A framework for bandwidth management in ATM networks-aggregateequivalent bandwidth estimation approach

A unified framework for traffic control and bandwidth management in ATM networks is proposed. It bridges algorithms for real-time and data services. The central concept of this framework is adaptive connection admission. It employs an estimation of the aggregate equivalent bandwidth required by connections carried in each output port of the ATM switches. The estimation process takes into account both the traffic source declarations and the connection superposition process measurements in the switch output ports. This is done in an optimization framework based on a linear Kalman filter. To provide a required quality of service guarantee, bandwidth is reserved for possible estimation error. The algorithm is robust and copes very well with unpredicted changes in source parameters, thereby resulting in high bandwidth utilization while providing the required quality of service. The proposed approach can also take into account the influence of the source policing mechanism. The tradeoff between strict and relaxed source policing is discussed     

Mechatronics-a powerful concurrent engineering framework

Mechatronics is emerging as a concurrent-engineering thinking framework in the process of designing complex machines. It is argued that mechatronics can be defined as the science of motion control. The different steps in the evolution from smart machines to intelligent autonomous systems are discussed and illustrated with many examples, mainly taken from the author's research experience.     

A low-state packet marking framework for approximate fair bandwidth allocation

Misbehaving, non-congestion-reactive traffic is on the rise in the Internet. One way to control misbehaving traffic is to enforce local fairness among flows. Locally fair policies, such as fair-queueing and other fair AQM schemes, are inadequate to simultaneously control misbehaving traffic and provide high network utilization. We thus need to enforce globally fair bandwidth allocations. However, such schemes have typically been stateful and complex to implement and deploy. In this letter, we present a low state, lightweight scheme based on stateless fair packet marking at network edges followed by RIO queueing at core nodes, to control misbehaving flows with more efficient utilization of network bandwidth. Additionally, with low-state feedback from bottleneck routers, we show that, in practice, we can approximate global max-min fairness within an island of routers. We show, using simulations, that we can indeed control misbehaving flows and provide more globally fair bandwidth allocation.     

On accounting for screen resolution in adaptive video streaming: QoE-driven bandwidth sharing framework

Screen resolution along with network conditions are main objective factors impacting the user experience, in particular for video streaming applications. User terminals on their side feature more and more advanced characteristics resulting in different network requirements for good visual experience. Previous studies tried to link mean opinion score (MOS) to video bitrate for different screen types (e.g., Common Intermediate Format [CIF], Quarter Common Intermediate Format [QCIF], and High Definition [HD]). We leverage such studies and formulate a Quality of Experience (QoE)-driven resource allocation problem to pinpoint the optimal bandwidth allocation that maximizes the QoE over all users of a network service provider located behind the same bottleneck link, while accounting for the characteristics of the screens they use for video playout. For our optimization problem, QoE functions are built using curve fitting on datasets capturing the relationship between MOS, screen characteristics, and bandwidth requirements. We propose a simple heuristic based on Lagrangian relaxation and Karush Kuhn Tucker (KKT) conditions to efficiently solve the optimization problem. Our numerical simulations show that the proposed heuristic is able to increase overall QoE up to 20% compared to an allocation with a TCP look-alike strategy implementing max-min fairness.     

Design and analysis of a bandwidth management framework forATM-based broadband ISDN

When designing and configuring an ATM-based B-ISDN, it remains difficult to guarantee the quality of service (QoS) for different service classes, while still allowing enough statistical sharing of bandwidth so that the network is efficiently utilized. These two goals are often conflicting. Guaranteeing QoS requires traffic isolation, as well as allocation of enough network resources (e.g., buffer space and bandwidth) to each call. However, statistical bandwidth sharing means the network resources should be occupied on demand, leading to less traffic isolation and minimal resource allocation. The authors address this problem by proposing and evaluating a network-wide bandwidth management framework in which an appropriate compromise between the two conflicting goals is achieved. Specifically, the bandwidth management framework consists of a network model and a network-wide bandwidth allocation and sharing strategy. Implementation issues related to the framework are discussed. For real-time applications the authors obtain maximum queuing delay and queue length, which are important in buffer design and VP (virtual path) routing     

