高速铁路宽带通信网络管理系统管理模式研究

为了保证高速铁路宽带通信网络管理的可靠性和实效性,依据网络的规模、结构、管理接口、支持业务等特点,提出了一种新型的管理模式.系统分析了基于TD-LTE (time division-long term evolution)无线通信技术的高速铁路宽带通信网络的结构特点,指出了有限的车地无线通信带宽是高铁宽带通信网络管理系统要克服的重大难点;针对高速铁路宽带通信网络的这个难点,提出了一种集中式/分布式相结合的混合管理模式,并对该管理模式进行了性能评估,验证了该设计的可靠性和实效性.     

支持实时宽带通信的Internet网络控制体系结构

1 引言目前从理论上只有基于ATM技术的B-ISDN可以支持实时宽带通信,满足各种业务的QoS需求(带宽、信息传输的延时、抖动和差错率)并且能够具有较高网络利用效率。前者意味网络必须采用面向连接的资源预留策略,后者说明必须采用分组复用技术。但B-ISDN体系结构过于复杂,协议的完备、设备的制造、市场的推广尚需相当长的时间,而且B-ISDN网络是无法从现有运作的通信网络上进行     

宽带通信网络中的保护／恢复机制

1.前言对于电信网络的用户和网络营运商而言,网络的抗毁能力是极其重要的。现代社会生活的各个方面都越来越依赖于通信网络,特别是骨干网络的可靠运行。事实上,电信业务的所有服务、逻辑网络,包括Inter-net,都共享数目相对较小的骨干光纤传送网络。北美地区骨干光纤遭受破坏的频率比人们预想的要高很多,经济损失也很大。在中国,也时有国家骨干光纤遭受破坏的报道。因此,现代通信网络的生存性能已成为网络规划的重要组成部分。目前已有大量的文献对电信网络的生存性问题进行了研究。包括对光传送网络的生存性问题进行的研究,和对电路交换传送网络的抗毁进行的广泛研究。本文将主要对这些技术,特别是在mesh网络中的恢复技术,进行回顾和总结。网络的生存性结构中通常采用的方式有两种:保护和恢复。在保护方案中,网络在进行工作通路分配的     

ATM宽带网络中话音通信的实现方法

本文介绍了几种ATM宽带网络中语音通信的实现方式，以及在光纤/同轴电缆混合网(HFC)中通过电缆调制解调器(Cable Modem)语音通信的实现方法。     

宽带网络，别忘了统一的计费

1995年至2002年的7年期间,中国互联网用户的数量一直在飞速增长,至今已超过了4000万人。因此有人预言,中国将在5年内成为全球最大的互联网用户市场,并带来无限的商机。在未来巨大市场前景的诱惑下,国内宽带的蓬勃发展为比较沉闷的IT行业带来了新的机遇和新的挑战。电信、广电、网通、长宽和众多的接入商纷纷投入宽带网络的建设和运营中,围绕着宽带的基础建设和用户推广,在不同层面展开了激烈地竞争。随着宽带网络工作的推广,广电城域网接入市场的赢利曙光渐趋到来。城域网的接入质量、服务和价格,直接关系到运营商争取更多的宽带用户,提高接入率和尽早实现赢利。随着竞争的升级,宽带用户面临着更多的接入选择。宽带运营商们如火如荼地的“跑马圈地”,已经不可避免地点燃了价格战的导火线。一视同仁的“包月制”,严重地制约着宽带用户的发展。如何实现多种价格套餐的计费组合,提供一套完善的计费体系,正在逐步得到各地运营商的重视。另外,搭建宽带网络之后,如何推出多样化的增值服务,提供有偿服务和计费内容,引导窄带用户升级,也是宽带运营商必须考虑的问题。     

论计算机通信网络的开放性

本文从开放性原理出发，描述了计算机通信网络系统开放性体系的思想及其实现技术。     

新一代通信网络敲定日本技术

国际电信联盟选定了由日本开发的一项宽带通信管理技术作为新一代宽带网络的基础。该技术是由日本通信省、NTT公司和NEC公司共同研发的。通过这项技术，新一代宽带网络速度将为目前网络的10倍以上，但该技术的商业化推广需等到2020年左右。     

军事通信系统网络管理体系研究与设计

为了能够很好地监控通信网络运行的性能,合理使用网络资源,需要完善网络管理的功能。主要介绍了现有军事通信系统网络管理的体系和设计,并且将这种体系应用到军事通信系统中。     

计算机通信网络维护及管理

目前,计算机技术已被应用到各个领域和行业,计算机通信网络安全可靠性关系到人们的日常生产与生活,因此,应加强网络运维管理。笔者先对计算机通信网络运行过程中主要的影响安全的因素进行分析,并在此基础上提出加强计算机通信网络运维管理的策略,以供参考。     

基于干扰对齐的高铁无线宽带接入方案

依据高速铁路信号传输的特点,提出了基于干扰对齐的高铁无线宽带接入系统。该系统车载两套双天线设备,可以同时支持两个双天线用户无线接入,而接收端可以分离有用信号与干扰信号,实现无干扰接收。在车载设备与高铁沿线基站的通信中,提出基于传输时延的干扰对齐算法及与之相适应的网络覆盖方案。该算法按照时间传输奇偶顺序将来自不同发送端的信号分离。仿真结果表明,基于干扰对齐的车内接入子系统信号传输时可以达到四个和自由度,系统误码率优于未采用干扰对齐的系统,且下行误码率的性能略优于上行;基于传输时延的干扰对齐车地回传子系统可以同时支持两套车载设备接入网络且解码复杂度低,其覆盖方案可解决高铁越区切换易失败的问题。     

