Fiber-based local access network architectures

The attributes of the various architectural alternatives are discussed. Several systems proposed for the delivery of telephone service and/or distributive video services in the local access network are described. The status of the standardization of interfaces for the broadband integrated services digital network (BISDN) based on the synchronous optical network (SONET) and asynchronous transfer mode (ATM) is examined     

EPON接入保护架构及其性价比分析

高性价比的保护架构对EPON接入网安全稳定和经济有效的运行具有重要作用.文章首先概述了现有EPON接入保护架构类型,并且通过可靠性框图计算分析了各种保护架构的性能价格参数;最后结合电力系统应用环境,给出了满足电力系统通信业务需求的EPON接入最佳保护架构.     

光纤接入网规划探讨

随着全业务运营的全面开展以及光纤接入网在当前形势下所发挥的重要作用,提出了如何在光纤接入网规划过程中对目标用户密度区、OLT覆盖区、分光区以及接入光缆网进行规划的思路及方法.     

An evaluation of architectures incorporating wavelength divisionmultiplexing for broad-band fiber access

Wavelength division multiplexing (WDM) offers the potential to transport very high bit rates in access systems serving residential and small business customers. We describe the options for WDM access systems, and evaluate them on the basis of an international standard that is emerging for passive optical networks (PONs) that use wavelength-independent power splitting. The greatest impediment to meeting the high-bandwidth potential of WDM for downstream (i.e., from the central office to the home) transmission is the need for a moderately priced multiple-wavelength light source, implementing WDM in the upstream (home to central office) direction presents greater hurdles than in the downstream. The technical aspects of overcoming these hurdles can all be met. The real challenge will be in finding technical solutions that can meet the very stringent cost requirements of access systems. Systems that use WDM in the downstream direction only, while using wavelength-independent power-combining in a PON configuration for upstream, may prove economical before full WDM systems. WDM may also prove valuable if upgrades are needed in the future for power-splitting PON's     

Telecommunication access network design with reliability constraints

In this paper, we study the problem of the design of telecommunication access networks with reliability constraints. These networks form an important part of the telecommunications infrastructure of large organizations, such as banks. Using data patterned after an actual bank network in the U.S., we formulate an optimization model for this problem which specifically takes into account the various cost, and discount structures offered by telecommunication carriers. We then develop dedicated solution procedures for obtaining solutions. Starting from a cluster solution, we then use perturbation techniques which we developed specifically for this problem within an overall simulated annealing solution algorithm. We show how to make the solution procedure more efficient by implicitly determining the values for many variables. We then report the results of our computational testing for a variety of problems. We compare our solution to a lower bound obtained using a linear programming relaxation. We show that substantial cost savings can be realized with our model, and solution procedure. Finally, we discuss which types of annealing steps in the simulated annealing algorithm are important.     

光接入网技术发展掠影

从光接入网的概念出发，介绍了光接入网的接入、应用类型及传输技术等，并阐述其主要发展趋势。     

RBF网络用于性能退化的可靠性评估

针对无法用数学式准确描述退化量与环境因子间复杂非线性关系的问题,提出了一种基于RBF网络的退化轨迹建模方法.利用RBF网络能够逼近任意非线性函数的特性,进行退化轨迹的建模,并结合失效值预测产品寿命.将所有估计寿命作为完全失效数据进行可靠性评估,有效地解决了失效数据少的问题.通过对疲劳裂纹增长数据的RBF网络建模分析,证明RBF网络具有很好的函数逼近能力,寿命预测结果非常理想.经验证,在更少的退化数据下,RBF网络仍能够较好地模拟退化轨迹,寿命预测精度较高.     

用户行为统计特性对通信网络性能可靠性的影响

针对二维方格网络模型,对用户访问网络资源过程中呈现的幂律特性和集聚特性进行了建模,借助网络相变分析了用户访问行为的统计特性对网络性能可靠性带来的影响。研究结果表明,用户访问资源节点形成的二分网络的度分布的幂律特性对网络性能可靠性的影响较小,但这种二分网络中具有高访问量的资源节点子集的频繁衍变会改善网络的性能可靠性;用户访问行为的集聚特性中突发性访问的强度、频率和持续时间在一定程度上影响着网络性能可靠性的相变行为;随着突发性访问与正常性访问时间单元之间活动用户数量比值的增大,网络性能可靠性的相变点逐渐右移,即网络更加能够容忍高强度的突发性访问。     

