bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evolution and service requirements of CBR applications on ATM networks
Authors: Shah Syed I. A. , Ashton P. , Wernik M. 
Published: July 2007

AbstractBroadband integrated networks based on asynchronous transfer mode (ATM) technology are being proposed to provide a single integrated access to a variety of services and applications. Constant bit rate services will form an important part of this unified networking solution. In this paper, we identify and describe the relevant aspects related to the implementation of CBR services on ATM. First, we identify two broad categories of potential CBR services for broadband ATM networks. The ATM infrastructure for the identified services is then developed along with the required functionalities of different network elements. Finally, end‐to‐end performance objectives for the ATM network are determined and verified empirically based on results of laboratory experiments. These performance objectives help us determine the minimum QOS required by the highest class of service category offered by an ATM network.
Frequency hopping sequences with small cross‐correlation
Authors: Komo John J. , Liu Shyh‐Chang 
Published: July 2007

AbstractThe cross‐correlation of frequency hopping sequences obtained from non‐binary m‐sequences represented as vector m‐sequences is developed. Preferred pairs of these vector m‐sequences then yield vector or frequency hopping m‐sequences which are shown to have small three‐and four‐level cross‐correlation values. Modified preferred pairs are developed that yield frequency hopping m‐sequences with reduced peak cross‐correlation.
A high‐capacity broadband packet switch architecture based on a multilink approach
Authors: Widjaja I. , Kim H. S. , Leon‐Garcia A. 
Published: July 2007

AbstractBroadband packet networks based on asynchronous transfer mode (ATM) are expected to provide a wide range of services, including motion video, voice, data and image. When these networks become prevalent, some applications such as motion video and high‐speed LAN interconnections will place a very large bit rate requirement on the channels. Currently, the physical layer supported by the synchronous optical network (SONET) allows the transmission of up to 2.4 Gbit/s with the OC‐48 optical interface. However, it is not feasible for the electronic packet switch to route packets at this rate on a single link. In this paper we present a design of a broadband packet switch that uses multiple links in parallel to realize a high‐speed channel. This implementation permits the switch to operate at the lower link rate, which can be at 150 Mbit/s, while having the ability to support a virtual circuit at a higher rate (up to 2.4 Gbit/s). The main contribution of the design is that packet sequence on a channel is still maintained even though packets are allowed to use any of the links belonging to the same channel. Besides allowing the switch to function at a slower rate than the transmission channel rate, the implementation of the multilinks benefits from statistical multiplexing gain. Analytical results show the performance advantages of multilink design with respect to delay, throughput and packet loss probability.
Response time performance of a narrowband information broadcast system
Authors: Siu Y. M. , Chan C. K. , Ho K. L. 
Published: July 2007

AbstractThis paper describes the architecture and performance analysis of a system using narrowband broadcasting channels for real‐time information delivery. Broadcast delivery is attractive because a single transmission of a piece of information will satisfy all users waiting for that information. Therefore, the system may support an unlimited number of users with no effect on system response time. The main drawback of these types of systems compared with interactive systems is that a user must wait until the required information arrives. In order to reduce this waiting time, high data rate networks must be used if real‐time information is to be broadcast. In this paper, a new method is proposed to enable inexpensive narrowband networks to be used.
Learning automata routeing in connection‐oriented networks
Authors: Economides Anastasios A. 
Published: July 2007

AbstractLearning automata are used at the source nodes of a connection‐oriented network to dynamically route newly arriving virtual calls to their destination.First, two new learning automata are introduced. Then, these two learning automata, as well as the well‐knownLLearning automaton and the deterministic shortest‐path algorithms are used in a simulation program to route virtual calls. The more frequent the updating and the more recent network state information used, the better the performance.In the sequence, the virtual link length is developed as a function of both the number of packets and the number of virtual calls at the network link. This virtual link length is used in the learning automata routeing algorithm and is shown via simulation to be superior to the minimum packet delay or shortest‐queue‐type link length, usually used in real networks. Thus, in connection‐oriented networks, not only the packet but also the virtual call traffic characteristics should be used in the routeing decisions.Furthermore, when the network state information is out‐of‐date, or when there are few virtual calls and each one carries a large number of packets, then the virtual link length should be based more on the number of virtual calls than on the number of packets at this link. On the other hand, when the network state information is current and there are many virtual calls and each one carries a small number of packets, then the virtual link length should be based more on the number of packets than on the number of virtual calls at this link.
Some analytical tools for the global performance evaluation of packet switching networks based on virtual paths
Authors: Borella Andrea , Chiaraluce Franco , Meschini Fabrizio 
Published: July 2007

