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提出了一种接入网系统中ISDN用户接口按需激活的新方案,该方案大大减少了用户终端设备的电能消耗.在接入网系统中,局端设备通过用户接口模块的TIP/RING引线与ISDN用户终端相连,用户一般通过手动拨极性开关或使用带自动极性反转的终端来激活线路,一旦极性匹配后,线路就一直处于激活状态,电能消耗很大.在新型按需激活方案中,通过局端设备线卡上的软件控制和硬件支持,使得一般情况下用户接口处于去激活状态,只有当用户摘机或用户被呼叫时该线路才被激活,从而大幅减少了用户终端设备的电能消耗. 相似文献
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随着多媒体时代的到来,世界各国都在进行多媒体通信商用系统的试验,日本也不例外,利用光缆传送有线电视业务,同时开放VOD业务,这是电信市场的一个热点问题。本文将介绍日本NTT公司在东京立川地区的实验系统。 相似文献
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本文对ADSL终端远程管理的技术方案进行了分析和讨论,并介绍了中兴通讯的ADSL终端远程管理的技术实现. 相似文献
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移动Adhoc网络的自组织、动态拓扑以及无线接入等特点使路由的安全性问题日益突出,而现有的Adhoc网络路由协议并没有提供安全的保护机制。论文首先论述了Adhoc网络几种常见的按需安全路由协议,指出有待解决的问题,在此基础上提出一种改进的、有效的安全路由协议(SEAR),阐述了该协议的路由请求、响应和维护的路由方式和过程,并通过协议间的比较分析其安全性和网络性能。该方案采用对称密钥协商和公钥认证方式,在兼顾性能资源的同时也保证了Adhoc网络的路由安全。 相似文献
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调频同步广播系统采用多点小功率同步发射解决覆盖问题,因此能否实现有效的远程管理,是确保安全优质播出的关键。近年来,建设调频同步广播系统越来越重视同步建设相应的远程管理系统。本文重点介绍了基于传输链路的远程管理方案和与链路无关的音频随路信令远程管理方案,提出并初步探讨多模式调频同步广播系统概念。 相似文献
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智能光网络是具有动态连接管理能力的光传送网,代表着未来网络发展的方向,可以提供光虚拟专用网(OVPN)、按需提供带宽(Bandwidth on,Demand)等服务。本文对智能光网络的增值业务——光虚拟专用网技术进行了研究。文章首先介绍了光虚拟专用网的服务需求和参考模型,接着分析了光虚拟专用网的关键技术,最后阐述了开展光虚拟专用网给服务提供商和用户带来的好处。 相似文献
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Aniello Gentile Michele Luglio Maurizio Manzo Francesco Zampognaro 《International Journal of Satellite Communications and Networking》2014,32(5):393-406
Broadband communication via satellite systems finds applications in several contexts where other technologies are not available or economically not convenient. Examples are remote areas, disaster struck areas, or vessels/ships. The scarce availability and the high cost of the bandwidth impose to improve flexibility in bandwidth management and dynamic allocation, especially on the shared return link. Typically, this capability is available only to the satellite operator (SO). An innovative dynamic bandwidth management of satellite capacity for the return link has been developed and prototyped as an Internet protocol‐based solution. This solution allows small operators renting bandwidth from the satellite operator and providing services to final customers, managing the permanently assigned resources in a flexible and efficient way. The scope of the paper is to illustrate this technique to achieve the dynamic bandwidth management for a subgroup of satellite terminals (subdomain) by using a centralized controller and distributed software with IP shaping capabilities, without interacting with the satellite operator. This approach has been applied in particular to a satellite maritime ship owner, which is thus able to dynamically distribute capacity among satellite terminals installed onboard of its ship fleet as required, as a network operator. The presented results are the outputs of simulations performed with the NS2 simulator and tests by using real hardware. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Güray Aar Catherine Rosenberg 《International Journal of Satellite Communications and Networking》2005,23(4):229-245
Advanced resource management schemes are required for broadband multimedia satellite networks to provide efficient and fair resource allocation while delivering guaranteed quality of service (QoS) to a potentially very large number of users. Such resource management schemes must provide well‐defined service segregation to the different traffic flows of the satellite network, and they must be integrated with some connection admission control (CAC) process at least for the flows requiring QoS guarantees. Weighted fair bandwidth‐on‐demand (WFBoD) is a resource management process for broadband multimedia geostationary (GEO) satellite systems that provides fair and efficient resource allocation coupled with a well‐defined MAC‐level QoS framework (compatible with ATM and IP QoS frameworks) and a multi‐level service segregation to a large number of users with diverse characteristics. WFBoD is also integrated with the CAC process. In this paper, we analyse via extensive simulations the WFBoD process in a bent‐pipe satellite network. Our results show that WFBoD can be used to provide guaranteed QoS for both non‐real‐time and real‐time variable bit rate (VBR) flows. Our results also show how to choose the main parameters of the WFBoD process depending on the system parameters and on the traffic characteristics of the flows. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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有线电视网络的互动式点播教学环境 总被引:1,自引:1,他引:0
远程教学是构建在电信、计算机、传播科技3者之间的应用,是兼有视觉与听觉的双向学习方式.目前远程教学的发展大致分成实时群播、虚拟网站、课程点播3个系统,虽然已经有完整的系统出现,但均存在受时间限制、网络带宽不足、影片画质差、互动性不佳等缺点.这里提出交互式点播教学环境的概念,是利用有线电视点播视频系统以及有线电视网络控制器,提出一套交互式点播教学系统,以解决目前远程教学发展所遇到的瓶颈. 相似文献
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Service-Oriented Software Engineering (SOSE) presents new challenges; in particular, how to promote interoperability and cooperation among loosely-coupled service resources. This is critical for service resource sharing and for implementing on-demand services. This paper discusses key technologies of service virtualization, including encapsulation of service interoperability (for available resources); ontology-based Role, Goal, Process, and Service (RGPS) metamodeling (for interoperable aggregation and organization of virtualization services); registration and repository management of Metamodel Framework for Interoperability (MFI) (for virtualization service management); and virtualization service ontology and its represented association with RGPS. Latest progress of the MFI and ISO standards is also discussed. 相似文献
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针对4G无线项目勘察过程中,现场勘察资料可靠性不高、管理不集中等问题,本文设计实现了一种远程辅助勘察系统,以信息化、集中化的方式管理、审核现场勘察信息,提高勘察数据的准确性和使用效率。 相似文献
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基于IP网的自主式多媒体远程教学系统 总被引:3,自引:0,他引:3
本文在简要分析多媒体远程教学需求的基础上,提出了一种包括教师T、学生P、课件资源R、协作教学环境E和网上教学管理M等表示远程教学的五元组结构模式,进一步设计了基于IP网的支持教学现场直播和按需点播的多媒体远程教学系统,并在校园网上进行了同步时授课以及按需点播的实验。 相似文献
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面向服务的语义互操作性技术及其标准 总被引:2,自引:0,他引:2
面向服务的软件工程面临新的挑战。促进互联网环境中松耦合式服务资源之间的互操作性行为协作,是实现服务资源深度共享与按需服务的关键。文章对服务虚拟化的关键技术:可用资源的服务互操作性封装方法、虚拟化服务组织的互操作性聚合的基于本体的RGPS元建模方法、虚拟化服务管理的互操作性元模型框架及其注册与存储管理、虚拟化服务本体及其与RGPS关联呈现等进行了研究。对研究的互操作性元模型框架(MFI)及ISO系列标准工作新进展进行了介绍。 相似文献