bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design centering for analog‐integrated circuits using spherical surface random numbers
Authors: Jyo Yoichi , Ikeda Hiroshi , Minamoto Suemitsu , Kojima Yoshiaki 
Published: July 2007

AbstractThis paper considers the semiconductor integrated circuit, and proposes a solution to the decision problem for the optimum design, where circuit‐element values are determined so that the yield is maximized. The spherical surface random number is employed in the calculation of the yield. Although various nonlinear programming methods can be applied to the optimization problem, this paper applies Newton's algorithm to the optimization algorithm. It is shown that the first‐ and the second‐order derivatives of the yield to the design value, which are needed in the calculation of the search vector in Newton's method, can also be derived using the spherical surface random numbers. I is also shown that the center of the element value determined by the design specification can be calculated using the spherical surface random numbers, and the optimization can be performed efficiently using the center as the initial point for the optimization. Applying the proposed method to the 5th‐order leapfrog‐type switched‐capacitor filter, the processing time is reduced to approximately onefourth compared with the case of the Monte‐Carlo method.
Hybrid ARQ system employing soft decoding algorithm
Authors: Kobayashi Hideo 
Published: July 2007

AbstractIt is known that by applying a soft decoding algorithm to the error‐detecting code in the ARQ system, a hybrid ARQ system can be realized in which error detection and correction are possible. This paper discusses the application of the soft decoding algorithm to the ARQ system, where the multivalued digital modulation is employed. A scheme for a practical system is proposed, including the detection of channel measurement information in the multivalued digital modulation system and estimation of error patterns. By the proposed method, the hybrid ARQ system can easily be realized by adding some peripheral circuits to the conventional ARQ receiver. Theoretical study is made on the number of error patterns that can be estimated for a long block length as well as the probability of miss and the probability of retransmission request. The proposed scheme was applied experimentally to the ARQ system employing SG VIII V.29 modem based on CCITT recommendation, and the usefulness of the proposed scheme was verified by experiment.
Round‐off error analysis for deadbeat control system using observer
Authors: Imai Nobuyuki , Hirai Kazumasa 
Published: July 2007

AbstractIn the control system using a digital computer with finite word‐length, the control performance is degraded by the quantization error of the signal and the control parameter, as well as the round‐off error in the computation. Consequently, one of the important problems is to establish the design method which can reduce the effect of the quantization error. This paper considers the deadbeat control system with an observer, and analyzes the round‐off error in the floating‐point computation. The effect of the round‐off error on the control system is evaluated quantitatively. Finally, a numerical example is presented demonstrating the validity of the result in this paper, as well as the effectiveness of the parameter determination method for the observer to reduce the effect of the error.
Processing of ultrasonic pulse‐echo signals to remove electroacoustic conversion distortion
Authors: Yamada Akira , Abe Kenichi 
Published: July 2007

AbstractIn the ultrasonic pulse‐echo system, the reflection characteristics of the acoustic system are reproduced faithfully by signal processing to remove electroacoustic conversion distortion contained in the pulse‐echo signal. The proposed signal processing has the feature that the two contradictory requirements for high resolution and high sensitivity can both be satisfied. Another feature is that the single‐peak impulse characteristics can easily be realized. Problems left to be solved for practical applications are the reduction of the processing noise and the improvement of the processing speed. A possible solution is to utilize effectively the a priori knowledge about the distortion characteristics. This paper presents a basic physical discussion on the convolution model for the pulse‐echo system. Presented also is a clear description of the distortion function. Based on the results, a high‐speed signal‐processing system with on‐line recursive computation is proposed using the least‐square transversal filter in the time domain. The solution to the forementioned problem toward practical application is discussed by examining the computation method for the filter coefficients with smaller processing noise. At the end of this paper, an evaluation experiment is performed for the proposed signal‐processing system, indicating that the reflection characteristics of the acoustic part can be restored with small processing noise and high quality.
Design of world loop networks and effectiveness evaluation of dynamic routing
Authors: Mori Hiromichi 
Published: July 2007

AbstractIntercontinental optical submarine cables with larger capacities than conventional coaxial cables are now being developed. In accordance with international communication demand evolution and digitalization, worldwide optical submarine cable networks will be constructed. A loop network around the world in an east‐west direction, composed of optical submarine cables is considered to be an international backbone trunk network due to the advantages in simplicity, efficiency and reliability. Since the proposed design method aims at making a macroscopic network planning outline rather than making a detailed network design, the stochastic process of traffic is neglected and the traffic is treated as stationary flow. We present the strategies to evolve the world loop network and the increased traffic demand that reflects the actual international communication traffic trend. In addition to the conventional routing scheme in which mainly direct routes are used, a dynamic routing scheme in which routes composed of up to two tandem links are used is studied, and its effectiveness through network evolution is quantitatively evaluated.
Edge extraction and restoration of noisy image by innovation process in kalman filter
Authors: Kawazoe Yasuhiro 
Published: July 2007

