Demand-wise Shared Protection for Meshed Optical Networks

In this paper, a new shared protection mechanism for meshed optical networks is presented. Significant network design cost reductions can be achieved in comparison to the well-known 1+1 protection scheme. Demand-wise Shared Protection (DSP) is based on the diversification of demand routings and exploits the network connectivity to restrict the number of backup lightpaths needed to provide the desired level of protection. Computational experiments illustrate the benefits of the DSP concept for cost efficient optical network designs.Arie M. C. A. Koster studied technical mathematics at Delft University of Technology, The Netherlands. His PhD thesis (University Maastricht, The Netherlands, 1999) deals with models and algorithms for frequency assignment in wireless networks. Currently, he is a researcher at the Zuse Institute Berlin (ZIB). His research interests are in mathematical optimization, algorithmic graph theory, and telecommunciation network design.Adrian Zymolka studied mathematics at the Philipps University in Marburg, Germany. Since 1999, he has been a research assistant at the Zuse Institute Berlin (ZIB) and works on mathematical optimization in telecommunications. His research focuses on the cost efficient design of survivable optical networks.Monika Jäger has been a senior scientist in the department of Photonic Networks and Network Architecture at T-Systems, Technologiezentrum in Berlin since 1998. She held previous positions with the Fraunhofer Institute for Open Communication Systems, and DeTeWe. In 1992, She graduated in Electrical Engineering fromMunich University of Technology,Germany.Her current research interests are in the area of optical transport network design.RalfHälsermann has been a junior research engineer in the department of PhotonicNetworks and Network Architecture at T-Systems Technologiezentrum in Berlin since August 2001. He graduated in 2001 from Deutsche Telekom AG, University of Applied Sciences, Leipzig, Germany. He is currently working on protection and restoration issues in optical networks.     

Survivable telecommunications network design under different types of failures

Telecommunications networks are expected to provide near-instantaneous restoration in the event that some network elements fail. Models for designing survivable networks are very complex and difficult to solve optimally. In this paper, we provide simple heuristics that augment existing network resources to ensure restoration under several scenarios of a single failure. The goal is to demonstrate that effective, though not necessarily optimal, survivable designs can be achieved by augmenting capacities along prudently selected variants of spanning tree and ring structures, without resorting to complex mathematical programming methods. The first model considers line restoration (reroutes around the failed link) under a partial link failure. We propose a heuristic that augments capacities of selected network links by forming a "virtual" spanning tree of restoration capacity. The second model provides line restoration under a complete link failure. We propose a heuristic that ensures survivability by repeatedly constructing spanning trees to various subnetworks. The third model provides path restoration (end-to-end reroutes) under a node failure. We propose a heuristic that repeatedly constructs restoration rings that cover a subset of source-destination nodes that carry traffic through intermediate nodes.     

Capacity assignment in computer communication networks with unreliable links

This paper considers the problem of selecting the optimum capacities of the links in a computer communication network which employs unreliable links. Given the nodes, links, link probabilities, grade of service and cost functions of the network, the objective of this problem is to find the optimum link capacities that minimize the network design cost, subject to the constraint equation involving the grade of service. This is essentially a combinatorial optimization problem. A general methematical model for this problem is formulated and a set of feasible solutions is obtained using Lagrangean relaxation and subgradient optimization techniques. A simulation study has been performed to verify the model, and favourable results obtained for a variety of nontrivial networks.     

Combination of clock-state and clock-rate correction in fault-tolerant distributed systems

