Showing papers in "IEEE Communications Magazine in 1992"

Designing an on-demand multimedia service

Abstract: A quantitative study of techniques for designing a high-performance multiuser multimedia on-demand information service is presented. The problem of maintaining continuity of playback of each media stream in the presence of multiple subscriber requests is formulated, and admission control algorithms that permit a multimedia server to satisfy the maximum number of subscribers simultaneously are presented. A feedback technique in which a multimedia service uses lightweight messages called feedback units that are transmitted back to it by subscribers' mediaphones to detect asynchrony among them and steer them back to synchrony thereafter is presented. The feedback technique guarantees synchronous playback of media streams transmitted by the multimedia server to subscribers over metropolitan-area networks. >

A portable multimedia terminal

Abstract: A personal communications system (PCS) that centers on integration of services to provide access to data and communications using a specialized, wireless multimedia terminal is described. The possible applications and support systems for such a terminal are outlined. Several of the major design issues behind portable multimedia terminals, including spectrally efficient picocellular networking, low-power digital design, video data compression, and integrated wireless RF transceivers, are discussed. It is argued that optimizing performance in each of these areas is crucial in meeting the performance requirements of the overall system and providing a small, lightweight terminal for personal communications. >

Wireless network access for personal communications

Abstract: An explanation of the widely different technological approaches and technologies being proposed for different interpretations of wireless personal communications services (PCS) is presented. Different wireless communications applications and issues surrounding the applications are discussed. Descriptions of the compromises that have been made in developing specific technologies optimized to serve the cordless telephone and the vehicular mobile radio applications are presented. Characteristics of a technology that is aimed at the widespread pedestrian PCS application and environment are outlined. Different wireless technologies that have been aimed at different applications and environments are compared. >

A self-organizing neural network for supervised learning, recognition, and prediction

Abstract: Fuzzy ARTMAP, one of a rapidly growing family of attentive self-organizing learning, hypothesis testing, and prediction systems that have evolved from the biological theory of cognitive information processing of which ART forms an important part is discussed. It is shown that this architecture is capable of fast but stable online recognition learning, hypothesis testing and adaptive naming in response to an arbitrary stream of analog or binary input patterns. The fuzzy ARTMAP neural network combines a unique set of computational abilities that are needed to function autonomously in a changing world and that alternative models have not yet achieved. In particular, fuzzy ARTMAP can autonomously learn, recognize, and make predictions about rare events, large nonstationary databases, morphologically variable types of events, and many-to-one and one-to-many relationships. The system's fast learning of rare events and error-based learning and alternatives are described, and uses for ART systems and the development of unsupervised ART systems are reviewed. >

Urban/suburban out-of-sight propagation modeling

Abstract: A model for the calculation of the path loss characteristics of a direct sequence (DS) spread spectrum signal which occurs when a mobile user is out-of-sight of the base station due to building blockage is presented. The environments studied are common throughout the world. Results for the experiments in which a base station antenna was set at heights of 6.6 m or 3.3 m, while the mobile antenna was fixed at a height of 1.5 m are presented. The goal of the experiments was to demonstrate the use of broadband DS spread spectrum code-division multiple-access (CDMA) as an efficient means of communication. >

The latency/bandwidth tradeoff in gigabit networks

Abstract: It is argued that delays through gigabit networks are dominated by propagation delay, so communications techniques and protocols for megabit networks would be inefficient or ineffective for gigabit networks. The latency-bandwidth tradeoff for gigabit networks is discussed, and an example of it is presented. It is concluded that gigabit networks have forced network designers to deal with propagation delays due to the finite speed of light. >

Coordination and control of multimedia conferencing

Abstract: It is shown that multimedia, multipoint conferencing systems create important requirements for the networks they use to transmit information among conference participants. These requirements, which stem from the need for conferencing systems to emulate the richness of control present in face-to-face conversations, may extend from the user interface to the control and coordination of communication networks. The user interface of a conferencing system should present users with the means to control the conduct of meetings, as well as the exchange and presentation of multimedia information. The virtual meeting room metaphor of Rapport, which provides the foundation for this system's user interface, is described. The creation and communication of multimedia information, conferencing over multiple and integrated networks, and requirements for multiport communications are discussed. >

