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Computers and Communications, 1993., Twelfth Annual International Phoenix Conference on

Date 23-26 March 1993

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Displaying Results 1 - 25 of 87
  • Proceedings of Phoenix Conference on Computers and Communications

    Publication Year: 1993
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    Freely Available from IEEE
  • PROTEAN: A tool for automated protocol analysis

    Publication Year: 1993 , Page(s): 346 - 352
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    A program which performs an automated analysis of a protocol specification is discussed. The input is a protocol specified formally using the systems of communicating machines (SCMs) model and the output is a system and/or global reachability graph, together with any protocol errors which were discovered. The program, called PROTEAN analyzes the protocol for errors such as deadlock and nonexecutable transitions. The SCM model uses a combination of finite state machines and variables, which may be local to a single machine or shared by two or more machines. The current implementation of the model is limited to two-machine protocols. An analysis of a simple data link protocol is included to illustrate the use of the SCM automated model View full abstract»

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  • A scheme for improved multicast efficiency in a ring network

    Publication Year: 1993 , Page(s): 332 - 338
    Cited by:  Patents (2)
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    The authors deal with the multicasting of a file to a number of stations in a ring network. A protocol is presented which is very effective in reducing the overall transmission time when the links are subject to errors. The scheme relies on giving extra error protection to acknowledgements. Simulations and comparisons are made with two other schemes. These comparisons show the potential of substantial efficiency increases by using the proposed protocol. The benefits stem from a large reduction of unneeded repetitions under error conditions View full abstract»

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  • Linda-LAN: a controlled parallel processing environment

    Publication Year: 1993 , Page(s): 112 - 119
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    An investigation is presented on a controlled parallel processing environment based upon the Linda paradigm, a conceptually simple programming and operational framework. The environment utilizes the unused computing resources available on a network of computers to provide a low-cost parallel processing solution. The environment efficiently and effectively manages system resources via a centralized control subsystem. A detailed overview of the environment executing on a local area network is presented along with an analysis on its control subsystem. In addition, the control subsystem's execution characteristics of stability and scalability are substantiated View full abstract»

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  • New MAC schemes: CTMA and CRMA-one approach for `hidden terminal problem'

    Publication Year: 1993 , Page(s): 326 - 331
    Cited by:  Papers (1)
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    The authors propose two new media access control (MAC) schemes to resolve the hidden terminal problem in the radio LAN environment. These schemes, called channel tone multiple access (CTMA) and channel reservation multiple access (CRMA), were compared with carrier sense multiple access (CSMA) through computer simulations in terms of throughput and delay characteristics. With the CTMA scheme, the maximum throughput and packet delay are sensitive to nomalized propagation delay. For small propagation delays, performance with hidden terminals is better than that of CSMA without hidden terminals, making CTMA attractive for the radio LAN environment. The CRMA scheme uses a control channel based on CSMA and is basically affected by hidden terminals. However, due to dynamic arrangement of reservations at a central station, CRMA performs much better than CSMA with hidden terminals. Making the request packet length sufficiently short compared with the data packet length can significantly reduce wasted transmissions caused by hidden terminals View full abstract»

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  • Deriving protocol specifications from service specifications written in LOTOS

    Publication Year: 1993 , Page(s): 310 - 318
    Cited by:  Papers (7)
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    Based on the relation between the service and protocol concepts the authors have developed algorithms for deriving protocol entity specifications from a formal service specification. The derived protocol entities ensure the correct ordering of the service primitives by exchanging synchronization messages through an underlying communication medium. A new version of the algorithms is proposed. It is an extension of the method to a more comprehensive specification language. This version of the algorithm can handle all operators and unrestricted process invocation and recursion as defined by basic LOTOS. LOTOS is a language which has been developed within ISO for the formal specification of standard OSI protocols and services. The correctness of the algorithm is formally proved View full abstract»

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  • Neural network recognition of human face images stored in the database

    Publication Year: 1993 , Page(s): 552 - 558
    Cited by:  Papers (1)  |  Patents (2)
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    The author describes an investigation of human face recognition using neural networks. The investigation is the basis for retrieval and management of human face images stored in the database. The database is similar to FBI or many other law enforcement agencies databases. The goal of the investigation is twofold. First, assuming that an existing database of the front face and profile images is available, the requirement is to know whether the neural network trained on the front image and the profile can recognize any other images of the same person. Second, a minimal set of snapshots of each person is desired consisting of at least the front face and profile, which are needed to train a neural network so that the trained network can then recognize many other snapshots of the same person. The research prototype of a postrelational database management system (DBMs) is discussed called CHINOOK being implemented at the University of Colorado at Colorado Springs. CHINOOK is intended to manage databases of digitized images and digitized one-dimensional data as well as text and tables. CHINOOK is intended to support the retrieval of images by their content View full abstract»