A game theoretic framework for bandwidth allocation and pricing inbroadband networks

In this paper, we present a game theoretic framework for bandwidth allocation for elastic services in high-speed networks. The framework is based on the idea of the Nash bargaining solution from cooperative game theory, which not only provides the rate settings of users that are Pareto optimal from the point of view of the whole system, but are also consistent with the fairness axioms of game theory. We first consider the centralized problem and then show that this procedure can be decentralized so that greedy optimization by users yields the system optimal bandwidth allocations. We propose a distributed algorithm for implementing the optimal and fair bandwidth allocation and provide conditions for its convergence. The paper concludes with the pricing of elastic connections based on users' bandwidth requirements and users' budget. We show that the above bargaining framework can be used to characterize a rate allocation and a pricing policy which takes into account users' budget in a fair way and such that the total network revenue is maximized     

Lightpath communications: an approach to high bandwidth opticalWAN's

An architectural approach that meets high bandwidth requirements by introducing a communication architecture based on lightpaths, optical transmission paths in the network, is introduced. Since lightpaths form the building block of the proposed architecture, its performance hinges on their efficient establishment and management. It is shown that although the problem of optimally establishing lightpaths is NP-complete, simple heuristics provide near optimal substitutes for several of the basic problems motivated by a lightpath-based architecture     

Routing bandwidth guaranteed paths for traffic engineering in WiMAX mesh networks

In this paper, the authors present a novel algorithm for computing bandwidth guaranteed paths for traffic engineering in WiMAX IEEE 802.16 standard based networks using the mesh topology. The underlying algorithm fulfills routing requests ‘on the fly’ without a priori knowledge of future requests. This problem is motivated by the need for efficient handling of traffic and network resource utilization. The key idea behind the solution is the use of heuristic methods to defer routing through certain nodes, which have a higher chance of getting selected because of hop constraints, so that they can be prevented from congestion. Simulation‐based performance evaluation shows that the proposed algorithm performs well in comparison with the selected benchmarks on metrics such as the number of rejected requests and the active links present in the network. Copyright © 2013 John Wiley & Sons, Ltd.     

Minimum interference routing of bandwidth guaranteed tunnels withMPLS traffic engineering applications

This paper presents new algorithms for dynamic routing of bandwidth guaranteed tunnels, where tunnel routing requests arrive one by one and there is no a priori knowledge regarding future requests. This problem is motivated by the service provider needs for fast deployment of bandwidth guaranteed services. Offline routing algorithms cannot be used since they require a priori knowledge of all tunnel requests that are to be rooted. Instead, on-line algorithms that handle requests arriving one by one and that satisfy as many potential future demands as possible are needed. The newly developed algorithms are on-line algorithms and are based on the idea that a newly routed tunnel must follow a route that does not “interfere too much” with a route that may he critical to satisfy a future demand. We show that this problem is NP-hard. We then develop path selection heuristics which are based on the idea of deferred loading of certain “critical” links. These critical links are identified by the algorithm as links that, if heavily loaded, would make it impossible to satisfy future demands between certain ingress-egress pairs. Like min-hop routing, the presented algorithm uses link-state information and some auxiliary capacity information for path selection. Unlike previous algorithms, the proposed algorithm exploits any available knowledge of the network ingress-egress points of potential future demands, even though the demands themselves are unknown. If all nodes are ingress-egress nodes, the algorithm can still be used, particularly to reduce the rejection rate of requests between a specified subset of important ingress-egress pairs. The algorithm performs well in comparison to previously proposed algorithms on several metrics like the number of rejected demands and successful rerouting of demands upon link failure     

MRMC:一种高效的EPON动态带宽分配方案

提出一种高效的EPON动态带宽分配方案,即多标准带宽请求动态带宽分配方案(MRMC).MRMC采用分步请求/集中授权的轮询机制,ONU向OLT提出多个基于不同标准的带宽请求,OLT权衡选择授权带宽.该分配方案既考虑了ONU适时队列负载情况,又解决了阻塞帧问题,同时兼顾了公平性原则,进一步提高了EPON的工作效率.     

