The achievable region is tight when either one of the decoders requires a lossless reconstruction, and when the distortion measures are degraded and deterministic. Furthermore, the gap between the inner and the outer bounds can be bounded by certain constants when the squared error distortion measure is used. The notion of perfect scalability is introduced, for which necessary and sufficient conditions are given for sources satisfying a mild support condition. Using SI-scalablecoding and successive refinement Wyner-Ziv coding as basic building blocks, we provide a complete characterization of the rate-distortion region for the important quadratic Gaussian source with multiple jointly Gaussian side informations, where the side information quality is not necessarily monotonic along the scalablecoding order. A partial result is provided for the doubly symmetric binary source under the Hamming distortion measure when the worse side information is a constant, for which one of the outer bounds is strictly tighter than the other.
The rate-distortion-equivocation region has been derived recently for the Heegard-Berger problem, in which only one of the decoders has access to the correlated side information, under the constraint of the side infor...
详细信息
ISBN:
(纸本)9781665450850
The rate-distortion-equivocation region has been derived recently for the Heegard-Berger problem, in which only one of the decoders has access to the correlated side information, under the constraint of the side information privacy which is desired to keep the side information private from the uninformed decoder. In this paper, this result is extended to two special cases of the scalable source coding problem, in which the encoder sends a two-layer description to two decoders such that the first layer can be received by both two decoders, while the second is only for one of two decoders. For the first case when the second-layer description is only available at the informed decoder, the set of all feasible rate-distortion-equivocation is characterized under the constraint of the side information privacy. For the other case when the second-layer description is only at the uninformed decoder, the inner bound and the outer bound of the rate-distortion-equivocation region are provided under the constraint of the side information privacy.
This paper proposes an optimized, low-complexity methodology that combines Joint source-Channel coding (JSCC) based on Forward Error Correction (FEC) coding and scalable Multiple Description coding (MDC) mechanisms fo...
详细信息
ISBN:
(纸本)9781424436095
This paper proposes an optimized, low-complexity methodology that combines Joint source-Channel coding (JSCC) based on Forward Error Correction (FEC) coding and scalable Multiple Description coding (MDC) mechanisms for error-resilient data transmission over error-prone packet-based channels. Additionally, we report a comparative theoretical analysis between (i) MDC, and FEC-based scalable JSCC for sources encoded using (ii) Single Description coding (SDC) and (iii) MDC. Our analysis assumes ideal source coders that can achieve the theoretical performance bounds for a Gaussian source. This source model is independent of the actual implementation and therefore allows to draw conclusions on the theoretical performance of these approaches and to determine which methodology should be employed in specific transmission scenarios.
The characterization of the set of achievable rate and distortion values for scalable source coding is extended to additionally account for error exponents, namely, the negative normalized asymptotic log likelihood of...
详细信息
The characterization of the set of achievable rate and distortion values for scalable source coding is extended to additionally account for error exponents, namely, the negative normalized asymptotic log likelihood of error events at different layers. The "error" at each layer is defined as the event that the source block is not reproduced within the prespecified fidelity at the corresponding decoder. We consider separate error events at each layer so as to allow a tradeoff analysis for the error exponents when the rate and distortion values are fixed. For two-step coding of discrete memoryless sources, we derive a single-letter characterization of the region of all achievable 6-tuples (R-1, R-2, E-1, E-2, D-1, D-2), i.e., the rate, error exponent, and distortion levels at each layer. We also analyze the special case of successive refinability, where (R-1, E-1, D-1) and (R-2, E-2, D-2) individually achieve the nonscalable bounds. A surprising outcome of the analysis is that for any D-1, D-2, and E-1, there exists a finite threshold (E) over cap (2) greater than or equal to E-1 such that successive refinability is ensured for all E-2 greater than or equal to (E) over cap (2).
Multirate multicast is a powerful methodology of multimedia communication in heterogenous networks. A variant of multirate multicast motivated by scalable multimedia streaming is layered multicast, where the transmitt...
详细信息
Multirate multicast is a powerful methodology of multimedia communication in heterogenous networks. A variant of multirate multicast motivated by scalable multimedia streaming is layered multicast, where the transmitted signal is presented in successive data layers. With recent advances of network coding theory, many layered multicast schemes using network coding have been proposed to improve the performance of traditional routing-based layered multicast. They divide the network into different layers and construct a unirate multicast network code for each layer. However, these schemes do not perform network coding between data layers, and consequently cannot realize the full potential of network coding. In this paper, we propose a novel approach to layered multicast that allows network coding of data in different layers. This relaxation lends the proposed scheme greater flexibility in optimizing the data flow than previous layered solutions, and thus achieves higher throughput.
A joint source/channel coding algorithm is proposed for the transmission of multiple image sources over memoryless channels. The proposed algorithm uses a quality scalable image coder to optimally allocate a limited b...
详细信息
A joint source/channel coding algorithm is proposed for the transmission of multiple image sources over memoryless channels. The proposed algorithm uses a quality scalable image coder to optimally allocate a limited bit budget among all the sources to achieve the optimal overall distortion reduction for the multiple reconstructed images. In addition to the conventional un gain, it provides channel multiplexing gain, which can be much more significant. Furthermore, an extended scheme is proposed to provide flexibility between the optimization performance and complexity.