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  • Managing software development to cost and schedule

    Publication Year: 1993 , Page(s): 475 - 482
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    The author reviews the approach and experiences in managing software development to cost and schedule on the survivable adaptive planning experiment (SAPE) program. SAPE was an Air Force Systems Command-Rome Laboratory program initiated to demonstrate the applicability of advanced computer and communications technology to the problem of quickly producing and maintaining the nation's strategic nuclear weapons plan. An overview of the program is followed by a discussion of the program challenges and experiences including a review of the software development model and management approach. The performance of the SAPE program was a remarkable achievement in that over 970 K source lines of code was successfully developed, integrated and demonstrated over a two year time period by a staff that peaked at approximately 50 personnel. The SAPE program success together with experience on and observations of a number of other projects to build large, complex software systems confirm that the correlation between success and failure for these systems is due to the engineering process chosen, i.e., the software development model, and the management process View full abstract»

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  • Xpress Transfer Protocol over the BERKOM B-ISDN network: Implementation and performance comparison with TCP/IP

    Publication Year: 1993 , Page(s): 296 - 302
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    The Xpress Transfer Protocol (XTP) is a typical example of a protocol with new mechanisms and functionality specifically designed for new high-speed network environments and applications. XTP can provide the full range of services needed to support distributed processing systems. A software implementation of XTP has been completed to run over the BERKOM broadband ISDN. The software architecture of the implementation is presented. Performance measurements of XTP over the BERKOM network are reported and compared to those of TCP/IP protocol. XTP has been found to perform about as well as and in some situations better than TCP/IP View full abstract»

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  • Load sharing using multicasting

    Publication Year: 1993 , Page(s): 303 - 309
    Cited by:  Patents (1)
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    The authors examine approaches to load sharing based on multicasting in a local area network environment. The results show that multicasting is an efficient method for locating lightly-loaded nodes with better response time and fewer messages to busy nodes, compared to previously proposed policies. The improved performance of the multicasting policies results from nodes maintaining state information by joining and leaving multicast groups, rather than probing or exchanging information between machines that may already be busy View full abstract»

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  • Measurement of parallelism in data communications protocol software

    Publication Year: 1993 , Page(s): 56 - 65
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    The authors report on an experimental investigation of a parallel implementation of OSI protocol software which, unlike a single application, is a continuous flow system in which the program runs forever. An important attribute of parallel jobs, the average parallelism measure is extended to the domain of continuous flow systems, using the notion of the total rate of work. Protocol execution is important because it is known to have a significant impact on the overall performance of distributed systems. Experiments were performed on a parallel protocol implementation to measure the impact of the average and distribution of message size, the transport protocol data unit (TPDU) size, the flow control window size and the number of processors on parallelism and speedup. They indicate that parallelism and speedup depend more strongly on the design of the software and on its operating environment than on the protocol parameters View full abstract»

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  • A resource allocation model for BISDN/ATM

    Publication Year: 1993 , Page(s): 282 - 288
    Cited by:  Papers (1)  |  Patents (1)
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    The authors outline a call control algorithm for high speed broadband networks using the burstiness associated with traffic sources in a heterogeneous asynchronous transfer mode (ATM) environment where calls are to be statistically multiplexed, and a bandwidth allocation strategy is required. An algorithm that accommodates the bursty nature of traffic is proposed for the dynamic assignment of bandwidth. An assignment which does not use this traffic characteristic cannot be optimal. The problem is cast into a constrained optimization problem subject to the dynamics of the task flow equation and resource constraints. This approach is very effective in the connection oriented transport of ATM networks where the decision to admit new traffic is based on a priori knowledge of the state of the route taken by the traffic. This proposal defines an analytically simple yet versatile virtual circuit acceptance algorithm to serve simultaneous connections View full abstract»

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  • An interactive parallel program slicer for the hypercube

    Publication Year: 1993 , Page(s): 66 - 72
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    Program slicing is an approach used in the debugging process. The authors report on the development of an interactive parallel program slicer (PPS) for distributed-memory parallel programs on the iPSC/2 Hypercube System. PPS focuses on the csend and crecv commands of the iPSC/2 Hypercube System. An extended slicing criterion is developed for applying program slicing to distributed-memory parallel programs. The design approach of the static-slicing-based PPS is discussed. Some basic rules for applying PPS to iPSC/2 Hypercube System programs are introduced. An example is also presented View full abstract»

