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3rd International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks

作者： Tang, Jia Zhang, Xi Networking and Information Systems Laboratory Department of Electrical and Computer Engineering Texas A and M University College Station TX 77843 United States

ISBN: (纸本)1595935371

We propose a cross-layer-model based adaptive resource-allocation scheme for the diverse quality-of-service (QoS) guarantees over downlink mobile wireless networks. Our proposed scheme dynamically assigns power-levels and time-slots for heterogeneous real-time mobile users to satisfy the variation of statistical delay-bound QoS requirements. To achieve this goal, we apply effective capacity approach to derive the admission-control and power/time-slot allocation algorithms, guaranteeing the statistical delay-bound for heterogeneous mobile users. When designing such an algorithm, we study the impact of physical-layer issues such as adaptive power-control on the QoS provisioning performance. Through numerical and simulation results, we observe that the adaptive power adaptation has a significant impact on statistical QoS-guarantees. In addition, the analyses indicate that our proposed resource-allocation algorithms are shown to be able to efficiently support the diverse QoS requirements for various real-time mobile users over different wireless channels. © 2006 ACM.

关键词： Wireless networks

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Cross-layer resource-consumption optimization for mobile multicast in wireless networks 06

Cross-layer resource-consumption optimization for mobile mul...

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WoWMoM 2006: 2006 International Symposium on a World of Wireless, Mobile and Multimedia Networks

作者： Qinghe, Du Xi, Zhang Networking and Information Systems Laboratory Department of Electrical and Computer Engineering Texas A and M University College Station TX 77843 United States

ISBN: (纸本)0769525938

To save the precious wireless resources In wireless networks, we Investigate cross-layer optimization schemes to reduce wireless resource consumption (WRC) for reliable mobile multicast. We characterize WRC by signal-to-noise ratio (SNR) per Information bit and by power-delay product for scenarios without and with delay quality of service (QoS) constraints, respectively. Aiming at decreasing WRC, we develop a cross-layer parameter-selection (CLPS) algorithm, which dynamically adjusts the parameters of the physical layer and the medium access control (MAC) layer according to the variations of multicast group size, transport-layer error-control parameters, and delay QoS constraints. In particular, we first derive the optimal physical-layer parameters, Including constellation size and transmit SNR, to minimize WRC for Threshold-0 multicast policy, where the sender transmits data regardless of channel qualities. Then, we develop a suboptimal approach for the selection of MAC-layer multicast threshold to achieve low powerdelay product. In addition, we study the effects of pure automatic repeat request (ARQ) and hybrid ARQ - forward error correction (FEC) based error-control schemes on the CLPS algorithm. Also conducted Is a set of numerical analyses to show the performance gain achieved through the cross-layer design and the Impacts of various system parameters on the WRC optimization. © 2006 IEEE.

关键词： Telecommunication networks

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Adaptive power and rate allocation for mobile multicast throughput optimization over fading channels in wireless networks

Adaptive power and rate allocation for mobile multicast thro...

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15th International Conference on computer Communications and Networks 2006, ICCCN 2006

作者： Qinghe, Du Xi, Zhang Networking and Information Systems Laboratory Department of Electrical and Computer Engineering Texas A and M University College Station TX 77843 United States

ISBN: (纸本)1424405726

We investigate adaptive power and rate allocation schemes for multicast over fading channels in wireless networks. Specifically, we take advantage of the superposition coding to achieve high multicast throughput, where the transmitted signal consists of multiple parallel sub-stream signals. Each receiver decodes the sub-stream signals within its decoding capability determined by the received signal to noise ratio (SNR). Under the above architecture, we first formulate the multicast throughput optimization problem to obtain the power allocation policy for each sub-stream signal subject to the total power constraint. Also, we develop a selective retransmission strategy to guarantee all receivers to recover the same data copy without unnecessary data reception. By introducing the concept of compensation ratio, we derive the optimal power allocation policy of the formulated throughput optimization problem for the two-receiver scenario. Numerical results are also presented to show the throughput improvement over the worst-case SNR-dominating (WSD) rate policy, the best-case SNR-dominating (BSD) rate policy, and the constant-rate policy. © 2006 IEEE.

关键词： Multicasting

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Optimal transmission range for cluster-based wireless sensor networks with mixed communication modes 06

Optimal transmission range for cluster-based wireless sensor...