ATM-based signaling network topics on reliability and performance

The authors consider some reliability and performance aspects of ATM-based signaling networks. They present ideas on how ATM technology, suitable system concepts, as well as simplified and enhanced protocols could maintain or even improve the reliability level of the existing Common Channel Signaling System No. 7. They also discuss possible scenarios for the interworking of ATM-based signaling networks with existing signaling networks. They also examine the aspect of performance enhancement in terms of reduced delays and increased throughput due to the ATM signaling connections with higher bit rates and protocol simplifications     

基于WDM/OCDMA-PON的光纤无线混合接入网结构

通过分析波分多址技术、码分多址技术的PON光纤接入技术和宽带无线技术相结合的混合光纤无线接入网技术的优越性和可行性,提出了基于WDM/OCDMA-PON光纤无线混合(HOWBAN)接入网技术的基本结构,给出WDM/OCDMA-PON光纤无线混合接入网系统的实现方案,提出了应用前景等.     

Impact of the access network topology on the handoff performance

Micromobility protocols such as Cellular IP, Hawaii and Hierarchical Mobile IP are developed to solve problems of high handoff latency and control overhead, which occur when Mobile IP is used in combination with frequent handoffs. Up to now, tree access network topologies are considered to evaluate the protocol performance. However, for reasons of robustness against link failures and load balancing, extra uplinks and mesh links in the topology are desired. This article makes a classification of several topology types and gives a model that points out to which extent the topology influences the protocol performance in terms of handoff latency and handoff packet loss. Simulations confirm the results calculated by the model. Performance metrics such as load balancing, end-to-end delay and robustness against link failures are also evaluated. The study points to several shortcomings of the existing micromobility protocols for different topology types. Several aspects of the studied handoff schemes, their advantages and drawbacks are identified. L. Peters is a Research Assistant of the Fund for Scientific Research – Flanders (F.W.O.-V., Belgium) Liesbeth Peters was born in Temse, Belgium, in 1978. She received her Master of Science degree in Electrotechnical Engineering from Ghent University, Gent, Belgium in 2001. Since August 2001, she has been working as a doctoral researcher with the Department of Information Technology (INTEC) of the Faculty of Applied Sciences, Ghent University, where she joined the Broadband Communications Networks Group. Since October 2002, she works there as a research assistant of the Fund for Scientific Research—Flanders (F.W.O.-V., Belgium). Her current research interests are in broadband wireless communication and the support of IP mobility in wired cum wireless networks. Ingrid Moerman was born in Gent, Belgium, in 1965. She received the degree in Electro-technical Engineering and the Ph.D degree from the Ghent University, Gent, Belgium in 1987 and 1992, respectively. Since 1987, she has been with the Interuniversity Micro-Electronics Centre (IMEC) at the Department of Information Technology (INTEC) of the Ghent University, where she conducted research in the field of optoelectronics. In 1997, she became a permanent member of the Research Staff at IMEC. Since 2000 she is part-time professor at the Ghent University. Since 2001 she has switched her research domain to broadband communication networks. She is currently involved in the research and education on broadband mobile & wireless communication networks and on multimedia over IP. Her main research interests related to mobile & wireless communication networks are: adaptive QoS routing in wireless ad hoc networks, personal networks, body area networks, wireless access to vehicles (high bandwidth & driving speed), protocol boosting on wireless links, design of fixed access/metro part, traffic engineering and QoS support in the wireless access network. Ingrid Moerman is author or co-author of more than 300 publications in the field of optoelectronics and communication networks. Bart Dhoedt received a degree in Engineering from the Ghent University in 1990. In September 1990, he joined the Department of Information Technology of the Faculty of Applied Sciences, University of Ghent. His research, addressing the use of micro-optics to realize parallel free space optical interconnects, resulted in a PhD degree in 1995. After a 2 year post-doc in opto-electronics, he became professor at the Faculty of Applied Sciences, Department of Information Technology. Since then, he is responsible for several courses on algorithms, programming and software development. His research interests are software engineering and mobile & wireless communications. Bart Dhoedt is author or co-author of more than 100 papers published in international journals or in the proceedings of international conferences. His current research addresses software technologies for communication networks, peer-to-peer networks, mobile networks and active networks. Piet Demeester finished his PhD thesis at the Department of Information Technology (INTEC) at the Ghent University in 1988. At the same department he became group leader of the activities on Metal Organic Vapour Phase Epitaxial growth for optoelectronic components. In 1992 he started a new research group on Broadband Communication Networks. The research in this field resulted in already more than 300 publications. In this research domain he was and is a member of several programme committees of international conferences, such as: ICCCN, the International Conference on Telecommunication Systems, OFC, ICC, and ECOC. He was Chairman of DRCN’98. In 2001 he was chairman of the Technical Programme Committee ECOC’01. He was Guest Editor of three special issues of the IEEE Communications Magazine. He is also a member of the Editorial Board of the Journals “Optical Networks Magazine” and “Photonic Network Communications”. He was a member of several national and international PhD thesis commissions. Piet Demeester is a member of IEEE (Senior Member), ACM and KVIV. His current research interests include: multilayer networks, Quality of Service (QoS) in IP-networks, mobile networks, access networks, grid computing, distributed software, network and service management and applications (supported by FWO-Vlaanderen, the BOF of the Ghent University, the IWT and the European Commission). Piet Demeester is currently full-time professor at the Ghent University, where he is teaching courses in Communication Networks. He has also been teaching in different international courses.     