AbstractEdge detection and restoration methods are considered from noisy images without a priori information about original images. The chi‐square test detects edges from an innovation process when applying the Kalman filter to the first‐order AR model. Image‐extracted edges are the binary image and the thin‐line image. The success of the algorithm depends heavily on the window width for the chi‐square test and the value of the threshold in which the detector operates.Also, edge information is used for restoring images to remove noise in the background of images using a smoother and to obtain sharp edges in other regions using a sensitive filter. The effect of the approach is illustrated by the simulations.
Study on a self‐routing switch network with mutual control
Authors: Uematsu Hitoshi , Watanabe Ryuichi 
Published: July 2007

AbstractRecently, the application of self‐routing switches to transport processing nodes such as the digital cross‐connect system and digital switching system is being studied to realize a large‐capacity enhanced transport processing node by distributed control. For this purpose, Shuffle‐Exchange networks, Batcher‐Banyan networks, etc., have been proposed so far. A Shuffle‐Exchange network is minimal in its switch size but is a limited‐availability system. The Batcher‐Banyan network is a full availability system in a sense that the routing is controlled and automatically rearranged in a distributed manner at a switch cell. This paper proposes a new type of packet switching network, which consists of self‐routing switches having mutual switching control for packet headers between a pair of self‐routing switches. All the switch cells are controlled with only one bit of input packet header by the same switching algorithm. The proposed switching network is a nonblocking (fully available) switch having a self‐rearrangeable function similar to the Batcher‐Banyan network and is controlled in a distributed manner within a switch cell. Its performance is compared with those of existing switching networks and its characteristics are shown.
Performance evaluation of processing element in a data‐flow control scheme
Authors: Nogami Shinya 
Published: July 2007

AbstractThis paper describes the behavior of the processing element (PE) generally used in applying the data‐flow control scheme to signal processing equipment in the switching system or in the computer system. A performance evaluation is presented in terms of the characteristics based on the theoretical analysis. It is important in this scheme to evaluate the time until the program execution is completed (program execution time) for the given parallelism of the data‐flow program and the multiplicity of the program (task). As a preliminary to the estimation of the program execution time, this paper evaluates PE as a whole.First, the matching‐store unit of PE is considered. A simple numerical analysis based on the traffic model is presented and the performance is evaluated. The characteristics such as the mean number of waiting calls and the mean waiting time are calculated. Using those results, the whole PE is modeled as a BCMP‐type queueing network, and the mean cycle time is derived. Finally, the result of numerical calculation and the result of simulation are illustrated. The range of application is described, together with some discussions.
Observation and interpretation of patched structures in the spectra of low‐latitude whistlers
Authors: Ohta Kenji , Eguchi Hiroyuki , Hayakawa Masashi 
Published: July 2007

AbstractIt has been known for a long time that the intensities of the whistlers observed on the ground sometime exhibit frequency dependence through analyses of sonograms. The frequency dependence of the intensities of whistlers observed at low altitudes was examined in detail with the aid of a PCM recorder and FFT analysis. As a result, whistlers were found whose intensity spectra were independent of the frequency spectra of their causative atmospherics. In other words, the changes of the received signal intensities of each whistler with respect to the frequency had patchy patterns. This paper describes various characteristics of patched whistlers. For their interpretation it is proposed that their generation was due to the wave interference by the irregularities of electron densities in the F‐layer ionosphere.
Adapative arq schemes and their performance evaluation under full‐duplex transmission
Authors: Ishibashi Yutaka 
Published: July 2007

AbstractAdaptive ARQ (automatic repeat request) is an error‐control scheme in data transmission in which the number of successively transmitted data blocks and the data block length are adjusted according to the bit error rate. This scheme performs better in half‐duplex transmission than the conventional selective repeat (SR) and go‐back‐N (GBN) schemes when the bit error rate is either not known or varies with time.This paper proposes a control procedure for the full‐duplex adaptive ARQ scheme. In this procedure an observation period is defined and the data block length is adjusted dynamically according to the success of the data block transmission in the observation period. The throughput of this scheme is analyzed. The proposed scheme is compared with nine conventional schemes, including SR and GBN, in terms of performance. The results indicate that the performance of the adaptive ARQ scheme is very close to that of the fixed data block scheme in which the optimal data block length is selected statically. It is also shown that the performance of the adaptive ARQ scheme does not degrade as rapidly as in other schemes when the bit error rate increases.
Comparative study on dpll's based on power density spectrum of phase error sequences
Authors: Nakao Mutsuhiko , Yamashita Kazumi 
Published: July 2007

