Microwave systems applications in deep space telecommunications andnavigation: Space Exploration Initiative architectures

The US Space Exploration Initiative (SEI) calls for the charting of a new and evolving manned course to the Moon, Mars, and beyond. The fundamental SEI support objectives are to provide the mission with means to monitor and control mission elements, acquire engineering, science, and navigation data, compute state vectors and navigate, and move these data efficiently and automatically between mission nodes for timely analysis and decision-making. Microwave links provide the means to communicate between system nodes, and the essential radio metrics to navigate; later, these probably will be augmented with optical links. The general mission telecommunications and navigation support requirements and resulting architectures for SEI mission support are described, and then the implications of these on the role of microwave technology in these architectures, particularly for Mars exploration support, are discussed     

Managing telecommunications networks

The authors suggest that one must view the network itself as the customer's database, and make sure it is self-diagnosing, self-healing, and intelligent. The perspective that the network is the database means moving away from the feeling that no trouble means total health, towards more preemptive maintenance. With fiber, capacity as a limiting factor is no longer an issue; the creative work will be in developing network capabilities. Universities need to accept the challenge of developing the theory of software stability. A crazy quilt of multiple equipment vendors cannot produce an integrated, problem-solving network. But if a network is self-diagnosing, self-healing, and intelligent, the available staff can focus on the customer and seize opportunities to introduce new services     

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.     

Photonics in future telecommunications

In future telecommunication systems, efforts will be made to exhaust the almost unlimited transmission capacity of optical fibers by applying optical frequency-division-multiplexing (OFDM) techniques. The switching elements of such networks must be able to process OFDM signals as well as time-division-multiplexing (TDM) signals. The extent to which optical signal processing can be brought into use instead of present-day electronic signal processing in such switching elements is examined. Several experiments involving OFDM technologies are described which are intended to underline the significance of those technologies for future telecommunication networks. Various techniques for and experiments on the optical switching of signals in the frequency, space, and time domain are described. Experiments dealing with optical signal regeneration are described     

Technology 1991: telecommunications

Noteworthy trends and occurrences in telecommunication during 1990 are examined. half a dozen countries deregulated their telephone companies to admit competition in the hopes of accelerating technological development. One of the leading technologies to take off was mobile communications, particularly services based on digital transmission. A worldwide standard for the broadband integrated-services digital network (ISDN) was finally accepted, allowing worldwide compatibility for the emerging fiber-optics-based broadband ISDN systems. Meanwhile, narrowband ISDN crossed international borders for the first time, offering transoceanic service. In optical-fiber transmission, the most promising development was erbium-doped optical amplifiers, which are cheaper and simpler for long-distance communications, especially if many signals are to be multiplexed onto one fiber. In addition, investigators demonstrated a simple processor entirely based on optical logic elements and parallel optical connections through free space, which may be another significant step toward an optical computer     

Data quality for telecommunications

The importance of data in large databases to the operation of telecommunications networks has grown considerably. For example, all provisioning, maintenance, and billing operations are critically dependent on data and many new network services are based on real-time access to data. This makes data quality a major issue for the industry. The purpose of the present paper is to outline an approach for addressing at least part of this issue. This approach makes use of process management to focus attention on processes that create data and data tracking, one method to quantify the performance of such processes. The merits of this approach are compared to more traditional methods of “cleaning” databases. A joint AT&T/LEC process, by which special services access is ordered and provisioned, is used as an example     

Speech coding for telecommunications

The function of a speech coding algorithm is to convert an analogue speech signal into a digital form for efficient transmission over a digital path, or efficient storage on a digital storage medium, and to perform the complementary function of converting a received digital signal back to analogue form. The article reviews those speech coding techniques which are already being extensively used in telecommunications applications. As well as explaining the basic principles employed by these speech coding algorithms to achieve efficient digital encoding, examples of telecommunications services which use these algorithms are presented     

Latin American telecommunications networks

The early history of telecommunications in Latin America is briefly recounted. Some activities arising from international American conferences are described. Differences between Latin American and US networks are identified. An overview of current Latin American systems is followed by details of networks in Colombia, Uruguay, and Costa Rica