Let G = (V, E) be an undirected graph and C a subset of vertices. If the sets B-r(v) boolean AND C, v is an element of V (respectively, v is an element of V \ C), are all nonempty and different, where B-r(v) denotes t...
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Let G = (V, E) be an undirected graph and C a subset of vertices. If the sets B-r(v) boolean AND C, v is an element of V (respectively, v is an element of V \ C), are all nonempty and different, where B-r(v) denotes the set of all points within distance r from v, we call C an r-identifying code (respectively, an r-locating-dominating code). We prove that, given a graph G and an integer k, the decision problem of the existence of an r-identifying code, or of an r-locating-dominating code, of size at most k in G, is NP-complete for any r. (C) 2002 Elsevier Science B.V. All rights reserved.
LDPC codes were invented in 1960 by R. Gallager. They were largely ignored until the discovery of turbo codes in 1993. Since then, LDPC codes have experienced a renaissance and are now one of the most intensely studie...
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LDPC codes were invented in 1960 by R. Gallager. They were largely ignored until the discovery of turbo codes in 1993. Since then, LDPC codes have experienced a renaissance and are now one of the most intensely studied areas in coding. In this article we review the basic structure of LDPC codes and the iterative algorithms that are used to decode them. We also briefly consider the state of the art of LDPC design.
In this paper we generalize the concept of a pair of complementary designs D = (D:(D) over bar) to the case that D is a U-type design and the Hamming distances between all pairs of runs are the same. Relationships of ...
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In this paper we generalize the concept of a pair of complementary designs D = (D:(D) over bar) to the case that D is a U-type design and the Hamming distances between all pairs of runs are the same. Relationships of the generalized word length pattern between a pair of complementary designs are established. Some applications of these relationships are given. Furthermore, we give connections between uniformity and generalized word length pattern for a pair of complementary designs. (C) 2002 Elsevier B.V. All rights reserved.
Discrete Fourier theory has been applied successfully in digital communication theory. In this correspondence, we prove a new inequality linking the number of nonzero components of a complex valued function defined on...
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Discrete Fourier theory has been applied successfully in digital communication theory. In this correspondence, we prove a new inequality linking the number of nonzero components of a complex valued function defined on a finite Abelian group to the number of nonzero components of its Fourier transform. We characterize the functions achieving equality. Finally, we compare this inequality applied to Boolean functions to the inequality arising from the minimal distance property of Reed-Muller codes.
The decoding of received error control encoded bit streams is fairly straightforward when the channel encoding algorithms are efficient and known. But if the encoding scheme is unknown or part of the data is missing, ...
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ISBN:
(纸本)0780377893
The decoding of received error control encoded bit streams is fairly straightforward when the channel encoding algorithms are efficient and known. But if the encoding scheme is unknown or part of the data is missing, how would one design a viable decoder for the received transmission. Communication engineers may not frequently encounter this situation, but for computational biologists this is an immediate challenge as we attempt to decipher and understand the vast amount of sequence data produced by genome sequencing projects. Assuming the systematic parity check block code model of protein translation initiation [1], this work presents an approach for determining the generator matrix given a set of potential codewords. The resulting generators and corresponding parity matrices are applied to valid and invalid Escherichia coli K-12 MG1655 messenger RNA leader sequences. The generators constructed using strict subsets of the 16S ribosomal RNA performed better than those constructed using the (5,2) block code model in earlier work [1], [2].
Studies of prokaryotic translation initiation sites reveal that ribosomal binding sites appear to evolve to functional requirements rather than to genetic sequences that produce the strongest binding site [1]. Several...
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ISBN:
(纸本)0780376676
Studies of prokaryotic translation initiation sites reveal that ribosomal binding sites appear to evolve to functional requirements rather than to genetic sequences that produce the strongest binding site [1]. Several factors influence translation of mRNA sequences, including: initiation codon, presence and location of the Shine-Dalgarno sequence, spacing between the initiation codon and the Shine-Dalgarno domain, the second codon following the initiator codon, and possibly other nucleotides in the -20 to +13 region of the mRNA leader region [2]. These factors influence how the small subunit of the ribosome interacts with and binds to the mRNA leader region such that conditions are favorable for successful translation initiation. In this work translation initiation models are constructed by analyzing possible binding patterns between mRNA leader sequences and the exposed portion of the 16S rRNA. Binding analysis data are used as inputs to a genetic algorithm which searches for optimal binary, convolutional codes to model the Eschericha coli K-12 translation initiation system. We present an evaluation of the coding models discovered.
