Feature interactions in telecommunications systems

The problems of defining features, services, and feature interactions in telecommunication systems are discussed. Several ways of classifying feature interactions are surveyed. Existing approaches for solving the feature-interaction problem are reviewed. It is seen that no full approach exists; they are all partial solutions. The approaches are divided into three classes: avoidance, detection, and resolution. Avoidance looks at ways to prevent undesired feature interactions. Detection assumes that feature interactions will be present, and determines methods for identifying and locating them. Resolution assumes that feature interactions will be present and detected, and looks at mechanisms for minimizing their potential adverse effects     

Distributed systems for telecommunications

The authors present an overview of the January/February 1994 issue of IEEE Network which includes seven articles on distributed telecommunications systems     

Expert systems and telecommunications

First there were databases and database management systems. Then information bases developed, whereby management information systems and decision support systems sprouted. Now, there are knowledge bases on which expert systems are being built. The age of “knowledge” is upon us, and computer programs are being developed to perserve this knowledge. These computer programs are “expert systems” which mimic the behavior of human experts in some specified domain of knowledge. This article addresses these expert systems and gives some applications in the telecommunications area.     

Modeling telecommunications networks' transmission systems

The author discusses the status of synchronous digital hierarchy (SDH) management standards and related matters such as plesiochronous digital hierarchy (PDH), and offers an overview of the information contained within these standards. He provides an overview of those areas that are still under study or need further investigation by international standardization bodies to cover all the management aspects of an SDH network. The ITU (previously the CCITT) undertook the drafting of a recommendation which specifies a generic model dealing with the high-level resources of a telecommunications network     

Electromagnetic radiation from selected telecommunications systems

Because of the growing interest in potential health effects associated with exposure to electromagnetic (EM) radiation at microwave and radio frequencies (RF's), a study was initiated within the Bell System to document existing levels of EM energy associated with various radio transmission systems. To this end, power density and electric field strength measurements were made at selected facilities, particularly at locations judged to be representative of those frequently encountered by various crafts personnel. For the case of point-to-point microwave radio, measurements were made in the vicinity of various antenna towers in order to obtain information that could be compared with the corresponding levels predicted by analytical techniques. These data allow one to assess the environmental impact, with respect to EM radiation, of the microwave radio system as well as the impact of future standards and guidelines on the system. This paper describes the instrumentation and measurement techniques used for this study and provides a summary of the results obtained for several different types of radio systems including high frequency (HF) radio, tropospheric scatter, earth-satellite and ubiquitous microwave radio relay.     

Analog CMOS building blocks for custom and semicustom applications

Standard analog building blocks developed for use in custom and semicustom LSI and VLSI designs are described. The analog blocks are built using a digital CMOS process modified to include high-value resistors and voltage independent capacitors. Designs for operational amplifiers, programmable voltage sources, comparators, bandgap voltage references, unit resistors, capacitors, and n-p-n devices are discussed. Performance characteristics including unity-gain bandwidth, output drive, output impedance, and common mode range are reviewed. MOS noise data, subthreshold operation, and device matching are analyzed. Layout guidelines are proposed as well as applications and limitations of the analog building blocks.     

A systems approach for national telecommunications policy

It is argued that the arrival of the age of information networking in the US is being slowed by the patchwork of ground rules in the telecommunications industry, which prevents the open and universal provision of information networking and related services, and that a national policy is needed. The history of regulatory policy is reviewed, and the current situation is described. The importance of user needs and wants in setting policy is described, and the use of a systems approach is suggested     

Analog reflection topology building blocks for adaptive microwavesignal processing applications

The synthesis and realization of an analog-phase shifter, delay line, attenuator, and group delay synthesizer-are presented. These variable control devices are all implemented using the same generic single stage reflection topology. The optimum conditions of operation have been determined and the corresponding group delay behaviors have been investigated to produce simple design equations. As proof-of-concepts, monolithic technology has been used to realize an X-band, phase shifter, delay line, and attenuator. Hybrid technology has been used to realize an L-band, group-delay synthesizer. Because of the high levels of performance measured, these control devices are ideally suited for use as general building blocks in adaptive signal processing applications, including large phased array applications     

Structured peer-to-peer systems for telecommunications and mobile environments

The peer-to-peer (P2P) paradigm not only allows end users to share own resources, but is also regarded as a new networking paradigm due to its robust, self-organizing character, abandoning infrastructure and relying on end-users equipment. In contrast to common fixed-line Internet file sharing P2P systems, in this paper, we address critical issues regarding scalable personal communications and heterogeneous mobile systems. We discuss challenges and present our solutions based on structured P2P.     

