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Computers and Communications, 1998. ISCC '98. Proceedings. Third IEEE Symposium on

Date June 30 1998-July 2 1998

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  • Proceedings Third IEEE Symposium on Computers and Communications. ISCC'98. (Cat. No.98EX166)

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    Freely Available from IEEE
  • Author index

    Page(s): 717 - 720
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    Freely Available from IEEE
  • Simulation of a FFT based multi-carrier system for ADSL and VDSL transmission

    Page(s): 537 - 542
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    This paper presents an efficient method for simulating the performance of multicarrier modulations. The method is based upon the Gauss quadrature rules and offers a significant computational advantage over commonly used Monte Carlo techniques. It takes into account the effects of intersymbol interference, interchannel interference and noise. BER performance curves of representative FFT based multicarrier systems for ADSL and VDSL are obtained using the simulation method described View full abstract»

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  • QoS routing in multihop packet radio environment

    Page(s): 582 - 586
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    We present a method to compute the path bandwidth for the DSDV (destination-sequenced distance-vector) based routing algorithm. The addressed network does not necessarily have a cellular structure and could have no fixed infrastructure. This network can be either stand-alone, or connected to the wired network. Each mobile station has to relay packets for others, thus achieving multihop routing. To calculate the available bandwidth of a path in this environment, it is incorrect to simply compute the minimum bandwidth of the links along the path. There are two crucial steps in the path bandwidth computation process of this multihop environment: (1) intersecting the sets of common free slots of two adjacent links, and (2) dividing the intersection for the adjacent links to share. We present two bandwidth computation rules including the half rule and the floating rule. Numerical results are given to evaluate the performance of applying these rules to the DSDV-based QoS routing algorithm View full abstract»

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  • Object-oriented development of telematic services

    Page(s): 276 - 280
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    This paper examines the application of object-orientation on the complete life cycle of telematic services. After an introduction in the discipline of service engineering, basic concepts of object-oriented technology are analysed. The main requirements associated with the design of telematic services are identified and ways that object-orientation can support them are examined. Then, an integrated approach to service engineering in the form of a framework for the development of telematic services is proposed. The constituent parts of this framework, which are an object-oriented service support environment, a design environment and an object-oriented methodology for the analysis and design of telematic services, are discussed in considerable detail. Finally, some conclusions are given View full abstract»

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  • Performance of a micro-macrocellular system with overlapping coverage and channel rearrangement techniques

    Page(s): 705 - 710
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    In this paper, a new way to manage users having different mobility in a two-tier cellular system, through the use of the techniques of overlapping coverage and channel rearrangement, is provided. Overlapping coverage areas of nearby base stations arise in cellular communications systems, especially in small cell high-capacity microcellular configurations. With overlap, some users may have access to channels at more that one base station. This enhanced access can be used to improve teletraffic performance characteristics. Channel rearrangements are used to benefit users who are in range of only one base station. An analytical model is developed to determine performance measures View full abstract»

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  • The clade vertebrata: spines and routing in ad hoc networks

    Page(s): 599 - 605
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    This work proposes a self-organizing, dynamic infrastructure called a spine for efficient routing in ad hoc networks. We present a scalable framework for routing that encompasses a range of knowledge at each spine node, and identify the trade-offs involved for routing at different points in this range. Our routing algorithm requires only partial topology information at each spine node, consisting of the spine structure, dependants of each spine node, propagation of long-lived links, and snooped routing information from ongoing flows. Through worst-case theoretical bounds and simulation of typical scenarios, we show that the spine-based routing with only partial topology information provides good routes at low overhead View full abstract»

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  • A low complexity baseband receiver for direct conversion burst-type radio systems

    Page(s): 246 - 250
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    The interest for small size low complexity radio systems has resulted in examination of efficient architectures for transceiver implementation. This in turn has pushed towards smaller RF subsystems and efficient digital baseband sections. An all-digital low complexity baseband receiver is presented for a DECT radio system employing the direct conversion approach. This approach permits generation of in-phase and quadrature (I/Q) signal components. We present a novel approach for the differential detector using a finite state machine approach. The symbol timing algorithm uses oversampling only during the packet synchronization word whereas the frequency offset correction algorithm operates on the symbol rate permitting corrections up to 12% of the symbol rate. The symbol timing and the frequency correction algorithms are also implemented in an all-digital fashion emphasizing low complexity realization View full abstract»

