Broadband transport — the synchronous digital hierarchy

All data networks require a physical transmission medium to convey information between network nodes. Within a local environment this physical medium might, for example, take the form of an Ethernet LAN, but wide area connections are provided using telecommunications constant bit rate transmission equipment. Furthermore, the assumption that data networking is simply the provision of WAN connectivity for large corporate networks is becoming dated. The explosion of interest in the Internet means that, for transport networks, the term data may encompass voice, video and multimedia applications for delivery to both home and office. This places additional requirements on the network infrastructure as each service has specific transport requirements.Network operators are currently in the process of deploying core networks of equipment conforming to the ITU-T Recommendations for a synchronous digital hierarchy (SDH), but many networks also contain a significant proportion of older transmission technologies. This paper provides a review of transmission technology and describes the impact of such networks on the transport of data.     

International fixed satellite systems in synchronous digital hierarchy transport networks

This paper discusses functional and architectural aspects and suitable networks scenarios for the integration of international fixed satellite systems, such as the INTELSAT system, in and between digital networks implementing the new CCITT synchronous digital hierarchy (SDH). The paper presents SDH transmission network functional requirements, and combines them with current and anticipated future FSS operational requirements. It is shown that integration permits the use of SDH functions and features for enhanced network service provisioning by FSS in the international network fabric, and leads to new FSS system design criteria.     

The impact of synchronous digital hierarchy on digital microwaveradio: a view from Australasia

The recently agreed upon synchronous digital hierarchy (SDH) standard, which will provide a means to manage, multiplex, and access various forms of digital traffic in an economical and efficient manner, is described, and it is explained how radio systems can be deployed in SDH networks. This is followed by a discussion on the technical requirements for SDH digital radio relay system equipment. Frequency planning issues are considered. Gross transmission capacities that can be realized for various options of modulation schemes and RF channel spacing are discussed     

The synchronous digital hierarchy. II. Survival of the fittest

For pt.I see ibid., vol.37, no.5, p.185-9, 1991. The authors explain how the synchronous digital hierarchy (SDH) offers a solution the problems caused by the digitalisation of the world's telecommunications networks. The principles and the pros and cons of SDH are also outlined     

The synchronous digital hierarchy. I. The origin of the species

Throughout the world, public network operators are set to begin trials of what are known as synchronous transmission systems. The authors look at plesiochronous digital hierarchy, its successor, and describe the nature of the new transmission systems, indicate why they are needed, and identify some of the benefits they will bring to operators and users alike     

异构认知网络环境下的动态分级资源管理方法

针对异构认知网络中的资源管理问题,提出了基于认知的动态分级资源管理方法(DHRM)。根据不同时间尺度,引入小波神经网络、基于维纳过程的预测方法和增强学习算法获得业务分布变化、切换呼叫资源需求量以及用户喜好等信息,从而动态调配异构多网络各级可用资源。在资源合理分配基础上,根据各网络实时状态以及用户喜好,通过多属性决策算法动态地将业务流分配到最佳接入网络中。仿真结果表明,DHRM相对于网间静态资源管理方法系统容量提高了约20%。     

A video conference network management system

Setting up either one or multiple conferences and managing the various devices can be a very difficult task. In this article a newly developed distributed video conference management system is explained and tested. © 1998 John Wiley & Sons, Ltd.     

北京-廊坊-天津DAB同步网的发射系统

DAB(数字音频广播)是以数字化和网络化为基础的新一代全数字化广播体制，是继调幅和调频广播后的第3代广播，与传统的模拟广播相比，具有许多新的特点和优势。主要有：(1)音质可达到CD质量；(2)传输系统的抗干扰能力强，适用于移动接收；(3)频谱利用率高，可以实现单频网广播；(4)与传统的调频广播相比，为覆盖同样大小的区域，DAB的发射功率小得多；(5)既可传送声音广播节目，又可传送数据业务和静止图像，是新的多媒体广播系统。     

A digital rights management system for digital broadcasting based on home servers

This paper presents a digital rights management (DRM) system for digital broadcasting based on home servers (DBHS) using receivers with large-capacity storage devices. DBHS will enable viewers to enjoy 'television anytime/anywhere' by utilizing these storage functions. Our proposed DRM system is suitable for broadcasting, and allows both rights protection and advanced access to content held on home storage devices (in terms of validity, usage and charge conditions, and so on). We developed a prototype DRM system using a Pentium3 personal computer (1 GHz) in order to evaluate the nonlinear playback and 'trick-play' modes of encrypted content on the hard disk drive (HDD). Using this prototype, we confirmed that the nonlinear playback of content encrypted using the proposed DRM system could be processed in real time. The functionality in terms of trick-play modes was equal to that of commercially available hard disk recorders. In addition, we developed a security module for the DRM system in the form of a smart card with a built-in processor. We confirmed that the proposed DRM system utilizing the new smart card could be applied to DBHS.     

