bluuebunny/crossref_metadata_2025_split huggingface dataset:
Remote control signal for submarine optical repeater fault location systems
Authors: Hayashi Yoshihiro , Miyawaki Youhou , Aiki Mamoru 
Published: July 2007

AbstractThis paper studies the remote control signal for submarine digital optical repeater fault location systems. The conditions to be satisfied by a submarine optical repeater fault location system are shown first and then a practical fault location system is proposed. The remote control signal is composed of a mark density modulated pulse stream whose on‐off is controlled by pulse width modulated command codes. This signal achieves performance improvement even when there are main transmission line errors, code identification of repeater, and simplification of supervisory control circuit. This remote control signal is validated through a transmission experiment using 445 Mb/s submarine optical repeater, and the robustness against main transmission errors and the error detection ability of transmission line errors are clarified.
Accurate numerical analysis of an elliptically cored optical fiber for polarization preservation, using mode‐matching method
Authors: Miyamoto Tokuo , Yasuura Kamenosuke 
Published: July 2007

AbstractThe Mode‐Matching Method has been known as an accurate and reliable method for numerical analysis not only on the diffraction problem in the electromagnetic field, but also on the elastic waveguide and the optical thin‐film waveguide. This method is applied for the rigorous analysis of an elliptically‐cored optical fiber with large ellipticity whose accurate analysis in the wide range of frequency including the cutoff has so far been difficult. Moreover, a very high degree of accuracy of five figures is achieved for the normalized propagation constant. Both the dispersion relation and the field distribution in the hybrid modes are clarified and it is also confirmed that the hybrid mode analysis is not always necessary in the case of larger ellipticity. The properties of the higher‐order mode cutoff and the polarization preservation whose rigorous discussion has not been always sufficient, are analyzed more accurately. The results are compared with the results obtained by other methods, and more exact design data for the single mode, polarization‐preserved optical fiber with elliptical core are presented. Through these analyses, it is also confirmed that the Mode‐Matching Method is still a useful and reliable method for rigorous analysis of the rod‐type dielectric waveguide with arbitrarily shaped cross section.
Variational analysis of GT‐Cut quartz crystal resonators with the supporting portions at the ends
Authors: Kawashima Hirofumi 
Published: July 2007

AbstractIt is well known that a GT cut quartz crystal resonator coupled between two extensional mode vibrations has a cubic curve in frequency‐temperature characteristics as well as an AT cut quartz crystal resonator. This paper studies frequency‐temperature characteristics and electrical characteristics of the GT cut quartz crystal resonator with the supporting portions at both ends of the vibrational portion.First, a secular equation is derived from a vibration analysis of the resonator consisting of the vibrational portion and the supporting portions, by applying the energy method. From this secular equation, a relationship of resonant frequency, frequency temperature coefficients vs. a cut angle, a dimensional ratio and a mass ratio for the GT cut quartz crystal resonator is clarified theoretically. At the same time, from comparison of the calculated values with the experimental values, it is confirmed that they agree very well. Next, electrical characteristics of the quartz crystal resonators manufactured for trial experiments are measured. As a result, it is confirmed that a GT cut quartz crystal resonator with excellent frequency temperature characteristics, low crystal impedance and a high quality factor is realized.
Traffic analysis of mail‐box storage file in voice message switching system
Authors: Hattori Shimmi , Abe Shunji , Noguchi Shoichi 
Published: July 2007

AbstractThe introduction of a storage function for subscribers' messages into switching systems improves serviceability, thereby enabling nonrealtime and called party oriented communication. However, the analysis method and the traffic performance of this voice message switching system, for example, the mail‐box storage system, has not been clarified yet. This paper presents the traffic design principle of the voice message switching system. The traffic analysis model of this system is proposed as a threestage serial model consisting of message writing, storing, and reading for the mailbox storage file. Next, this model is approximated to the separate model of M/H2/S(0) loss systems and its validity is evaluated by using a simulation method, etc. Finally, some traffic characteristics of the mailbox storage file are studied by theoretical analysis and simulation methods.
Selection method for both‐way circuit groups between multiunit offices
Authors: Toda Akira , Imai Mitsuru 
Published: July 2007

AbstractIntroduction of common channel signaling system makes the both‐way circuit operation easy and therefore efficient operation of communication network is expected. An effective selection method is required for the circuit groups with both‐way circuit operation between multiunit offices in order to avoid service degradation in traffic between the offices caused by improper selection method at one side. In this paper, we propose new selection methods which make use of the number of idle circuits and the idle probability of circuit groups. We also clarify the effectiveness of these methods by a comparison with existing methods, e.g., the method of selecting a circuit group in proportion to the number of idle circuits in each group, etc., that had been used in oneway circuit operation, from the viewpoint of traffic characteristics.
Dynamic measurement of temperature dependence of complex permittivities at microwave frequency
Authors: Tashiro Shinjiro , Okada Fumiaki 
Published: July 2007

