bluuebunny/crossref_metadata_2025_split huggingface dataset:
An object‐oriented approach to dynamic service descriptions
Authors: Hellemans Patrick , Behnke Ulf , de Smedt Alex , Ronchetti Luigi 
Published: July 2007

AbstractThe former CCITT has defined a methodology, consisting of three stages, to evolve from a set of service descriptions to a protocol definition that supports these services. In the first stage, the service is described from a user's viewpoint. A part of this first stage consists of the descriptions of the dynamic behaviour of the service. The introduction of this paper elaborates on the interpretation of the ‘user's viewpoint’ of dynamic service descriptions. In the subsequent sections we introduce an object‐oriented approach to define a framework for the dynamic service descriptions. The flexible definition of services is facilitated by decomposing the service into a standard set of building blocks, referred to as service objects. A service object is the smallest service element that a user can independently reference and manipulate. By modelling in terms of service objects, we avoid the presumption that the total service consists of a specific number of parties or connections. The definition of a service mainly consists of imposing additional semantic rules on the way service objects can be manipulated within the context of that service. The complete system will thus consist of a servicespecific part and a generic part, i.e. a part which is common to all services. An overview of the system configuration and the behaviour of the generic part is illustrated by SDL Descriptions. Finally, we illustrate the method by describing a typical multiconnection multiparty service. The work presented within this paper is based on the results of the RACE MAGIC project.
Expanse software for distributed call and connection control
Authors: Bussey Howard , Minzer Steven , Mouchtaris Petros , Moyer Stanley L. , Porter Frederick 
Published: July 2007

AbstractThe experimental ATM network services environment (EXPANSE) prototype provides an experimental testbed for multimedia multiparty telecommunications services over heterogeneous communications networks. The EXPANSE software architecture supports the functional separation of call and connection control. At the call control layer an object‐oriented, transaction‐based call model provides for the co‐ordination of the negotiations among users for the establishment, modification and disconnection of telecommunications services. The connection control layer provides an object‐oriented protocol for the dynamic establishment, modification and release of network connections which include the control and allocation of network resources required for multimedia multiparty services.The EXPANSE software includes an application programming interface (API) to the signalling protocol at the call control level. The API provides a uniform and powerful interface to the call model and allows different applications to co‐ordinate the control of local resources and session state.
VP dimensioning for high‐speed data communication in ATM networks
Authors: Saito Hiroshi 
Published: July 2007

AbstractThis paper describes a VP bandwidth dimensioning method for dynamic connection admission control (CAC) in ATM networks. Dynamic CAC judges the admission of a connection by using the measured number of cells arriving at each VP as well as the source traffic descriptor. The bandwidth assignment can therefore reflect the actual traffic characteristics so that the dynamic CAC can compensate for the difference between the negotiated and the actual values of the descriptor. This kind of CAC is especially appropriate for a service for which users have difficulties specifying accurate values for the source traffic descriptor.The procedure for dimensioning the VP bandwidth is important for providing a service economically when the dynamic CAC is used. This paper develops the dimensioning method of the VP bandwidth for long‐term VP bandwidth management. The VP bandwidth management under dynamic CAC is difficult because this dimensioning method cannot use on‐line traffic measurement even though the CAC (the short‐term management) can. The dimensioning of the VP bandwidth is a key to making the service successful.
Performance analysis for the dynamic virtual path bandwidth control method in ATM networks
Authors: Baba Ken‐Ichi , Murata Masayuki , Miyahara Hideo 
Published: July 2007

AbstractBroadband ISDN (integrated services digital network) should provide various kinds of communication services for multimedia traffic, including voice, computer data, still picture and motion video, and an ATM (asynchronous transfer mode) technology is expected to satisfy those demands. In ATM networks, a VP (virtual path) concept is introduced for simplifying the network resource management. However, if the bandwidth of each VP is fixed, it cannot absorb traffic load fluctuation. In this case, it is likely to happen that one VP has no remaining bandwidth while other VPs on the same physical link have free capacities. Another extremity is that a VP is not introduced, and that all VCs along the same physical link share the whole bandwidth of the link. This can achieve an efficient use of the link, but it apparently requires complicated call set‐up procedures.In this paper, we propose a new dynamic VP bandwidth control method, in which the bandwidth allocated to each VP is dynamically changed according to traffic fluctuation. More specifically, in the case that multiple VPs are multiplexed on the same link between two nodes, when the utilization of some VP is increased, that VP requests an additional bandwidth. When the traffic load becomes low and the utilization of a VP is decreased, a part of the assigned bandwidth is released. We consider two methods for this purpose; one is the basic method in which the bandwidth increase request is issued after the VP bandwidth is exhausted. The other is the look‐ahead method where the bandwidth increase is requested in advance before the bandwidth starvation. An approximate analysis for the above methods is provided, and the validation of its accuracy is assessed by comparing with simulation results. Through numerical examples, we show that our methods can provide performance improvement in terms of call loss probabilities of each VP.
Virtual spacing for flexible traffic control
Authors: Roberts J. W. 
Published: July 2007