This paper proposes the integration of internal and external clock synchronization by a combination of a fault-tolerant distributed algorithm for clock state correction with a central algorithm for clock rate correction. By means of hardware and simulation experiments it is shown that this combination improves the precision of the global time base in a distributed single cluster system while reducing the need for high-quality oscillators. Simulation results have shown that the rate-correction algorithm contributes not only in the internal clock synchronization of a single cluster system, but it can be used for external clock synchronization of a multi-cluster system with a reference clock. Therefore, deployment of the rate-correction algorithm integrates internal and external clock synchronization in one mechanism. Experimental results show that a failure in the clock rate correction will not hinder the distributed fault-tolerant clock state synchronization algorithm, since the state correction operates independently from the rate correction. The paper introduces new algorithms and presents experimental results on the achieved improvements in the precision measured in a time-triggered system. Results of simulation experiments of the new algorithms in single-cluster and multi-cluster configurations are also presented. Hermann Kopetz (Fellow, IEEE) received the Ph.D. degree in physics ísub auspiciis praesidentis from the University of Vienna, Vienna, Austria, in 1968. He was Manager of the Computer Process Control Department at Voest Alpine, Linz, Austria, and Professor of Computer Process Control, Technical University of Berlin, Berlin, Germany. He is currently Professor of Real-Time Systems, Vienna University of Technology, Vienna, Austria, and a Visiting Professor at the University of California, Irvine, and the University of California, Santa Barbara. In 1993, he was offered a position as Director of the Max Planck Institute, Saarbrcken, Germany. Prof. Kopetz is the key architect of the Time-Triggered Architecture. Astrit Ademaj (IEEE member) received the Dipl-Ing. degree (1995) at the University of Prishtina, Kosova, and a doctoral degree (2003) in computer science from the Technical University of Vienna. He is currently working as Assistant Professor at the Technical University of Vienna and as a Visiting Lecturer at the University of Prishtina. His research interests are design and validation of communication systems for safety-critical and real-time applications. He is a member of the IEEE Computer Society. Alexander Hanzlik received a diploma (1995) and a doctoral degree (2004) in computer science from the Technical University of Vienna. From 1995 to 1998, he was concerned with voice communication system design for air traffic control for the Service de Navigation Aérienne (STNA). Since 1998, his focus is on embedded systems in the fields of telecommunication, automation and process control. Since 2001, Dr. Hanzlik is a member of the Real-Time Systems Group and works as a research assistant at the Technical University of Vienna. His main research activities deal with fault-tolerant clock synchronization in distributed systems and simulation. Currently, he is working on SIDERA, a simulation model for time-triggered, dependable real-time architectures.     

基于端到端的单播层析网络时延分布

推断网络内部各链路的特性,已成为管理和评估大型电信网络的重要条件.通过某个特定路径直接监测每个链路是不现实的,所以一般通过发送端到端的探测包,利用网络的终端节点来收集网络链路的特征信息.通过单播探测包方法来推断链路的时延特性.针对网络内部链路时延累积量生成函数(CGF),提出一种基于端到端的单播探测包时延测量的偏差校正...     

Linear programming models for traffic engineering in 100% survivable networks under combined IS–IS/OSPF and MPLS-TE

This paper concerns the problem of minimizing the maximum link utilization of IP telecommunication networks under the joint use of traditional IGP routing protocols, such as IS–IS and OSPF, and the more sophisticated MPLS-TE technology. It is shown that the problem of choosing the optimal routing, both under working conditions and under single link failure scenarios, can be cast as a linear program of reasonable size. The proposed model is validated by a computational experimentation performed on synthetic and real networks: the obtained results show that the new approach considerably reduces the maximum link utilization of the network with respect to simply optimizing the IGP weights, at the cost of adding a limited number of label switched paths (LSPs). Optimizing the set of IGP weights within the overall approach further improves performances. The computational time needed to solve the models matches well with real-time requirements, and makes it possible to consider network design problems.     

Design Models for Robust Multi-Layer Next Generation Internet Core Networks Carrying Elastic Traffic

This paper presents three mathematical formulations for designing robust two-layer networks carrying elastic traffic. The formulations differ in the way flow reconfiguration is performed in the case of link failures. An iterative algorithm to solve the problems is given and a numerical study is provided comparing the effectiveness of the three reconfiguration mechanisms. The formulations can be applied for designing Next Generation Internet (NGI) core networks with the two-layer, IP-over-WDM, structure.Eligijus Kubilinskas received BS and MS degrees in Electronics Engineering, respectively from Kaunas University of Technology, Lithuania, in 1999 and Siauliai University, Lithuania, in 2001. Since 2002 he has been a PhD student at the Department of Communication Systems at Lund University, Sweden. His research interests are modeling and design/optimization of multi-layer networks.Pål Nilsson received MS from Lund University, Sweden, in 2001, and Lie Eng in Telecommunications from the same university in 2003. He is currently a PhD student at the Department ofCommunication Systems at Lund University. His main research interests are graph theory and network optimization, applied to backbone communication networks.Michal Pióro is a full professor at Warsaw University of Technology, Poland and at Lund University, Sweden. He is an author of four books (see for example [6]) and around 100 technical papers presented in the telecommunication journals and conference proceedings. He has led many research projects for telecom industry in the field of network modeling, design, and performance analysis.     

