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adaptive Spectral Transform for Wavelet-Based Color Image Compression

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2011年第7期21卷 983-992页

作者： Bayazit, Ulug Istanbul Tech Univ Dept Comp Engn TR-34469 Istanbul Turkey

Since different regions of a color image generally exhibit different spectral characteristics, the energy compaction of applying a single spectral transform to all regions is largely inefficient from a compression perspective. Thus, it is proposed that different subsets of wavelet coefficients of a color image be subjected to different spectral transforms before the resultant coefficients are coded by an efficient wavelet coefficient coding scheme such as that used in JPEG2000 or color set partitioning in hierarchical trees (CSPIHT). A quadtree represents the spatial partitioning of the set of high frequency coefficients of the color planes into spatially oriented subsets which may be further partitioned into smaller directionally oriented subsets. The partitioning decisions and decisions to employ fixed or signal-dependent bases for each subset are rate-distortion (R-D) optimized by employing a known analytical R-D model for these coefficient coding schemes. A compression system of asymmetric complexity, that integrates the proposed adaptive spectral transform with the CSPIHT coefficient coding scheme yields average coding gains of 0.3 dB and 0.9 dB in the Y component at 1.0 b/p and 2.5 b/p, respectively, and 0.9 dB and 1.35 dB in the U and V components at 1.0 b/p and 2.5 b/p, respectively, over a reference compression system that integrates the single spectral transform derived from the entire image with the CSPIHT coefficient coding scheme.

关键词： adaptive coding color image coding Karhunen-Loeve transform quadtree wavelet transform

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Semiunitary Precoding for Spatially Correlated MIMO Channels

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IEEE TRANSACTIONS ON INFORMATION THEORY 2011年第3期57卷 1284-1298页

作者： Raghavan, Vasanthan Sayeed, Akbar M. Veeravalli, Venugopal V. Univ Wisconsin Dept Elect & Comp Engn Madison WI 53706 USA Univ Illinois Dept Elect & Comp Engn Urbana IL 61801 USA Univ Illinois Coordinated Sci Lab Urbana IL 61801 USA

The focus of this paper is on spatial precoding in correlated multiantenna channels where the number of data-streams is adapted independent of the number of transmit antennas. Towards the goal of a low-complexity implementation, a statistical semiunitary precoder is studied where the precoder matrix evolves fairly slowly with respect to the channel evolution. While prior work on statistical precoding has focussed on information-theoretic limits, most of these computations result in complicated functional dependencies of the mutual information with the channel statistics that do not explicitly reveal the impact of statistics on performance. In contrast, estimates that are directly in terms of the channel statistics are obtained here for the relative mutual information loss of a semiunitary precoder with respect to a perfect channel information benchmark. Based on these estimates, matching metrics are developed that capture the degree of matching of a channel to the precoder structure continuously and allow ordering two matrix channels in terms of their mutual information performance. While these metrics are based on bounds, numerical studies are used to show that the proposed metrics capture the performance tradeoffs accurately. The main conclusion of this work is a simple-to-state fundamental principle in the context of signaling design for single-user MIMO systems: the best channel for the statistical precoder is the channel that is matched to it.

关键词： adaptive coding correlated channels low-complexity signaling MIMO systems multimode signaling semiunitary precoding spatial precoding

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Neural circuits underlying adaptation and learning in the perception of auditory space

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NEUROSCIENCE AND BIOBEHAVIORAL REVIEWS 2011年第10期35卷 2129-2139页

作者： King, Andrew J. Dahmen, Johannes C. Keating, Peter Leach, Nicholas D. Nodal, Fernando R. Bajo, Victoria M. Univ Oxford Dept Physiol Anat & Genet Oxford OX1 3PT England

Sound localization mechanisms are particularly plastic during development, when the monaural and binaural acoustic cues that form the basis for spatial hearing change in value as the body grows. Recent studies have shown that the mature brain retains a surprising capacity to relearn to localize sound in the presence of substantially altered auditory spatial cues. In addition to the long-lasting changes that result from learning, behavioral and electrophysiological studies have demonstrated that auditory spatial processing can undergo rapid adjustments in response to changes in the statistics of recent stimulation, which help to maintain sensitivity over the range where most stimulus values occur. Through a combination of recording studies and methods for selectively manipulating the activity of specific neuronal populations, progress is now being made in identifying the cortical and subcortical circuits in the brain that are responsible for the dynamic coding of auditory spatial information. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Auditory cortex Inferior colliculus Sound localization Binaural adaptive coding Perceptual learning Plasticity Descending pathway Corticocollicular projection Chromophore-targeted laser photolysis Cholinergic Nucleus basalis

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adaptive coding and modulation for the DVB-S2 standard interactive applications: Capacity assessment and key system issues

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IEEE WIRELESS COMMUNICATIONS 2007年第4期14卷 61-69页