AbstractWeighted fair queuing emerges as an elegant and effective solution to the problem of integrating real time services with strict delay constraints and high‐speed data services for which significant delays cannot always be avoided. Virtual spacing is a weighted fair queuing scheduling algorithm intended to be applied in the context of the ATM based BISDN. After discussing how virtual spacing allows flexible traffic control for a variety of service types, we discuss the issue of its implementation in switching nodes. The aim of the paper is to highlight the advantages of weighted fair queuing in enabling a truly integrated services network and to propose a technologically feasible implementation.
Methodologies for characterizing traffic in wide area networks: Analysis and benchmarking
Authors: Khalil K. , Hand J. C. , Mariswamy M. , Obaidat M. S. 
Published: July 2007

AbstractSince computer networks play an important role in distributed computing environments, an application's performance depends heavily on the quality of service provided by the communication networks. To ensure a high performance, the characteristics of wide area networks, WANs, must be well understood. This paper presents methodologies to characterize WAN traffic based on real measurements from Bellcore's backbone network that connects remote sites using dedicated T1 links. This paper also suggests some workload models that can be used for wide area network sizing and performance evaluation studies. It is found that the inter‐site traffic pattern depends on the time of the day and the day of the week. Furthermore, the traffic between two sites is found to be reasonably symmetric, except for those sites designated as back‐up sites. The coefficient of variation is used as a measure for the traffic burstiness and it is found to be 1·5 degree during working hours. The methods presented here are easy to use and cost‐effective.
Network planning based on virtual path bandwidth management
Authors: Logothetis Michael , Kokkinakis George 
Published: July 2007

AbstractPeriodical performance evaluation and adaptive resource assignment, already proposed as performance‐oriented management, seems to be the most suitable strategy for network planning under demand uncertainty. In this paper, we exploit the inherent capability of ATM networks to rearrange dynamically the already installed resources, and propose performance‐oriented management combined with virtual path bandwidth (VPB) control for the planning of the extensions of bandwidth capacities of virtual paths (VPs) and transmission links of the network. We define a large network optimization problem and solve it by a rigorous, analytical procedure. The optimization model comprises specific requirements of the network‐planning problem and a bandwidth distribution scheme ensuring network reliability. We reveal the efficiency of the proposed scheme by applying it on a model network, considering two realistic case‐studies of network‐traffic evolution. We show that in the presence of VPB control: (a) the initial distribution of the total bandwidth to VPs is of no importance, since it can be adaptively rearranged according to the offered traffic, (b) the network is well used and bandwidth investment could be saved, and (c) whenever additional bandwidth must be installed in VPs which have an unanticipated bad grade‐of‐service, time savings result. We present the network performance in detail, in figures, and compare this with the performance of the network in the absence of VPB control.
Performance study of ATM multicast switching systems
Authors: Chen Xing , Lambadaris I. , Hayes Jeremiah F. 
Published: July 2007

AbstractWe evaluate the performance of anN × NATM discrete time multicast switch model with input queueing operating under two input access disciplines. First we present the analysis for the case of a purely random access discipline and subsequently we concentrate on a cyclic priority access based on a circulating token ring. In both cases, we focus on two HOL (head‐of‐line) packet service disciplines. Under the first (one‐shot transmission discipline), all the copies generated by each HOL packet seek simultaneous transmission during the same time slot. Under the second service discipline (call‐splitting), all HOL copies that can be transmitted in the same time slot are released while blocked copies compete for transmission in subsequent slots. In our analysis the performance measures introduced are the average packet delay in the input buffers as well as the maximum throughput of the switch. A significant part of the analysis is based on matrix geometric techniques. Finally, numerical results are presented and compared with computer simulations.
Analysis of leaky bucket mechanism based on burstiness characterization
Authors: Au Tat‐Ming , Mehrpour Hassan 
Published: July 2007

AbstractIn high‐speed networks, a congestion control strategy has to manage bandwidth allocation based on the characteristics of input traffic sources. Accordingly, the definition of traffic characterization becomes significant in all aspects concerning network performance. In this paper, the burstiness characterization of a traffic stream is based on a virtual queue principle. We study the leaky bucket mechanism as a regulator element that controls input traffic before access to a newwork, as well as inside a network. To protect an input traffic stream, we investigate the optimal parameter settings of a leaky bucket. In addition, we analyse the worst case performance, and obtain upper bounds on loss probability and packet delay. We also determine the characteristics of an output stream in the worst case. Such performance bounds reveal the effectiveness of a leaky bucket, and provide enough information for the QOS satisfaction of the network users.
Photonic transport networks based on optical paths
Authors: Sato Ken‐Ichi , Okamoto Satoru , Watanabe Atushi 
Published: July 2007

