Trends in U.S. Broad-Band Fiber Optic Transmission Systems

Fiber optic media are rapidly penetrating the telecommunications network. They are used as undersea and terrestial trunk lines, central-office loops, optical data links, and will eventually be included within the distribution plant which connects directly into individual premises. The rapid implementation of lightwave systems is occurring because the high bandwidths and low losses of optical fibers enable broad-band communication services to be provided between widely spaced repeaters and also allows users to upgrade currently installed systems to meet future needs. This paper will describe current applications and show how future trends will depend upon the continuing evolution of lightwave components and optical fiber designs.     

Undersea fiber optic cable communications system of the future: Operational, reliability, and systems considerations

The systems and operational requirements, reliability, and cost estimates for several undersea fiber optic cable communications systems of varying capacities, data transmission rates, and link distances are analyzed in detail to highlight relevant design tradeoff parameters. It is shown that systems with a high data rate per fiber are more economical and reliable than low data rate systems with multiple fibers. This study concludes that undersea optic cable systems can soon provide reliable broad-band digital services.     

A Field Trial of Fiber Optic Subscriber Loop Systems Utilizing Wavelength-Division Multiplexers

Future subscriber loops will provide various services including broad-band video. Fiber optic technology is the key for introducing these services. The Electrical Communication Laboratories (ECL) of Nippon Telegraph and Telephone Public Corporation (NTT) have been promoting research and development on basic technology of fiber optic subscriber loops, and studying the ways to use fiber optic subscriber loops for new services. As one of the programs, a field trial of fiber optic subscriber loops was planned and conducted in the Yokosuka area from April 1980 until May 1981. This paper first describes fiber optic transmission technologies for subscriber loops. Then, the system configuration and experimental results of the Yokosuka field trial are presented.     

Fiber Optic Transport Systems for Present and Future Local Networks

This paper describes fiber optic transport systems for present and future local networks. The present most important fiber optic system in a local network emerges as a broad-band video distribution system, because large-scale system introduction might be attained only for distributed video services. The system architecture and system parameters are presented. As for future integrated services, a highspeed digital transmission system and local network architecture are very important. The network architecture should be constructed to meet the demands for increased flexibility, capacity, reliability, and economy. Considering expected future demands and technologies, a new fiber optic local network architecture is proposed. The architecture's main features are the use of transmission processing nodes and a multilane-ring structure in subscriber transfer networks in combination with star-shaped subscriber access lines.     

Home Communication Systems

New small-band and broad-band communication services will expand possible application for the user. For the benefit of these services, home communication systems are required with TV sets, video recorders, microcomputers, and telephones as key components. In the residential area a trend can be observed from single terminals for specific services towards multiservice home terminals. In-house transmission systems with future home terminals and today's development trends are described in this paper.     

Applications of Future Braod-Band Services in the Office and Home

The demand for broad-band services in connection with numerous applications in the business and private sectors will be economically met in the future by the broad-band ISDN, the internationally standardized universal network for all services. Broad-band services and their applications can be roughly divided into four types of communication. The "dialogue" services include video telephony, video conferencing, and high-speed document and data transmission. "Retrieval" services cover film retrieval, broad-band videotex, document retrieval, high-definition image retrieval, and retrieval of graphics, text, and data. One representative of "access" services is cabletext. Of the "distribution" services, television is the most prominent. The demand for broad-band services in the office will depend primarily upon cost-effectiveness, and in the home will depend primarily upon anticipated benefits, cost, available purchasing power, and leisure time. In either case, prestige considerations may also play a part. The sine qua non for the fast spread of new broad-band services will at all events be-in addition to acceptable terminal equipment-low user charges.     

Broad-Band Systems Standards

The broad-band communications industry is small and fractionated (about 3100 cable television systems serving 8.5 million subscribers in the U.S.), but has a high potential for growth by offering a wide variety of communications services. If this large number of systems is to collectively provide nationwide services, performance and interconnection standards will be essential. In this paper we note relevant existing standards and examine highlights of ongoing standards-making activities.     

Fiber-Optic Broad-Band Integrated Distribution-Elie and Beyond

A field trial for integrated broad-band services offering cable TV, telephone, and data (Telidon) over a star-type fiber optic network was cut over to operational status in October 1981. Two switching centers interconnected with a fiber optic trunkline serve 150 subscribers who are connected to the centers through fiber optic lines. To date, no failures in the optical and optoelectronic components have occurred. The flexibility of the centrally switched configuration allows future expansion towards provision of demand-access video services based on the videodisc. Still-picture service using frame grabbers at the subscriber's home can also be considered. Eventually, high definition television (HDTV) might also be offered.     