AbstractWe present a simple model for the global performance evaluation of a packet switching network. Through a detailed analytical treatment, a set of formulae is derived which allow a compact and reliable evaluation of the most significant statistical properties of the network, such as the arrival probabilities, the queue states distribution and the mean utilizations of the links. Starting from the knowledge of these quantities, the network can be characterized also taking into account the mutual interaction between different nodes. An example is given with reference to a mesh‐connected structure.
Estimating cell loss rates in high‐speed networks with leaky bucket controlled sources
Authors: Johri Pravin K. 
Published: July 2007

AbstractThis paper deals with high‐speed networks, such as the ATM network, over which data is transferred in cells or packets. Results based on asymptotic analysis of stochastic fluid flow models imply that these networks would have to be run at very low utilization to satisfy the stringent performance requirement of very low cell loss rates. Recent papers have quantified that asymptotic approximations can be quite bad with even a modest number of users sending traffic into the network. In this paper it is shown that two more assumptions in the asymptotic analysis may lead to significant overestimation of the cell loss rates. The more significant of these is the use of the underlying exponential ON durations if sources are policed. The second and less significant is the assumption of an infinite buffer. A new approximate nalytic method is then developed for estimating the cell loss rate with sources policed by a leaky bucket type mechanism. This method focuses directly on the problem of measuring cell losses in the presence of many sources simultaneously bursting in a time period small enough to cause buffer overflow. It turns out to be highly accurate even with some rather drastic simplifying assumptions.
Performance analysis of fast distributed link restoration algorithms
Authors: Chow C. Edward , Bicknell John D. , McCaughey Steve , Syed Sami 
Published: July 2007

AbstractFour distributed link restoration algorithms are analysed in detail using a set of important performance metrics and functional characteristics. The functional characteristics are used to explain how these algorithms function and provide insight into their performance. The analysis and simulation results indicate that the two prong link restoration algorithm, which is based on issuing aggregate restoration requests from both ends of the disruption and on an intelligent backtracking mechanism, outperforms the other three algorithms in terms of restoration time. The RREACT link restoration algorithm consistently found paths that use fewer spares.
The correlation effects on service control point response time
Authors: Wey Jyhi‐Kong , Sun Lir‐Fang , Yang Wei‐Pang 
Published: July 2007

AbstractAs the centralized database for the integration across multiple wireless tiers and wireline access, traffic design considerations for SCP performance measurement are of great important in the personal communications era. By neglecting the effect of disk access time, the SCP response time R includes the SCP processing time P and signalling link delay L only. A bivariate normal distribution has been proposed for modelling (P, L) such that some statistical estimations of L given P can be conveniently obtained in different combination of SCP processing load and link utilization. Further, the correlation effects of (P, L| P=p) on R are investigated. After a Tukey one degree of freedom test with one observation of μL|P=p per treatment (n=1) under different normalized processing times and correlations, the two‐factor ANOVA model becomes an interaction model without pure error effects due to the computed F* values being significantly greater than the critical F (0.95; 1, 11). Besides, rejection threshold criteria of SCP response time with minimum loss rate (0.01 per cent) of messages are proposed to ensure a good service quality of SCP.
Congestion detection based on rate and buffer occupancy measurements
Authors: Cheng T. H. , Cheah K. L. , Oh S. H. 
Published: July 2007

AbstractBased on traffic simulation studies at an FDDI/BISDN gateway, this paper evaluates the relative merits of using rate and buffer occupancy measurements in the detection of congestion and the use of such measures to provide simple bandwidth management. In addition, a detection scheme based on using both rate and buffer occupancy measurement is recommended as it combines the advantages of both schemes and provides more reliable performance over a range of bursty traffic.
Analysis of acoustic prism couplers for rayleigh and lamb waves
Authors: Takeuchi Masao , Shimizus Hiroshi 
Published: July 2007

AbstractThe prism coupler has long been used for excitations of Rayleigh and Lamb waves. Since analysis is lacking in the leaky wave phenomenon on the guided wave path due to the prism perturbation, many problems are not explained. In this paper, the solid and liquid prism couplers are analyzed by the leaky wave concept and modeconversion theory, the following problems are clarified: the mode conversion efficiency expected to be obtained in theory, the coupling length between the prism and the guided wave path as related to the mode‐conversion efficiency, the difference between the p‐ and sv‐wave in the solid prism coupler, the effect of the liquid couplant, and the effect of the absorption loss in the prism material. Three of the universal diagrams are also provided. It is confirmed that the measured and theoretical available conversion efficiency for the Rayleigh wave transducer consisting of the bulk wave transducer are in good agreement.
Deficient decoding for convolutional codes
Authors: Hashimoto Takeshi , Arimotos Suguru 
Published: July 2007