The challenge of the VLSI technique to telecommunications systems

The rapid evolution from the transistor to the LSI circuit revolutionized telecommunications systems. In particular, the low-cost IC's triggered the transition from wired- to stored-program control and from analog to digital techniques by introducing standard IC's as microprocessors, memories, etc. The availability of analog-digital interface circuits, for example codecs, filters, SLIC's, and vocoders, has become very important. In addition to the technical revolution, the economical aspects must be considered. LSI circuits enter more and more into the vicious circle of greater complexity-fewer applications and thus higher costs. An escape from this circle is offered by programmable circuits such as microprocessors or new circuits with a regular architecture. Nevertheless, custom circuits will always be used in order to protect the system know-how. The blend of standard and custom circuits will be important for the success of a systems house. Since vertical integration activities will be unlikely, different concepts of cooperation between IC manufacturers and system house become more and more important.     

Fusing hard and soft computing for fault management in telecommunications systems

Global telecommunication systems are at the heart of the Internet revolution. To support Internet traffic they have built-in redundancy to ensure robustness and quality of service. This requires complex fault management. The traditional hard approach is to reduce the number of alarm events (symptoms) presented to the operating engineer through monitoring, filtering and masking. The goal of the soft approach is to automate the analysis fully so that the underlying fault is determined from the evidence available and presented to the engineer. This paper describes progress toward automated fault identification through a fusion between these soft and hard computing approaches.     

Three keys to developing and integrating telecommunications servicemanagement systems

With the deregulation of the telecommunication industry in Europe and the United States, communication and information services (e.g., multimedia entertainment services, educational services) are being increasingly delivered across value chains of network, service, and value-added service providers. The benefit of such interoperable services is the provision of “one-stop shopping” in which “tailored” services are delivered without their customers dealing with the multiplicity of underlying telecommunication services and network providers. The difficulty with such delivery chains is the complexity of managing these services across the different provider organizations (i.e., across both administrative and technological domains). These difficulties include achieving an understanding of business process across the organizations and the heterogeneity of the components to be (re)used to support these business processes in the organizations. This article examines three crucial elements in ensuring successful and flexible development of such service management systems-namely, a development process which is customized to support management system component development and component reuse; the development of business models capable of representing the underlying business processes for these systems; and an integration strategy designed to assist the flexible and timely cooperation of these management components both within a single organization (single administrative domain) as well as across organizations (multidomain)     

Intelligent scheduling and planning systems for telecommunications resource management

This paper discusses the importance of resource management in the telecommunications industry. It argues for intelligent resource management systems (IRMSs) that are capable of providing flexible and dynamic resource management. It introduces the main requirements and benefits of an IRMS and describes the technical basis of current research activities which are leading towards the development of constraint technology based IRMS platforms.     

The potential for open source software in telecommunications operational support systems

Over the last five years, open source software has moved into mainstream areas such as Internet and financial applications, with software such as Linux and Apache Web Server now supporting mission-critical operations. Open source software can offer both cost reductions and improvements in software quality. However, the uptake by incumbent telecommunications providers has been virtually zero, instead focusing on major commercial-off-the-shelf (COTS) packages, due to a mixture of prior strategic investments and perceptions over open source risks. This paper addresses the scope for use of open source software in telecommunications operational support systems (OSS). Firstly, the technical scope for open source software is addressed, covering the maturity of available open source software components, and the ways in which these components can have an impact on OSS software architecture. Secondly, the commercial aspects are presented, covering benefits, commercial models and risks. An OSS life cost comparison of open source versus COTS software is included. Thirdly, a test OSS created by BT using primarily open source software, combined with OSS standards to provide a minimum cost base, is presented and analysed. The paper concludes with a statement on the potential for the use of open source software in OSS, and suggests possible next steps.     

Analog laser predistortion for multiservice radio-over-fiber systems

We have developed some low-cost predistortion circuits to compensate second- and third-order laser distortions in multiservice radio-over-fiber industrial systems. Depending on the predistorter configuration implemented, average reductions of 10-15 dB and of 8-10 dB have been observed in the laser second- and third-order distortions, respectively, within the cellular bands relevant to the European TETRA, GSM, and DCS standards. In particular, the development of the prototypes here illustrated is based on a new and original procedure that formalizes and suitably integrates in a sinergistic way modeling, design, and experimental activities.