一种光网络中统一网管的实现方案

自动交换光网络(ASON)是下一代光网络的研究热点,随着ASON技术的不断成熟和实现,ASON网络的网管实现变得更为迫切,文章通过对ASON网管功能进行分析,提出了一种光网络中的统一网管实现方案。     

数字孪生在网络全生命周期管理中的研究

随着消费者对于通信业务的需求日益丰富和多样化,通信网络架构和功能也变得越来越庞大和复杂。随着5G通信技术的应用,5G通信网络可以实现网络能力的按需编排与灵活开放,对于网络在全生命周期中的管理提出更高的要求。随着数字孪生技术的发展,可以应用数字孪生技术辅助通信网络全生命周期管理,从而提升网络管理质量,降低网络风险和成本,实现可视化感知和实时闭环控制。在网络数字孪生方面相关的实践工作说明,所提网络数字孪生平台可以实现通信网络运行指标的可视化监控分析和网络故障快速诊断。     

数字集群系统的虚拟专网

自信息产业部公布我国数字集群系统标准以来,数字集群通信系统网络的规划与实施已引起多方面的关注与探讨。我国模拟集群通信系统的使用和欧美等国相比并不晚,但是使用情况和用户数量不理想。主要问题有多种制式、信令不一、互不相通;频谱效率低、系统容量小;功能单一、只有语音调度;干扰大、盲区多。为了克服模拟集群投资分散,各自管理,系统规模小,用户发展规模有限等弊端,提出了数字集群“共网”概念,它充分发挥数字集群系统的高质量语音;频谱利用率高;系统容量大;以及无线分组数据传输及应用等优势。为了满足网内各专网用户…     

数字网络型光纤振动传感系统

设计了一种新型光纤振动传感系统,该系统借鉴光通信中的无源光网络(PON)技术、光纤时分和波分混合复用传感侦测技术组建了数字网络型无源传感网络,系统传感单元的最大容量为32×8,有效地扩大了传感范围,实现了多传感单元系统化的集中管理,在处理算法中采用动态阈值自适应管理,可以根据环境变化实时改变阈值.在报警处理中,采用声、...     

A high-efficiency fully digital synchronous buck converter power delivery system based on a finite-state machine

A fully digital, self-adjusting, and high-efficiency power supply system has been developed based on a finite-state machine (FSM) control scheme. The system dynamically monitors circuit performance with a delay line and provides a substantially constant minimum supply voltage for digital processors to properly operate at a given frequency. In addition, the system adjusts the supply voltage to the required minimum under different process, voltage, and temperature and load conditions. The design issues of the fully digital power delivery system are discussed and addressed. This digital FSM scheme significantly reduces the complexity of control-loop implementation (<1800 gates) and power consumption (< 100 /spl mu/W at 1.2 V) compared to other approaches based on proportional-integral-differential control. The power delivery control system is fabricated in a 0.13-/spl mu/m CMOS process and its core die size is 160 /spl times/ 110 /spl mu/m/sup 2/.     

Total network management in the British Telecom digital public switched telephone network

The benefits of an integrated digital network are well known but such a network requires careful monitoring and management to obtain the full service and cost benefits. This paper describes the strategy that British Telecom has adopted to manage its long distance digital network.     

A QoE management system to improve the IPTV network

One of the biggest problems of the IPTV providers is to offer enough quality of experience (QoE) to their customers. The minimum bandwidth in the access network required to provide IPTV services, jointly with the necessity to guarantee the QoE to the customers, creates the need for new type of algorithms to satisfy the network requirements. Apart from the parameters that depend on the application aspect and design, the user's QoE mainly depends on the video quality (VQ), which can be affected by the network parameters (jitter, delay, lost packets, etc.), and on other parameters, such as zapping time and synchronization time. In this paper, we implement several benches to know how each measurable parameter affects the user's QoE. Taking into account these parameters, we propose an analytical expression for the QoE calculation. Then, the paper presents a network management algorithm that takes into account the information received by the user to take the appropriate actions and vary some features of the IP network to provide enough IPTV QoE to the customer. Finally, we measure how one of the actions taken by our system affects the network performance and the VQ. Copyright © 2010 John Wiley & Sons, Ltd.     

A multimedia front-end for an expert network management system

A multimedia natural-language interface for an expert network-management system is described. The different media discussed are speech, text, and graphics. An object-oriented, multimedia interaction language called Milan is used to describe the multimedia information. Application of the multimedia interface to a digital data services (DDS) network is illustrated. It is believed that such multimedia front ends will play a major role in the design of intelligent human-machine interfaces     

无线电管理信息网络系统建设浅析

无线电管理信息系统承载着国家极其重要的无线电管理业务，保证无线电管理信息系统的网络系统、主机系统、业务应用系统的稳定、高效运转，以及关键数据的可靠性是我们必须重点解决的问题。本文针对无线电管理信息系统的运行维护需求．提出了无线电管理信息系统的网络管理系统建设思路。文中提到的网络管理是广义的网络管理．涵盖了网络、主机、业务系统和关键数据等。[第一段]     

基于FPGA的数字复接系统帧同步器设计与实现

介绍了应用FPGA技术进行帧同步器设计的实现原理、系统框图及设计中需要注意的问题，给出了用VHDL描述的几个模块的源代码。     

A dynamic key management solution to access hierarchy

Hierarchical access control (HAC) has been a fundamental problem in computer and network systems. Since Akl and Taylor proposed the first HAC scheme based on number theory in 1983, cryptographic key management techniques for HAC have appeared as a new and promising class of solutions to the HAC problem. Many cryptographic HAC schemes have been proposed in the past two decades. One common feature associated with these schemes is that they basically limited dynamic operations at the node level. In this paper, by introducing the innovative concept of ‘access polynomial’ and representing a key value as the sum of two polynomials in a finite field, we propose a new key management scheme for dynamic access hierarchy. The newly proposed scheme supports full dynamics at both the node level and user level in a uniform yet efficient manner. Furthermore, the new scheme allows access hierarchy to be a random structure and can be flexibly adapted to many other access models such as ‘transfer down’ and ‘depth‐limited transfer’. Copyright © 2007 John Wiley & Sons, Ltd.