bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time sidelobe suppression for coded pulse compression via nonlinear optimization method
Authors: Nishimoto Shinkichi 
Published: July 2007

AbstractIn the pulse compression radar, it is necessary to suppress the time sidelobes which can cause a false alarm so that reliability of target detection is improved. For the pulse compression system to be adaptable for radar management which is considered to be important in recent years, it is indispensable that the radar waveforms be controlled flexibly by means of pulse compression. A method to this end can be provided by the pulse compression system using several random binary sequences with maximum entropy. However, since a coded sequence generated with a probabilistic manner is used in this method, both the time sidelobes and the mismatch loss tend to increase. Therefore, it is necessary to reduce both of them. From the forementioned viewpoint, in the case that the number of stages of the pulse compression filter is set equal to the code length, a method for deriving the filter coefficients realizing the minimum value of the peak time sidelobe level is analyzed as an optimization problem in the nonlinear programming. The pulse compression characteristics obtained by this method are described.
Multiring local area network system
Authors: Kanada Yoshihisa , Ikeda Tetsuo 
Published: July 2007

AbstractThe network interconnection technique is one of the keys for expansion of a local area network. This paper gives a performance evaluation of the multiring local area network system which consists of several token ring networks interconnected by using this technique. The result shows that this network system is better than the single‐ring network system, which is an ordinary token ring network, at heavy load operation. This paper also gives a performance comparison among three network interconnection topologies, “MESH connection,” “RING connection,” and “BUS connection,” and the optimum regions for these network interconnection topologies are suggested.
Low‐frequency crosstalk loss characteristics of balanced cables
Authors: Tomita Nobuo , Ohmura Makoto 
Published: July 2007

AbstractThe low‐frequency crosstalk loss characteristics are analyzed by a statistical method which derives the mean square of the crosstalk coupling. The theoretical formulas are derived for the near‐end and far‐end crosstalk losses in which mismatch terminations are taken into consideration. From both the theoretical and experimental viewpoints, the frequency dependence, terminal impedance dependence and cable length dependence of the crosstalk loss are studied. At low frequencies below a few tens kilohertz, both the near‐end and far‐end crosstalk losses decrease at the rate of 20 dB/decade for an increasing frequency. In the case of the terminal impedance of about 100 ω, the near‐end crosstalk loss decreases at the rate of 20 dB/decade for the increase of the terminal impedance. The far‐end crosstalk loss has a larger decreasing characteristic than this. Further, in the near‐end crosstalk, the crosstalk component at the far‐end due to the reflection at the cable end causes the cable length dependence in which the crosstalk loss decreases at 10 dB/decade for the increase of the cable length. In the case of far‐end crosstalk, the crosstalk of the forementioned far‐end is superposed on the intrinsic crosstalk. Therefore, the crosstalk attenuation decreases at the rate of 20 dB/decade.
A wideband sidelobe canceller for an earth station antenna
Authors: Takao Kazuaki 
Published: July 2007

AbstractAs Earth stations for satellite communication become smaller, the problem of interference with existing communication links becomes more serious. This paper proposes a technique to apply cancelling sidelobes to suppress such interference. A detailed examination of the location of auxiliary antennas was made to realize favorable characteristics to suppress the interference over a wide bandwidth. For an analytic study, a uniformly excited circular aperture antenna was assumed. Its characteristics for different sizes were obtained numerically. First, a case of the known arrival direction of the interfering waves was considered where only two auxiliary antennas are needed. However, their placement must be determined exactly depending on the arrival direction of the interfering waves and the diameter of the main antenna. If the arrival direction of the interfering waves is unknown, five auxiliary antennas are needed to achieve a fairly favorable interference suppression. To decide the optimum location of the auxiliary antennas, a normal projection of the two properly chosen antennas in the arrival direction of the interfering waves is required to coincide as closely as those for two antennas used in the case of the known arrival direction.
Analysis of microstrip antenna
Authors: Morishita Hisashi , Hirasawa Kazuhiro , Fujimoto Kyohei 
Published: July 2007

AbstractA microstrip antenna is divided into an interior region and an aperture region contributing to the radiation. The structure is then analyzed by applying the transmission line model to the interior and the magnetic and electric currents are assumed at the aperture where the moment method is used. In the interior, transmission lines are combined into triangular meshes so that the loading of a circuit element is easily done, and the method can be applied to an arbitrarily shaped microstrip antenna. At the aperture, the magnetic current distribution is obtained by the moment method so that the effect of the external electromagnetic field can be taken into account. Computations are carried out for four types of antennas on an infinitely large ground plane. For the input impedance characteristics, magnetic current distributions and radiation patterns, the computed results agree well with measured data.
Rayleigh fading compensation method for 16qam modem in digital land mobile radio systems
Authors: Sampei Seiichi 
Published: July 2007