AbstractA method is presented for measuring relatively easily the temperature dependence, particularly at high temperature, of the complex permittivity at microwave frequencies. In this method, a sample is inserted into a cavity resonator and is heated with a micowave source. The change of input admittance of the cavity is measured while heated, and the temperature dependence of complex permittivity of the sample is calculated by a perturbation method. Since the microwave power for heating and the microwave signal for measurement is performed, configurations of the measurement apparatus is simmple and the temperature dependence over a broad range can be measured in a short period of time.A TE103 rectangular cavity at 2.45 GHz has been used for a mullite (3A12O3 · 2SiO2) protective tube. The results indicate that the method is effective for temperature range from room temperature to about 1000°C.
Analysis of piezoelectric ceramic length‐expansion‐mode resonators using interdigital electrodes for both poling treatment and ac excitation
Authors: Hirose Seiji , Nakamura Hisashi , Shimizu Hiroshi 
Published: July 2007

AbstractWhen interdigital electrodes set on the surface of a rectangular piezoelectric plate are used for poling and ac excitation, a length‐expansion‐mode resonance in the Lamé‐mode system alone is emphasized. However, this does not occur easily in conventional length‐expansion‐mode resonators having a uniform poling across the thickness and electrodes on the entire surface. The proposed method offers a resonator with very little spurious oscillation in this mode. To obtain a guideline for designing interdigital electrodes, the relationships between the width of electrodes, the period of electrodes and the capacitance ratios were analyzed theoretically in detail by using conformal mapping. The strength and direction of the dc electric field of this type of resonator at a poling state vary with positions, since the poling treatment is also carried out with interdigital electrodes, i.e., its dielectric constant, piezoelectric constant, and elastic constant vary significantly with positions. In this analysis, the distributions of these constants in various positions were considered by using the dependence of the poling electric field obtained experimentally, and they are not averaged. The results of the analysis agree well with the experimental values. The characteristics of two configurations were compared: a piezoelectric longitudinal coupling with electrodes set rectangularly to the direction of vibrations; and piezoelectric transverse coupling with electrodes set in parallel to it.
Two‐dimensional interpolative DPCM
Authors: Handa Shiro , Tanaka Hatsukazu 
Published: July 2007

AbstractDifferential PCM (DPCM) has often been used for encoding of images, but its efficiency is very poor at low transmission rates. Discussion of DPCM is based on an autoregressive (AR) model which is causal in the case of raster scan sampling. However, originally, images do not satisfy causality in this sense, and a better description of the two‐dimensional image information can be obtained by an interpolative model representing the relations between neighboring pixels. This paper proposes a two‐dimensional interpolative DPCM which is based on such a model. This method has the following special feature: if the output samples of a DPCM process based on a causal AR model are regarded as intermediate decoded values, then the final decoded values are yielded by a filtering process based on an interpolative model. The results of simulation using actual images demonstrate SN ratio improvement at a low bit rate (1 bit/pel) and also the stability of encoding characteristics in the case of quantitative step‐size variations. It is shown that fixing of the prediction and interpolation coefficients results only in slight deterioration.
Design of two‐stage cascade FIR digital filters with coefficients of limited word‐length
Authors: Imai Satoshi , Fukuda Yutaka 
Published: July 2007

AbstractIt is shown that the two‐stage cascade construction is very effective in the realization of a digital filter with a sufficiently large attenuation in the stop‐band. A design method for the two‐stage cascade FIR filter with limited word‐length is described. Compared with the direct construction, the word‐length of the filter coefficient in the two‐stage cascade FIR filter is reduced to less than 60 percent. In general, compared with the direct construction, the word‐length of the filter coefficient is reduced in the cascade construction, while the order is increased. However, in the proposed method, the order of the two‐stage cascade construction need not be very large, compared with the case of direct construction, being 1.5 times in the worst case. By imposing less strict limitation on the word‐length of the filter coefficient, the order of the two‐stage cascade construction FIR filter never exceeds 4/3 times that of the direct‐type FIR filter. In the realization of a linear‐phase, two‐stage cascade FIR filter, lower‐order minimum‐ and maximum‐phase filters than the linear‐phase filter can be applied as subfilters. This is effective in further reducing the order of the two‐stage cascade FIR filter, thereby reducing the order to 0.8 to 0.9 times the case of the construction based on the linear‐phase subfilter.
Variable‐length‐code‐selective reversible predictive coding for multilevel images
Authors: Taniguchi Takayuki , Kamikura Kazuto , Itoh Susumu , Utsunomiya Toshio 
Published: July 2007

