Showing papers in "IEEE Communications Magazine in 1989"
TL;DR: The author extends a previous review and focuses on feed-forward neural-net classifiers for static patterns with continuous-valued inputs, examining probabilistic, hyperplane, kernel, and exemplar classifiers.
Abstract: The author extends a previous review and focuses on feed-forward neural-net classifiers for static patterns with continuous-valued inputs. He provides a taxonomy of neural-net classifiers, examining probabilistic, hyperplane, kernel, and exemplar classifiers. He then discusses back-propagation and decision-tree classifiers; matching classifier complexity to training data; GMDH (generalized method of data handling) networks and high-order nets; K nearest-neighbor classifiers; the feature-map classifier; the learning vector quantizer; hypersphere classifiers; and radial-basis function classifiers. >
836 citations
TL;DR: A detailed study was made of the Transmission Control Protocol (TCP), the transport protocol from the Internet protocol suite, and it was concluded that TCP is in fact not the source of the overhead often observed in packet processing, and that it could support very high speeds if properly implemented.
Abstract: The transport layer of the protocol suite, especially in connectionless protocols, has considerable functionality and is typically executed in software by the host processor at the end points of the network. It is thus considered a likely source of processing overhead. However, a preliminary examination has suggested to the authors that other aspects of networking may be a more serious source of overhead. To test this proposition, a detailed study was made of the Transmission Control Protocol (TCP), the transport protocol from the Internet protocol suite. In this set of protocols, the functions of detecting and recovering lost or corrupted packets, flow control, and multiplexing are performed at the transport level. The results of that study are presented. It is concluded that TCP is in fact not the source of the overhead often observed in packet processing, and that it could support very high speeds if properly implemented. >
663 citations
TL;DR: Two novel methods for achieving handwritten digit recognition are described, based on a neural network chip that performs line thinning and feature extraction using local template matching and on a digital signal processor that makes extensive use of constrained automatic learning.
Abstract: Two novel methods for achieving handwritten digit recognition are described. The first method is based on a neural network chip that performs line thinning and feature extraction using local template matching. The second method is implemented on a digital signal processor and makes extensive use of constrained automatic learning. Experimental results obtained using isolated handwritten digits taken from postal zip codes, a rather difficult data set, are reported and discussed. >
430 citations
TL;DR: This pragmatic approach to all coding applications permits the use of a single basic coder and decoder to achieve respectable coding (power) gains for bandwidth efficiencies from 1 b/s/Hz to 6 b/S/Hz.
Abstract: Since the early 1970s, for power-limited applications, the convolutional code constraint length K=7 and rate 1/2, optimum in the sense of maximum free distance and minimum number of bit errors caused by remerging paths at the free distance, has become the de facto standard for coded digital communication. This was reinforced when punctured versions of this code became the standard for rate 3/4 and 7/8 codes for moderately bandlimited channels. Methods are described for using the same K=7, rate 1/2 convolutional code with signal phase constellations of 8-PSK and 160PSK and quadrature amplitude constellations of 16-QASK, 64-QASK, and 256-QASK to achieve, respectively, 2 and 3, and 2, 4, and 6 b/s/Hz bandwidth efficiencies while providing power efficiency that in most cases is virtually equivalent to that of the best Ungerboeck codes for constraint length 7 or 64 states. This pragmatic approach to all coding applications permits the use of a single basic coder and decoder to achieve respectable coding (power) gains for bandwidth efficiencies from 1 b/s/Hz to 6 b/s/Hz. >
308 citations
TL;DR: The transfer mode chosen by the CCITT Study Group XVIII Task Group on ISDN Broadband Aspects as the basis of broadband ISDN is called the asynchronous transfer mode (ATM) as discussed by the authors.
