网状WDM网络的抗毁设计

本文使用整数线性规划法对多光纤网状WDM网络进行抗毁设计,使用的保护策略为共享通道保护和共享链路保护,网络设计的优化目标是使全网铺设的光纤总长度最短。然后以类CERNET为例,求解出不同保护策略下网络需要的光纤总长度,并分析了它们各自的特点以及波长转换对目标函数值的影响。     

Error resilient video transmission over ATM networks

In the transmission process of a variable bit rate video signal over an ATM network, cells are inevitably exposed to delays and losses due to the statistical multiplexing used in these networks. These phenomena affect the quality of the video signal, and without adequate measures to control the propagation of impairments, the quality of service may fall below acceptable levels. We introduce a set of control mechanisms at different levels of the protocol architecture to support MPEG-2 based video communications systems using ATM networks as their underlying transmission mechanism. We argue that in order to be able to create video systems able to cope with cell losses encountered in computer communications systems, a structured set of protocol mechanisms is required. Our results show the effectiveness of the proposed set of mechanisms in improving the robustness of the video delivery system     

CORA: Correlation-based resilient aggregation in sensor networks

In this paper, we consider the problem of resilient data aggregation in sensor networks, namely, how to aggregate sensor readings collected by the base station when some of those sensor readings may be compromised. Note that an attacker can easily compromise the reading of a sensor by altering the environmental parameters measured by that sensor. We present a statistical framework that is designed to mitigate the effects of the attacker on the output of the aggregation function. The main novelty of our approach compared to most prior work on resilient data aggregation is that we take advantage of the naturally existing correlation between the readings produced by different sensors. In particular, we show how spatial correlation can be represented in the sensor network data model, and how it can be exploited to increase the resilience of data aggregation. The algorithms presented in this paper are flexible enough to be applied without any special assumption on the distribution of the sensor readings or on the strategy of the attacker. The effectiveness of the algorithms is evaluated analytically considering a typical attacker model with various parameters, and by means of simulation considering a sophisticated attacker.     

Designing secure sensor networks

Sensor networks are expected to play an essential role in the upcoming age of pervasive computing. Due to their constraints in computation, memory, and power resources, their susceptibility to physical capture, and use of wireless communications, security is a challenge in these networks. The scale of deployments of wireless sensor networks require careful decisions and trade-offs among various security measures. The authors discuss these issues and consider mechanisms to achieve secure communication in these networks.     

Analysis and design of resilient multifiber wavelength-routedoptical transport networks

Wavelength-routed optical networks (WRONs) are attracting significant attention for future high-capacity transport applications. This paper studies resilient multifiber WRONs, investigating the influence on the network performance of the maximum number of wavelengths per fiber W restoration strategies, node functionality, and physical topology. Fiber requirements are analyzed for numerous network topologies both without and with link failure restoration, considering different optical cross-connect (OXC) configurations and terminal functionalities. An integer linear program (ILP) formulation is presented for the exact solution of the routing and wavelength allocation (RWA) problem, with minimal total number of fibers, F_T (W). Lower bounds on F_T(W) are discussed, and heuristic algorithms proposed. Three restoration strategies are considered and compared in terms of capacity requirement. Different network topologies are analyzed, to evaluate the influence of physical connectivity and network size on the restoration capacity. Network evolution in terms of growth in traffic demand is investigated to study the importance of wavelength conversion within the OXC's as a function of network size and connectivity, traffic demand, and wavelength multiplicity W     