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  • Simulation of pointer activity in synchronous digital hierarchy networks

    Publication Year: 1993 , Page(s): 409 - 415
    Cited by:  Papers (1)
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    Pointer activity in synchronous transport module 1 (STM1) networks is presented based on simulated models of various STM1 network payload configurations. A statistical clock model is used to simulate the effects of clocking instabilities. The clock model used is based upon a root-mean-square (RMS) time interval error (RMSTIE) metric and conforms to the RMSTIE mask as defined by CCITT and other standards committees. Traditional pointer activity studies have been done on a behavioral basis, minimizing byte by byte calculations to reduce simulation time and resolution of results. Additionally, previous studies have examined the effects of constant clock frequency offsets on pointer activity. This study approaches the problem by using byte by byte calculations coupled with a statistical clock model and constant frequency offsets to determine pointer generation and interactions at a level of detail not presented previously. The results of this study are the expected nature of pointer activity in synchronous digital hierarchy (SDH) networks for clock instabilities within the CCITT clock stability specification View full abstract»

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  • Queued transaction processing within the UNIX operating system environment

    Publication Year: 1993 , Page(s): 441 - 446
    Cited by:  Papers (2)  |  Patents (3)
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    The authors discuss queued transaction processing as it relates to the UNIX operating system environment. They briefly discuss the essence of the queued transaction processing model and how it relates to distributed computing models. Requirements and methods for introducing true queued transaction processing within the UNIX system environment are considered. The conclusion is that extending the UNIX system to provide queued transaction processing is relatively straightforward and is a requirement for the large scale adoption of UNIX, both to allow for further porting of legacy systems to UNIX, and because of the intrinsic need to do queued transaction processing in many large applications View full abstract»

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  • Customer-focused initiative management: Reengineering the process

    Publication Year: 1993 , Page(s): 483 - 487
    Cited by:  Papers (3)
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    The authors discuss the evolution of project management by Bellcore from a service specific focus to a strategic initiative focus. They consider the evolution of the project planning management and tracking (PPMT) system into P++, a system that provides a comprehensive framework for managing Bellcore technical functions, both strategic and tactical. The PPMT was created to manage software projects and the staff working on those projects. By employing the full ranges of features within P++, Bellcore can successfully manage the transition from a customer focus based on separate deliverables, to one based on strategic initiatives View full abstract»

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  • First class functions and dynamic binding of methods to classes

    Publication Year: 1993 , Page(s): 217 - 223
    Cited by:  Patents (1)
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    The implementation of the object-oriented paradigm adopted by Oberon, Oberon-2 and Modula-3 is analyzed and compared with a new technique proposed. The design principles adopted in the method are orthogonality with respect to the role of first-class procedures, minimality of extension, and generality of application. The constructs used are record type extensions and first-class procedures. The new concepts introduced are the shared virtual part of a record type also called a virtual data table, and self-bound record fields View full abstract»

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  • Architectural support for high-performance distributed computing

    Publication Year: 1993 , Page(s): 319 - 325
    Cited by:  Papers (1)  |  Patents (1)
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    Software and hardware support are presented to transform a local area network of workstations into a high-performance distributed computing environment. A host interface processor (HIP) and a communication protocol (HCP) are presented to improve the application-level transfer rates. The authors analyze the performance of a distributed application when it runs on computers of HIP-based local networks and compare it with the performance of a single computer execution View full abstract»

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  • A functional reconfigurable architecture and compiler for adaptive computing

    Publication Year: 1993 , Page(s): 49 - 55
    Cited by:  Papers (1)  |  Patents (4)
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    Many computationally intensive tasks spend nearly all of their execution time within a small fraction of the executable code. Substantial gains can be achieved by allowing the configuration and fundamental operations of a processor to adapt to these frequently accessed portions. A method is presented which improves the performance of many computationally intensive tasks by utilizing information extracted at compile-time to synthesize new operations which augment the functionality of a core processor. The newly synthesized operations are targeted for RAM-based field-programmable gate array (FPGA) devices which provide a mechanism for fast processor reconfiguration. A proof-of-concept system called PRISM, consisting of a specialized C configuration compiler and a reconfigurable hardware platform, is presented. Compilation and performance results are provided which confirm the concept viability, and demonstrate significant speed-up over conventional general-purpose architectures View full abstract»

