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1.
In response to the continuous growth in network bandwidth and application requirements, specialized chips called network processors have been built to deliver high performance and flexibility at moderate cost. Network processors often employ parallelism to achieve this high performance/cost ratio. However, the same parallelism can also make the behavior of the software difficult to understand. When applications need to maintain reliable performance under heavy load, seemingly unrelated code fragments can interact with each other unexpectedly because of hardware resource contention, thereby impacting performance. To help software designers deal with this problem, we propose using software simulation to compare the impact of different design choices on performance. We show that it is possible to use relatively simple models, yet still extract information that aids in performance tuning the system.  相似文献   

2.
Network processors are emerging as a programmable alternative to the traditional ASIC-based solutions in scaling up the data plane processing of network services. This work, rather than proposing new algorithms, illustrates the process of, and examines the performance issues in, prototyping a DiffServ edge router with IXP1200. The external benchmarks reveal that although the system can scale to a wire speed of 1.8 Gb/s in simple IP forwarding, the throughput declines to 180-290 Mb/s when DiffServ is performed due to the double bottlenecks of SRAM and microengines (coprocessors). Through internal benchmarks, the performance bottleneck was found to be able to shift from one place to another given different network services and algorithms. Most of the results reported here should be applicable to other NPs, since they have similar architectures and components.  相似文献   

3.
《Spectrum, IEEE》2001,38(1):66-68
The author describes how rapidly expanding network applications and soaring performance requirements need flexible microprocessor solutions that are powerful enough to handle ever-growing data traffic  相似文献   

4.
宽带通信已进入重大变革时期。随着信道密度 和每个信道处理性能的增加,使得大多数产品的结构显得过时。演变中的市场和多种标准,要求设备生产商增加系统软件的可编程性。网络处理器和新的数字信号处理器(DSP)已开始瞄准已有通信链路中的局部解决方案,但主要的瓶颈依然存在。最新出现的解决方案是可配置平台,它能提供多处理、指令级并行性和适应特定范围要求的灵活性。 迅速变化的标准和市场条件,连同需要在整个通信架构中保持稳定的设备环境,促使人们对宽带通信领域采用宽范围可…  相似文献   

5.
Existing knowledge about the correlates of innovation and the context of strategic decisions is used to develop propositions about the differences in the correlates of innovation in marketing and manufacturing functions. The theoretical model proposed is eclectic: it draws upon theory development in the fields of economics, engineering management, and corporate strategy. It is proposed that manufacturing managers link their innovation decisions to their assessment of the product's uniqueness in comparison with competitor's products. In contrast, marketing managers link their innovation decisions to the clarity of innovation objectives based on the customers' needs. The analysis of data from key informants in 172 firms is used to test the propositions. Whereas product uniqueness and clarity are significant correlates of innovation in the total sample, support is found for the proposition that the manufacturing subgroup focuses more on clarity  相似文献   

6.
The impact of network performance on user experience is important to know, as it determines the success or failure of a service. Unfortunately, it is very difficult to assess it in real-time on an operational network. Monitoring of network-level performance criteria is easier and more usual. But the problem is then to correlate these network-level Quality of Service (QoS) to the Quality of Experience (QoE) perceived by the users. Efforts have been done in the previous years to map user behaviour to traffic characteristics on the network to QoS. However, being able to successfully relate these traffic characteristics to user satisfaction is not a simple task and still requires further investigations. In this work, we try to associate on one side the correlations between various traffic characteristics measured on an operational network and on the other side the user experience tested on an experimental platform. Our aim is to observe some pronounced trends regarding relationships between both types of results. More precisely, we want to validate how and to what extent the volumes of user sessions represent the level of user satisfaction. Along this way, we need to revise classical relationships between some of the network performance indicators such as loss, download time and throughput in order to strengthen the understanding of this impact on each other and on user satisfaction. This preliminary study is based on the application web.  相似文献   