A randomized energy-conservation protocol for resilient sensor networks*

In this paper we present PEAS, a randomized energy-conservation protocol that seeks to build resilient sensor networks in the presence of frequent, unexpected node failures. PEAS extends the network lifetime by maintaining a necessary set of working nodes and turning off redundant ones, which wake up after randomized sleeping times and replace failed ones when needed. The fully localized operations of PEAS are based on each individual node's observation of its local environment but do not require per neighbor state at any node; this allows PEAS to scale to very dense node deployment. PEAS is highly robust against node failures due to its simple operations and randomized design; it also ensures asymptotic connectivity. Our simulations and analysis show that PEAS can maintain an adequate working node density in presence of as high as 38% node failures, and a roughly constant overhead of less than 1% of the total energy consumption under various deployment densities. It extends a sensor network's functioning time in linear proportional to the deployed sensor population. Fan Ye received his B.E. in Automatic Control in 1996 and M.S. in Computer Science in 1999, both from Tsinghua University, Beijing, China. He received his Ph.D. in Computer Science in 2004 from UCLA. He is currently with IBM Research. His research interests are in wireless networks, sensor networks and security. Honghai Zhang received his BS in Computer Science in 1998 from University of Science and Technology of China. He received his MS and Ph.D. in Computer Science from University of Illinois at Urbana-Champaign. He is currently with the Wireless Advanced Technology Lab of Lucent Technologies. His research interests are wireless networks, WiMAX, and VoIP over wireless networks. Songwu Lu received both his M.S. and Ph.D. from University of Illinois at Urbana-Champaign. He is currently an associate professor at UCLA Computer Science. He received NSF CAREER award in 2001. His research interests include wireless networking, mobile computing, wireless security, and computer networks. Lixia Zhang received her Ph.D in computer science from the Massachusetts Institute of Technology. She was a member of the research staff at the Xerox Palo Alto Research Center before joining the faculty of UCLA’s Computer Science Department in 1995. In the past she has served on the Internet Architecture Board, Co-Chair of IEEE Communication Society Internet Technical Committee, the editorial board for the IEEE/ACM Transactions on Networking, and technical program committees for many networking-related conferences including SIGCOMM and INFOCOM. Zhang is currently serving as the vice chair of ACM SIGCOMM. Jennifer C. Hou received the Ph.D. degree in Electrical Engineering and Computer Science from The University of Michigan, Ann Arbor in 1993 and is currently a professor in the Department of Computer Science at University of Illinois at Urbana Champaign (UIUC). Prior to joining UIUC, she has taught at Ohio State University and University of Wisconsin - Madison. Dr. Hou has worked in the the areas of network modeling and simualtion, wireless-enabled software infrastructure for assisted living, and capacity optimization in wireless networks. She was a recipient of an ACM Recognition of Service, a Cisco University Research Award, a Lumley Research Award from Ohio State University, and a NSF CAREER award. ^*A Shorter version of this paper appeared in ICDCS 2003.     

Designing multiprotocol label switching networks

Multiprotocol label switching adds to the capabilities of IP networks in several ways. Despite new capabilities, MPLS technology has much in common with ordinary IP networks. In turn, the design process for MPLS networks has much in common with the design of any IP network. This article examines MPLS and IP technology with particular emphasis on what is common between them. The common design steps of MPLS networks and other IP networks are outlined briefly, and those issues specific to MPLS networks are covered in more detail. This article emphasizes MPLS point of presence design, routing design issues for MPLS, and provisioning of sufficient label space     

Centralized vs. distributed algorithms for resilient 5G access networks

Photonic Network Communications - Cloud radio access networks (C-RANs), relying on network function virtualization and software-defined networking (SDN), require a proper placement of baseband...     

Designing reliable networks with short paths

We present a technique for constructing highly reliable networks in which locations consist of pairs of redundant vertices and in which every pair of locations has a pair of short disjoint paths connecting them. One of the paths between locations has one hop and, in most cases, the other path between locations has two hops. We further show that the networks have as few edges as possible and the vertices in the networks have nearly as small a degree as possible.     

Designing communication subsystems for high-speed networks

Is shown that system structure and implementation of a communication subsystem are vital elements in high-throughput protocol implementation. A well-structured and carefully implemented subsystem can exploit high-speed transmission links and preserve their speed up to the application. The issues of memory management and organization are presented as examples. Support for data movement and processing overlap, and intelligent DMA, two alternatives for the communication subsystem to achieve higher performance and scale to higher-speed links, are discussed     

Designing service-independent capabilities for intelligent networks

A key attribute desired of intelligent networks is the ability to design multiple services from a set of service-independent capabilities. Some aspects of the planning, requirements specification, design. and development processes to produce such capabilities are examined. Important factors and considerations necessary to the successful realization of service independence are described     

Designing long reach optical access networks

The long reach optical access concept promises to reduce the cost of a future BT network through simplification. This is achieved by extending the reach and split of today’s passive optical network systems (PONs) to 100 km and 1024 respectively, thus eliminating the need for separate backhaul equipment. Compact, low-power optical amplifiers are used at exchange locations requiring very low electrical power consumption. Ultimately this could effectively eliminate local exchange buildings and consolidate BT’s network to around a hundred metro nodes, drastically reducing operational costs. In this paper we describe research to date on the techniques to overcome physical layer impairments at costs appropriate for residential access. We also highlight from an operator’s point of view the protocol requirements of the LR-PON concept, point out the necessary changes to the GPON protocol, and describe an experiment to show its suitability to work over 100 km distances at 10 Gbit/s.     

Designing power aware self-reconfiguring topology for mobile wireless personal area networks using fuzzy logic

In mobile wireless personal area networks (WPAN), the position of each node changes over time. A network protocol that is able to dynamically update its links in order to maintain strong connectivity is said to be "self-reconfiguring." We propose a mobile wireless personal area networks (WPAN) design method with self-reconfiguring protocol for power efficiency. The WPAN is self-organized to clusters using an unsupervised clustering method, fuzzy c-means. A fuzzy logic system is applied to master/controller election for each cluster. A self-reconfiguring topology is proposed to manage the mobility and recursively update the network topology. We also modify the mobility management scheme with hysteresis to overcome the ping-pong effect. Simulation results show that our scheme performs much better than the existing algorithm.     