In this paper we examine the Distortion-Rate (D-R) performance of two competing approaches for error-resilient transmission of scalablesources over error-prone packet-based memoryless channels. Thereby, we consider s...
详细信息
ISBN:
(纸本)9781424432974
In this paper we examine the Distortion-Rate (D-R) performance of two competing approaches for error-resilient transmission of scalablesources over error-prone packet-based memoryless channels. Thereby, we consider scalable Joint source-Channel coding (JSCC) based on Forward Error Correction (FEC) and scalable Multiple Description coding (MDC). Our analysis considers memoryless Gaussian input sources encoded using source coders that can achieve theoretical performance bounds. This input source model is independent of actual implementations of the source coders and therefore allows drawing conclusions on the theoretical D-R performance of both approaches. Our comparative analysis indicates that in matched channel conditions, the use of an optimized FEC-based JSCC approach yields significantly better error resilience compared to the use of scalable MDC. Moreover, it is shown that in mismatched conditions a scalable JSCC approach has the potential to outperform a scalable MDC approach.
The common practice for achieving unequal error protection (UEP) in scalable multimedia communication systems is to design rate-compatible punctured channel codes before computing the UEP rate assignments. This paper ...
详细信息
The common practice for achieving unequal error protection (UEP) in scalable multimedia communication systems is to design rate-compatible punctured channel codes before computing the UEP rate assignments. This paper proposes a new approach to designing powerful irregular repeat accumulate (IRA) codes that are optimized for the multimedia source and to exploiting the inherent irregularity in IRA codes for UEP. Using the end-to-end distortion due to the first error bit in channel decoding as the cost function, which is readily given by the operational distortion-rate function of embedded source codes, we incorporate this cost function into the channel code design process via density evolution and obtain IRA codes that minimize the average cost function instead of the usual probability of error. Because the resulting IRA codes have inherent UEP capabilities due to irregularity, the new IRA code design effectively integrates channel code optimization and UEP rate assignments, resulting in source-optimized channel coding or joint source-channel coding. We simulate our source-optimized IRA codes for transporting SPIHT-coded images over a binary symmetric channel with crossover probability p. When p = 0.03 and the channel code length is long (e.g., with one codeword for the whole 512 x 512 image), we are able to operate at only 9.38% away from the channel capacity with code length 132380 bits, achieving the best published results in terms of average peak signal-to-noise ratio (PSNR). Compared to conventional IRA code design (that minimizes the probability of error) with the same code rate, the performance gain in average PSNR from using our proposed source-optimized IRA code design is 0.8759 dB when p = 0.1 and the code length is 12800 bits. As predicted by Shannon's separation principle, we observe that this performance gain diminishes as the code length increases.
This paper considers designing and applying punctured irregular repeat-accumulate (IRA) codes for scalable image and video transmission over binary symmetric channels. IRA codes of different rates are obtained by punc...
详细信息
This paper considers designing and applying punctured irregular repeat-accumulate (IRA) codes for scalable image and video transmission over binary symmetric channels. IRA codes of different rates are obtained by puncturing the parity bits of a mother IRA code, which uses a systematic encoder. One of the main ideas presented here is the design of the mother code such that the entire set of higher rate codes obtained by puncturing are good. To find a good unequal error protection for embedded bit streams, we employ the fast joint source-channel coding algorithm in Hamzaoui et al. to minimize the expected end-to-end distortion. We test with two scalable image coders (SPIHT and JPEG-2000) and two scalable video coders (3-D SPIHT and H.26L-based PFGS). Simulations show better results with IRA codes than those reported in Banister et al. with JPEG-2000 and turbo codes. The IRA codes proposed here also have lower decoding complexity than the turbo codes used by Banister et al..
Methods for determining and computing the rate-distortion (RD) bound for N-layer scalable source coding of a finite memoryless source are considered. Optimality conditions were previously derived for two layers in ter...
详细信息
Methods for determining and computing the rate-distortion (RD) bound for N-layer scalable source coding of a finite memoryless source are considered. Optimality conditions were previously derived for two layers in terms of the reproduction distributions q(y1) and q(y2/y1). However, the ignored and seemingly insignificant boundary cases, where q(y1) = 0 and q(y2/y1) is undefined, have major implications on the solution and its practical application. We demonstrate that, once the gap is filled and the result is extended to N-layers, it is, in general, impractical to validate a tentative solution, as one has to verify the conditions for all conceivable q(yi+1,...,yN/y1,...,yi) at each (y(1), ..., y(i)) such that q(y1,...,yi) = 0. As an alternative computational approach, we propose an iterative algorithm that converges to the optimal joint reproduction distribution q(y1',...,yN), if initialized with q(y1,...,yN) > 0 everywhere. For nonscalablecoding (N = 1), the algorithm specializes to the Blahut-Arimoto algorithm. The algorithm may be used to directly compute the RD bound, or as an optimality testing procedure by applying it to a perturbed tentative solution q. We address two additional difficulties due to the higher dimensionality of the RD surface in the scalable (N > 1) case;namely, identifying the sufficient set of Lagrangian parameters to span the entire RD bound;and the problem of efficient navigation on the RD surface to compute a particular RD point.
暂无评论