Abstract: The transfer mode chosen by the CCITT Study Group XVIII Task Group on ISDN Broadband Aspects as the basis of broadband ISDN is called the asynchronous transfer mode (ATM). ATM is a high-bandwidth, low-delay, packetlike switching and multiplexing technique. It is essentially a connection-oriented technique, although it is envisioned as a basis for supporting all services, connectionless as well as connection-oriented. The basic transfer mode concepts are explained. The limits of synchronous transfer mode (ATM) are discussed and reasons for choosing ATM over STM are given. The main technical issues having an impact on the ATM specifications are discussed. >
251 citations
TL;DR: It is demonstrated that neural networks are able to extract speech information from the visual images and that this information can be used to improve automatic vowel recognition.
Abstract: Results from a series of experiments that use neural networks to process the visual speech signals of a male talker are presented. In these preliminary experiments, the results are limited to static images of vowels. It is demonstrated that these networks are able to extract speech information from the visual images and that this information can be used to improve automatic vowel recognition. The structure of speech and its corresponding acoustic and visual signals are reviewed. The specific data that was used in the experiments along with the network architectures and algorithms are described. The results of integrating the visual and auditory signals for vowel recognition in the presence of acoustic noise are presented. >
212 citations
TL;DR: Radio wave propagation experiments at 1300 MHz, which were conducted by the author in five operational factories, are described, and studies of multipath propagation are discussed, and techniques for overcoming it are considered.
Abstract: The need for reliable, real-time communication for automated factories is discussed. The ability of narrowband digital radio systems to meet that need is examined. The major problems encountered in multipath propagation, resulted from multiple reflections of the transmitted signal from the building structure and surrounding inventory. Radio wave propagation experiments at 1300 MHz, which were conducted by the author in five operational factories, are described. Other studies of multipath propagation are discussed, and techniques for overcoming it are considered. Research on multiple-access networking is summarized. >
187 citations
TL;DR: In this article, the authors discuss aspects of the SONET (synchronous optical network) standards and standardization process, both national and international, that they consider to be of particular interest.
Abstract: The authors discuss aspects of the SONET (synchronous optical network) standards and standardization process, both national and international, that they consider to be of particular interest. Restricting their attention to the standard dealing with rates and formats, they consider the SONET signal hierarchy, overhead channels, multiplexing, STS-1 payload pointer, sub-STS-1 payloads, and optical interface parameters. They include a brief history of the SONET standard and an outline of future work. >
175 citations
TL;DR: The design of the Versatile Message Transaction Protocol is described and some performance measurements of the protocol used in the V-Distributed System are described and it is shown that VMTP addresses all of the above issues within a single protocol without significant compromise.
Abstract: The authors identify and discuss three major categories of deficiencies in current transport protocols: performance, naming, and functionality. They describe the design of the Versatile Message Transaction Protocol (VMTP) and some performance measurements of the protocol used in the V-Distributed System. They show that VMTP addresses all of the above issues within a single protocol without significant compromise. >
144 citations
TL;DR: The European cellular environment is described, and the types of cellular environments that are able to support lightweight handheld portables are addressed and narrowband transmission of subband-coded speech by 16-level QAM and high-bit-rate transmission are discussed.
Abstract: The European cellular environment is described, and the types of cellular environments that are able to support lightweight handheld portables are addressed. Microcellular structures are considered, covering propagation measurements, rapid handover, interfacing with local area networks, and highway microcells with an overlaying macrocell. Narrowband transmission of subband-coded speech by 16-level QAM and high-bit-rate transmission are discussed. Picocells, i.e., very small areas or volumes that might encompass an office, a house and its immediate environment, or a hot spot that provides high-capacity communication, are considered. >
131 citations
TL;DR: The authors review noncoherent, frequency-tunable filter (receiver) technologies and describes three basic mechanisms of wavelength filtering: filters based on the wavelength dependence of interferometric phenomena, with emphasis on Fabry-Perot interferometer filters.