Topological network design for SONET ring architecture

Service restoration and survivability have become increasingly important in telecommunications network planning with the introduction of fiber-optic high-speed networks. Synchronous optical network (SONET) technology promotes the use of interconnected rings in designing reliable networks. We describe a heuristic approach for designing networks comprised of interconnected rings. Our approach is particularly attractive for relatively sparse networks in which the set of all cycles (constituting the potential rings) can be determined at a reasonable computational effort. Most networks fall into this category. Given a set of nodes, with demand among all possible node-pairs, and a set of available links that connect the nodes, the problem is to select an optimal subset of rings, utilizing only allowable links, such that each node is included in at least one ring and each ring is connected to at least one other ring at two or more nodes. Such a multiple ring network ensures instantaneous restoration of service in case of a single link or node failure. We first generate a large set of candidate rings and approximate the cost of each ring based on the nodes that are served by the ring and based on the demands. We then apply a set covering algorithm that selects a (minimum cost) subset of the candidate rings such that each node is included on at least one ring. Finally, we select a few additional rings in order to achieve the required connectivity among the rings. We present computational results for realistic-size (e.g., 500 nodes) telecommunication networks     

Semantics of finite and infinite networks of concurrent communicating agents

A language for describing finite and infinite networks of loosely coupled, concurrent, nondeterministic, communicating agents is introduced. To every program a finite or infinite graph (network) is related representing graphically the communication structure of the described system. A denotational semantics is defined based on fixed point theory. Algebraic laws for the networks are studied that allow to transform them without changing their denotational meaning. Following the increasing complexity of denotational models for stream-processing networks a hierarchy of five languages is treated: first a language of finite, deterministic networks, then infinite (i.e., recursively defined), deterministic ones, then nondeterministic finite and nondeterministic infinite networks with free choice merge. Finally we study a language including fair, nonstrict merge. Manfred Broy finished his studies with the Diplom in Mathematics and Computer Science at the Technical University of Munich. Till 1983 he was research and teaching assistant at the Institut für Informatik and the Sonderforschungsbereich 49 «Programmiertechnik». At the Technical University of Munich he also did his Ph.D. (in February 1980 with the subject: «Transformation parallel ablaufender Programme») and qualified as an university lecturer (in 1982 with the subject: «A Theory for Nondeterminism, Parallelism. Communication and Concurrency»). March 1982 he spent as a Visiting Professor at the University Paris Sud. Since April 1983 he has been Full Professor for Computer Science at the Faculty of Mathematics and Computer Science at the University of Passau. His fields of interest are: Programming languages, program development and distributed systems.     

A relative total cost index for the evaluation of transportation network robustness in the presence of degradable links and alternative travel behavior

In this paper, we demonstrate how to capture the robustness of a transportation network in the case of degradable links represented by decreasing capacities. In particular, with the use of Bureau of Public Roads user link travel cost functions, we propose two relative total cost indices to assess transportation network robustness in the case of travel behavior associated with either user optimization or system optimization. We derive upper bounds of the relative total cost index for transportation networks with special structure and congestion parameters under the user optimal flow pattern. We also derive an upper bound for the relative total cost index under the system optimal flow pattern for general transportation networks. Numerical examples are presented for illustration purposes. This research is the first to quantify transportation network robustness in the presence of degradable links and alternative travel behavior. This research has implications for transportation planning and management, for vulnerability analysis, as well as for security issues.     

Max–min fairness in multi-commodity flows

In this paper, we provide a study of Max–Min Fair (MMF) multi-commodity flows and focus on some of their applications to multi-commodity networks. We first present the theoretical background for the problem of MMF and recall its relations with lexicographic optimization as well as a polynomial approach for achieving leximin maximization. We next describe two applications to telecommunication networks, one on routing and the second on load-balancing. We provide some deeper theoretical analysis of MMF multi-commodity flows, show how to solve the lexicographically minimum load network problem for the link load functions most frequently used in telecommunication networks. Some computational results illustrate the behavior of the obtained solutions and the required CPU time for a range of random and well-dimensioned networks.     

