A global network management framework for the '90s

A network management solution for today's computer networks must address several factors, including performance, stability, and needs characterized by new applications and requirements for greater access. The author discusses network management standards, profiles, architectures and frameworks     

A cool package for the 90s

Ceramic packaging offers a variety of properties that may be essential for the reliable operation of critical devices. Aluminum nitride, a relatively new and intriguing ceramic, may ultimately provide the best solution for a wide variety of electronic packaging tasks. Indeed, AlN-based packages have reached the marketplace. One obstacle remains, however: its relatively high cost     

Second-derivative sensitivity using the concept of the adjoint network

Second-derivative sensitivities for linear time-invariant networks are derived by an extension of the method used by Director and Rohrer to calculate first-derivative sensitivities.     

Communications satellites: orbiting into the 90s

Engineering advances in satellite communications are discussed. These include sophisticated switchboards, narrow beams, source coding for higher capacity, larger networks, and the use of higher and lower frequency bands and lower orbits. One of the most popular new 14/11-14/12 GHz commercial services has been time-division multiplexing of multiple carriers operating at low to medium bit rates. Multiple-carrier, low-burst-rate TDMA (time-division multiple access), in which several TDMA carriers are shared among ground terminals, is widely used with very small-aperture terminals (VSAT) on the customer's premises. NASA's (US National Aeronautic and Space Administration) ACTS and Italy's Italsat both plan to use signal regeneration at 30/20 GHz. Onboard switching and multiplexing will not only minimize noise and boost power, but also trim the cost of the entire satellite network     

A new generation of 90 Mb/s systems: bandwidth efficient, fieldtested 16-QAM

16-QAM (quadrature amplitude modulation) digital satellite broadcast equipment and satellite communications (SATCOM) systems that double the spectral efficiency of currently operational satellite links is described. It is shown that with this field-proven system, data transmission at a rate of 90 Mb/s (two multiplexed DS-3 signals) is feasible in a transmission bandwidth of 30 MHz. Extensive operational satellite tests performed over the T-303 satellite of AT&T demonstrated a BER <10^-10 and no errors for several days. The practical bandwidth efficiency of these SATCOM systems is 3 b/s/Hz, i.e. double the currently used 1.5 b/s/Hz QPSK (quadrature phase-shift keyed) systems. The doubling of the spectral efficiency is attained with advance modem (modulation-demodulation), adaptive equalization robust synchronization, high-power amplifier (HPA) linearization (predistortion), and low redundancy powerful forward-error-correction (FEC) subsystems. The systems may make possible the conversion of currently operational analog FM links into bandwidth efficient digital systems. In one 30 MHz satellite transponder three to four digitized high quality TV signals could be broadcast, or two standard rate DS-3 signals time-division multiplexed with a DS-1 rate signal and additional auxiliary data streams     

二十世纪九十年代的通信卫星技术和业务

从商用和军用两个方面论述了卫星通信的未来。讨论了卫星通信的技术发展和新业务。同时，对用户和需求进行了评估。     

A long way from the abacus-computing into the 90s

The past two decades have seen computers becoming orders of magnitude smaller, cheaper and more powerful. While memory manufacturers have been packing more and more memory cells onto a single piece of silicon, processor designers have been taking a similar line in the design of single-chip microprocessors. The author also looks at supercomputing and parallelism which could lead to a global computer network     

The telephone network of the 1960s

In 1960 the transmission technology of the public switched telephone network was ordinary cable pairs, carrier systems on both paired and coaxial cable, and point-to-point microwave radio systems. Voice signals were frequency multiplexed for efficient transmission, but remained in analog form from end to end of a connection. Electromechanical switching systems provided circuit-switched connections, and about half of the customers could directly dial long distance calls. The following decade saw the beginnings of electronic switching and direct distance dialing on a global basis. Meanwhile, applying digital technology to achieve lower costs and better quality for voice transport began in earnest, and the interconnection of data terminals and computer centers became an increasingly important communications need. The initial data communications approach, still used with ever increasing sophistication and speed, was to convert data to speech-like form with data modems. Later, the direct connection of digital data to digital network facilities became the method of choice for building computer communications networks and the backbone of the Internet. It now appears likely that one day all signals, including voice, will be transported by unified high-speed digital networks with a common set of protocols     

FDDI and beyond-a network for the 1990s

The availability of cheap optical fibre and associated transceivers has encouraged the development of the next generation of computer networks. Most prominent among these is the fibre distributed-date interface (FDDI), which is expected to become a standard. The authors describe the principal advantages of the FDDI (namely its size and transmission rate) and outline the apparently bright future of FDDI networks and their applications     

