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Equivalence and generalization in a layered network model

JOURNAL OF COMPUTER AND SYSTEM SCIENCES 2015年第8期81卷 1698-1714页

作者： Fortune, Steven Bell Labs Murray Hill NJ 07974 USA

We propose a formal model of layered telecommunication networks. The model includes ports, which are access points to data streams;links, which transmit data streams;and adapters, which convert data streams from one layer to another. Two ports communicate if there is a path from one to the other in which every adaptation is balanced by a reverse adaptation. Two networks M and N with the same public ports are equivalent if for any other network Q, two ports in the composition M o Q communicate exactly if they communicate in No Q. M generalizes N if whenever two ports communicate in No Q, the ports also communicate in M o Q. We give linear time algorithms to decide equivalence and generalization of networks when adaptation is "simple", i.e. one or more data streams can be adapted into only a single data stream. If adaptation models "protection switching," then testing equivalence is co-NP-complete. (C) 2015 Elsevier Inc. All rights reserved.

关键词： Network model Layers Generalization Equivalence adaptation algorithms

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Performance directed energy management for main memory and disks

Performance directed energy management for main memory and d...

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11th International Conference on Architectural Support for Programming Languages and Operating Systems

作者： Li, XD Li, ZM David, F Zhou, P Zhou, YY Adve, S Kumar, S Univ Illinois Dept Comp Sci Urbana IL 61801 USA Intel Labs Santa Clara CA USA

ISBN: (纸本)1581138040

Much research has been conducted on energy management for memory and disks. Most studies use control algorithms that dynamically transition devices to low power modes after they are idle for a certain threshold period of time. The control algorithms used in the past have two major limitations. First, they require painstaking, application-dependent manual tuning of their thresholds to achieve energy savings without significantly degrading performance. Second, they do not provide performance guarantees. In one case, they slowed down an application by 835%! This paper addresses these two limitations for both memory and disks, making memory/disk energy-saving schemes practical enough to use in real systems. Specifically, we make three contributions: (1) We propose a technique that provides a performance guarantee for control algorithms. We show that our method works well for all tested cases, even with previously proposed algorithms that are not performance-aware. (2) We propose a new control algorithm, Performance-directed Dynamic (PD), that dynamically adjusts its thresholds periodically, based on available slack and recent workload characteristics. For memory, PD consumes the least energy, when compared to previous hand-tuned algorithms combined with a performance guarantee. However, for disks, PD is too complex and its self-tuning is unable to beat previous hand-tuned algorithms. (3) To improve on PD, we propose a simple, optimization-based, threshold-free control algorithm, Performance-directed Static (PS). PS periodically assigns a static configuration by solving an optimization problem that incorporates information about the available slack and recent traffic variability to different chips/disks. We find that PS is the best or close to the best across all performance-guaranteed disk algorithms, including hand-tuned versions.

关键词： memory and disk energy management low power design adaptation algorithms control algorithms multiple power mode device

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New high-resolution imaging technology Application of advanced radar technology for medical imaging

New high-resolution imaging technology Application of advanc...

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Conference on Medical Imaging - Physics of Medical Imaging

作者： Gorwara, Ashok Molchanov, Pavlo Planar Monolith Ind Inc 7311-F Grove Rd Frederick MD 21704 USA

ISBN: (数字)9781510607101

ISBN: (纸本)9781510607095;9781510607101

Image resolution for RF/microwave relatively long waves is limited by the diffraction limit (Abbe diffraction limit). Each point of reflecting object will work as source of diffractive waves if wavelength longer than object. But phase front of diffracted waves still will consist information about object shape. Image can be recovered from multi frequency digital hologram by combination of interferograms. In this case resolution of recovered image will be determined by receiver bandwidth, digitizing frequency and accuracy of processor time. Faster processor - better image resolution. Low frequency non-scanning wide beam in monopulse radar system can cover all object and same time provide high resolution phase measurement relative to reference beam.