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  • Comparative analysis of the notions of equivalence for process specifications

    Page(s): 711 - 716
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    Several notions for semantic equivalence of process specifications have been developed. It has widespread applicability in verification and testing. Each notion has its criteria for checking equivalence. We develop a comparative analysis of these notions where we investigate their limitations and their adequacies to meet the requirements of conformance testing and verification. Then, we order the various notions according to their distinguishing powers. We also develop generalizations of failure weak observation, and strong observation notions to ratify shortcomings View full abstract»

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  • Design and implementation of a TCP/IP protocol analyser

    Page(s): 468 - 472
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    This paper examines the design and implementation of a TCP/IP protocol analyser using the programming language Occam. After an overview of the analyser, important design matters related with the monitoring process and the choice of data flow process decomposition as the design method are considered. The detailed examination of the design of the TCP/IP protocol analyser follows, including the channel protocols that it uses and its software structure. Important implementation issues are also highlighted. Finally, three test environments are presented, together with an analysis of the behaviour of TCP/IP protocol analyser in each of them, and some conclusions are given View full abstract»

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  • A simulation study on the performance of integrated switching strategy for traffic management in ATM networks

    Page(s): 13 - 18
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    Designing effective congestion control strategies for broadband networks is known to be difficult because of the variety of dynamic parameters involved such as link speeds, burstiness of the traffic, and the distances between traffic sources and switching nodes. We propose a traffic management scheme, which is insensitive to the propagation delay between the sources and switching nodes. We achieve this by combining connection admission control with a bandwidth allocation strategy. By seeking the cooperation of the available bit rate (ABR) sources (to limit their peak cell rate, PCR) at the time of admission of a variable bit rate (VBR) source to the network, the scheme eliminates the continuous congestion control. Our simulations show that the strategy is able to eliminate the ABR cell losses, achieves effective server and buffer utilization, and provides bounded delays to the VBR traffic (unlike the case without any controls) View full abstract»

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  • SET and SSL: electronic payments on the Internet

    Page(s): 353 - 358
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    This paper presents a service architecture that combines SET and SSL to provide a lightweight secure electronic commerce system. Although both protocols secure data over an open network like the Internet, they differ in their mode of operation. SET defines secure transaction-oriented exchanges for payment systems whereas SSL secures point-to-point communications. SET and SSL are complementary and the combined architecture permits a gradual introduction of SET services by reducing the need for cardholder certification View full abstract»

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  • Adaptive rate-based feedback flow control algorithms-extensions to multicast connections

    Page(s): 154 - 160
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    The performance of two previously proposed asymptotically stable unicast flow control algorithms for high-speed networks is compared. We extend one of them to the multicast case. The multicast algorithm is modeled by a set of delay-differential equations. Despite the difficulties in analyzing the second order system with multiple different delays, the algorithm is analytically proven to be stable, and this is supported by extensive simulations. This work should prove useful in the design of multicast flow control algorithms View full abstract»

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  • A generic legality checker and attribute evaluator for a distributed enterprise environment

    Page(s): 286 - 292
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    The present state of communication networks with respect to speed and reliability and the recent growth of distributed applications have created a need for a global enterprise solution to the legality checking and attribute evaluation requirement. Traditionally, the mainframe systems provided the cohesion of all the processes with respect to the company regulations. When decentralized systems and applications became widely used the legality checking mechanism lost its central role and became a necessary component for every decentralized system. In this paper a methodology to reconnect these systems with respect to their legality checking and attribute evaluation needs is presented. A generic Legality Checking system has been developed and integrated with scheduling systems of the airline domain. It is shown that the client-server model adopted can bring back in a flexible manner the lost homogeneity of the central legacy systems View full abstract»

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  • On thorough garbage collection in distributed systems