AbstractTo cope with the increasing demands for the land mobile communication with a limited frequency band, it is necessary to improve the spectral efficiency beyond the present state. QAM (quadrature amplitude modulation) is one of the effective means for this purpose. When QAM is applied to land mobile communication, however, a great distortion is produced in the envelope and the phase due to fading fluctuation. Because of this property, few discussions have been made on the application of QAM to land mobile communication. This paper proposes the following system for such an application. The fading distortion is measured from the periodically inserted known frame symbol. By interpolating the obtained time‐series, the fading distortion for all symbols is estimated. Then the distortion is compensated. The performance when the proposed method is applied to 16QAM is examined by computer simulation. It is seen as a result that the fading distortion can be compensated with high accuracy, making 16QAM applicable to land mobile communications.
A burst error tolerant synchronization method in an asynchronous transport system
Authors: Kitami Tokuhiro 
Published: July 2007

AbstractThis paper proposes a burst error tolerant synchronization method in an asynchronous transport system. In this method, the received original cell stream is branched off into several streams and these branched streams are then delayed differently so that the bursty errored periods in the resulting streams rarely coincide. The synchronization pattern is detected using these streams based on N‐out‐of‐M logic.This technique is applicable to cell alignment using empty cells with synchronization pattern, as well as to frame alignment. The analyses include synchronization pattern detection probability, alignment recovery time, and misalignment probability performance. This method has the following advantages.(1) It yields a highly tolerant performance against long burst errors because processing with signals at different time positions is introduced.(2) Degradation caused by burst errors is reduced regardless of the synchronization pattern insertion probability.(3) Alignment performance is considerably improved even for a simplified configuration with a majority‐logic synchronization pattern detection for only three branched streams.
Design of a multistage self‐routing switch with a distributed cell sequence control
Authors: Obara Hitoshi 
Published: July 2007

AbstractAs a technique for constructing the switch fabric in the ATM (asynchronous transfer mode) communication system, the self‐routing switching network has been proposed where the buffered Banyan network is used as the distribution network as well as the routing network. The features of this kind of switch are that it is of a distributed structure, being suited to the modular construction, the large capacity system can easily be realized, and the performance is stable for diversified traffic. On the other hand, it has a problem in that the order of the transmitted information (cells) is not preserved.This paper proposes anew a switch construction with time stamps attached to the cells. The cell sequence is preserved by controlling the sequence of the time stamps, and the system can be controlled in a distributed way. The feature of the method is that the cell sequence is preserved while maintaining the self‐routing property of the traditional multistage buffered switch.Also, the principle and the optimal construction are described. Basic system parameters such as the required word length for the time stamp signal are determined. The delay characteristics of the proposed system for various kinds of traffic are evaluated by a computer simulation.
Analysis of call admission control in the atm network
Authors: Arai Hideaki , Kawarasaki Masatoshi , Nogami Shinya 
Published: July 2007

AbstractIn the ATM network, where multimedia information such as voice, video, and data are transmitted in a unified way, it is very important to establish a control technique to secure the required network quality for the traffic with various speeds and bursti‐ness. A discussion is made for the ATM network to introduce the call admission control function based on the loss probability, instead of the flow control within the network.This paper considers the situation where traffic with varous speeds and bursti‐nesses arrive, and discusses the call admission control for each call, to suppress the cell loss probability below a certain value.First, a method is considered in which multimedia information is divided into the high‐speed and low‐speed media, and the two media are multiplexed. The cell loss probability is analyzed.As the analysis model, MMPP/D/1/(1 +N) is employed, where the arrival follows the Markov‐modulated Poisson process. It is shown as a result that the peak‐bit‐rate of the high‐speed calls and the mean‐bit‐rate of low‐speed calls have greater effects on the cell loss probability.It is shown also that the cell loss probability can be approximated by that of M/D/1/(1 +N) with the sum of the two fore‐mentioned parameters as the input traffic. Finally, a call admission algorithm is proposed and evaluated based on the result derived. The feature of the control method using this algorithm is that it is simple and easy to realize.
Channel assignment in a cellular mobile communication system and an application of neural networks
Authors: Sengoku Masakazu , Nakano Keisuke , Yamaguchi Yoshio , Abe Takeo , Shinoda Shoji 
Published: July 2007