AbstractTo construct efficiently an image database system for high‐tone images, a variable‐length, code‐selective reversible predictive coding scheme with a high‐compression ratio is proposed. This coding scheme is based on application of the quantizer‐selective method in the DPCM coding [11] (previously proposed by the present authors) to an adaptive selection of a variable‐length code. This is an adaptive coding scheme in which a suitable code is selected from the pre‐designed variable‐length codes for each pel. This code selection method requires no additional information, since the code selection is carried out based only on information of pels for which the coding has already been completed. The predesigned variable‐length codes and the threshold values for the code selection are determined by a model of the probability distribution of transformed prediction‐error signals. The initial setting of coding parameters is constant and independent of the image to be encoded. This scheme has, therefore, much generality that is independent of any kinds of images. The coding rate of this scheme is improved by about 0.3 to 0.5 bit/pel compared with the optimal nonadaptive coding scheme using a single Huffman code. It was confirmed that the proposed scheme has the highest coding efficiency compared with several conventional representative reversible coding schemes.
Performance of a viterbi decoder using simplified digital metric calculation
Authors: Miyake Makoto , Fujino Tadashi , Fujiwara Ken‐Ichi 
Published: July 2007

AbstractRecently, convolutional coding with Viterbi decoding has been used widely in digital satellite communication systems. This paper addresses the problem of simplifying the process of digital metric calculation in a Viterbi decoder to realize reduced hardware complexity and increased operating speed.An analytical expression is introduced for the bit error rate (BER) performance of such a Viterbi decoder, and effects of the simplifications are evaluated for a typical convolutional code. It is shown that measured data agree well with theoretical curves, and that the simplifications can be introduced with no significant performance degradation. Finally, a method is proposed to design Viterbi decoders so that the degree of soft decision is increased and the number of bits for branch metrics is reduced to a specified value using a nonlinear transformation. For a constant number of bits for branch metrics, the BER performance realized by the proposed design method can be superior to that realized by the conventional design method. Results in this paper would be useful in designing simple Viterbi decoders for high‐speed applications.
Highly reliable subscriber cable network construction
Authors: Yamamoto Hideo , Oikawa Hisao , Iwashita Motoi 
Published: July 2007

AbstractA cable network with high standards of reliability and cable usability is proposed. In a feeder cable system, Free Access Points (FAPs), in which all fibers can be cross‐connected, are set on each main feeder route; and loop cables are installed between adjacent FAPs. Using the cut‐set concept of graph theory, the relation between link addition and reliability improvement is shown and network constitution patterns for high reliability are shown. From the viewpoint of network availability, the optimum FAP location is determined to be the point which is about half the subscriber area radius from the center office. Finally, through the simulation of user demand increase it is shown that the proposed constitution system can improve the cable use efficiency more than the conventional individual cable distribution system. Thus, the high reliability as well as the high flexibility of the proposed system is shown.
Operational characteristics of a bistable laser‐diode memory for optical switching networks
Authors: Habara Keishi 
Published: July 2007

AbstractTo realize a high‐speed time division optical switching network, optical bistability devices including optical memory are important. In this paper, a bistable laser‐diode memory made of an APD, an LD and an optical feedback circuit is studied from the point of low set power and high speed. To attain a low set power, the effect of spontaneous emission of an LD cannot be neglected. Therefore, the input and output characteristics of an optical memory are studied including the spontaneous emission coefficient. Next, the response speed at a low input power is studied and the relationship between the response speed and the optical memory design parameters is derived. The input‐output characteristics and the response speed are verified with an experimental circuit. Finally, a high‐speed optical memory with a low set power is fabricated. The results of operating experiments of optical memories in an optical switching network are described.
A transform coding for compression of offset‐sampled image data
Authors: Sawami Hideo , Morikawa Yoshitaka , Hamada Hiroshi 
Published: July 2007