Web engineering: an introduction

Within a short period, the Internet and World Wide Web have become ubiquitous, surpassing all other technological developments in our history. They've also grown rapidly in their scope and extent of use, significantly affecting all aspects of our lives. Industries such as manufacturing, travel and hospitality, banking, education, and government are Web-enabled to improve and enhance their operations. E-commerce has expanded quickly, cutting across national boundaries. Even traditional legacy information and database systems have migrated to the Web. Advances in wireless technologies and Web-enabled appliances are triggering a new wave of mobile Web applications. As a result, we increasingly depend on a range of Web applications. Now that many of us rely on Web based systems and applications, they need to be reliable and perform well. To build these systems and applications, Web developers need a sound methodology, a disciplined and repeatable process, better development tools, and a set of good guidelines. The emerging field of Web engineering fulfils these needs. It uses scientific, engineering, and management principles and systematic approaches to successfully develop, deploy, and maintain high-quality Web systems and applications. It aims to bring the current chaos in Web based system development under control, minimize risks, and enhance Web site maintainability and quality     

一种增强型的移动数据交换系统架构模型

为解决移动网络环境质量对于移动互联平台的限制,研究了一种同时支持在线、离线的增强型移动数据交换方式,以尽可能小的代价,实现传统移动应用在无网络/网络异常/网络质量低下的情况下,进行正常作业的架构模型。该架构模型能够实现网络状况无关的移动数据访问,并保证在离线访问下数据的安全性。该架构模型支持多种移动操作系统,具有实现代价小,抗劣质网络环境、应用稳定、应用安全、提高移动数据访问速度等良好的优点。     

Extending the bandwidth of an instrumentation amplifier

A new configuration for operational amplifier based instrumentation amplifier is presented. The analytical expressions are obtained and the performance of the proposed circuit is examined in relation to the conventional circuit. Simulation and experimental results are presented which establish the superiority of the proposed instrumentation amplifier topology over the conventional circuit. The effect of second pole of op amps on the circuit stability has also been investigated. Numerical results are given in support of theoretical conclusions.     

A decision analytic framework for evaluating concurrent engineering

This paper quantifies key issues with regard to concurrent engineering through the use of risk and decision analysis techniques that enable us to better understand, structure, and manage the design process. In concurrent engineering, the information structure of a design process does not usually imply the execution patterns of the corresponding design tasks. On the contrary, this gap between the information structure and execution patterns is the essence of concurrent engineering and its basic advantage over traditional sequential design. In this paper, we relate the structure of information flow in a design process to three different execution strategies: sequential, partial overlapping, and concurrent. The risks of excessive task iterations or redesigns associated with each execution pattern are probabilistically modeled. Risk and decision analysis methodology is used to determine the best execution strategy and the optimal overlapping policy for a set of activities given their information structure. Applying this theoretical framework to a real-world design application of an automotive cylinder block suggested a potential 18% reduction in development cycle time     

复杂航空软件工程化综合管理框架

为规范软件研制管理工作,满足航空软件复杂性、可靠性、安全性高的特点需求,提高软件研制质量和效率,提出一个适合复杂航空软件研制特点的软件工程化综合管理框架。按照软件工程化开发、软件质量管理和软件验证三条主线推进软件研制能力的提高,结合某航空装备软件实际项目,给出实施软件工程化的管理体系和实施方法。     