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WoWMoM 2006: 2006 International Symposium on a World of Wireless, Mobile and Multimedia Networks

作者： Su, Hang Zhang, Xi Networking and Information Systems Laboratory Department of Electrical and Computer Engineering Texas A and M University College Station TX 77843 United States

ISBN: (纸本)0769525938

Prolonging the network lifetime is one of the most important designing objectives in wireless sensor networks (WSN). We consider a heterogeneous cluster-based WSN, which consists of two types of nodes: powerful cluster-heads and basic sensor nodes. All the nodes are randomly deployed in a specific area. To better balance the energy dissipation, we use a simple mixed communication modes where the sensor nodes can communicate with cluster-heads in either single-hop or multi-hop mode. Given the initial energy of the basic sensor nodes, we derive the optimal communication range and identify the optimal mixed communication mode to maximize the WSN's lifetime through optimizations. Moreover, we also extend our model from 2-D space to 3-D space. © 2006 IEEE.

关键词： Telecommunication networks

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Quality-of-service driven power and rate control in mobile wireless networks

Quality-of-service driven power and rate control in mobile w...

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2006 IEEE International Conference on Communications, ICC 2006

作者： Tang, Jia Zhang, Xi Networking and Information Systems Laboratory Department of Electrical and Computer Engineering Texas A and M University College Station TX 77843 United States

ISBN: (纸本)1424403553

We propose a Quality-of-Service (QoS) driven power- and rate-control scheme in mobile wireless networks. Specifically, the proposed scheme aims at maximizing the system throughput subject to a given delay QoS constraint. Over the block fading channel, we derive the optimal adaptation policy by integrating information theory with the concept of effective capacity. The analyses demonstrate that there exists a fundamental tradeoff between spectral efficiency and QoS provisioning. When the QoS constraint is loose, the optimal power control policy converges to the well-known water-filling scheme, where the Shannon capacity can be achieved. On the other hand, when the QoS constraint is stringent, the optimal policy converges to the total channel inversion such that the system operates with a constant service rate. © 2006 IEEE.

关键词： Wireless networks

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On transmit-diversity based multicast in mobile wireless networks

On transmit-diversity based multicast in mobile wireless net...

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2006 IEEE International Conference on Communications, ICC 2006

作者： Du, Qinghe Zhang, Xi Shen, Xuemin Networking and Information Systems Laboratory Department of Electrical and Computer Engineering Texas A and M University College Station TX 77843 United States Centre for Wireless Communications Department of Electrical and Computer Engineering University of Waterloo Waterloo ON Canada

ISBN: (纸本)1424403553

We investigate the variations of using the different transmit-diversity techniques for multicast in mobile wireless networks. In particular, we propose and study two different schemes using transmit-diversity for mobile multicast. First, we propose the antenna-beamforming-based mobile multicast scheme which derives the transmit antenna weights by formulating/solving an optimization problem to minimize the average Symbol Error Rate (SER) over all multicast receivers. The simulations results show that our proposed beamforming-based scheme achieves lower SER compared with the existing beamforming-based mobile multicast algorithms which either maximize the instantaneous combined Signal to Noise Ratio (SNR) averaged over all receivers, or maximize the worst-case instantaneous combined SNR among all multicast receivers. Second, we apply the antenna-selection scheme in mobile multicasting to achieve the low average SER. We identify that the antenna-selection scheme is suitable for the scenario where different receivers/receiver-groups in a multicast session, experiencing different channel qualities, need to receive different error-control data. The analyses and numerical results show that the proposed scheme improves the SER performance through selecting antennas with better channel qualities and can flexibly support various antenna configurations. © 2006 IEEE.

关键词： Wireless networks

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Designing an embedded video processing camera using a 16-bit microprocessor for a surveillance system

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Journal of VLSI Signal Processing systems for Signal, Image, and Video Technology 2006年第1期42卷 57-68页

作者： Sato, Koichi Evans, Brian L. Aggarwal, J.K. Department of Electrical and Computer Engineering Computer and Vision Research Center University of Texas at Austin Austin TX 78712 United States Department of Electrical and Computer Engineering Embedded Signal Processing Laboratory University of Texas at Austin Austin TX 78712 United States Department of Electrical and Computer Engineering University of Texas Austin Design and Implementation of Signal Processing Systems Technical Committee IEEE Signal Processing Society IEEE Department of Electrical and Computer Engineering Computer and Vision Research Center IEEE Computer Society

This paper describes the design and implementation of a hybrid intelligent surveillance system that consists of an embedded system and a personal computer (PC)-based system. The embedded system performs some of the image processing tasks and sends the processed data to the PC. The PC tracks persons and recognizes two-person interactions by using a grayscale side view image sequence captured by a stationary camera. Based on our previous research, we explored the optimum division of tasks between the embedded system and the PC, simulated the embedded system using dataflow models in Ptolemy, and prototyped the embedded system in real-time hardware and software using a 16-bit CISC microprocessor. This embedded system processes one 320 × 240 frame in 89 ms, which yields one-third of the rate of 30 Hz video system. In addition, the real-time embedded system prototype uses 5.7 K bytes of program memory, 854 K bytes of internal data memory and 2 M bytes external DRAM. © Springer Science + Business Media, Inc. 2006.