    Page(s): 576 - 581
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    In this paper, we consider the hard problem of the thorough garbage collection in uncoordinated checkpointing algorithms. After introduction of the traditional garbage collecting scheme, with which only the obsolete checkpoints can be discarded, we show that this kind of traditional method may fail to discard any checkpoint in some special cases, and point our that it is very necessary and urgent to find a thorough garbage collecting method, with which all the checkpoints useless for any future rollback-recovery including the obsolete ones can be discarded. Then, we propose and prove the Thorough Garbage Collection Theorem, which ensures the feasibility of the thorough garbage collection, and gives the method to calculate the set of the useful checkpoints as well View full abstract»

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  • Performance and reliability optimization for distributed computing systems

    Page(s): 611 - 615
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    This paper discusses a performance and reliability optimization approach for distributed systems under a given budget constraint using the genetic algorithm (GA). The overall effectiveness of a distributed system is measured in terms of the average network throughput. This measure computes performance and reliability from network connectivity point of view. In order to carry out this optimization a distributed genetic algorithm (DGA) based scheme is developed. To demonstrate the effectiveness of the proposed approach, the results obtained from the distributed genetic algorithm approach is compared with single machine genetic algorithm and optimal solutions computed using exhaustive searches. Moreover, a brief discussion on the speed up over single machine implementation is also included View full abstract»

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  • An algorithmic approach for the planning of partial access ETSI SDH SNCP-ring subnetworks

    Page(s): 193 - 197
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    With the development of rings employing subnetwork connection protection (SNCP-rings) numerous complex solutions can be realised in the design of survivable synchronous digital hierarchy (SDH) networks. Three algorithms for optimising the planning of equipment cost-effective SDH networks using SNCP-ring solutions have been implemented. Results indicating the efficiency of the algorithms and the factors affecting this efficiency, supported by simulation work, are presented and discussed View full abstract»

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  • User-programmable flexible ATM network architecture. Active-ATM-experimental results

    Page(s): 178 - 182
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    Proposes active-ATM, a flexible, simple and cost-effective ATM-WAN architecture that can handle multiple user-customized ATM-layer protocols, such as ABR and ABT, by using a simple universal ATM transit network. The architecture enables the construction of flexible networks that can evolve easily. With active-ATM and the ATM multi-protocol emulation network architecture called ALPEN, it is easy to implement new ATM-layer protocols by using user-created programs called active-program capsules that modify only the edge nodes. Because these user-sent program capsules can be used to quickly customize the edge nodes, there is no waiting for standardization and implementation of new services. The ATM-layer protocols are emulated only at the edge nodes, making the transit network independent of customer ATM-layer protocols. The active-ATM edge node is based on the flexible programmable node architecture called PUN (programmable unified node). PUN is a platform for user-programmable ATM-layer services. A prototype system has demonstrated the flexibility of the resulting ATM network. The simple and high-speed universal ATM transit network periodically reports to the edge nodes the performance of the its routes by using periodical route performance check sequences, which are independent of the ATM-layer protocols. The information is used by the edge nodes to manage user cell rates in real time. Flexible, adaptive, and sophisticated protocols that efficiently utilize network resources can be easily supported by the network's edge nodes View full abstract»

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  • Scalability improvement of the real-time control protocol (RTCP) leading to management facilities in the Internet

    Page(s): 125 - 129
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    We address some of the problems concerning RTCP scalabilty in large multicast groups. The problems are summarised as the increased storage state maintained by every member about every other member in the group, the feedback delay, and the bandwidth usage problem especially for receivers that obtain incoming RTCP reports through low bandwidth links. We designed a scheme to tackle these problems and to improve the RTCP scalability. Our scheme is based on a hierarchical structure in which members are grouped dynamically, into local regions and receiver reports (RRs) are sent with limited scope. As a result, the load is distributed among members in the group. Each region has an aggregator (AG) that receives the RRs feedback, performs some aggregation statistics on this control data, then sends these statistics to a manager. The manager performs additional analysis to evaluate the network performance and to estimate regions which are suffering from significant congestion. Finally, we present the benefits of using our scheme View full abstract»

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  • Bandwidth allocation for interactive video-on-demand