Improving proactive routing with a multicriteria and adaptive framework in ad-hoc wireless networks

Wireless Networks - Ad hoc wireless networks have aroused much interest of the scientific community in the last two decades. The provision of Quality of Service (QoS) is a prominent challenge in...     

Optimal placement and routing strategies for resilient two‐tiered sensor networks

In hierarchical sensor networks using relay nodes, sensor nodes are arranged in clusters and higher powered relay nodes can be used as cluster heads. The lifetime of such a network is determined primarily by the lifetime of the relay nodes. In this paper, we propose two new integer linear programs (ILPs) formulations for optimal data gathering, which maximize the lifetime of the upper tier relay node network. Unlike most previous approaches considered in the literature, our formulations can generate optimal solutions under the non‐flow‐splitting model. Experimental results demonstrate that our approach can significantly extend network lifetime, compared to traditional routing schemes, for the non‐flow‐splitting model. The lifetime can be further enhanced by periodic updates of the routing strategy based on the residual energy at each relay node. The proposed rescheduling scheme can be used to handle single or multiple relay node failures. We have also presented a very simple and straightforward algorithm for the placement of relay nodes. The placement algorithm guarantees that all the sensor nodes can communicate with at least one relay node and that the relay node network is at least 2‐connected. This means that failure of a single relay node will not disconnect the network, and data may be routed around the failed node. The worst case performance of the placement algorithm is bounded by a constant with respect to any optimum placement algorithm. Copyright © 2008 John Wiley & Sons, Ltd.     

基于DMA的接口板设计与开发

本文介绍了某型飞机飞参系统信息记录的数据结构,论述了一种基于DMA传送方式的飞参接口板设计思想、基本原理、开发中的难点,以及未来的发展方向。     

Designing multihop wireless backhaul networks with delay guarantees

As wireless access technologies improve in data rates, the problem focus is shifting towards providing adequate backhaul from the wireless access points to the Internet. Existing wired backhaul technologies such as copper wires running at DSL, T1, or T3 speeds can be expensive to install or lease, and are becoming a performance bottleneck as wireless access speeds increase. Longhaul, non-line-of-sight wireless technologies such as WiMAX (802.16) hold the promise of enabling a high speed wireless backhaul as a cost-effective alternative. However, the biggest challenge in building a wireless backhaul is achieving guaranteed performance (throughput and delay) that is typically provided by a wired backhaul. This paper explores the problem of efficiently designing a multihop wireless backhaul to connect multiple wireless access points to a wired gateway. In particular, we provide a generalized link activation framework for scheduling packets over this wireless backhaul, such that any existing wireline scheduling policy can be implemented locally at each node of the wireless backhaul. We also present techniques for determining good interference-free routes within our scheduling framework, given the link rates and cross-link interference information. When a multihop wireline scheduler with worst case delay bounds (such as WFQ or Coordinated EDF) is implemented over the wireless backhaul, we show that our scheduling and routing framework guarantees approximately twice the delay of the corresponding wireline topology. Finally, we present simulation results to demonstrate the low delays achieved using our framework.     

Automated ischemic beat classification using genetic algorithms and multicriteria decision analysis

Cardiac beat classification is a key process in the detection of myocardial ischemic episodes in the electrocardiographic signal. In the present study, we propose a multicriteria sorting method for classifying the cardiac beats as ischemic or not. Through a supervised learning procedure, each beat is compared to preclassified category prototypes under five criteria. These criteria refer to ST segment changes, T wave alterations, and the patient's age. The difficulty in applying the above criteria is the determination of the required method parameters, namely the thresholds and weight values. To overcome this problem, we employed a genetic algorithm, which, after proper training, automatically calculates the optimum values for the above parameters. A task-specific cardiac beat database was developed for training and testing the proposed method using data from the European Society of Cardiology ST-T database. Various experimental tests were carried out in order to adjust each module of the classification system. The obtained performance was 91% in terms of both sensitivity and specificity and compares favorably to other beat classification approaches proposed in the literature.     

Designing scalable on-demand policy-based resource allocation in IP networks

Today, the policy-based management approach is recognized as an efficient solution to simplify the complex task of managing and controlling networks. To this end, the IETF has introduced a reference framework to build PBM systems. However, this framework only addresses the provisioning of relatively long validity period services based on pre-defined service level agreements. Furthermore, very little work addresses the scalability properties of the instantiation of this framework in a real network. This work aims to extend the IETF PBM framework in order to support dynamic provisioning of short term services (end system signaling) as well as an instantiation scheme that is scalable (distributed provisioning of edge routers). This instantiation scheme is based on the distribution of the provisioning process while keeping centralized only the parts that involve critical resources, that is, the bandwidth brokerage. The performance properties of the proposed scheme are then demonstrated throughout both extensive experimentation and a short analytical study. The results of this work are intended to be used as a guideline to help network operators to design scalable PBM system in order to offer to their customers services with QoS assurance in an on-demand basis.