关键词： Microprocessor chips

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Value-based design of software V&V processes for NASA flight projects

Value-based design of software V&V processes for NASA flight...

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AIAA Space 2007 Conference

作者： Madachy, Raymond Boehm, Barry Richardson, Julian Feather, Martin Menzies, Tim University of Southern California Los Angeles CA 90089 United States National Aeronautics and Space Administration AMES Research Center Moffett Field CA 94035 United States National Aeronautics and Space Administration Jet Propulsion Laboratories Pasadena CA 91109 United States West Virginia University Morgantown WV 26506 United States University of Southern California Center for Systems and Software Engineering SAL 328 941 W. 37th Place Los Angeles CA 90089 United States AIAA RIACS USRA NASA Ames Research Center Moffett Field CA 94035 United States Software Quality Assurance Office Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive Pasadena CA 91109-8099 United States West Virginia University Lane Department of Computer Science and Electrical Engineering PO Box 6109 Morgantown WV 26506 United States

ISBN: (纸本)1563479079

Software risk advisory tools have been developed to support Verification and Validation (V&V) processes for NASA flight projects on the Constellation program. The Orthogonal Defect Classification COnstructive QUALity MOdel (ODC COQUALMO) predicts software defects introduced and removed classifying them with ODC defect types, allowing various tradeoff analyses. We have been exploring methods to design and optimize V&V processes with static and dynamic versions of the quality model by integrating it with different risk minimization techniques. These techniques allow "what-if" experimentation to determine the impact of V&V techniques on specific risks and overall flight risk. V&V techniques are quantified from a value-based perspective when the defect model is integrated with machine learning, strategic optimization and JPL's Defect Detection and Prevention (DDP) risk management method. Results to-date show that the automated methods are practical for flight projects to design higher value V&V processes in shorter time and with fewer resources.

关键词： Software design

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Coding for additive white noise channels with feedback corrupted by uniform quantization or bounded noise 44

Coding for additive white noise channels with feedback corru...

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44th Annual Allerton Conference on Communication, Control, and Computing 2006

作者： Martins, Nuno C. Weissman, Tsachy Electrical and Computer Engineering Department and the Institute for Systems Research University of Maryland College Park United States Department of Electrical Engineering and the Information Systems Laboratory United States

ISBN: (纸本)9781604237924

We present simple coding strategies, which are variants of the Schalkwijk-Kailath scheme, for communicating reliably over additive white noise channels in the presence of corrupted *** specifically, we consider a framework comprising an additive white forward channel and a backward link which is used for feedback. We consider two types of corruption mechanisms in the backward link. The first is quantization noise, i.e., the encoder receives the quantized values of the past outputs of the forward channel. The quantization is uniform, memoryless and time invariant (that is, symbol-bysymbol scalar quantization), with bounded quantization error. The second corruption mechanism is an arbitrarily distributed additive bounded noise in the backward link. Here we allow symbol-by-symbol encoding at the input to the backward channel. We propose simple explicit schemes that guarantee positive information rate, in bits per channel use, with positive error exponent. If the forward channel is additive white Gaussian then our schemes achieve capacity, in the limit of diminishing amplitude of the noise components at the backward link, while guaranteeing that the probability of error converges to zero as a doubly exponential function of the block length. Furthermore, if the forward channel is additive white Gaussian and the backward link consists of an additive bounded noise channel, with signal-To-noise ratio (SNR) constrained symbol-by-symbol encoding, then our schemes are also capacity-Achieving in the limit of high SNR.

关键词： Exponential functions

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A decentralized computational infrastructure for grid-based parallel asynchronous iterative applications

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Journal of Grid Computing 2006年第4期4卷 355-372页

作者： Li, Zhen Parashar, Manish The Applied Software Systems Laboratory Department of Electrical and Computer Engineering Rutgers University Piscataway NJ 08854 United States

Parallel asynchronous iterative algorithms relax synchronization and communication requirements, and can potentially extend Desktop Grids beyond embarrassingly parallel applications to support a broader class of parallel iterative applications. This paper presents the design and implementation of CometG, a decentralized (peer-to-peer) computational infrastructure that extends Desktop Grid environments to support these applications. CometG provides a decentralized and scalable tuple space, efficient communication and coordination support, and application-level abstractions that can be used to implement Desktop Grid applications based on parallel asynchronous iterative algorithms using the master-worker/BOT paradigm. The deployment and evaluations of CometG and a CometG-based application in a wide-area environment using the PlanetLab [7] test bed, as well as a campus network are presented. © Springer Science + Business Media, Inc. 2006.

关键词： Decentralized (peer-to-peer) tuple space Desktop Grids Parallel asynchronous iterative algorithms

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