基于高速铁路通信的多波束机会波束赋形技术

鉴于高速铁路通信中,列车位置信息可预测、列车车顶中继转发天线数有限,以及反馈信息时延大、多普勒衰落较大、频繁切换等特性,传统的波束赋形并不适用于高速铁路场景。位置信息辅助的多波束机会波束赋形能够利用列车位置信息可预测的优势,在机会波束赋形算法中有效地提高发送波束随机相位与来波相位匹配的概率,同时支持多个波束并行传输,以多波束选择实现更好的多用户分集增益,且机会波束赋形无需反馈完全信道状态信息。因此位置信息辅助的多波束机会波束赋形技术适用于高速铁路通信。     

宽带无线IP网络安全体系结构模型

由于BWIP网络的非对称性特点,现有ISO/IEC7498-2、IPsec、WAP、3GPP、CDSA等安全体系结构框架都不能完全满足未来BWIP网络的安全需求。提出了一种适合未来BWIP网络的安全体系结构模型,该模型对BWIP网络所涉及的网络管理、安全操作、AAA、PKI、安全策略实施等技术进行了有机集成。给出了BWIP网络安全体系结构流入和流出的详细处理流程,并指出未来BWIP安全体系结构的研究方向。     

Routing in broadband communication networks using neural computations

This paper will briefly review some of the published work on applying Artificial Neural Networks (ANN) to routing in Asynchronous Transfer Mode (ATM) networks and critically appraise some of the conclusions which have been drawn from these studies. The paper will go on to explain the design and implementation of a simulation of a neural network array superimposed on a simulated ATM network. The results of routing experiments, which were compared with decisions made using Shortest Path First (SPF) routing, will be discussed and the need for appropriate comparison metrics explained. The paper will end with a review of what needs to be considered when the applicability of ANNs to ATM network control is being assessed and the required functionality of simulation tools which allow these assessments to be made.     

Concurrent communication in high-speed wide area networks

A performance metric called receptivity is introduced for quantifying the degree of concurrent communication possible in high-speed wide area networks (WAN's). Given a stochastic demand pattern model, receptivity is defined to be the probability that all requested connections can be established concurrently. Because calculation of the exact value of receptivity is shown to (generally) have an exponential complexity, an analytic estimate for its value is derived. The derived estimate is dependent on network parameters such as the number of links, link capacity values, and a weighted hop distance metric (which depends on the topological structure of the network and its relationship to parameter values of the stochastic model for the demand patterns). The derived estimate for the proposed metric compares reasonably well with simulated values for several asymmetric topological structures ranging from planar meshes to random graphs. The utility of the estimate is twofold. First, it can be computed quickly, i.e., in polynomial time. Second, its simple analytic form provides the network architect with insight into some of the inherent limitations and consequences associated with topological design choices for high-speed WAN's     

Scheduling support for multicasting sessions in broadband communication networks

Multimedia applications require support from the underlying broadband network at the end-to-end communication level. Multicasting is an important paradigm of end-to-end communication. The root node of a multicasting session is responsible for controlling the session including monitoring, maintenance, and the implementation of the multicasting protocol. The job that controls the multicasting session executes as a group of tasks at the root node of a multicasting tree. The scheduling scheme at the root node should give support to a multicasting session by improving the completion time of the jobs controlling the multicasting session, hence increasing throughput and the probability of admitting new multicast sessions into the system. In this paper, we model the tasks that carry out the multicasting session monitoring and maintenance as a fork-join job executing on a multiprocessor system. We assume that an executing task blocks for device I/O as a part of the activities associated with sending and receiving data packets. We develop two analytic models for scheduling a session control job on a multiprocessor system. The first model allows incoming job tasks to multiplex processors with existing tasks of another multicasting session, while the other model schedules a task of the incoming job to an idle processor. We assume that the overhead of rescheduling a task to another processor is large. We compare the performance of both models and show the range of conditions under which a model outperforms the other. We point out how the results can be used in the design of an adaptive scheduler that uses both models to improve throughput and consequently the probability of admitting new multicast sessions.     

基于移动式网络技术的卫星星座网络结构设计与仿真

随着星上处理能力地日益增强,降低卫星星座通信网络对地面网络的依赖性,增强为用户段提供IP接入服务的能力,是未来卫星星座网络的需要解决的关键问题。提出了基于移动式网络技术的LEO卫星星座网络体系结构,引入了新的网络组件,提出了新的卫星星座网络组网策略,讨论了星地间的切换模型,并提交了基于NS2的网络性能仿真结果。仿真试验表明,该方案是一种满足未来卫星星座发展需求的有效方案,星地间的切换是影响该方案中卫星星座通信网络数据传输延时的主要因素。     

Inter-domain service management of broadband virtual private networks

The emergence of an open market for telecommunication services provides a wide range of opportunities for the provision of value-added services by providers other than public network operators. One service already available today is a Virtual Private Network (VPN) that provides dispersed corporate sites with wide-area data communication capabilities using public network services. The introduction of Broadband ISDN allows for the provision of VPN services in a more integrated fashion. However, any effective VPN service must be able to deal with the technological and organizational heterogeneities that are present when providing a high level of service functionality over an arbitrary number of administrative and technological domains. This paper presents a management service for a VPN service that addresses some multi-domain and network heterogeneity issues. It outlines how a design based on the ITU-T's Telecommunications Management Network (TMN) Recommendation was developed and how working prototypes were implemented over real broadband networks.