Abstract: The authors review noncoherent, frequency-tunable filter (receiver) technologies. They describe three basic mechanisms of wavelength filtering: filters that are based on the wavelength dependence of interferometric phenomena, with emphasis on Fabry-Perot interferometer filters; filters that are based on the wavelength dependence of coupling between optical fields (modes) induced by external perturbations (both acoustooptic and electrooptic filters are described); and filters that are based on resonant amplification of optical signals in semiconductor laser diode devices (these devices provide gain in addition to wavelength selectivity). For each technology the authors explain briefly the principles of operation and quantify the relevant system parameters: tuning range, channel separation, number of channels, crosstalk isolation, gain and distortion, speed of wavelength tuning, and complexity. They present a unified picture of filtering mechanisms in an appendix. >
TL;DR: A description is given of a proposed use of digital radio technology as a drop/distribution/loop technology for local exchange access and the integration of this radio technology with network intelligence to provide the added functionality of portability.
Abstract: The evolution of current technologies that provide either wireless exchange access or access and communications to people away from their own telephones is outlined. A description is given of a proposed use of digital radio technology as a drop/distribution/loop technology for local exchange access and the integration of this radio technology with network intelligence to provide the added functionality of portability. Issues surrounding portable digital radio as an exchange access technology are discussed. >
TL;DR: The author shows how the bandwidth available through the use of multiwavelength optical-fiber technology can be used to achieve novel large-capacity switching systems to address anticipated switching bottlenecks.
Abstract: The author shows how the bandwidth available through the use of multiwavelength optical-fiber technology can be used to achieve novel large-capacity switching systems to address anticipated switching bottlenecks. He does so by describing the features and network applications of a specific multiwavelength network, the Bellcore LAMBDANET packet switch. The discussion is then extended to a number of recent proposals for switching fabrics based on this new multiwavelength technology. The particular technologies he discusses are: the photonic knockout switch, a proposal similar to the concept of the LAMBDANET, but not requiring N receivers at each node; the FOX (fast optical cross-connect), an active wavelength routing approach; the ShuffleNet architecture; the HYPASS and BHYPASS switches; the coherent wavelength division lambda switch; and the Bellcore Star-Track multicast switch. >
TL;DR: The author explores the relationship between the bandwidth of the fiber, the available power and the loss in various network designs, and the throughput of networks as limited by the medium- access techniques and control mechanisms, and discusses medium-access considerations.
Abstract: The author presents an overview of fundamental considerations that guide and motivate research in this area. He explores the relationship between the bandwidth of the fiber, the available power and the loss in various network designs, and the throughput of networks as limited by the medium-access techniques and control mechanisms. He discusses two approaches to opening up the bottleneck that seem particularly promising. The first, multihop, uses a novel network architecture to achieve high capacity with existing devices; the second, wavelength division multiple access (WDMA), emphasizes new devices in a relatively conventional architecture. Noting that the primary disadvantage of the bus topology, poor energy efficiency, could be overcome with a suitable optical amplifier to compensate for the high signal attenuation in the network, the author discusses one of the most promising candidates, the traveling-wave semiconductor amplifier. He also discusses medium-access considerations. >
TL;DR: The author argues that a strong impetus for using neural networks is that they provide a framework for designing massively parallel machines and presents two switching applications in which neural networks can solve the problems efficiently.
Abstract: The author argues that a strong impetus for using neural networks is that they provide a framework for designing massively parallel machines. He notes that the highly interconnected architecture of switching networks suggests similarities to neural networks. He presents two switching applications in which neural networks can solve the problems efficiently. He shows that a computational advantage can be gained by using nonuniform time delays in the network. >
TL;DR: The present status of wavelength-tunable and single-frequency devices needed for the broadband integrated services digital network (BISDN) of the future is reviewed and the various systems applications and requirements are described.
Abstract: The present status of wavelength-tunable and single-frequency devices needed for the broadband integrated services digital network (BISDN) of the future is reviewed. The various systems applications and requirements and, in turn, the device parameters that are relevant to those requirements are described. The basic material and structural parameters of the lasers are discussed, and the fundamental operational principles are explained. Various single-frequency, high-speed, and tunable laser structures are reviewed, and their characteristics are presented. >
TL;DR: The various existing or envisioned applications for so-called telemedicine networks are described and current and future medical environments are examined with respect to the use of such networks.