AbstractTree codes are so important that they often appear in information theory. Highly reliable coding systems may be realized in view of their sequential decoding. While a number of analyses have been made of the probability of error in sequential decoding and of the amount of calculation required for decoding only a few analyses are presently available on the various characteristics when sequential decoding is applied to convolutional codes. Here, we shall evaluate the so‐called deficient decoding that occurs when convolutional codes are sequentially decoded by decoders with finite decoding speeds. The evaluation will be based on the findings of recent studies on the amount of calculation required for the sequential convolutional codes.
Theoretical analysis of a grounded monopole antenna
Authors: Nakagawa Kinsaku , Inagaki Naoki 
Published: July 2007

AbstractThe grounded monopole antenna without earthing used as a basic ground antenna is analyzed by the moment method. Its current distribution, input impedance, directivity and antenna efficiency as functions of earth dielectric constant and conductivity, antenna height and frequency are obtained. The generalized impedance can be made calculable even for the case of nonzero current at the end of the antenna. Numerical results show that the current distribution varies subtly with the earth electrical properties. The small‐area effect of earth is clarified. For the quarter‐wave monopole antenna, the efficiency increases with decreasing frequency but it is below 50% for typical earth conditions when the frequency is above 0.1 MHz. For large antenna height, the antenna efficiency is large, the maximum directivity becomes closer to the horizon, but at 0.6 wavelength the radiation along the sky direction is strong, and the fact that at 0.53 wavelength it is used as an end‐firing antenna can be explained. It is shown that the antenna efficiency becomes lowest when the earth displacement and conduction currents are equal.
Analysis of tapered optical slab waveguides with hypothetical boundaries
Authors: Sawa Shinnosuke , Onos Kazuo , Odaka Hironobu , Sakuma Masaki 
Published: July 2007

AbstractIt is proposed that the tapered optical waveguide be analyzed by the nonopen system treatment method in which hypothetical boundary walls (electric or magnetic walls) are added to the exterior of the open‐type waveguides. In addition, the step‐approximation method is used for analyzing the single‐mode slab optical waveguide taper. It is shown here that the basic properties of tapers, in which the TE mode propagates, for example, the radiation power and pattern as well as power distribution on the waveguide cross section, can be obtained. The conditions that allow the open‐type tapered waveguide to be treated as a nonopen system are investigated numerically. This paper shows that for long tapers, the hypothetical walls must be farther away from the waveguide, whereas for obtaining the radiation power and pattern, as well as the radiation field, these walls do not have to be separated considerably from the waveguide. Moreover, it is seen that not all the propagating modes need to be used in calculations; even if only about 10 modes are chosen, the radiation power and field distribution can be obtained without loss of accuracy and within a short computation time.
Active rc synthesis of arbitrary admittance matrix
Authors: Matsumoto Tadashi , Takahashi Tohru , Takahashis Shin‐Ichi 
Published: July 2007

AbstractIt is shown that any p × p admittance matrix can be realized using at most 4 p operational amplifiers regardless of the Mac Millan order by means of reactance extraction applied to comrade matrix and generalized Luenberger form. In the comrade matrix, there is a clear relation between elements and polynomial series of elements. Once a set of polynomial series and characteristic polynomials are determined, the comrade matrix can be determined uniquely. For oneport network, the conductance matrix obtained by reactance extraction can be related to the RC ladder‐type network with the current feedback if proper polynomial is selected. The realization method for the one‐port network can be extended to the multiport network by using the generalized Luenberger form in which the diagonal portion is a comrade matrix.
High‐order digital phase‐locked loop using integrators in pulse frequency modulation system
Authors: Iritani Tadamitsu , Kinouchi Yohsuke , Ushitas Tomiyuki 
Published: July 2007

AbstractThe carrier‐tracking loop that employs a digital phase‐locked loop (DPLL) can be made very stable in operation. From the signal with frequency offset or Doppler shift, carrier tracking without steady‐state phase error, requires the use of higher‐ (greater than second) order DPLLs. The first‐order DPLL published earlier provides a linear operation characteristic in a wide range besides being improved for digitalization of the past analog PLL. The output phase of this first order DPLL can be controlled externally. Combining the first‐order DPLL with a variable‐phase PFM integrator, and controlling the phase of each, higher‐order DPLLs are realized. Five types of second‐order DPLL's are built and analyzed. Comparison with analog PLL shows that the closed‐loop transfer function can be approximately linearly to that of an analog PLL. The range of synchronization and time of synchronization are of the same order in the case of perfect second‐order. However, in the case of imperfect second‐order systems, the DPLL is more superior. Further, third‐order DPLL's are analyzed and constructed and a method of realizing nth‐order DPLL is established.
Radar reflectors with controllable reflection
Authors: Onoe Morio , Hasebe Nozomu , Zamas Tomoyuki 
Published: July 2007