    Page(s): 89 - 93
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    Video-on-demand in education is used in a very different way to entertainment video. Usage is much more interactive. Viewers will frequently pause, fast-forward, skip and view frame-by-frame. Designing a network and server able to support interactivity and make efficient use of bandwidth is difficult. In this paper we suggest that in designing a system neither the network nor the server can be considered in isolation, but must be designed so as to take advantage of each others features. We present some preliminary data on interactive behaviour obtained during our video-on-demand trials and use it to illustrate the theoretical treatment of two different system designs View full abstract»

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  • Design and performance assessment methods for third generation cellular systems

    Page(s): 685 - 689
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    It is envisaged that future cellular systems, e.g., UMTS, will consist of three network segments, namely, core, access, and intelligent. In the context of this paper, we define and solve some of the design problems related to the design of the access and intelligent network segments. In addition, we present a platform that enables the assessment of the derived solutions by means of simulation. Our aim is to analyse, formally state, and theoretically formulate these problems, and to provide a platform for assessing the efficiency of the solutions to these problems View full abstract»

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  • Signalling channel handling in wireless ATM networks

    Page(s): 423 - 428
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    The introduction of ATM in wireless CPN environments (WATM) necessitates the design of mobility related protocols, since the existing versions of B-ISDN signalling (ITU-T Q.2931, ATMF UNI 3.1) do not provide the means for terminal mobility. Such protocols can be deployed either as extensions to the standard signalling capabilities or as individual solutions that have little or no impact on existing infrastructures (switches, signalling software, etc.). In this paper, after presenting a WATM architecture, we study the problem of the switching/rerouting of the signalling connections that need to be performed whenever a mobile terminal crosses cell boundaries (handover, location update). Registration and forward hard handover algorithms are proposed View full abstract»

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  • A two-level strategy for software fault tolerance of service control point

    Page(s): 616 - 621
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    Fault tolerance (FT) is a feature of top importance in the long-life real-time systems. The service control point (SCP) in the intelligent network (IN) is just one of this type of systems. Its dependability affects directly the quality of service (QoS) of the whole network. We give an overview on the software fault tolerance (SFT) at first, and decide to adopt the time-redundancy approach to implement the SFT of the SCP according to the special features of the IN application. Based on the processing mechanism of IN calls and with the consideration of the load-balance, software fault-tolerance and software upgrading on-line, we present a two-level concurrency model of the SCP software, and give our implementation of this model in the multi-task environment. Furthermore, we discuss in detail the issues of the SFT based on this model, and give the corresponding strategies and algorithms to achieve the specified whole FT targets. Finally, we discuss the system effectiveness of the SCP software, and provide a method of computing the effectiveness of the SCP software based on the Markov model View full abstract»

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  • In-service methods for performance management in switched broadband networks

    Page(s): 183 - 187
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    The introduction of switched virtual connections and value-added services in ATM networks create new conditions for network management. A general model for performance management in switched broadband networks, based on interaction between management functions and control functions is presented. Finally, in-service methods for monitoring of network performance (especially cell losses) in switched ATM networks are covered in more detail View full abstract»

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  • An overview of off-the-shelf tools and their applications to telecom and enterprise networking

    Page(s): 483 - 487
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    The Internet is radically changing the field of networking. A wide variety of technologies, protocols and internetworking techniques are now available and continuously changing with the rapid developments in the Internet scenario. For example, whereas ATM was heretofore viewed as the solution for all networking problems, today increasingly there is a debate whether IP will dominate or ATM and the general consensus is that IP over ATM will be the long term networking scenario. With the rapid increase of Internet service providers worldwide and the introduction of Internet telephony, an exponential increase in networking traffic is taking place. Furthermore, cost is increasingly becoming a criterion along with mathematical performance. In spite of this reality, networking experts surprisingly continue to use rules of thumb to design networks based upon outdated systems engineering practice methodologies. This necessitates the use of networking tools in order to evaluate and study different architectures, technologies and what-if internetworking strategies. This paper is intended to be an overview and application of more than forty leading tools being used in the field of networking. The purpose of this paper is to update and inform potential users of trends in the industry by providing an overview of some of the capabilities of each tool View full abstract»

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