AbstractThis paper explores the technologies that will enable a further leap forward in transport network evolution. First, requirements of the future transport network are elucidated. Existing network cost is evaluated and the viable means to reduce transport network cost are identified. It is demonstrated that optical path technologies such as WP (wavelength path) and VWP (virtual wavelength path) will play a key role in this. They enhance not only transmission capacity but also cross‐connect node throughput cost‐effectively by capitalizing on the wavelength routeing scheme. Optical path realization technologies focusing on optical path cross‐connect systems are examined. Requirements for the optical path cross‐connect system are then elucidated, and a new cross‐connect system architecture is evaluated. The architecture exploits PLC (planar lightwave circuit) and other commercially available technologies suitable for large‐scale production. The evaluations include cross‐connect node upgradability, modular growth capability, total node cost, optical loss and switching power consumption. It is proved that the architecture has significant advantages over existing switch architectures. The optical path technologies provided in this paper will pave the way for a new transport network paradigm, a ubiquitous, bandwidth‐abundant and affordable broadband ISDN.
Some extension of modal‐decomposition theory and computational methods in multi‐conductor transmission lines
Authors: Sasaki Hiroshi 
Published: July 2007

Abstract“Decomposition into independent line groups” is usually possible for multi‐conductor transmission lines in case the product of the per‐unit‐length impedance (z) and admittance (y) matrices, for uniform lines L can be diagonalized. Some reports have suggested that L could be “practically” decomposed into independent line groups just as the F‐matrix is decomposed by the “quasi‐real ideal transformer networks” (QRITN) P‐1 + tp. Here, P is a similarity transformation matrix that diagonalizes zy; + denotes the direct sum of the matrices, and tX is the transpose of X. This paper points out that some points in decomposition theory for transmission lines remain to be studied; these points are further examined by the author. First, the L decomposition theory is also applied to the ease when both Z and y are symmetric and non‐singular and the product z y is not necessarily diagonalizable. As a result, it is demonstrated that L can in general be decomposed by the QRITN into a set consisting of a few independent transmission lines. Second, a computer method for calculating a decomposition matrix for L is introduced, together with the L's F‐matrix. The method is a natural generalization of the conventional procedure for computing the L decomposition matrix and is only applicable in case no multiple eigenvalues exist. Finally, the author proposes a new method for computing the “reference zy matrix”, even for non‐uniform lines, as an application by the procedure.
Radiation characteristics of axial‐mode helical antenna
Authors: Shiokawa Takayasu , Karasawas Yoshio 
Published: July 2007

AbstractThe axial‐mode helical antennas with finitely large reflectors radiate sharp, circularly polarized beams along the antenna axis when the circumference of the helix is about one wavelength long and the pitch angle is 12° ∼ 14°. Although experimental results and approximate theories have been reported, no detailed theory has ever appeared. This paper discusses the radiation characteristics of the axial‐mode helical antenna with the reflector both theoretically and experimentally. First, assuming the reflector is infinite in size, we solve an integral equation satisfying the boundary conditions and obtain the current distributions on the antenna. Characteristics have been studied even for the case with a large number of turns. Next, using the current distribution thus obtained, we find the current distributions on the reflector. By means of the induced emf method, we analyze the radiation characteristics (directivity, power gain and axial ratio) of the axial‐mode helical antenna. Further, we confirmed the analysis experimentally.
Digital filters using round‐off noise control in frequency domain
Authors: Miyata Masachika 
Published: July 2007

AbstractThis paper proposes and discusses the noise feedback rounding using an integral‐coefficient digital filter in order to reduce round‐off noise caused by fixed point arithmetic. The following conventions are used; ΓX(z) and ΔX(z) denote the integer and fractional part of a sampled signal X(z), respectively; X(z) is abbreviated as X; N denotes a noise caused by rounding × to Γ (X + R) (R=z‐1GΔ (X + R)); and the round‐off noise HN under ΔG = 0 at an output is given byHN=K≥,K=‐H(1 ‐z‐1ΓG),N= Δ (1 ‐z‐1ΓG)‐1Xwhere H is the transfer function from a rounding point to the output point. Since N is ordinarily nearly at random, the power of HN can be controlled by determining G for the zeroes of (1 ‐z‐1ΓG) to be in the vicinity of the poles of H. In addition, the maximum value Poof the power HN is in the range of 2−2μ (K) ≤P0< μ (K) and therefore μ(K) can be used as an estimator for the worst design value where μ(K) is the maximum value of K(z) K(z‐1) on a unit circle. Both multipliers and combinatorial digital filters described in this paper are simpler in construction and more economical than the ordinary rounding using longer word length or the random rounding.
Design considerations on high sensitivity mos area image sensor
Authors: Ohba Shinya , Nakai Masaaki , Ando Haruhisa , Kubos Masaharu , Shimada Shigeru 
Published: July 2007