Switching in the Broad-Band ISDN

The enhancement of ISDN with broad-band services is investigated from the viewpoint of switching systems. Approaches in system architecture and switching technology are described. The extension of an ISDN switch with broad-band modules is presented as an example.     

Interactive Broad-Band Dialogue Systems in the Integrated Services Digital Network (ISDN)

In the integrated services digital network of the future, Which will also have broad-band capacity, it will be possible to offer information services with multimedia presentation (e.g., with support of audiovisual material). For easy use, dialogue structures must be developed which lower the barrier of access for casual users. Offering information in a variety of applications at any place, a technical system consisting of different types of storage devices, operating Systems, and terminals, connected by a narrow- and broad-band switching and transmission system, must be available.     

Voice access of global information for broad-band wireless:technologies of today and challenges of tomorrow

The rapid development of the Internet and the World Wide Web has created a global network that will soon become a physical embodiment of the entire human knowledge and a complete integration of the global information activities. The traditional approach to access the network is through a computer physically tied to the network. As broad-band wireless takes off, the traditional tethered approach will gradually become obsolete. It is believed that one of the most natural and user-friendly approached for accessing the network will be via human voice, and the integration of spoken language processing technologies with broad-band wireless technologies will be a key to the evolution of a broad-band wireless information community. This paper offers a vision of the above concept. Technical considerations and some typical example applications of accessing the information and services using voice in a broad-band wireless environment are discussed. Fundamentals of spoken language processing technologies that are crucial in such a broad-band wireless environment are briefly reviewed. Technical challenges caused by the unique nature of wireless mobile communications are also presented along with some possible solutions     

Classification and Assessment of Telecommunication Services in Broad-Band Networks

Communication systems have become a fundamental utility for many facets of private and public life. Increasing system capabilities and advances in technology stimulate expectations of the public for new telecommunication services. Quite a variety of new services have been proposed which will have to be analyzed as to their utility, customer acceptance, and feasibility of implementation. In this paper an analytical approach is selected to assess these services by defining their communication structure and arranging them into classes corresponding to information flow, mode of information exchange, and communication pattern. Services requiring considerable technical expenditures and having a significant impact on future network configurations are pointed out. These services reqmre subscriber-individual and broad-band communication channels. For selected classes of services, a conceptual implementation in three types of networks is presented. It is recommended that several new services be implemented by using facilities of the existing public telecommunication network.     

Electronic Systems and Equipment for Evolving Loop Plant

This paper discusses a French plan for enhanced subscriber service, and some of the systems and equipment that will meet these goals on existing loop plant. Since 1972, the French PTT has been installing digital central offices at the national, regional, and local levels. Coverage is expected to reach 10000000 lines by 1985, so that when integrated services can be offered, the nation will be ready to take advantage of them. A PTT-sponsored program, directed toward all-digital subscriber loops, has revealed four principal phases. The first of these is already in progress: both digital and analog pair-gain systems are now being installed on existing loop plant. Soon to come is the second Phase: residential subscribers will be able to obtain two-channel subscribercarrier installations, with the carrier channel supporting data services, independent of the voice service on the same loop plant. Integrated Services Digital Networks, the third phase, should stretch the French loop plant to maximum capacity. When the demand for broad-band services overrides the capabilities of the existing copper pair plant, fiber optics cable installation will be fully planned and implemented as the fourth phase.     

System-defined design and performance of RFICs for W-CDMA mobile radio terminals

Third generation wideband CDMA (W-CDMA) systems like UMTS will add broad-band data to support video, Internet access, and other high speed services for untethered devices. They are currently deployed in Japan and will be introduced in Europe in 2002. Despite sufficient RF performance has been assumed in the standardization bodies, especially in mobile devices the RF part is still a limiting factor for the overall system characteristics. Only an integral design approach including both RF and baseband functionalities makes it possible to achieve analog front-ends with sufficient performance. This paper reviews transceiver architectures with respect to W-CDMA and presents some of the recent silicon-based radio frequency integrated circuits for mobile terminals.     