The Universal Mobile Telecommunication System

Abstract: The concepts, requirements, and technologies of Europe's third generation mobile communication system-the Universal Mobile Telecommunications System (UMTS)-are discussed. The cellular architecture, radio resource, adaptive resource allocation and handover enabling techniques for realizing an effective UMTS access network are described. The modulation schemes, multiple access methods, and duplexing methods used in the third generation mobile system's flexible radio interface are also described. The architecture, mobility support, and protocol development of the UMTS fixed network are outlined. >

Multimedia traffic characteristics in broadband networks

Abstract: It is pertinent to develop a set of simple parameters that can best characterize the variability and the statistical correlations of the packet arrival process. These parameters are then used by the network to allocate its resources among the different users in order to avoid congestion and maintain a predefined quality of service (QOS) for each user. The traffic characterization and modeling of the real-time bursty traffic, mainly voice and video traffic sources, using statistical methods are described. It is shown that the variability of the variance of the sum of consecutive packet interarrival times leads to significant queuing delays and therefore is a major cause of congestion in broadband networks. >

Implications of mobile cellular CDMA

Abstract: The results of four extensive field tests of code division multiple access (CDMA) cellular technology performed between November 1991 and September 1992 are presented. These tests include: validation system field tests conducted in San Diego, California, operating over five cell sites, comprising a total of eight sectors, and involving up to 70 mobile units, plus simulated other user and other base station interference; tests in Munster, Germany, the configuration of which consisted of two cell sites and two mobiles plus 20 simulated other users operating in the 1700-MHz band; tests in Geneva, Switzerland, the same as in Munster, but operated in the 800-900-MHz band, with cells located at GSM base station sites; and a field test conducted in Washington, DC, operating on two-sectored cell sites involving seven mobile units, plus simulated other user and other base station interference. >

ATM technology for corporate networks

Abstract: Asynchronous transfer mode (ATM) technology is discussed in relation to the requirements of corporate networking. An introduction to ATM switch architecture is presented. The various approaches to ATM switch design that have appeared in previously published literature are reviewed. A discussion is presented of some current issues facing the development of the ATM networks. It is argued that much simpler solutions to many of these issues may be adopted in the context of the corporate network than is permissible for the public broadband network. >

Intelligent network concepts in mobile communications

Abstract: A mobile cellular network architecture that is based on intelligent network concepts is presented. Subscriber service mobility and call management attributes of the network, including location information retrieval and updating, authentication, call routing, handover, charging, and operations and maintenance, are discussed. >

Microcells in personal communications systems

Abstract: Research projects involving fiber-connected microcell base units, measurements and models of propagation in urban microcells, and radio link performance in urban microcells are summarized. Developments in microcell system issues, such as channel assignments and handoff in microcells and architectures for combining microcells with traditional macrocells, are discussed. Research on both indoor radio propagation and wireless indoor systems is reviewed. >

Perspectives on the AIN architecture

Abstract: The advanced intelligent network (AIN) is examined in terms of its history, present day architecture, and future evolution. The history of the AIN is traced from predivestiture 800 and calling card service capabilities, through IN/1, IN/2, and IN/1+, leading to the various AIN releases. The present-day view of the AIN architecture includes the switching system and other network systems, as well as operations. The AIN functionality supported by this architecture is described from a customer point of view, by means of an illustrative service that could be provided from an AIN platform. The next steps in the AIN evolution are discussed. An appendix that provides detailed information about the AIN Release 1 call model is included. >

Gigabit local area networks: a systems perspective

Abstract: A broad overview of gigabit local area networks (LANs) is presented from a systems perspective. Motivations and technical goals of gigabit LANs and challenges of coping with highly bursty traffic and large bandwidth mismatches between network links are described. The focus is on concerns unique to gigabit LANs, especially issues that differentiate them from gigabit wide area networks (WANs), metropolitan area networks (MANs), and lower-speed LANs. Major systems issues are discussed, and possible solutions, such as the virtual-connection architecture, are presented. The hardware technology required by gigabit LANs is illustrated by SONET components. >