iVoIP: an intelligent bandwidth management scheme for VoIP in WLANs

Voice over Internet Protocol (VoIP) has been widely used by many mobile consumer devices in IEEE 802.11 wireless local area networks (WLAN) due to its low cost and convenience. However, delays of all VoIP flows dramatically increase when network capacity is approached. Additionally, unfair traffic distribution between downlink and uplink flows in WLANs impacts the perceived VoIP quality. This paper proposes an intelligent bandwidth management scheme for VoIP services (iVoIP) that improves bandwidth utilization and provides fair downlink–uplink channel access. iVoIP is a cross-layer solution which includes two components: (1) iVoIP-Admission Control, which protects the quality of existing flows and increases the utilization of wireless network resources; (2) iVoIP-Fairness scheme, which balances the channel access opportunity between access point (AP) and wireless stations. iVoIP-Admission Control limits the number of VoIP flows based on an estimation of VoIP capacity. iVoIP-Fairness implements a contention window adaptation scheme at AP which uses stereotypes and considers several major quality of service parameters to balance the network access of downlink and uplink flows, respectively. Extensive simulations and real tests have been performed, demonstrating that iVoIP has both very good VoIP capacity estimation and admission control results. Additionally, iVoIP improves the downlink/uplink fairness level in terms of throughput, delay, loss, and VoIP quality.     

Neural networks: an engineering perspective

The development and application of neural networks are presented from an engineering perspective. It is stated that neural computing is a collection of mathematical techniques that have been gaining growing acceptance as plug-compatible replacements for statistical and other data-modeling techniques. Two of these techniques, function approximation and clustering, are discussed. The forces shaping the future of neural networking systems, including plug compatibility, hybrid systems-neural computing concepts integrated with expert systems, fuzzy logic, and genetic algorithms-and application specification systems, are reviewed     

Measurement of the bandwidth of an optical transphasor

We report measurements on the frequency dependence of transphasor gain using an indium antimonide etalon. Experimental results and a theoretical model indicate that the product of bandwidth and low frequency gain is approximately constant and that this constant is determined by the recombination rate of free carriers. The results should be generally applicable to devices of this type.     

Enhanced security protocol engineering through a unified multidimensional framework

Multidimensional security protocol engineering is effective for creating cryptographic protocols since it encompasses a variety of design, analysis, and deployment techniques, thereby providing a higher level of confidence than individual approaches offer. SPEAR II, the Security Protocol Engineering and Analysis Resource II, is a protocol engineering tool built on the foundation of previous experience garnered during the SPEAR I project in 1997. The goal of the SPEAR II tool is to facilitate cryptographic protocol engineering and to aid users in distilling the critical issues during an engineering session by presenting them with an appropriate level of detail and guiding them as much as possible during design, analysis and implementation. The SPEAR II tool currently consists of four components that have been integrated into one consistent and unified graphical interface: a protocol specification environment (GYPSIE), a GNY statement construction interface (visual GNY), a Prolog-based GNY analysis engine (GYNGER), and a message rounds calculator. The multidimensional approach realized by SPEAR II is combined with a graphical interface that focuses on making specification of a protocol and its associated conditions for formal analysis as straight forward and painless as possible. Experiments that we have conducted confirm that the analysis engine is able to generate accurate proofs for achievable GNY-based goals, while preliminary usability experiments have indicated that the interface utilized by SPEAR II is both expressive and simple to use for specifying cryptographic protocols and constructing logic statements pertaining to these protocols.     

CIRUS: an elastic cloud-based framework for Ubilytics

The Internet of Things (IoT) has become a reality with the availability of chatty embedded devices. The huge amount of data generated by things must be analysed with models and technologies of the “Big Data Analytics”, deployed on cloud platforms. The CIRUS project aims to deliver a generic and elastic cloud-based framework for Ubilytics (ubiquitous big data analytics). The CIRUS framework collects and analyses IoT data for Machine to Machine services using Component-off-the-Shelves (COTS) such as IoT gateways, Message brokers or Message-as-a-Service providers and big data analytics platforms deployed and reconfigured dynamically with Roboconf. In this paper, we demonstrate and evaluate the genericity and elasticity of CIRUS with the deployment of a Ubilytics use case using a real dataset based on records originating from a practical source.