Stereophotogrammetric 3D real-time machine vision

Signal processing algorithms often have to be modified significantly for implementation in hardware. Continuous real-time image processing at high speed is a particularly challenging task. In this paper a hardware-software codesign is applied to a stereophotogrammetric system. To calculate the depth map, an optimized algorithm is implemented as a hierarchical-parallel hardware solution. By subdividing distances to objects and selecting them sequentially, we can apply 3D scanning and ranging over large distances. We designed processor-based object clustering and tracking functions. We can detect objects utilizing density distributions of disparities in the depth map (disparity histogram). Motion parameters of detected objects are stabilized by Kalman filters. The text was submitted by the authors in English. Michael Tornow was born in Magdeburg, Germany, in 1977. He received his diploma engineer degree (Dipl.-Ing.) in electrical engineering at the University of Magdeburg, Germany, in 2002. He is currently working on a PhD thesis focusing on hardware adapted image processing and vision based driver assistance. Robert W. Kuhn received his diploma engineer degree (Dipl.-Ing.) in geodesy at the Technical University of Berlin, Germany, in 2000. His current work on a PhD thesis focuses on calibration and image processing. Jens Kaszubiak was born in Blankenburg, Germany, in 1977. He received his diploma engineer degree (Dipl.-Ing.) in electrical engineering at the University of Magdeburg, Germany, in 2002. His current research work focuses on vision-based driver assistance and hardware-software codesign. Bernd Michaelis was born in Magdeburg, Germany, in 1947. He received a Masters Degree in Electronic Engineering from the Technische Hochschule, Magdeburg, in 1971 and his first PhD in 1974. Between 1974 and 1980 he worked at the Technische Hochschule, Magdeburg, and was granted a second doctoral degree in 1980. In 1993 he became Professor of Technical Computer Science at the Otto-von-Guericke University, Magdeburg. His research work concentrates on the field of image processing, artificial neural networks, pattern recognition, processor architectures, and microcomputers. Professor Michaelis is the author of more than 150 papers. Gerald Krell was born in Magdeburg, Germany, in 1964. He earned his diploma in electrical engineering in 1990 and his doctorate in 1995 at Otto-von-Guericke University of Magdeburg. Since then he has been a research assistant. His primary research interest is focused on digital image processing and compression, electronic hardware development, and artificial neural networks.     

A new stochastic approach for a reliable p-hub covering location problem

A hub location problem (HLP) is a fertile research field, in the aspect of interdisciplinary studies, such as transportation, operation research, network design, telecommunication and economics. The location of hub facilities and allocation of non-hub nodes to hubs configure the backbone of HLPs. This study presents a new mathematical model for a reliable HLP by a new stochastic approach to minimize the total transportation cost and obtain maximum flows that the network can carry, when its link capacities are subject to stochastic degradations, as in a form of daily traffic, earthquake, flood, etc. We consider the road capacity reliability as a probability that ensures the maximum network capacity is greater than or equal to the total incoming flow to the network by considering the road capacity as random variable. As a result, this paper assumes that link capacities satisfy in a Truncated Erlang $(\mathit{TErl})$ distribution function. Due to complexity of the HLP, a meta-heuristic algorithm, namely differential evolution (DE) algorithm, is applied on the problem in order to achieve near-optimal solutions. Furthermore, the performance of the proposed algorithm (i.e., DE) is evaluated by the performance of the genetic algorithm (GA) applied on the given problem. Some computational experiments are presented to illustrate the effectiveness of the presented model and proposed algorithm. Finally the conclusion is provided.     

多链路因特网接入网络出口路径选择研究

针对当前企事业单位广泛使用多链路因特网接入问题,选取链路成本和影响网络性能的路由跳数作为多链路因特网接入网络的研究对象,建立多链路出口路径选择优化模型,在链路成本满足不大于zC_min的约束条件下,将多链路出口路径选择转化为路由跳数优化问题,并提出一个自适应多链路出口路径选择算法,模拟结果表明,提出的算法能达到提高网络性能,降低网络链路成本的目的。     

Competitive routing in networks with polynomial costs

We study a class of noncooperative general topology networks shared by N users. Each user has a given flow which it has to ship from a source to a destination. We consider a class of polynomial link cost functions adopted originally in the context of road traffic modeling, and show that these costs have appealing properties that lead to predictable and efficient network flows. In particular, we show that the Nash equilibrium is unique, and is moreover efficient. These properties make the polynomial cost structure attractive for traffic regulation and link pricing in telecommunication networks. We finally discuss the computation of the equilibrium in the special case of the affine cost structure for a topology of parallel links     