AbstractRadar reflectors have been used to increase the reflectivity of small vessels and navigation guides for easy detection. If the reflectivity is controllable by some electrical or mechanical means, then a passive telemetry would be possible, which transfers some information from the site of a target to a radar station. This paper presents a controllable radar reflector, which consists of an array of resonant dipoles or slots combined with a reflecting plate. When the array of slots is placed at the focal plane of a Luneberg lens, an electrical or mechanical reflectivity modulation of more than 10 dB is obtained for wide angle of incidence in laboratory and field experiments.Additional features, such as sturdy structure, slight scattering, wide bandwidth (more than 4 percent at the modulation of 10 dB), easy construction and adjustment, and the optional ability of mechanical control make the slots array practical.
Limited scan characteristics of short backfire dipole phased arrays for is radars
Authors: Tokumaru Shinobu , Nakanishi Hideki 
Published: July 2007

AbstractThe basic characteristics of short backfire dipole phased arrays for use in the IS radar are analyzed. The array must have the active independence 50 ω in the scanning range and element pattern less than ‐10 dB for the observation angle above 60°. Some of the arrays in a rectangular arrangement with element interval 0.75 λ, 0.8 λ, and 0. 85 λ satisfy the above requirement, but the arrays in a twisted rectangular arrangement can not satisfy this requirement. The frequency characteristics of phased arrays are also discussed.
Learning routing applied to large scale packet–switched communication networks
Authors: Kuribayashi Shin‐Ichi , Nakamura Tadao , Satos Risaburo 
Published: July 2007

AbstractLearning routing is introduced to large‐scale communication network to compensate the lack of a priori information on the network behavior. Learning routing consists of learning automaton as a learning controller placed at each network node. This learning automaton makes decision on routes for packets which are the basic unit of data to be transmitted through the network. Using learning automaton we propose two routing methods, LRI and LRI, which are basically reinforcement methods for the learning automaton. The effectiveness of these proposed methods is shown by means of simulation on a concrete network topology.
An analysis of thin‐film resistance networks with two resistive materials
Authors: Iwakura Hiroshi , Arakawas Teruaki 
Published: July 2007

AbstractIn designing the planar resistor and attenuator using uniform resistive media, if the electrode and structural dimension ratio are extremely small or large, the design is not realizable. In such cases, the realizable design range can be enlarged by using two kinds of resistive media. However, the resistance value can be obtained by solving nonuniform boundary value problems. In this paper, we report an approximate method for evaluating resistances using two kinds of resistive media. Further, the design method for composite thin‐film resistance and three‐port attenuator is proposed based on the analysis result and conformal mapping. The result of the analysis agrees with the experiment within the practical accuracy.
Effect of the circuit of second‐harmonic frequency on impatt oscillators
Authors: Shindo Yoichi , Okamuras Sogo 
Published: July 2007

AbstractThe effects of a second harmonic resonance circuit on IMPATT oscillator characteristics have been investigated. The admittance of an IMPATT diode is measured using an injection locking method simultaneously at the fundamental and second harmonic frequencies. A computer analysis, approximating the p+nn+ IMPATT structure with a Read diode, is carried out and the results are compared with the experiment. The theory agrees well with the experiment and has revealed characteristics of IMPATT diodes in the presence of an ac voltage component at second harmonic frequency. It is found that the negative conductance at the fundamental frequency is increased by properly selecting the load admittance at the second harmonic frequency. Characteristics of an IMPATT oscillator with a second harmonic resonance circuit at microwave and millimeter wave frequencies then are examined based on the computer simulation. The output power at the fundamental frequency varies over 10 dB when the second harmonic circuit conditions are varied near the resonance condition. The output power at fundamental frequency can be made a few decibels higher for optimized admittance at the second harmonic circuit than under off‐resonance conditions. Considerable output power at the second harmonic frequency is obtained under the above resonance conditions, and is described in detail.
Superconducting cavity stabilized oscillators by self‐injection locking
Authors: Komiyama Bokuji , Yasudas Yoshiyuki 
Published: July 2007

AbstractIn the superconducting cavity stabilized oscillator (SCO), which has extremely high‐frequency stability, the power input to the superconducting cavity (SC) must be minimized since the energy stored in the SC causes a shift in the resonance frequency away from its value at zero stored energy due to the electromagnetic radiation pressure and nonlinear surface reactance. Therefore, in the SCO with self‐injection locking, a loosely coupled directional coupler is used to couple a free running oscillator to an SC. This paper describes the design of self‐injection‐locked SCO's.The effects on frequency stability of the SC coupling factor and electrical line length between the SC and oscillating device are discussed. Oscillation frequency is given as a function of electrical line length. Optimum line length is discussed and the stability criteria for the oscillating device are derived. Based on this design consideration, an X‐band Gunn effect oscillator is stabilized. The SC is fabricated from solid Nb and has an unloaded Q‐factor of 6.7 × 106. The noise floor of frequency stability as low as 8.5 × 10‐11 has been obtained.