AbstractUntil now, four different types of first‐order digital phase‐locked loop (DPLL) for tracking of clock signal have been reported which are distinguished mainly by a difference in the control circuit. The performance of these digital loops is determined by rms phase error and transient response which are obtained in the reporter's own way established on a basis of Markov theory. However, performance comparison has not yet been made.In this paper, first, it is proved that phase error sequences of four digital loops are all classified into semi‐Markov sequences (SMS) if time jitter in each cycle of the input signal is an independent random variable with a certain distribution function.Second, under the condition that time jitter is an independent random variable with Gaussian distribution, the rms phase error and power density spectrum of the phase error sequence are computed for typical values of input variance according to formulas derived for SMS.Finally, using this curve and equivalent first‐order linear PLL, the rms phase error, loop noise bandwidth and phase amplification factor are obtained; and based on these results, the performance of four digital loops is discussed.
Proposition of observation system by distributed circuit for fast transients due to discharge in electric contact
Authors: Kawamata Kei , Yang Xinwei , Haga Akira , Sato Risaburo 
Published: July 2007

AbstractIn the detailed time domain analysis of high‐speed transient phenomena in connection with discharge of an electric contract viewed as a noise source, an experimental circuit for observation of the phenomena was investigated. It was found that the effect of wiring cannot be neglected and the investigation becomes more difficult in the experiment with a lumped element system if the sampling rate of the waveform observer is high. For this reason, a distributed experimental circuit system suitable for observation of a high‐speed phenomenon was set up and an experiment was carried out with this circuit.From the results of observation of transient voltage variation in connection with the discharge, it was found that the transient waveform agrees well with the theoretical waveform and a detailed observation is possible even if the sampling rate is 1 GS/s. In this experimental circuit, there is no effect of the interior of the power supply, of the load and of the reactance and interference of wiring and devices. Since the charge is stored in the distributed circuit, it is possible to generate discharge with a supply of a homogeneous electric energy for a given time. Therefore, detailed observations of various phenomena are possible.
Performance improvement of dpll with adaptive binary quantized phase‐frequency comparator
Authors: Nakajima Osamu , Hikawa Hiroomi , Inoue Takashi , Mori Shinsaku 
Published: July 2007

AbstractPLL's (phase‐locked loops) are playing widely important roles in various fields of communication. In recent years, efforts have been shifted toward implementation of the PLL's by means of digital circuits. There arise various problems which are common to that approach, such as the contradictory relation between the phase‐locking range and the jitter suppression, as well as the steady‐state phase error due to the frequency offset.This paper attempts to cope with those problems by improving the conventional binary quantized phase comparator which produces only +1 and ‐1 outputs. A new phase‐frequency comparator is proposed which adaptively modifies the phase comparison characteristics according to the frequency error and the input phase jitter, aiming at an improvement of DPLL performance.The modified comparator improves performance of the loop by increasing its output gain in the pull‐in state, and decreasing the gain in the steady state. When there exists a frequency offset, the cycle slip and the steady‐state phase error are detected, and the output frequency is controlled by adding a constant quantity which reduces the frequency error to the comparator output in the steady state.By this scheme, the locking range is increased. Theoretical analyses are made for the frequency acquisition, phase acquisition and jitter suppression for the proposed loop. The result of the theoretical calculation is compared with the result of simulation, and it is verified that the proposed loop structure offers a wide locking range and a high jitter suppression, at the same time improving the steady‐state phase error.
A ring cavity antenna of wide beamwidth
Authors: Arai Hiroyuki , Goto Naohisa 
Published: July 2007

AbstractMobile telecommunication systems by satellite meet the requirement of antenna radiation pattern of wide beamwidth. The wide beamwidth of the circular microstrip disk antenna is obtained by high dielectric constant substrate. However, the dielectric losses and difficulty in manufacturing are problems for high dielectric constant materials.Wide beamwidth is obtained also using the antenna with an electrically small magnetic current loop.This paper presents the ring cavity antenna without dielectric materials. It also has electrically small magnetic current loop. Antenna characteristics calculated by the cavity model showed that the ring cavity antenna has wide beamwidth. Theoretical values are verified also by the measured radiation pattern and the input impedance.
Performance analysis of improved stutter go‐back‐n arq scheme
Authors: Komatsu Masaharu , Hayashida Yukuo 
Published: July 2007

AbstractIn the stutter go‐back‐N ARQ scheme proposed by Towsley, a packet is transmitted by sending its copies in idle slots. Thus, it can achieve very small packet delay at light‐offered traffic load, but the maximum throughput is small.The stutter go‐back‐N scheme is improved by sending a multiple copy of a negatively acknowledged packet at retransmission time. The improved scheme is analyzed, and average packet delay, maximum throughput, and so on, are derived. Furthermore, from numerical examples, it is shown that the improved scheme can achieve higher throughput and smaller average packet delay than the basic go‐back‐N and the original stutter go‐back‐N schemes.
V dipole antenna with multiple stub loading
Authors: Nakamura Takashi , Fushimi Hideki , Yokokawa Senji 
Published: July 2007