Abstract: The various existing or envisioned applications for so-called telemedicine networks are described. The current and future medical environments are examined with respect to the use of such networks. The characteristics of medical images that affect their transmission and storage are discussed. Medical communication field trials using the emerging broadband networks are described. Some service scenarios and concepts are presented. >
TL;DR: A conceptual model for representing integrated-services digital network (ISDN) calls is presented as the basis for structuring a more flexible signaling protocol to meet the needs for a broadband environment.
Abstract: User networks signaling is considered. The evolution of signaling protocols is outlined, analyzing the forces producing changes in the past. Emerging broadband switching technologies and services are discussed, emphasizing capabilities that might be required. A conceptual model for representing integrated-services digital network (ISDN) calls is presented as the basis for structuring a more flexible signaling protocol to meet the needs for a broadband environment. >
TL;DR: Network applications of multichannel wavelength-division multiplexing (WDM) techniques are considered and interoffice and subscriber loop architectures that utilize the unique properties of WDM to achieve important advantages over more traditional network designs are presented.
Abstract: Network applications of multichannel wavelength-division multiplexing (WDM) techniques are considered. The photonic technologies that will be critical to future systems using WDM are reviewed. Both interoffice and subscriber loop architectures that utilize the unique properties of WDM to achieve important advantages over more traditional network designs are presented. Several experimental demonstrations that illustrate how these architectures can be realized with currently available components are described. >
TL;DR: Burst transport is integrated in that voice and data are switched through the same switching fabric and transmission media as discussed by the authors, and round-trip delay performance is calculated to be less than 5 ms.
Abstract: Burst switching research in dispersed control and integrated switching is described. Burst transport is integrated in that voice and data are switched through the same switching fabric and transmission media. Burst switching is compared to and distinguished from fast packet, fast circuit, and ATM (asynchronous transfer mode) switching. Misunderstandings about burst transport that have appeared in the literature are corrected, to wit: burst does not immediately clip in case of channel contention; burst switches voice and data in the same way; and a burst switch interfaces naturally to other types of switches. Round-trip delay performance is calculated to be less than 5 ms. The current status of the burst project is described. >
TL;DR: Measurements of the end-of-end delay and maximum throughput are reported for a typical implementation of the bottom four layers of the Open Systems Interconnection protocols, which comprise the transport, network, data link, and physical protocols.
Abstract: Measurements of the end-of-end delay and maximum throughput are reported for a typical implementation of the bottom four layers of the Open Systems Interconnection (OSI) protocols. These comprise the transport, network, data link, and physical protocols. An overview of the four protocols is given, and the experimental environment is described. The measurement results are discussed, and some of the implementation factors that affect the performance of OSI protocols are identified. >
TL;DR: A description is given of AT&T's nationwide synchronization network along with a tutorial on the importance of and need of synchronization.
Abstract: A description is given of AT&T's nationwide synchronization network along with a tutorial on the importance of and need of synchronization. The primary reference clock (PRC) is described along with its verification methodology, capabilities, and performance. The clock and transmission models are discussed along with methods of specifying and testing clock performance. Planning tools and methodology for the synchronization of private digital networks are presented. An expert system that uses the clock models to prepare the optimum performance synchronization plan for a private network is introduced. >
TL;DR: Several systems proposed for the delivery of telephone service and/or distributive video services in the local access network are described and the status of the standardization of interfaces for the broadband integrated services digital network based on the synchronous optical network and asynchronous transfer mode is examined.
Abstract: The attributes of the various architectural alternatives are discussed. Several systems proposed for the delivery of telephone service and/or distributive video services in the local access network are described. The status of the standardization of interfaces for the broadband integrated services digital network (BISDN) based on the synchronous optical network (SONET) and asynchronous transfer mode (ATM) is examined. >
TL;DR: A model of multiservice network architecture (M-architecture) is presented and an attempt is made to describe the traffic management and control schemes in a systematic way to solve multiplexing, routing, and flow control problems in the ISDN.