作者： Alberty, Eric Defever, Sophie Moreau, Cyrille De Gaudenzi, Riccardo Ginesi, Alberto Rinaldo, Rita Gallinaro, Gennaro Vernucci, A. EADS Astrium Toulouse France European Space Agcy ESTEC RF Payload & Syst Div NL-2200 AG Noordwijk Netherlands Space Engn SpA Rome Italy

Point-to-point multibeam satellite systems based on the DVB-S standard [1] are currently designed for link closure in the worst-case propagation and location conditions. The DVB-S standard, conceived for broadcasting applications, considers a fixed coding rate and modulation format that are selected according to the assumed coverage and availability requirements. This approach implies the occurrence of high margins in the majority of the cases, when interference and propagation conditions allow for higher signal-to-noise-plus-interference ratio. The adaptive coding and modulation (ACM) introduction in the new DVB-S2 standard [2] for the interactive service profile opens up a number of appealing opportunities for the design and development of satellite broadband networks. In this article we show how the ACM introduction in the,satellite downlink enables greatly enhanced system performance but also has a profound impact on the way the system and some of the key system components are designed.

关键词： adaptive coding Modulation coding Digital video broadcasting Physical layer Satellite broadcasting Downlink Attenuation Satellite antennas Interference Bit rate

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Generalized Zigzag Scanning Algorithm for Non-square Blocks

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17th International Multimedia Modeling Conference, MMM 2011

作者： Ding, Jian-Jiun Lin, Pao-Yen Chen, Hsin-Hui Natl Taiwan Univ Grad Inst Commun Engn Taipei 10617 Taiwan

ISBN: (纸本)9783642178283

In the shape-adaptive compression algorithm, an image is divided into irregular regions instead of 8x8 blocks to achieve better compression efficiency. However, in this case, it is improper to use the conventional zigzag of JPEG to scan the DCT coefficients. For example, for a region whose height is M and width is N, if N is much larger than M, then the DCT coefficient in the location (0, b) is usually larger than that in (b-1, 0). However, when using the conventional zigzag method, (b-1, 0) is scanned before (0, b). In this paper, we propose new algorithms to perform coefficient scanning for irregular regions. The proposed methods are easy to implement and can obviously improve the coding efficiency of the shape-adaptive compression algorithm.

关键词： image coding zigzag object oriented methods image compression adaptive coding

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Optimal Distributed Relay Selection in Underlay Cognitive Radio Networks: An Energy-Efficient Design Approach

Optimal Distributed Relay Selection in Underlay Cognitive Ra...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Chen, Dan Ji, Hong Li, Xi Beijing Univ Posts & Telecommun Minist Educ Key Lab Universal Wireless Commun Beijing 100876 Peoples R China

ISBN: (纸本)9781612842547

Most previous work in CR relay networks concentrates on maximizing physical layer QoS (e. g., capacity, spectral efficiency and achievable data rate) as relay selection criteria. However, the energy state of relay nodes is largely ignored, which has significant effects on the network lifetime. This paper proposes a distributed relay selection scheme for cooperative transmissions over underlay CR networks, while considering adaptive modulation and coding (AMC) strategy and energy state of relay nodes. The objective is to increase spectral efficiency as well as prolong the average network lifetime (i.e., achieve a good tradeoff between them). With the stochastic optimization formulation, the optimal relay selection policy has indexability property that dramatically reduces the computation and implementation complexity. Simulation results are presented to show the effectiveness of the proposed scheme.

关键词： CR relay networks Energy states Indexes Interference Markov processes Modulation Relays Wireless communication adaptive codes adaptive coding adaptive modulation adaptive modulation average network lifetime cognitive radio cooperative transmissions energy-efficient design approach indexability property optimal distributed relay selection optimal relay selection policy physical layer QoS quality of service relay selection criteria spectral efficiency stochastic optimization stochastic programming underlay cognitive radio networks

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Energy-Efficient Cross-Layer Enhancement of Multimedia Transmissions over Cognitive Radio Relay Networks

Energy-Efficient Cross-Layer Enhancement of Multimedia Trans...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Chen, Dan Ji, Hong Leung, Victor C. M. Beijing Univ Posts & Telecommun Minist Educ Key Lab Universal Wireless Commun Beijing 100876 Peoples R China Univ British Columbia Dept Elect & Comp Engn Vancouver BC Canada

ISBN: (纸本)9781612842547

In cognitive radio (CR) networks, cooperative relaying is a promising technology to improve the performance of secondary users (SUs), while ensuring the quality of service (QoS) of primary transmissions. Most previous work in CR relay networks concentrates on maximizing physical layer QoS, e. g., system capacity, as the design criteria. However, the application layer QoS perceived by SUs, such as multimedia distortion, is largely ignored. In this paper, we take a cross-layer design approach to jointly consider optimal relay selection, power allocation, adaptive modulation and coding, as well as intra-refreshing rate to improve multimedia transmissions over underlay CR relay networks, while guaranteeing that the primary link is provided with a minimum-rate for a certain percentage of time. The objective is to minimize multimedia distortion, increase spectral efficiency as well as prolong network lifetime. With this stochastic optimization formulation, the optimal policy has indexability property that dramatically reduces the computation and implementation complexity. Simulation results are presented to show the effectiveness of the proposed scheme.