AbstractA V dipole antenna with multiple stub loading is proposed as a traveling wave antenna with a wide bandwidth in both the gain and input impedance. It is considered that the present antenna is essentially a tapered transmission line loaded with open stubs. Then the operating principle is studied by reducing the structure to an equivalent nonuniform transmission line. It is found from the relationship between the equivalent distributed parameters and the stub that the dipole‐type stub array with its stub length reduced gradually from a half wavelength to a quarter wavelength is a basic structure for the broadband nature by the decaying traveling wave. Based on this concept, an actual stub‐loaded V dipole antenna was characterized numerically.It is demonstrated that uniform characteristics of an input admittance of 5 mS, a gain of 8 dB and a front‐to‐back ratio of 10 dB are obtained over ±30 percent around the center frequency in the case of a V dipole with an included angle of 30°. This antenna was fabricated and the validity of the present theory was confirmed because the theoretical and experimental results agreed well.
Optimization of error probability in quantum control communication processes
Authors: Ohya Masanori , Suyari Hiroki 
Published: July 2007

AbstractRigorous study of optical communication processes has become interesting since around 1970. Especially, quantum information theory has been developed in both mathematics and engineering. In this paper, by controlling the energy associated with a quantum input state, we obtain an optimal solution (optimal state, optical modulation, etc.) giving the minimum value to the error probability in the attenuation optical communication process. For instance, we find some relations between the energy constraint of the input state and the optimal error probabilities in each modulation.
Characteristics improvement by synthesizing nonaxisymmetrical aperture distribution
Authors: Karikomi Masahiro , Yamada Yoshihide 
Published: July 2007

AbstractImprovement of the radiation characteristics by the “nonaxisymmetrical aperture field distribution” is described. The aperture distributions in the horizontal and vertical planes are designed to be a low‐sidelobe type and a high‐efficiency type, respectively. As a measure of the degree of nonaxisymmetry, the ratio of the edge levels in the vertical and horizontal planes is introduced. The dependences of the degrees of improvement of the aperture efficiency and the wide angle radiation pattern upon the edge level ratio were studied and the amount of improvement was presented quantitatively.For example, the wide angle radiation level was reduced by about 15 dB by nonaxisymmetric aperture distribution with the aperture efficiency kept constant. On the other hand, if the wide angle levels were kept constant, the aperture efficiency was improved by about 0.4 dB with nonaxisymmetric distribution. In the case of an offset antenna, sidelobe levels in the wide‐angle region were increased from the numerical results with the aperture field method by the effect of the edge diffraction.The increase is shown to be less than 3 dB in the case of an offset angle of 60°. Moreover, the wide‐angle directivity can be improved in a certain region centered on the plane in which the attempt was made to achieve a low sidelobe level by means of a nonaxlsymmetric distribution. Possibilities and examples of widening or reducing this region and furthermore shifting it to the surface other than the horizontal one were described.
Performance analysis of wide zone AVI systems
Authors: Mukumoto Kaiji , Fukuda Akira 
Published: July 2007

AbstractThe wide zone AVI system is an automatic vehicle identification system that can cope with more than one vehicle in the detection zone. Such a system includes a possibility of identification failure by the collision of ID packets, in addition to the ordinary transmission failure. A method to remedy this is to transmit the ID packet several times. This paper considers two methods of transmitting the ID packet from each vehicle. In the first, the packet transmission interval follows an exponential distribution, and in the second, a specified number of transmissions are made at random points which are distributed uniformly during the zone pass period.Using approximate analyses of the identification failure probability, the effects of the design parameters on the system performance are examined for each method. As a result, it is shown that the constant number transmission method has a better performance than the exponential transmission interval method, in terms of the probability of identification success, the number of ID packet transmissions, and other aspects.
Error performance of triangular‐shaped signal set
Authors: Oshita Shinjiro , Yamazato Takaya 
Published: July 2007

AbstractThe error performance of an amplitudephase shift keying system with triangularshaped signal set (TSSS) is discussed. Expressions for the probability of error performance of this scheme are derived for the case of 64, 128, 256, 512, 1024 states and compared to QAM and modified QAM (MQAM) for the same number of states. It is shown that this signal set outperforms both QAM and MQAM in the presence of an additive Gaussian noise channel.The performance improvement is attributed to the larger decision region obtained for each state in the signal constellation, as compared to QAM and MQAM. Degradation due to the phase error is also discussed in detail.