7.
In the last few years, evidence theory, also known as Dempster-Shafer theory or belief functions theory, have received growing attention in many fields such as artificial intelligence, computer vision, telecommunications and networks, robotics, and finance. This is due to the fact that imperfect information permeates the real-world applications, and as a result, it must be incorporated into any information system that aims to provide a complete and accurate model of the real world. Although, it is in an early stage of development relative to classical probability theory, evidence theory has proved to be particularly useful to represent and reason with imperfect information in a wide range of real-world applications. In such cases, evidence theory provides a flexible framework for handling and mining uncertainty and imprecision as well as combining evidence obtained from multiple sources and modeling the conflict between them. The purpose of this paper is threefold. First, it introduces the basics of the belief functions theory with emphasis on the transferable belief model. Second, it provides a practical case study to show how the belief functions theory was used in a real network application, thereby providing guidelines for how the evidence theory may be used in telecommunications and networks. Lastly, it surveys and discusses a number of examples of applications of the evidence theory in telecommunications and network technologies.  相似文献   

8.
The paper deals with the ATM (asynchronous transfer mode)-specific functions of source policing and connection acceptance control and their relationship to network management. The aspects of ATM-specific network management are based on the results achieved by the RACE project R1022, `Technology for ATD'. It is shown how these functions can be implemented according to the TMN (telecommunications management network) architecture suggested by the RACE project GUIDELINE (R1003). The interaction between these functions and other network management functions is discussed and the interaction of these functions with the management layers is presented in a way which is not dependent on the specific algorithms used for source policing and connection acceptance control  相似文献   

9.
Traditional in-class writing assignments often fail to engage students effectively. This problem may be compounded when students are forced into group projects, where a student may rightly feel that he or she could complete the entire assignment more effectively alone than the whole group could working together. In an attempt to alleviate these concerns, I assigned my university science writing class-half Professional Writing majors, half science majors and minors-the creation of an interactive, electronic murder mystery game. The students used PowerPoint to create linked slides in which the clues and cause of death were scientific information. While working on this assignment in class, a number of students forgot the time and kept working long after class was over. Several students reported losing track of time and place when working on the game at home.  相似文献   

10.
沙川 《电子测试》2016,(1):49-50
目的:探讨网络辅助教学平台对护生学习的促进作用。方法:选取我院护理专业600名学生,以使用THEOL网络教学平台用户体验为出发点,分别从主要原因、频率、帮助程度、满意度分析几个方面讨论网络教学平台可用性特点,用问卷调查的方法进行测试,通过该项测试发现存在的部分可用性问题,并针对问题提出可用性改进的建议。结果:问卷调查发现大部分同学认为网络教学平台对提高同学学习效率“有帮助”和“比较有帮助”。结论:应该将网络教学平台与护理教学结合起来,对学生学习有一定的促进作用。  相似文献   

11.
A survey of associative processing, techniques is presented, together with a guide to the published literature in this field. Some familiarity with the basic concepts of associative-processing is assumed. The references have been divided into four groups dealing with architectural concepts, hardware implementation, software considerations, and application areas. The discussion of architectural concepts consists of a classification of associative devices into four major categories (fully parallel, bit-serial, word-serial, and block-oriented) and an enumeration of techniques for dealing with multiple responses and hardware faults. With respect to hardware implementation, considerations are given to the basic operations implemented, hardware elements used (e.g., cryoelectrics, magnetic elements, and semiconductors), and physical characteristics such as speed, size, and cost. The discussion of software aspects of associative devices deals with synthesis of algorithms, programming problems, and software simulation. The application areas discussed include solution of some mathematical systems, radar signal processing, information storage and retrieval, and performance of certain control functions in computer systems.  相似文献   

12.
Boutaba  R. Polyrakis  A. 《IEEE network》2002,16(1):28-33
Active networks is a promising technology that allows us to control the behavior of network nodes by programming them to perform advanced operations and computations. Active networks are changing considerably the scenery of computer networks and, consequently, affect the way network management is conducted. Current management techniques can be enhanced and their efficiency can be improved, while novel techniques can be deployed. This article discusses the impact of active networks on current network management practice by examining network management through the functional areas of fault, configuration, accounting, performance and security management. For each one of these functional areas, the limitations of the current applications and tools are presented, as well as how these limitations can be overcome by exploiting active networks. To illustrate the presented framework, several applications are examined. The contribution of this work is to analyze, classify, and assess the various models proposed in this area, and to outline new research directions  相似文献   

13.
LSI Logic公司推出一系列适用与下一代ADSL2和ADSL2+技术客户接入端设备(CPE)的网络处理器芯片产品,该系列产品与LSI Logic的SpeedREACH模拟前端器件(AFE)以及相应的软件解决方案一起构成了一套完整解决方案.  相似文献   