关键词： Encoding Energy consumption Energy states Markov processes Multimedia communication Quality of service Relays adaptive codes adaptive coding adaptive modulation adaptive modulation cognitive radio cognitive radio relay network cooperative relaying cross-layer design approach cross-layer enhancement distortion intra-refreshing rate multimedia communication multimedia distortion multimedia transmission optimal relay selection optimisation power allocation primary link quality of service quality of service radio links secondary user stochastic optimization formulation stochastic programming

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Location-Dependent Power Setting for Next Generation Femtocell Base Stations

Location-Dependent Power Setting for Next Generation Femtoce...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Tsao, Kang-Ju Shen, Sung-Chieh Hou, Ting-Chao Natl Chung Cheng Univ Dept Commun Engn Chiayi Taiwan Natl Chung Cheng Univ Dept Commun Engn Ctr Telecommun Res Chiayi Taiwan

ISBN: (纸本)9781612842547

In this paper, we study how the downlink received signal quality and throughput will be affected by deploying the Open Subscriber Group (OSG) Femtocell [1] using Location-Dependent Power Setting (LDPS) scheme with spectrum allocation (1,3,3) in the next generation mobile network. The LDPS scheme aims to use a suitable power for femtocell base station to maintains its indoor user coverage. The design of mandating indoor users to connect to femtocells ensures the transmission quality of indoor users and reduces the load of the macrocell base stations. Furthermore, by introducing transmit power upper bound (P-max) and lower bound (P-min), LDPS can better save power or trade power with throughput. Our study uses a large-scale macrocell/femtocell deployment model and considers many aspects of the next generation mobile communication systems, including OFDMA, adaptive modulation and coding, diverse propagation loss models, etc. This study sheds new insight on the self-optimization/self-configuration aspect of the next-generation femtocell deployment.

关键词： Base stations Interference LDPS scheme Macrocell networks OFDM modulation OFDMA Signal to noise ratio Throughput Ultrafast optics adaptive codes adaptive coding adaptive modulation adaptive modulation diverse propagation loss downlink received signal quality femtocellular radio frequency division multiple access indoor user coverage location-dependent power setting macrocell base stations mobile communication next generation femtocell base stations next generation mobile communication next generation mobile network next generation networks open subscriber group femtocell resource allocation self-configuration self-optimization spectrum allocation

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QoS Oriented Cross-Layer Design for Improving Multimedia Transmissions over Cooperative Relaying Networks

QoS Oriented Cross-Layer Design for Improving Multimedia Tra...

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54th Annual IEEE Global Telecommunications Conference (GLOBECOM)

作者： Chen, Dan Ji, Hong Beijing Univ Posts & Telecommun Key Lab Universal Wireless Commun Minist Educ Beijing 100876 Peoples R China

ISBN: (纸本)9781424492688

We propose in this paper, a distributed optimal relay selection scheme for cooperative wireless networks to improve the performance of multimedia transmissions, while taking into account application layer quality of service (QoS), i.e., multimedia distortion. We formulate the cooperative relaying network as a stochastic bandit system. Moreover, the adaptive modulation and coding (AMC) strategy at the physical layer and the intra-refreshing rate at the application layer are jointly considered from a cross-layer design perspective. The objective is to minimize multimedia distortion, increase spectral efficiency, as well as prolong the average network lifetime. The optimal relay selection policy has an indexability property that dramatically reduces the on-line computation and implementation complexity. Simulation results are presented to show the effectiveness of the proposed scheme.

关键词： Energy states Multimedia communication Optimization Peer to peer computing QoS oriented cross-layer design Quality of service Relays Wireless communication adaptive codes adaptive coding adaptive modulation adaptive modulation average network lifetime cooperative communication cooperative relaying networks cooperative wireless networks distributed optimal relay selection scheme multimedia communication multimedia distortion multimedia transmissions optimal relay selection policy quality of service spectral efficiency stochastic bandit system

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A Lossy acoustic Logging While Drill Compression Scheme based on Differential Prediction and FFT

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International Conference on Frontiers of Manufacturing Science and Measuring Technology (ICFMM2011)

作者： Liu, Yujie Zhou, Yunkai Xiao, Hongbing China Univ Petr Sch Comp Sci & Commun Engn Dongying 257062 Shandong Peoples R China

ISBN: (纸本)9783037851333

In this paper, by analyzing the characteristics of the data, we adopt lossy compression based on predictive coding method and FFT. Firstly, two-way differential prediction method is used for data, and then the predicted data is transformed into the frequency-domain data and only the significant components are selected, and finally three classical adaptive compression algorithms are used to compress the significant components, and have made a good compression ratio. Then, our algorithm is tested and compared with Winrar software, and our algorithm is superior to it using our test data.

关键词： acoustic logging while drill adaptive coding two-way prediction compression rate FFT

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