关键词： Advanced radar technology Fly Eye imaging radar holographic radar monopulse cross-correlation adaptation algorithms spectrum signature high-resolution high scattered media

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Performance Directed Energy Management for Main Memory and Disks

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ACM Transactions on Storage 2005年第3期1卷 346-380页

作者： Li, Xiaodong Li, Zhenmin Zhou, Yuanyuan Adve, Sarita University of Illinois at Urbana-Champaign Siebel Center for Computer Science Urbana IL 201 North Goodwin Ave. 61801 United States

Much research has been conducted on energy management for memory and disks. Most studies use control algorithms that dynamically transition devices to low power modes after they are idle for a certain threshold period of time. The control algorithms used in the past have two major limitations. First, they require painstaking, application-dependent manual tuning of their thresholds to achieve energy savings without significantly degrading performance. Second, they do not provide performance guarantees. This article addresses these two limitations for both memory and disks, making memory/disk energy-saving schemes practical enough to use in real systems. Specifically, we make four main contributions. (1)We propose a technique that provides a performance guarantee for control algorithms. We show that our method works well for all tested cases, even with previously proposed algorithms that are not performance-aware. (2) We propose a new control algorithm, Performance-Directed Dynamic (PD), that dynamically adjusts its thresholds periodically, based on available slack and recent workload characteristics. For memory, PD consumes the least energy when compared to previous hand-tuned algorithms combined with a performance guarantee. However, for disks, PD is too complex and its self-tuning is unable to beat previous hand-tuned algorithms. (3) To improve on PD, we propose a simpler, optimization-based, threshold-free control algorithm, Performance-Directed Static (PS). PS periodically assigns a static configuration by solving an optimization problem that incorporates information about the available slack and recent traffic variability to different chips/disks. We find that PS is the best or close to the best across all performance-guaranteed disk algorithms, including hand-tuned versions. (4) We also explore a hybrid scheme that combines PS and PD algorithms to further improve energy savings. © 2005, ACM. All rights reserved.

关键词： adaptation algorithms algorithms control algorithms Disk energy management lowpower design memory energy management multiple-power mode device performance guarantee

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Parallel-pipelined architecture for the Kalman based adaptive equalizer

Parallel-pipelined architecture for the Kalman based adaptiv...

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International Conference on Signal Processing, Communications and Networks

作者： Santha, Kr. Vaidehi, V.

ISBN: (纸本)9781424409969

The requirement of, many data communication systems is to employ an adaptive equalizer to minimize the inter-symbol interference. Several adaptive Kalman equalizers have been reported in literature. In these works either the Least Mean Square (LMS) or the Recursive Least Squares (RLS) or the Kalman algorithm have been adopted for channel estimation. The Kalman estimation method can lead to significant improvement in the receiver bit error rate (BER) performance. The use of a Kalman filter for channel estimation leads to a state model of size 2nx2n, where n is the number of filter taps. These solutions are computationally intensive and follow a nonlinear relation in the observation equation. New methods have to be followed to solve the nonlinear model resulting in complex parallel structures. This paper proposes a new approach for the real time implementation of the adaptive Kalman equalizer by providing two Kalman filters that run concurrently to perform the estimation and detection. Thus the Kalman estimator operates in parallel with the Kalman filter based equalizer following a linear model and the size of the state matrix reduces to nxn. Parallel-Pipelined architectures are proposed to perform the time update and measurement update equations of the Kalman equalizer and Kalman estimator. The functionality of the proposed architecture has been verified through VHDL simulation. The synthesis results are presented. It is shown that the convergence performance of the proposed approach is superior to that of the Kalman-RLS and Kalman-LMS adaptive equalizers.

关键词： channel estimation equalization systolic architecture adaptation algorithms

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Integrated dynamic QoS control for multimedia applications

Integrated dynamic QoS control for multimedia applications

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EUROPTO Symposium on Broadband European Networks (SYBEN 98)

作者： Bom, J Marques, P Correia, M Pinto, P Univ Tecn Lisboa Inst Super Tecn P-1000 Lisbon Portugal

ISBN: (纸本)0819428604

This paper presents an algorithm to control QoS for distributed multimedia applications. The algorithm approaches the problem in an integrated way solving both the problems of the network bandwidth and the load at the workstations. It interacts with the applications by an abstract sequence to describe values for QoS that are more meaningful to application programmers than the low-level entities such as cell loss rate, throughput, etc. Some experimental results of the algorithm are presented.

关键词： quality of service distributed multimedia applications real-time transport adaptation algorithms

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Wireless Bandwidth Management for Multiple Video Clients through Network-assisted DASH 17

Wireless Bandwidth Management for Multiple Video Clients thr...

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17th IEEE International Symposium on A World of Wireless, Mobile and Multimedia Networks (WoWMoM)

作者： Ojanpera, Tiia Kokkoniemi-Tarkkanen, Heli VTT Tech Res Ctr Finland Ltd Kaitovayla 1 Oulu Finland

ISBN: (纸本)9781509021857

Today's video streaming services utilize widely adaptive streaming techniques implemented over HTTP. While the approach is robust and compatible with today's internet architecture, middleboxes, and CDNs, it leaves several places for optimization. This paper proposes enhancements to the video bitrate adaptation solution of adaptive HTTP streaming by defining two network-assisted adaptation approaches based on a cognitive network management architecture. The architecture considered in the paper supports enhanced network and service awareness and distributed control over video bitrate adaptation. The presented bandwidth management concepts are experimented in a testbed environment, including prototypes of the proposed algorithms, signaling framework, and video streaming service supporting MPEG-DASH. The implementation details and evaluation results of the work introduced in this overview paper are planned to be included into a follow-up paper.