14.
In the last few years, programmable architectures centered around high-end DSP processors have emerged as the platform of choice for high-volume embedded vision applications, such as automotive safety and video surveillance. Their programmability inherently addresses the problems presented by the sheer diversity of vision algorithms. This paper provides an overview of high-impact algorithmic and software techniques for embedded vision applications implemented on programmable architectures and discusses several system-level issues. We provide a general discussion and practical examples for the following categories of algorithmic techniques: fast algorithms, reduced dimensionality and mathematical shortcuts. Additionally, we discuss the importance of software techniques such as the use of fixed-point arithmetic, reduced data transfers and cache-friendly programming. In our experience, each of these techniques is a key enabler for real-time embedded vision systems.  相似文献   

15.
Architectures, algorithms, and applications for systolic processors are described with attention to the realization of parallel algorithms on various optical systolic array processors. Systolic processors for matrices with special structure and matrices of general structure, and the realization of matrix-vector, matrix-matrix, and triple-matrix products and such architectures are described. Parallel algorithms for direct and indirect solutions to systems of linear algebraic equations and their implementation on optical systolic processors are detailed with attention to the pipelining and flow of data and operations. Parallel algorithms and their optical realization for LU and QR matrix decomposition are specifically detailed. These represent the fundamental operations necessary in the implementation of least squares, eigenvalue, and SVD solutions. Specific applications (e.g., the solution of partial differential equations, adaptive noise cancellation, and optimal control) are described to typify the use of matrix processors in modern advanced signal processing.  相似文献   

16.
We consider optimum space-time equalizers with unknown dispersive interference, consisting of a linear equalizer that both spatially and temporally whitens the interference and noise, followed by a decision-feedback equalizer or maximum-likelihood sequence estimator. We first present a unified analysis of the optimum space-time equalizer, and then show that, for typical fading channels with a given signal-to-noise ratio (SNR), near-optimum performance can be achieved with a finite-length equalizer. Expressions are given for the required filter span as a function of the dispersion length, number of cochannel interferers, number of antennas, and SNR, which are useful in the design of practical near-optimum space-time equalizers  相似文献   

17.
In this opinion article, we see digital multimedia communications of the future dependent on business vision, evolving networking and consumer electronics technologies, and public policies regarding intellectual property and investment in communications infrastructure. As always, it is easy to predict a rich networked multimedia future, but difficult to say when or exactly how. These will be determined by social and business understandings on the divisive issues, by still uncertain consumer tastes and willingness to pay, and by resolving some technical obstacles. This brief article gives our personal perspectives on the current status of networked multimedia, the most promising multimedia applications, and the social and technical bottlenecks.  相似文献   

18.
Green power: status and perspectives   总被引:1,自引:0,他引:1  
The main objective of the so-called green power marketing is to provide selective customers of electric energy with choices to purchase electric energy from sustainable, environmentally friendly sources. This paper presents a rationale for marketing of green power provides a brief overview of some of the existing efforts in the United States and abroad, and attempts to identify the conditions and future trends for survival of renewable energy in the energy marketplace. Our goal is primarily to provide a representative sample of the current technology status, rather than a comprehensive coverage of worldwide initiatives in this area  相似文献   

19.
以太网无源光网络(EPON)和IEEE 802.16(WiMAX)的融合网络在固定移动混合接入网中被认为是很有前景的接入方式.文中提出了3种WiMAX无线网络与EPON网络系统融合架构,融合系统同时具有光网络的高带宽和无线网络的灵活性.为了在接入网中支持QoS,本文为融合结构提出了一种动态带宽分配算法(DBA)和调度机...  相似文献   

20.
Reliability of the current microprocessor technology is seriously challenged by radiation-induced soft errors. Accurate Vulnerability Factor (VF) modeling of system components is crucial in designing cost-effective protection schemes in high-performance processors. Although Statistical Fault Injection (SFI) techniques can be used to provide relatively accurate VF estimations, they are often very time-consuming. Unlike SFI techniques, recently proposed analytical models can be used to compute VF in a timely fashion. However, VFs computed by such models are inaccurate as the system-level impact of soft errors is overlooked.  相似文献   

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