Facial expression recognition based on Haar-like feature detection

In this paper we propose a novel approach for facial feature detection in color image sequences using Haar-like classifiers. The feature extraction is initialized without manual input and has the capability to fulfill the real time requirement. For facial expression recognition, we use geometrical measurement and simple texture analysis in detecting facial regions based on the prior detected facial feature points. For expression classification we used a three layer feed forward artificial neural network. The efficiency of the suggested approach is demonstrated under real world conditions. The text was submitted by the authors in English. Axel Panning was born in Magdeburg, Germany, in 1980. He received his Masters Degree (Dipl.-Ing.) in Computer Science at the University of Magdeburg, Germany, in 2006. He is currently working on a PhD thesis focusing on image processing, tracking, and pattern recognition. Ayoub K. Al-Hamadi was born in Yemen in 1970. He received his Masters Degree (Dipl.-Ing.) in Electrical Engineering and Information Technology in 1997 and his PhD in Technical Computer Science at the Ottovon-Guericke-University of Magdeburg, Germany, in 2001. Since 2002 he has been Assistant Professor and Junior-Research-Group-Leader at the Institute for Electronics, Signal Processing, and Communications at the Otto-von-Guericke-University Magdeburg. His research work concentrates on the field of image processing, tracking analysis, pattern recognition, and artificial neural networks. Dr. Al-Hamadi is the author of more than 60 articles. Robert Niese was born in Halberstadt, Germany, in 1977. He received his Masters Degree (Dipl.-Ing.) with distinction in computer science at the Otto-von-Guericke-University Magdeburg, Germany, in 2004. He gathered broad experience in several international internship investigations on medical image and data analysis, including MRI, CT, and EEG. He is currently working at Magdeburg University on his PhD thesis, which focuses on 3D, image processing, tracking, and pattern recognition. Robert Niese is the author of more than 15 publications. Bernd Michaelis was born in Magdeburg, Germany, in 1947. He received a Masters Degree in Electronic Engineering from the Technische Hochschule Magdeburg in 1971 and his first PhD in 1974. Between 1974 and 1980 he worked at the Technische Hochschule Magdeburg and was granted a second doctoral degree in 1980. In 1993 he became Professor of Technical Computer Science at the Otto-von-Guericke University Magdeburg. His research work concentrates on the field of image processing, artificial neural networks, pattern recognition, processor architectures, and microcomputers. Professor Michaelis is the author of more than 200 papers.     

Strategic Network Restoration

For any networked infrastructure, damage to arcs and/or nodes and associated disruption of network services is inevitable. To reestablish service in a damaged network, affected components must be repaired or reconfigured, a process that can be time consuming and costly, so care must be taken to identify network restoration strategies that reestablish service most efficiently. A strategic goal of service restoration, therefore, is to ensure that facility restoration is prioritized so that system performance is maximized over a planning horizon within budgetary restrictions. To address this problem, this paper proposes a multi-objective optimization approach for network restoration during disaster recovery. The proposed model permits tradeoffs between two objectives, minimization of system cost and maximization of system flow, to be evaluated. A telecommunication application illustrates the significance of the developed approach.     

网络编码下的编码开销-链路开销联合优化

网络编码是一种新的网络传输技术,能够充分利用网络的理论组播速率上限.讨论了在网络编码下综合考虑编码开销和网络链路开销的网络总开销优化问题,将由网络编码引起的编码开销同样纳入优化问题的考虑范围.给出了2种各有优劣的网络信息流模型描述这一问题,并在不同模型下定义了2种开销的一般形式.由于这一优化问题属于NP难问题,目前一般采用启发式算法获得近似的优化解.随后的实验中,在不同规模的拓扑下对比了基于2种不同信息流模型的启发式算法的性能.由于考虑了编码开销使得联合优化问题远比链路开销优化问题复杂,模拟实验显示,只有当编码开销与链路开销价值系数之比达到1000以上时,才能获得比单纯链路优化更小的总开销.在提出基于遗传算法的方案之前,还简单地讨论了联合优化问题的复杂度.