Investigators within the law enforcement and cyber forensics communities are generally aware of the concept of steganography, but their levels of expertise vary dramatically depending upon the incidents and cases that...
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ISBN:
(数字)9780203504765
ISBN:
(纸本)9780849324338
Investigators within the law enforcement and cyber forensics communities are generally aware of the concept of steganography, but their levels of expertise vary dramatically depending upon the incidents and cases that they have been exposed to. Now there is a book that balances the playing field in terms of awareness, and serves as a valuable refer
With the improvement in communication technology, broadband services are readily available for general multimedia communications. While the bottleneck in communication bandwidth has been relieved, the quality of the d...
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With the improvement in communication technology, broadband services are readily available for general multimedia communications. While the bottleneck in communication bandwidth has been relieved, the quality of the delivered images and videos becomes the next major concern when designing the communication systems. In this research work, we consider two important topics as far as quality image and video communications is concerned: (1) image enhancement; (2) source coding schemes for reliable transmission. Current studies on image and video communications consider only the problem due to the transmission channel. To achieve quality image and video delivery, the problems incurred when acquiring the images or videos should not be ignored. In this work, we investigated two major kinds of image or video acquisition problems: blurring and noise contamination. We study the enhancement techniques for such problems. In particular, to deal with the blurring problem of acquired images, a fast algorithm is proposed for blind image restoration based on the discrete periodic Radon transform (DPRT). With the DPRT, the original 2-dimensional blind image restoration problem is converted into 1-dimensional ones such that the complexity is much reduced and thus faster restoration can be achieved. Besides, to enhance the performance of compression with noisy acquired image, we investigate the adaptive thresholding technique that is particularly suitable for the MPEG-4 still texture image codec in coding noisy images. It integrates the denoising process and the coding process into a single step for the traditional MPEG-4 still image coder such that the visual quality of the decoded images are much improved. For video communication, a novel model is proposed to describe the relationship between the quantization and the rate-distortion (RD) performance of block-based video codec. We show that the distortion-quantization relationship, D(Q), of most coded sequences, encoded with different
The increasing demand for higher data rates and higher quality in wireless communications has motivated the use of multiple antenna elements at both the transmitter and the receiver sides in a wireless link. The probl...
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The increasing demand for higher data rates and higher quality in wireless communications has motivated the use of multiple antenna elements at both the transmitter and the receiver sides in a wireless link. The problem discussed in our research is the development of fundamental space-time (ST) coding and modulation methods to achieve the gains provided by multiple antennas, in terms of both improved robustness of the link and a higher spectral efficiency. We focus on a point-to-point wireless environment, in which the channel is modeled as flat fading, and channel knowledge is not available at the transmitter. Several new and improved schemes tailored for different applications are proposed. We first consider the design of ST trellis codes that reduce the probability of error without loss of spectral efficiency. It is found that the typical assumption of high signal-to-noise ratio (SNR) and, consequently, traditional design criteria are invalid in certain situations. Analyzing pair-wise error probability, we derive two sets of tighter design criteria for low and moderate SNR regions, respectively. New ST trellis codes optimized for moderate SNR are provided via a computer search. To avoid the prohibitively high complexity of searching for good codes with a larger number of transmit antennas and higher-level modulation, we introduce a novel systematic code construction method, diagonal block ST coding. This two-step approach demonstrates promising results at the commonly assumed high SNR. We then conduct an intensive study into generalized layered ST architecture that allows a tradeoff between error probability and spectral efficiency. Our goal is to enhance the tradeoff by further reducing the error probability. Techniques with no or little increase in receiver complexity, such as optimal power allocation and optimal decoding order, are introduced. A hard-decision iterative decoding algorithm that significantly enhances the system performance is also proposed. Fina
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