Device CAD in the '90s: at the crossroads

Various issues concerning technology computer-aided design (TCAD), including fundamental research, practical issues of user friendliness, experimental verification, and framework initiatives are discussed. The focus is on device CAD, in which there is a continuing shift of emphasis from basic issues of device physics and engineering to questions of manufacturability and technology scalability. The automation of input, computational mesh, and electrical biasing information generation in TCAD systems is described. The visualization and interpretation of simulated results, the advent of new computer hardware, and the use of statistical simulations in TCAD technology are discussed. It is argued that while technology experts are willing to tolerate awkwardness in a TCAD system, new users of TCAD, such as circuit designers and manufacturing engineers, demand automation, robustness, and reliability as standard features     

基于PON的接入网工程设计思路

从PON网络结构设计以及系统保护设计入手,对ODN配置、OLT配置、传输距离计算、带宽测算等方面提出了EPON和GPON工程设计思路,为PON接入网络设计提供参考.     

Meeting the challenge of assuring dependable telecommunicationservices in the '90s

Assuring the dependability of telecommunication services in the face of increasing customer expectations, revolutionary changes being made or proposed in networks, and recent disruptive disasters are discussed. Work focused on reducing vulnerability to network element outages is described and examined for three new technologies: fiber network architectures, common channel signaling, and intelligent network architectures. A comprehensive service dependability management process to be established by service providers is recommended     

Improving the dependability of network management systems

As computer networks expand, there is a pressing need for management systems capable of handling errors. This article proposes an approach based on management proxies to improve the dependability of fault management systems. An effective MIB to implement the proxies is presented, which allows their deployment at virtually no cost. As an example, a case study of a WAN is carried out. © 1998 John Wiley & Sons, Ltd.     

IST-DAVID: concept presentation and physical layer modeling of the metropolitan area network

The data and voice integration over dense-wavelength-division multiplexing (DAVID) metropolitan area network (MAN), following the packet-over-wavelength-division-multiplexing (WDM) approach, introduces a fast, agile, dynamically reconfigurable, and service-transparent optical layer. The fast reconfiguration allows the implementation of statistical multiplexing purely in the optical domain. Scalability limitations in the MAN network are attributed to noise accumulation, crosstalk, spectral narrowing from long cascades of multiplexers/demultiplexers, and fiber nonlinearities. Physical layer studies carried out using both analytical modeling and a commercial simulation tool show that the predominant source of Q degradation is spectral narrowing. It is shown that considering the longest protection path, a DAVID MAN network offering a 1.5-Tb/s capacity is feasible.     

哈尔滨移动本地传输网组网思路

介绍哈尔滨移动本地传输网的业务特点、组网原则、网络结构及设备配置方案。     

Personal communications services through the evolution of fixed andmobile communications and the intelligent network concept

New telecommunications services tend to consider fixed network subscribers' requirements as well as mobile network subscribers' requirements. On one hand, subscribers of fixed networks would like to benefit from the mobility offered in mobile networks. On the other hand, mobile subscribers would like to access to services inherent in fixed networks. Personal communications services (PCS) meet this trend while allowing fixed and mobile convergence. In this environment, the application of intelligent networks (INs) to fixed and mobile networks is very convenient to realize PCS. Thus, the natural advancement of telecommunications systems (fixed and mobile) consists in the definition of new telecommunications architectures which take into account technologies from both fixed and mobile environments. This article studies how the IN is used to support mobility and interworking for PCS. Although mobility management already exists in cellular networks like GSM, it is desirable to use the IN concept to introduce flexibility. In addition, the IN allows the introduction of new supplementary services in PCS. Furthermore, the IN concept can be utilized to provide necessary networking functions for the integration of fixed and mobile networks. This article also highlights the involvement of IN in the definition of the global communications systems such as Telecommunication Information Networking Architecture (TINA), Universal Mobile Telecommunications System (UMTS), and International Mobile Telecommunications in the year 2000 (IMT2000)     

A self-calibration concept for establishing the complex measurementability of homodyne network analyzers

A homodyne phase-shifter-controlled double reflectometer is presented. Its ability to make complex measurements of a network depends on a knowledge of the phase-shifter characteristics. This knowledge is established using fully unknown standards merely by exploiting reciprocity. If a system error correction is performed, the data needed for error correction contain enough information to determine the behavior of the phase shifter, and no additional standards are needed. It is shown by simulation that the measurement of the parameters of the device under test is only weakly influenced by errors in the phase-shifter behavior