AbstractIn cellular mobile communication, the same channel is shared by a number of cells. Up to now, the model has been considered where the same channel is used with a sufficient separation, so that the radiowave interference is sufficiently small for any call generated in the cell.Recently, on the other hand, a model has been proposed where the same channel is assigned independently of the specified cell separation, as long as the carrier‐interference ratio is above a certain value. Although the assignment algorithm has been discussed for the traditional model, no report has been made on the detailed assignment procedure for the new model.With such a situation as the background, this paper proposes an application of Hopfield's neural net as an approach to the channel assignment in the new model and derives the energy function. Several results of computer simulation are shown where the proposed neural net is applied to the mobile communication model. It is not always true that the neural net produces the optimal solution, but it is interesting that an unexpected improvement of the channel utilization is observed in the communication traffic as far as the result of computer simulation is concerned.
Object‐oriented switching program structure
Authors: Maruyama Katsumi , Kubota Minoru 
Published: July 2007

AbstractPublic switching systems are severely real‐time and multiprocessing, very large, long‐lived, and frequently modified. Programs that control switching systems therefore are required not only to have run‐time efficiency but also to be easy to maintain and expand.This paper proposes a concurrent object model and an object‐oriented switching program structure. The concurrent object model ensures simple and efficient real‐time multiprocessing. Also, it allows logical switching components to be implemented as “objects” in software, and the structure of the program coincides with the structure of the logical model. The program structure proposed here uses distributed call processing, which allows building‐block structured switching systems. A prototype switching program confirmed the effectiveness of this approach and showed that the static and dynamic overheads are within the capacity of present VLSI technology.
Design of a folded banyan switching network with by‐pass links using a distribution cell sequence control
Authors: Okamoto Satoru 
Published: July 2007

AbstractThe asynchronous transfer mode (ATM) is considered to be important as a key technology in realizing a broadband ISDN that can handle diversified services in a unified way. The high‐speed burst multiple transmission system using ATM is proposed. This paper considers the folded Banyan network with by‐pass links which is proposed as a cross‐connect switch to be applied to the cross‐connect MUX of the high‐speed burst multiple transmission system. A routing method that preserves the time sequence of cells also is proposed and its cell transfer performance is analyzed.The proposed routing method is realized by a distributed control. It is shown that the method can be applied at the same time preserving the features of the folded Banyan network with by‐pass links, which are the unified modularity and the expansion without interruption. For the performance evaluation, a method of analysis is presented which improves the approximation of the traditional analysis of the cell loss rate.
Polarization diversity detection performance of 2.4 Gbit/s CPFSK heterodyne system
Authors: Hayashi Yoshihiro , Ichihashi Yasutaka , Imai Takamasa , Yanai Daisuke , Ito Takeshi 
Published: July 2007

AbstractIn the practical implementation of the coherent optical transmission system, it is important to establish the techniques for stabilizing the optical frequency considering the actual environmental condition, as well as a technique for compensating for the variation of the state of polarization in the usual single‐mode optical fiber cable.This paper considers the application of the polarization diversity receiver to the CPFSK heterodyne delay detection in the 2.4‐Gbil/s band and discusses the construction and performance. The regenerative repeater equipment is designed in a compact form to be implemented in a commercial rack (INS cabinet rack). Using the designed equipment and the existing trunk fiber transmission route, an experiment in the actual site is conducted and the results are shown.The first part of this paper presents the construction of both the automatic frequency control (AFC) system and the automatic gain control (AGC) system suited to the polarization diversity system. The design guides are presented for the required frequency response speeds of AFC and AGC, the required frequency stability of AFC, and the response performance to the fluctuation of polarization. A high‐output, high‐sensitivity 2.4‐Gbit/s regenerative repeater equipment (with repeater gain above 48 dB) is realized with the overall performance that the variation of optical received sensitivity against the polarization fluctuation can be suppressed to within 0.5 dB.Finally, the stable operation of the equipment is verified by the experiment at the actual site, and the practical usefulness is indicates.
Cost‐effective configuration for large‐scale optical distribution system utilizing optical fiber amplifiers
Authors: Matsuura Masaaki 
Published: July 2007

AbstractThis paper investigates the cost‐effective optimum configuration of large‐scale optical distribution systems utilizing optical fiber amplifiers.First, the relation between network topology and the number of equipment is discussed. It is shown that in low‐loss optical fiber distribution systems, the tree configuration is more advantageous than the bus configuration from the viewpoint of required optical fiber amplifiers.Next, the relation between the network topology or distribution scale and the cost of each equipment is investigated. It is shown that when the cost of the fiber amplifier dominates, the tree distribution system with multilayer structure divided properly into subsystems is the optimum one. It is clarified that the structure with a large number of layers and the minimum number of segments in each layer is the economical configuration.
A study on a TDMA system with dispersive delay lines
Authors: Miyauchi Kazuhiro , Hangai Seiichiro , Mizoguchi Masato 
Published: July 2007