A Strategy for Broad-Band Network Introduction in Italy

Studies are being carried out in Italy concerning the strategy for the introduction in the 1990's of optical fiber systems in the distribution network, in order to supply customers with broad-band services (in particular with video services). This paper deals with some of the main choices that are being done, in particular in view of a field trial which is planned in Rome in 1988.     

Introduction of Optical Broad-Band Networks in France

Whereas optical fibers are today the most successful transmission medium in the long-haul links of the telecommunication networks, it is less obvious how to introduce them in local broad-band networks. The French Administration of Telecommunication adopted an evolutionary concept in order to be able to install an optical cable infrastructure in its videocommunication networks. This approach will permit the French Administration to explore quickly a wide range of interactive services, enabled by the star-type structure of the optical broad-band networks, and to evaluate their demand.     

基于法布里-珀罗波长选择器的毫米波信号产生的研究

随着移动增值服务的快速增加,对无线通信带宽的需求越来越高,光纤无线电系统作为宽带无线接入系统受到越来越多的关注。理论分析了将法布里-珀罗(F-P)波长选择器引入光纤无线电系统中从可调谐激光器中选出两束相位近似相等的相干光,利用光外差的原理经过光电探测器接收之后产生的毫米波信号,降低了相位噪声对产生的毫米波信号的影响。通过仿真发现在带通滤波器的输出端产生了频率为两束相干光频率差60GHz的毫米波信号,分析了随着光纤的长度增加,信号在光纤中的损耗越来越大,噪声也随之增加,毫米波信号的功率越来越低。     

A new cellular architecture based on an interleaved cluster concept

Personal communications services (PCSs) and future broad-band wireless systems are and will continue to be driven mainly by three challenging objectives: high-spectrum reuse efficiency, high-quality channels, and low infrastructure costs. We propose a new interleaved narrow-beam trisector cell (INBTC) architecture with a newly developed interleaved channel assignment (ICA) scheme to achieve these three objectives. Originating from the ICA scheme, we introduce the concept of interleaved cluster, within which a channel set can be assigned more than once. The INBTC architecture with interleaved clusters can enhance the performance of cellular/PCS systems from several perspectives. We demonstrate that to achieve high-spectrum efficiency, specifically in the range of reuse factors N=2-7, the INBTC system improves 3-5 dB at the 90th and 95th percentiles of signal-to-interference ratio (SIR) compared to conventional cellular systems. For a typical cellular environment, with a shadow fading standard deviation σ=8 dB and an SIR requirement of 17 dB at the 90th percentile, the INBTC system can increase system capacity by 75% over current systems. Because the INBTC architecture can utilize the base-station equipment of current cellular/PCS systems, implementing it should be simple and carry no attendant infrastructure costs. Hence, the proposed INBTC system (the cell layout plus the channel assignment scheme) has significant potential value in future cellular/PCS systems, as well as in broad-band wireless applications     

Broad-band OFDM radio transmission for multimedia applications

Future multimedia services will require the transmission of very high data rates over broad-band radio channels. In order to provide these services to mobile users, an appropriate transmission technique has to cope with frequency-selective and time-variant radio channels. The computation complexity for an equalizer increases in a frequency-selective radio channel for high data rate applications. Furthermore, the overhead for channel estimation procedures increases in time-variant channels. To overcome these drawbacks orthogonal frequency division multiplexing (OFDM) has been considered for broadband applications in many publications. The objective of this paper is to describe the large potential, the flexibility and adaptivity of the OFDM transmission technique in frequency-selective and time variant radio channels. Several technical aspects of OFDM transmission systems are discussed, especially the topics of differential modulation for which we compare different demodulation methods and channel coding with soft decision decoding. For higher level differential modulation, multilevel coding is taken into consideration     

Operating and powering optical fiber network

Fiber-in-the-loop (FITL) systems enable the distribution transport of existing telecommunications services and future broadband services over fiber optic media. An FITL system comprises a host digital terminal (HDT) connected to some number of optical network units (ONUs) via a fiber optic passive distribution network (PDN). Each ONU provides metallic service interfaces via short drops consisting of metallic wire pairs or coaxial cable. FITL systems that carry plain old telephony services (POTS) are referred to as “POTS FITL” systems. FITL systems that deliver VDT services or combined VDT and telephony services are referred to as “VDT FITL” systems. There are a number of architectural alternatives for VDT FITL, including configurations involving the use of parallel technologies for transporting video signals in the distribution. The authors discuss network operations and powering in particular