AbstractBy clarifying the design approach of the photoelectric conversion of the two‐dimensional MOS solid‐state image sensor, a 320 × 244 element high responsivity MOS sensor has been fabricated and characterized. In the design of the photodiode design formulas for sensing capacity, responsivity and spectral response are presented and are in good agreement with the measurement. In order to suppress blooming without lowering the responsivity, the threshold voltage of the vertical switch transistor is raised and the photodiode whose n+‐diffusion layer of the signal wire is surrounded by the p+‐layer is proposed. In the horizontal switch transistor design, the signal reading residue is obtained and a simple formula describing the vertical resolution affected by the residue is also obtained.The main features of the MOS sensor developed by this design approach are: (1) high responsivity; (2) high resolution; and (3) strong blooming. The main characteristics are: for 1.4 μA saturation signal current, 71x saturation faceplate illumination (by Tungsten source) at 550 nm, the responsivity is 0.22 μA/μW, horizontal resolution is 240 TV lines, vertical resolution 190 TV lines and dissipation power is 30 mW.
A design of single‐tuned bandpass filters using charge transfer device
Authors: Iwanami Yasunori , Yoshida Bunya , Ikedas Tetsuo 
Published: July 2007

AbstractIn accordance with the recent tendency of miniaturizing failure with active elements, the non recursive transversal CTD (Charge Transfer Device) filters and the recursive CTD filters by means of the signal delay effect of CTD's have been analyzed and constructed. Comparing the latter with the former, a faster frequency response can be realized with less order although there exists a stability problem due to the poles produced by the recursive loop of the circuit. The recursive circuit is suitable in realizing a high‐Q single‐tuned bandpass filter. In this paper, a design method for the single‐tuned bandpass filter with CTD having higher stability against Q variation than that of the conventional second‐order CTD filters [6, 7] is presented. Assuming a pole and a zero which can move along the prescribed closed loci on the Z‐plane depending on the input frequency, the low coefficient sensitivity transfer function is obtained and an economical canonic form circuit is realized. A consideration on the proposed concept that poles and zeros can move corresponding to the input frequencies is presented in the Appendix and the experimental confirmation is shown.
Some methods of estimating the magnitude of total sensitivities for the transfer characteristics of a reactance filter
Authors: Kida Takuro , Kurogochis Katsumi 
Published: July 2007

AbstractThis paper proposed two methods (the decision theory method and the probability method) for estimating the approximate magnitude of the tolerances of the transfer characteristics which are caused by the deviation of elements of a reactance filter. The first method estimates the total element sensitivities of the filter by an estimation measure which gives an upper bound of the absolute sum of the second‐order element sensitivities for the attenuation characteristic of the reactance filter. The estimation measure is represented by the various quantities which can be derived from the characteristic function of the filter only. Therefore, the element sensitivities of the filter can be estimated by its characteristic function only before actually constructing the network. The second method is for determining the statistical mean value and variance of the tolerance of the transfer characteristics for a reactance ladder filter. A calculation algorithm for this method is proposed. The transfer characteristics include the attenutation characteristic and phase characteristic as well as the real and imaginary parts of the characteristic function expressed in nepers. The analytical technique is based on Taylor's series expansion. The first‐order to third‐order terms and the mean value of the fourth‐order term are used. The second method differs from the first in that the former utilizes the information about the internal structure of the network.
Two‐dimensional computer analysis of current‐phase relations in microbridge josephson junction
Authors: Sakura Shigeyuki , Kawamuras Mitsuo 
Published: July 2007

AbstractIn the microbridge Josephson junction, the current‐phase relation is obtained by solving simultaneously the Gintzburg‐Landau equation and Maxwell equation. The optimum geometry of the microbridge which produces a large Josephson effect is clarified. Unlike other Josephson junctions, the microbridge Josephson junction is of the strong‐weak‐strong superconducting structure which is generated by the current flow. A large Josephson effect is obtained when the bridge length is less than the coherence length and when the bridge width is less than the magnetic penetration depth, In and Sn are superior to Cd and Al as superconducting materials.