AbstractThis paper discusses a satellite TDMA system with two dispersive delay lines of opposite characteristics in earth stations and in the satellite transponder to reduce the peak transmitting power of the earth stations. Reduction effect is estimated for available SAW devices and the reduction in peak transmitting power of about 27 dB is achieved in the single‐pulse transmission mode.In actual TDMA systems, however, burst pulses must be transmitted and bursts of about 1000 symbols in length are used. Since only relatively short bursts (about 20 symbols long) are allowable in this system, various study subjects are discussed to realize it, such as the increase of burst length, reference time establishment at earth stations, modulation/demodulation and clock recovery.The effects of several kinds of system impairments, such as residual response of modulator, effect of characteristic deviation of dispersive delay lines, and dynamic range of receiver amplifier of transponder are studied.
Performance of CMA adaptive array optimized by the marquardt method for suppressing multipath waves
Authors: Fujimoto Mitoshi , Kikuma Nobuyoshi , Inagaki Naoki 
Published: July 2007

AbstractConstant modulus algorithm (CMA) adaptive array has been proposed as a countermeasure to frequency selective fading; but since the evaluation function is nonlinear with respect to weight, the conventional steepest gradient method is being used for optimization. However, if there is a large variation in the eigenvalue of the correlation matrix of the input, then the convergence becomes very slow.In this paper, Marquardt's method of optimizing the CMA adaptive array is proposed. This method is based on a nonlinear least‐square algorithm, and its dynamic characteristics are clarified by computer simulations.First, the fundamental characteristics of the algorithm are investigated. It is shown that this algorithm gives satisfactory convergence even for those cases where the convergence performance of the conventional steepest gradient method has degraded and where waves approach by multiple paths.Next, the performance of the algorithm is studied under the influence of Doppler shift or in the case where the wave conditions vary and satisfactory performance is obtained under frequency selective fading environment.
A multimedia intelligent message communication system for distributed coordination environments
Authors: Hattori Shinmi , Kuramoto Keisuke , Nakazawa Minoru 
Published: July 2007

AbstractThis paper proposes a new multimedia message communication system. This system is strongly integrated with deskwork operation by multiple polymorphism of object‐oriented construction in a distributed computer resource OA environment consisting of networks, personal computers, and workstations.Here, a message communication system and desk‐work system are regarded as a means of processing mail with undecided/decided boxes as start/end points. Further, automated generation of an individual action schedule and response mail has been implemented by using a distributed coordination algorithm of 1: N conversation element module with knowledgebase of individual action status, and its application to automated and personalized secretary work in OA environments has been studied.
Generation of efficient test sequences from lotos specifications
Authors: Okazaki Naonobu , Noguchis Shoichi , Takahashi Kaoru , Shiratori Norio 
Published: July 2007

AbstractLOTOS is a formal description technique (FDT) developed by ISO. This paper proposes a formal technique for generating test sequences from a LOTOS specification. In the proposed technique, test sequences correspond to a finite “tree” which is represented as a TreeLOTOS expression which is a subset of LOTOS. A labelled transition system (LTS) with variables called VTS is introduced to generate test sequences, which is useful not only for compactness of expression but also for effective selection of test sequences at the execution of tests. Furthermore, the concept of the reduced form of a VTS is introduced and, by using this concept, efficient test sequences can be obtained.
Switched snubber for high‐frequency switching converters
Authors: Sakamoto Hiroshi , Noguchi Seiichi , Haradas Koosuke 
Published: July 2007

AbstractThis paper proposes a switched snubber circuit for the switching converter. The switched snubber is made of a series connection of a switch and a capacitor. The switched snubber can suppress the surge over a wide range of duty ratio and is basically lossless. The switched snubber features zero‐voltage switching. A PWM controllable and low‐stress converters are developed by replacing the resonant capacitor with a switched snubber in the voltage‐mode resonant converters. Also, the region where the output voltage increases abnormally is narrow in the converters with a switched snubber.
Analysis of parallel plate mode in slot‐coupled microstrip antenna
Authors: Iwasaki Hisao , Shoki Hiroki , Kawabatas Kazuaki 
Published: July 2007

AbstractIn the electromagnetic slot‐coupled microstrip antenna in which a triplate transmission line is used and a patch antenna is fed via a slot on the ground plane, a parallel plate mode (TEM wave) propagating between the ground planes is excited so that a power leakage causes unwanted coupling and radiation.This paper studies the Poynting power and the electric field of this parallel plate mode. The amount of the parallel plate mode generated and the propagation behavior are investigated analytically by means of the Spatial Network Method. The method for installing shorting pins known for their suppression of the parallel plate mode is studied in its relationship to the generation of the parallel plate mode.A method for placing pins with a least number of pins is proposed. The relationship between the resonance of the parallel plate mode and the external dimensions of the dielectric substrate comprising the triplate transmission line is studied experimentally. It is found that the resonance of the parallel plate mode coincides with that of an open resonator with its dimensions identical to a finite dielectric substrate comprising the triplate transmission line.