关键词： Network-assisted video streaming MPEG-DASH SAND adaptation algorithms testbed

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Towards Closed-Loop Brain-Machine Experiments across Wide-Area Networks

Towards Closed-Loop Brain-Machine Experiments across Wide-Ar...

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5th International IEEE Engineering-in-Medicine-and-Biology-Society (EMBS) Conference on Neural Engineering (NER)

作者： Rattanatamrong, Prapaporn Matsunaga, Andrea Brockmeier, Austin J. Sanchez, Justin C. Principe, Jose C. Fortes, Jose Univ Florida Dept Elect & Comp Engn Gainesville FL 32611 USA Univ Miami Dept Biomed Engn Coral Gables FL 33146 USA

ISBN: (纸本)9781424441419

Experiments for the online closed-loop control of neural prosthetics require feedback within 100ms. In a typical neurophysiology laboratory with local computing machines, a majority of this time is spent on acquiring and analyzing the neural signals and a minority (i.e. less than a millisecond) is actual data transfer among machines on local-or campus-area networks. However, the local computing machines may not offer the computational resources necessary for running complex algorithms or scenarios that have been recently proposed. While scientists can take advantage of remote computing resource providers, wide-area networks present much larger latencies that can affect an online experiment. This work presents a split modeling approach that allows the execution of a controller on the neurophysiology resource and the execution of computationally intensive modeling and adaptation algorithms on a remote datacenter, even with the inevitable network latency. Simulation results are presented to quantify how the accuracy of the controller is affected by the split modeling approach in the presence of delays, and to demonstrate that scientists can take advantage of remotely available massive resources.

关键词： adaptation model Computational modeling Data models Delay Neurophysiology Prosthetics Servers adaptation algorithms brain-computer interfaces closed-loop brain-machine experiments computationally intensive modeling computer centres controller data transfer delays local computing machines medical signal processing neural prosthetics neural signals neurophysiology neurophysiology laboratory prosthetics remote data center remotely available massive resources split modeling approach telemedicine wide area networks wide area networks

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Experimental Evaluation of a Wireless Bandwidth Management System for Multiple DASH Clients 59

Experimental Evaluation of a Wireless Bandwidth Management S...

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59th Annual IEEE Global Communications Conference (IEEE GLOBECOM)

作者： Ojanpera, Tiia Kokkoniemi-Tarkkanen, Heli VTT Tech Res Ctr Finland Ltd Kaitovayla 1 Oulu Finland

ISBN: (纸本)9781509013289

The paper proposes enhancements to adaptive video streaming over HTTP using a wireless bandwidth management architecture. The architecture enforces distributed control over video bitrate adaptation by providing additional network-side control information to video clients in order to assist them in their decision-making. The architecture and included distributed decision algorithms are network and service aware thanks to a cross-layer signaling framework. The paper presents an MPEG-DASH based testbed implementation of the architecture and studies its performance in the context of two network-assisted video adaptation use cases. The results, obtained in an experimental evaluation conducted using the testbed, attest the benefits of the proposed solution against a state-of-the-art client-side approach.

关键词： Network-assisted video streaming MPEG-DASH SAND adaptation algorithms testbed

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QoS control: An application integrated framework 1

QoS control: An application integrated framework

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1st IEEE International Conference on ATM (ICATM 98)

作者： Bom, J Marques, P Correia, M Pinto, P Univ Tecn Lisboa Inst Super Tecn Lisbon Portugal

ISBN: (纸本)0780349822

Network technology is becoming simpler in order to support the widest possible range of user applications. Therefore, the specific requirements of each application must be performed outside of the network and the adaptation mechanisms should be done by the applications. For the case of multimedia applications the programming task can even be more simplified if several "low-level" aspects can be made transparent by the use of a suitable framework. This paper presents such a framework with some algorithms to control some of the previous aspects, namely data handling and dynamic QoS control. It provides the application with a mechanism to constantly adapt the quality of the continuous media being transmitted. The algorithm takes into account not only the network conditions but the end host conditions as well. Some experiments are presented.

关键词： distributed multimedia quality of service dynamic QoS control adaptation algorithms

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