Computing with uncertainty

Abstract: The role of and interaction between statistical, fuzzy, and neural-like models for certain problems associated with the three main areas of pattern recognition system design are discussed. Some questions concerning fuzzy sets are answered, and the design of fuzzy pattern recognition systems is reviewed. Pattern recognition, statistical pattern recognition and fuzzy pattern recognition systems are described. The use of computational neural-like networks in fuzzy pattern recognition is also discussed. >

Network control for wireless communications

Abstract: Existing wireless network architectures and the increasing demand for cellular services are reviewed. Wireless network control tasks and the structure of a cellular packet switch (CPS) based on an optical fiber metropolitan area network (MAN) are described. Protocols for moving information through the MAN focusing on handoff, a crucial function of wireless networks, are discussed. The results of an analysis of switch performance as measured by capacity and the distribution of functionality are presented. Several open issues regarding the capability of the CPS to deliver telephone service to wireless terminals, including privacy and security issues, are discussed. >

Multipoint multimedia conferencing

Abstract: The development of multipoint multimedia services for conferencing is described. The use of integrated services digital network (ISDN) as part of the work carried out in the European collaborative projects Multipoint Interactive Audiovisual Communication (MIAC) and Multipoint Interactive Audiovisual System (MIAS) is emphasized. The history of multipoint teleconferencing, the different types of multipoint conferencing systems, and protocol requirements for multipoint multimedia conferencing systems are also discussed. >

Intelligent network requirements for personal communications services

Abstract: It is shown that a moderate set of capabilities within the service switching point (SSP), service control point (SCP), and intelligent peripheral (IP), which are the intelligent network (IN) components directly responsible for the real-time execution and control of end-user services, can engender a wide range of end-user personal communication service (PCS) features. These capabilities could be used as the starting point for an economic analysis of IN implementation costs versus service worth. From a very large target set of call model trigger check points (TCPs), the dozen or so identified in the CCITT Capability Set 1 are shown to be sufficient. The SCP and IP functional entity actions identified are also sufficient to support PCS core network functions. >

International standards for intelligent networks

Abstract: An overview of the current state of intelligent network (IN) standards as described on CCITT's capability set 1 (CS1) is presented. The key to the success of CS1 lies in it being simple enough to be realizable with limited impact on existing software technology and network signaling, rich enough to provide a nontrivial, commercially deployable, initial set of services, and open-ended for growth, both in terms of service richness and penetration, and new capabilities enabled by new technologies. The objectives of IN and CS1, the main characteristics of CS1, and the framework and directions for IN evolution are discussed. >

Multimedia communications for users

Abstract: Research on next-generation multimedia communications services and technologies within a highly interdisciplinary research program that encompasses behavioral science, computer science, and electrical engineering is discussed. The authors state that they have taken an approach to their research that allows the needs of users and the demands of end-to-end applications to shape the future of the multimedia communications network. They use several examples to show how such a perspective affects the development of practical, advanced communications services. These examples span a wide range, including: empirical studies of people's use of technology to communicate in collaborative work settings; the design of software supporting the real-time network delivery of interactive multimedia documents for casual information users in the home; and the creation of next-generation prototypes that support the transmission and viewing of multimedia information in homes, offices and classrooms. >

Standardizing hypermedia information objects

Abstract: The level of complexity that should be addressed by a standard for the interchange of multimedia and hypermedia information, leading to a layered structure which separates a generic object layer from upper layers dealing with specific applications and from lower layers dealing with operating systems and file formats is discussed. The presentation and encoding of such multimedia and hypermedia information objects for the special needs of real-time, interactive, and communicating applications is the purpose of an International Organization for Standardization/Interexchange Carrier (SIO/IEC) group, known as Multimedia and Hypermedia Information Coding Expert Group (MHEG), the work of which is presented. The scope of the MHEG standard is explained, and an overview of the hierarchy of objects classes is provided, followed by a description of the methodology and coding principles developed in MHEG. The authors describe several categories of multimedia synchronization, making use of spatial and temporal relations between component objects, and relying on a scriptlike structure for more demanding situations. >

Residential video services

Abstract: A local exchange telephone company's (LEC's) investigation and development of new residential video services and the technologies and market needs that are making such services possible are discussed. Several potential LEC residential video services are described, and the technology necessary to implement such services is discussed, including network access and transport, switching, network management, and customer premises equipment (CPE). The LEC's experiences with residential video technology and service trials are presented along with new service implementation plans. >