Abstract: A model of multiservice network architecture (M-architecture) is presented. An attempt is made to describe the traffic management and control schemes in a systematic way. The basic concepts are developed, and examples are given that indicate how the proposed framework can be used to solve multiplexing, routing, and flow control problems in the ISDN. The emphasis is on the traffic control schemes. The M-architecture can be regarded as either a reference architecture for future multiservice networks or an abstract model of traffic management and control in currently used networks. >
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TL;DR: The author discusses the global network for international communications being constructured by Cable and Wireless Ltd., entitled the Global Digital Highway (GDH), which will provide a digital, fiber-optic link connecting major commercial and financial centers around the world.
Abstract: The author discusses the global network for international communications being constructured by Cable and Wireless Ltd., entitled the Global Digital Highway (GDH), which will provide a digital, fiber-optic link connecting major commercial and financial centers around the world. He suggests that the world is waiting for basic global facilities that will be exclusively dedicated to facilitating international communications and networking. He examines the trend toward liberalization in telecommunications policies, led by the US, which has recently been joined by both the UK and Japan. He discusses the role of Cable and Wireless in the context of these liberalization policies. >
TL;DR: The author examines some of the ways that speech signals, subjected to certain degradations, can be processed to increase the likelihood of being correctly understood.
Abstract: The author examines some of the ways that speech signals, subjected to certain degradations (e.g. additive noise, interfering speakers, bandlimiting, single-channel data), can be processed to increase the likelihood of being correctly understood. He concentrates on applications that involve monaural listening. He treats spectral and time-domain subtraction techniques, methods involving fundamental frequency tracking, and enhancement by resynthesis. >
TL;DR: A nomenclature describing a set of essential dimensions or characteristics germane to integrated broadband switching architectures is presented, intended to afford the switch designer an ordered and reasoned approach to deciding among the numerous choices in the design of broadband switches.
Abstract: A nomenclature describing a set of essential dimensions or characteristics germane to integrated broadband switching architectures is presented. Using this vocabulary, a classification of switching architectures is proposed. The classification is intended to afford the switch designer an ordered and reasoned approach to deciding among the numerous choices in the design of broadband switches. >
TL;DR: It is suggested that the IC-card, which can store various information for telephone calls, will become a useful device in multifunction telephone sets because of its portability, security, and large memory capacity.
Abstract: An IC-card is a memory card that can be substituted for existing magnetic-striped cards. It is suggested that the IC-card, which can store various information for telephone calls, will become a useful device in multifunction telephone sets because of its portability, security, and large memory capacity. The information that should be stored on an IC-card is discussed, and the practicality of creating personal telephone services by combining telephone services with the stored user information is addressed. An experimental telephone set with an IC-card reader/writer developed to verify feasibility is presented. Service grades of IC-cards, according to their level of functionality versus the functionality of the terminal equipment, are discussed. >
TL;DR: The authors describe how SPIMS can be used to measure response time, throughput, and the time to open and close connections, and describe the protocols and their implementations, and draw some conclusions.
Abstract: The authors present results from performance measurements of application services. They have chosen widely available implementations of the file transfer protocols File Transfer Access and Management (FTAM) and FTP, and the transaction protocols Remote Operations Service Element (ROSE) and Sun's Remote Procedure Call (SunRPC). The measurements have all been run on the same Sun 3/60 workstations over Ethernet, using protocol-independent benchmarks. A tool called SICS Protocol Implementation Measurement System (SPIMS) is used for the measurements. It is structured as a protocol, with two peer entities communicating with each other using the service of the measured protocol. The authors describe how SPIMS can be used to measure response time, throughput, and the time to open and close connections. They describe the protocols and their implementations, and draw some conclusions, and present and comment on the results. >
TL;DR: The concept of learning by example as it applies to neural networks is examined and the main results in the mathematical evaluation of neural networks as information processing systems are discussed.
Abstract: Some of the main results in the mathematical evaluation of neural networks as information processing systems are discussed. The basic operation of feedback and feed-forward neural networks is described. Their memory capacity and computing power are considered. The concept of learning by example as it applies to neural networks is examined. >