In this paper we present a cross-layer solution to the problem of unreliability in IEEE 802.11 wireless multicast network, where an Access Point (AP) is multicasting a data file to a group of receivers over independen...
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In this paper we present a cross-layer solution to the problem of unreliability in IEEE 802.11 wireless multicast network, where an Access Point (AP) is multicasting a data file to a group of receivers over independent wireless erasure channels. We first present a practical scheme for collecting feedback frames from the receivers by means of simultaneous acknowledgment (ACK) frames collision. Based on these feedback frames, we design an online linear XOR coding algorithm to retransmit the lost packets. Through simulation results we first show that our proposed coding algorithm outperforms all the existing XOR coding algorithms in terms of retransmission rate. We further show that our proposed coding algorithm has the lowest average decoding delay of all the known network coding schemes. XOR coding and decoding only requires addition over GF(2), hence it enjoys lower encoding and decoding computational complexities. Because of these features such an online XOR coding algorithm is also of interest for delay-sensitive applications such as multicast audio video (AV) streaming, and in battery constrained devices such as smartphones. (C) 2013 Published by Elsevier B.V.
Recently, a new class of image coding algorithms coupling standard scalar quantization of frequency coefficients with tree-structured quantization (related to spatial structures) has attracted wide attention because i...
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Recently, a new class of image coding algorithms coupling standard scalar quantization of frequency coefficients with tree-structured quantization (related to spatial structures) has attracted wide attention because its good performance appears to confirm the promised efficiencies of hierarchical representation [1], [2]. This paper addresses the problem of how spatial quantization modes and standard scalar quantization can be applied in a jointly optimal fashion in an image coder. We consider zerotree quantization (zeroing out tree-structured sets of wavelet coefficients) and the simplest form of scalar quantization (a single common uniform scalar quantizer applied to all nonzeroed coefficients), and we formalize the problem of optimizing their joint application. We develop an image coding algorithm for solving the resulting optimization problem, Despite the basic form of the two quantizers considered, the resulting algorithm demonstrates coding performance that is competitive, often outperforming the very best coding algorithms in the literature.
In pyramidal wavelet representation, an image is decomposed into multiresolution and multifrequency subbands with sets of tree-structured coefficients, Le. a spatial orientation tree which consists of coefficients at ...
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In pyramidal wavelet representation, an image is decomposed into multiresolution and multifrequency subbands with sets of tree-structured coefficients, Le. a spatial orientation tree which consists of coefficients at different resolutions and different orientations but associated with the same spatial location. The magnitudes of the coefficients in these trees measure the signal activity level of the corresponding spatial areas. A novel coefficient partitioning algorithm is introduced for splitting the coefficients into two sets using a spatial orientation tree data structure. By splitting the coefficients, the overall theoretical entropy is reduced due to the different probability distributions for the two coefficient sets. In the spatial domain, it is equivalent to identifying smooth regions of the image. A lossless coder based on this spatial coefficient partitioning has a better coding performance than other wavelet-based lossless image coders such as S + P and JPEG-2000.
The paper presents a mathematical model of a subsystem for multimodal information coding. Analytical expressions for the quality and speed of information transmission are obtained. The results of experimental studies ...
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ISBN:
(纸本)9783319403496;9783319403489
The paper presents a mathematical model of a subsystem for multimodal information coding. Analytical expressions for the quality and speed of information transmission are obtained. The results of experimental studies of the developed multimodal information coding system are presented. The requirements for using the developed model and system for data processing in wearable devices of advanced uniform are discussed.
The paper considers methods for assessing the timeliness of detection and the efficiency of the suppression of large forest fires based on a complex analysis of their dynamics, meteorology data, and involved resources...
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The paper considers methods for assessing the timeliness of detection and the efficiency of the suppression of large forest fires based on a complex analysis of their dynamics, meteorology data, and involved resources. The methods were implemented via the ArcGIS GIS application, which enables the dynamics of each fire to be analyzed as it develops and reports the results of the analysis in the table, graphic (diagram), and cartographic formats.
In this article, we are going to present the issue concerning the tautology for the three-valued logic of beliefs - LB3. The aim of the paper is to present a machine implementation of tautology analysis for the given ...
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ISBN:
(纸本)9781628418804
In this article, we are going to present the issue concerning the tautology for the three-valued logic of beliefs - LB3. The aim of the paper is to present a machine implementation of tautology analysis for the given logic. Due to the presented analysis, we can classify a given LB3 language formula as: tautology, contradiction, or a satisfiable function. We also present the method for decoding LB3 logic expressions, since machine implementation of any aspects related to logical systems require proper coding.
This paper aims to perform a comparative analysis, based on experimental results obtained in practical tests, of the correlation that can be identified between a transform and an encoding algorithm for lossless compre...
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ISBN:
(纸本)9781665418782
This paper aims to perform a comparative analysis, based on experimental results obtained in practical tests, of the correlation that can be identified between a transform and an encoding algorithm for lossless compression of data from text files. At the same time, the paper offers the user the opportunity to test these concordance techniques, allowing him/her to draw personal conclusions about the most appropriate combination of methods in order to obtain best performance in a specific data context. Finally, some recommendations are offered on the optimal concordance between transform-based methods and encoding algorithms for lossless text compression.
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