Modulation methods for PCNs

Abstract: The interference levels that may be expected for a range of conventional cellular and microcellular clusters used in personal communication networks (PCNs) and personal communication systems (PCSs) are discussed. Simulation results show that for conventional size cells, 32- and 64-level quadrature amplitude modulation (QAM) schemes are preferred for bit error rates (BER) above 1*10/sup -2/, while 4PSK or variable-rate QAM schemes are better for lower BER. For microcells with communications at both 900 MHz and 1.8 GHz, four- or six-cell clusters are advocated, depending on the SNR expected. Based on the expected signal-to-noise ratio (SNR) and interference levels, it is argued that variable-rate QAM schemes are superior to the other modulation schemes considered. For low BERs 4PSK may often provide the best performance, whereas for high BERs, particularly when the SNR is high, 32- and 64-level star QAM are the most suitable. >

The emerging gigabit environment and the role of local ATM

Abstract: Several office application areas that, it is argued, cannot be explored effectively without an improvement in networking capabilities are described. Since the applications are predominantly based on the transmission of moving or still images, recent progress in data representation and compression that has an impact on the networking requirements is discussed. It is shown that asynchronous transfer mode (ATM) techniques can provide an acceptable, cost-effective means for meeting these requirements. The challenges that must be met, particularly in the local area, before the applications can be found in every laboratory and on every office desktop are outlined. >

Congestion control methods for BISDN

Abstract: Several congestion control methods for asynchronous transfer mode (ATM,) networks that support multimedia traffic by providing different guaranteed quality for each class of traffic are discussed. The two categories of congestion control methods presented are preventive congestive control and reactive congestive control. Preventive congestion control takes any action necessary to prevent congestion Reactive congestion control is responsible for any necessary action to recover from a congested situation, A summary of a proposed multilevel control scheme is also presented. >

The infrastructure for gigabit computer networks

Abstract: The key features of the synchronous optical network (SONET) and asynchronous transfer mode (ATM) standards for the broadband integrated services digital network (B-ISDN) public network, which is expected to provide a powerful and ubiquitous infrastructure to support the emerging gigabit-per-second data and multimedia applications, are reviewed. The advantages of ATM, the ATM cell format, the B-ISDN protocol reference model and the ATM layer, the ATM adaptation layer, and ATM traffic management and signaling are discussed. An experimental high-performance parallel interface (HIPPI)-ATM-SONET interface is presented as an example to illustrate how the SONET and ATM techniques can be used to provide end-to-end transport for applications requiring a bandwidth of 800 Mb/s and possibly 1600 Mb/s. >

Cordless personal communications

Abstract: The role of digital cordless technology in the transition to personal communication systems (PCSs) is discussed. The evolution of the pan-European digital cordless standards-CT2 and DECT-and industry progress in equipment availability and service implementation are reviewed. The application of cordless access to the domestic market in the United Kingdom and European telepoint, wireless PABXs, and radio drops are described. CT2 product development and availability and cordless data applications are outlined. The migration of microcellular cordless techniques for wider area systems including ETSI's universal mobile telecommunications system (UMTS) and the future public land mobile telecommunications systems (FPLMTS), now under development by CCIR with assistance from CCITT, are also discussed. >

Delivering interactive multimedia documents over networks

Abstract: A family of applications that consists of interactive multimedia documents, such as electronic magazines and interactive TV shows, is examined and the links between application architecture, user behavior, and network performance are investigated. The kinds of application-specific information that influence the end-to-end quality of service are discussed. The architecture and dynamics of the interactive document in terms of presentation objects (P-Objects), which are the segments of information accessed by the application and which are described according to their size, media composition, and access links, are described. The same structural characteristics that may make an interactive multimedia document appealing to the end user are the characteristics that are helpful during dynamic network performance optimization. This observation is based on the hypothesis that the P-Objects' access graph, together with viewing time statistics, is the information most useful to the network delivery control mechanism for optimizing network performance. Preliminary guidelines for both network and application designers to address each other's concerns are presented. >