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  • A fast link assignment algorithm for satellite communication networks

    Publication Year: 1993 , Page(s): 401 - 408
    Cited by:  Papers (5)
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    In satellite communication networks using laser transceivers, each satellite has a limited number of transceivers with a very narrow field of view. The authors consider the problem of deciding which logical connections should be formed among satellites out of all the possible connections that can be made depending on the line-of-sight (LOS) visibility of satellites. These logical connections can be decided to meet various objectives of the underlying network. The objective functions can be maximizing the number of links formed, thus, maximizing the transceiver utilization, maximizing network connectivity, minimizing link re-targeting, or minimizing average distance between nodes. Here, the satellite networks are assumed to be independent from intervention by ground stations. Hence, the decisions made should be autonomous. Another assumption is that all the computations and decisions made are either aperiodic or the input to computation is too unpredictable to be precomputed. Various approaches to link assignment with different objective functions and algorithms for some specific functions are described. Simulation results and performance analyses for some of the algorithms are also presented View full abstract»

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  • A static semantic analyzer for LOTOS specifications

    Publication Year: 1993 , Page(s): 585 - 592
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    The authors present some aspects related to the implementation of the formal flattening rules and static semantic requirements defined for the standard specification language LOTOS that are to be faced in developing tools based on LOTOS descriptions. The approach led to the implementation of a C program consisting of a syntax-driven parser whose actions are the flattening functions. The flattening functions, formally defined in the standard document, involve forward references that should be resolved before implementing the flattening and static semantic functions. The tool is able to read a LOTOS specification and produces a data structure which corresponds to a formal data structure called the canonical LOTOS specification (CLS) in the standard LOTOS document. Examples and measures of performance that have been collected by testing the tool on some significant case studies taken from the existing literature are also given View full abstract»

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  • Performance analysis of integrated voice/data communication in cellular systems with virtually fixed channel assignment

    Publication Year: 1993 , Page(s): 370 - 375
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    The authors present a performance evaluation model for an integrated cellular mobile communication systems that uses virtually fixed channel assignment (VFCA). FCA is efficient in channel reuse, but it is not flexible. A channel allocated to a set of co-channel cells cannot be used in other cells even if it is idle. VFCA is a flexible fixed channel assignment or borrowing channel assignment scheme. Channels available in a system are all allocated to cells according to FCA, so that each cell has a list of nominal channels. A cell request is assigned a nominal channel if one is available in its cell; otherwise a nonnominal channel is borrowed to service this call. VFCA and an associated analytical model are outlined. Numerical results for an example scenario are given View full abstract»

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  • A methodology for partitioning long local computer networks

    Publication Year: 1993 , Page(s): 275 - 281
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    The authors present a new methodology for partitioning long local computer networks. The proposed technique relies on dividing the long network into subnets that are interconnected using a multistage delta interconnection network and an interface device. The performance of the proposed partitioning method is studied using simulation modeling. It is found that the throughput of the proposed partitioned network is improved and the average packet delay is reduced as compared to the single long network View full abstract»

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  • A visual design support system for telecommunication services

    Publication Year: 1993 , Page(s): 593 - 599
    Cited by:  Papers (1)
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    The authors propose a visual design support system for telecommunication services that uses the state transition rule (STR) as specification knowledge and a description language. The system has excellent design support facilities, which are discussed. A designer, who has no knowledge of the professional aspects of network specifications, can describe various services from the user's viewpoint using the STR-GR (graphical representation) description method. Merely by synthesizing some service descriptions, the system can automatically validate the service interactions by means of rule conflict detection. A designer can verify a service specification by simulating a designed service description and displaying its execution processes in an animated form. The experimental evaluation of the design support system is presented View full abstract»

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  • Extension of Stone's task assignment model for distributed computer systems

    Publication Year: 1993 , Page(s): 73 - 78
    Cited by:  Papers (2)
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    The authors consider optimal static assignment of a group of communicating tasks among a set of processors. The assignment is based on the throughput metric optimality criteria by H.S. Stone (1977) which is the total cost for execution and interprocess communication. Stone's model is generalized with the addition of an important factor called processor connectivity. The scheme is necessary in situations where the processors need not exhibit full connectivity. It is shown that a graph-theoretic approach similar to that proposed by C.C. Shen and W.H. Tsai (1985) for a delay metric can be used to solve the ensuing problem and it is found empirically that the procedure is computationally more efficient for the throughput metric View full abstract»

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