ROF接入网络认知MAC信道最优迭代注水算法研究

研究基于认知多址接人信道（C—MAC）的光纤无线通信（ROF）接入网络在发射功率以及干扰温度约束下的系统加权总容量（we岫ted—SumRate）最大化问题。由单人多出（SIMO）模型的特殊算法作为切入点,通过部分对偶分解技术,松弛干扰温度约束,将原始问题分解为较易处理的子问题;另外针对文献[133所提方法的不足,提出一种适用于多人多出（MIMO）天线系统的迭代注水算法以求解最大系统加权容量。最后通过仿真表明算法的有效性。     

WLAN无线接入网络规划及其网络性能优化研究

随着WLAN无线的发展,其覆盖区域、用户量、网络容量不断增加,使其接入网络规划的问题逐渐成为建设公共无线局域网的重要问题.同时,对WLAN无线接入网络性能优化是满足用户需求的关重要手段,网络性能优化主要有覆盖优化、容量优化、设备优化.     

分布式电源对配电网供电可靠性的影响及接入优化研究

分布式电源接入对配电网供电可靠性的影响是目前供电企业研究的主要问题,分布式电源技术在我国起步较晚,仍旧属于新型技术。在发挥着重要作用的同时,也存在一些问题。本文对分布式发电技术进行了分析,并研究了对配电网供电可靠性的影响,同时对接入优化展开了相关的研究。     

高性能网络接入服务器底层通信模块的设计

能高速有效响应海量客户端连接请求和处理数据通信是设计高性能网络接入服务器的关键。基于对完成端口封装的情况下,使用池、环形缓冲区等技术设计一种具有高性能的网络接入服务器底层通信模块。压力和性能测试结果表明,该模块在低消耗系统资源的情况下支持海量并发连接,并具有较高的吞吐率。     

未来网络体系架构研究综述

现有互联网正面临着前所未有的挑战,包括可扩展性、安全性、管控性、移动性、内容分发能力、绿色节能等一系列问题,难以通过增量式的研究模式彻底解决。在这样的背景下,创新型的未来网络体系架构研究成为当前全球关注的热点领域。通过介绍全球在该领域的研究进展情况,阐述当前该领域主要的研究成果,总结分析该领域的研究发展趋势与核心问题,期望对国内该领域的研究起到参考和帮助。     

E-BAMA vs. RAMA [multiple access protocols]

The article presents a performance comparison of two random access protocols for wireless mobile signaling in which a single channel is dedicated to the signaling function, enhanced beacon assisted multiple access (E-BAMA) and resource auction multiple access (RAMA). Data traffic is transported separately on a set of orthogonal channels. The beacon assisted multiple access (BAMA) protocol was first presented as a method of providing mobility management functions, e.g., handover, while minimizing the processing burden placed on the mobile. In BAMA, throughout the duration of its call, an active user repeatedly and quasi-periodically broadcasts a beacon containing its ID using the Aloha protocol. Quasi-periodicity prevents a pair of users from repeatedly colliding with each other. When a base successfully receives the beacon and assigns a channel, it uses a separate downstream channel to send to the mobile an acknowledgement that contains the number of the assigned channel. The BAMA protocol includes a scheme to maintain lists of active mobiles in nearby cells and to exchange periodically these lists among the base-stations. The authors evaluate the capacity and delay performance of E-BAMA and RAMA. Then, they present a numerical comparison of the parameters. Finally, the results are summarized qualitatively. Some additional derivation is included in the appendix     

宽带接入网中的噪声闪断技术研究

针对上行带宽资源有限，反向通道噪声大造成上行速率低、运行不稳定问题，利用神经网络理论、小波理论和遗传算法实现宽带接入网的上行带宽智能控制和噪声闪断技术，从而提高宽带接入网的上行频带利用率和抗干扰能力。