AbstractThis paper derives a transform coding method for offset‐sampled image data. The method is based on the idea that the usual discrete‐cosine transform (DCT) as well as the symmetrical cosine transform (SCT) are regarded as discrete Fourier transforms for the signal sequences obtained by forming mirror images of the given signal sequence. The derived transform is composed of DCT and SCT, which have one‐half transform length of the ordinary square lattice DCT.Using the proposed method which corresponds to the DCT with the block size of 8 lines × 8 pixels, the number of multiplications required in the transform is reduced drastically to approximately one‐fourth. The coding efficiency between the proposed method and the DCT is compared by a computer simulation, and it is shown that the proposed method has a higher coding efficiency. Especially, the following advantage should be noted.The slope of the proposed method in the linear part of the rate‐SNR characteristic is steeper than the DCT (the slope of the proposed method is 1/0.64 of DCT) for the forementioned block size, resulting in a more remarkable improvement of the coding efficiency for higher rate coding. This improvement is the result of the gain due to sample reduction of a factor 2 per image area, and the loss due to the duplicate block partitioning.
A priority control method of burst multiplexing network with the feedback of delay quality
Authors: Su Jing , Sakai Yoshinori 
Published: July 2007

AbstractIn multimedia communication, where media data with various requirements for the delay quality are transmitted through the multinode network, it is desirable to apply a priority control method according to the nature of the media. This paper proposes a new priority control method whereby the delay quality of each medium is evaluated by the fuzzy satisfaction, and the priority is adjusted through the feedback of the delay quality. The performance of the system is examined by a simulation.In the proposed system, the delay time is observed for each origination/destination pair at the destination node, and the fuzzy satisfaction of the delay quality is determined. The average satisfaction of the whole system is determined. Then the priority is renewed according to the difference between the satisfaction for each origination/destination pair and the average satisfaction of the system. It is shown that by the proposed method, the delay quality of the whole system is made almost uniform.
Design and performance of a repeater for CSMA/CD passive optical star network connection
Authors: Hakamata Yoshiro , Oguchi Kimio , Tokura Nobuyuki 
Published: July 2007

AbstractOne method to expand a network is to employ repeaters operating at layer 1. When networks using the optical passive star coupler are connected through repeaters with only a relaying function, there arises the problem of “self‐collision.” This problem occurs when the packet returned from the optical star coupler connected to the destination network is relayed unconditionally by the repeater to the originating network.As a means to avoid the self‐collision, the authors have proposed a repeater with wavelength‐division multiplex technique and gate control [1]. Through the design of the wavelength filter, it is shown that a satisfactory performance is obtained [3]. This paper shows further the results of studies, from the functional viewpoint, for the transmission design of the repeater, the control method for the gate, and the relaying method for the code rule violation. The repeater is built into a system constructed experimentally for the star configured optical transmission system with the transmission rate of 32 Mbit/s. The result of measurement of the transmission performance and the functional operation are described. The design for the repeater, which is applicable to the connection of the passive star network, is now described clearly.
Performance evaluation of radio link control protocol using stop‐and‐wait arq in mobile radio systems
Authors: Hiroike Akira , Matsumoto Tadashi 
Published: July 2007

AbstractIn land mobile data transmission, the error control by FEC and ARQ generally is employed to improve the reliability of transmission. In the control signal transmission for the radio link control in the mobile communication system, the error usually is detected by FEC, and the reliability is improved by ARQ. Under the condition of motion velocity of 40 to 50 km/h and the tolerable transmission delay of several seconds, the transmission characteristics of ARQ depend greatly on the short‐term median variation of the received level of the retransmitted signal, together with the packet signal transmission characteristics under the instantaneous received level variation due to fading. No evaluation has been presented for the transmission characteristics of ARQ considering such a median variation.This paper considers the stop‐and‐wait (SAW) ARQ where the number of retransmissions is limited to a finite value, and presents an evaluation of the transmission characteristics considering the correlation of the short‐term median variation of the retransmitted signal. Numerical examples are presented. Assuming that SAW‐ARQ is applied to the transmission protocol of the common control channel, the blocking probability is examined, together with numerical examples.
Revenue maximization control of a communication network by the use of hierarchical fuzzy system
Authors: Tanaka Yoshiaki , Miyakoshi Katsuyuki , Akiyama Minoru 
Published: July 2007

AbstractThe call‐wise control of a communication network, such as dynamic routing, is a very complex problem, although the extent of difficulty depends on the control target. Especially, the optimization of a communication network in a multiservice environment contains the difficulty of the choice of the state variables. The analytical method is limited in handling such a problem.This paper discusses the application of the fuzzy system by extending the range of search for the optimal solution for the communication network control from the analytic single expression to the description by the combination of several rules. The usefulness of the idea is demonstrated by a simulation. Then aiming at the full utilization of the descriptive power of the fuzzy system, the modularization of the control system corresponding to network installations, as well as the hierarchical structure corresponding to the data abstract level, is proposed. Further, this paper considers the revenue maximization control of the communication network as an example, and the usefulness of the hierarchical fuzzy system is demonstrated through a simulation. By applying the proposed method, it is made possible to cope with a range of problems not previously handled by the analytical method.