bluuebunny/crossref_metadata_2025_split huggingface dataset:
Introduction of interleaving in packet voice communications
Authors: Matsuo Naoki , Yuito Mitsuhiro , Tokunaga Yukio 
Published: July 2007

AbstractIntroduction of an interleaving method in packet voice communications, called packet interleaving, is proposed as a means to reduce speech quality deterioration caused by packet losses.This interleaving method and methods of substituting for missing samples, are evaluated by subjective tests. The results show that the packet interleaving can reduce speech quality degradation significantly if the values of samples which are missing are replaced with the mean values of their adjacent samples.
Single‐mode fiber transmission using edge‐emitting led for broadband subscriber loops
Authors: Ohtuka Tomoyuki , Yamashita Haruo , Yamaguchi Kazuo , Naitou Hidetoshi , Kondou Ryuichi 
Published: July 2007

AbstractThe edge‐emitting LED, which is less expensive and more reliable than the laser diode, is studied for use in the broadband subscriber loop in combination with a single‐mode fiber. In comparison to the conventional surface‐emitting LED, the present device has a better efficiency in coupling with a single‐mode fiber and has a narrower emission spectrum. In this paper, a method of simple time domain calculation is proposed for the S/N ratio taking into account the wavelength dependence on the dispersion and loss of the fiber, the emission spectrum profile of the edge‐emitting LED, and the pulse response speed. The validity of the computation method and the high‐speed modulation characteristics of the edge‐emitting LED are confirmed through the optical transmission experiment of 600 Mbit/s and 20 km with a simple waveform compensation circuit. Further, the temperature characteristic of the edge‐emitting LED is studied since it is important in the application to a practical system. A method for temperature compensation is investigated. Finally, based on these studies, the maximum transmission distance is studied in which the temperature variations of the optical output, center emission wavelength and the spectral width as well as the device fluctuation are considered. It is shown that the present edge‐emitting LED is capable of an application to broadband ISDN and optical CATV subscriber loops.
Communication protocol for vehicle packet‐communication system using continuously allocated small zones
Authors: Sakai Sei‐Ichirou , Takaba Sadao 
Published: July 2007

AbstractA new vehicle communication system is proposed to realize an excellent movement control of vehicles on highways. In this system, small communication zones of about 10 m long are allocated continuously along the road, and every vehicle in the zone transmits and receives digital data through the same signal communication channel using the TDM.In the communication protocol for this system, data packets are divided into small blocks to reduce wasted data to vehicles leaving the zone. A new concept of using information concerning vehicle movement for channel accessing is introduced. When a vehicle leaves a zone, the next zone to which the vehicle arrives is found from this information. Then exclusive trigger pulses are generated in the next zone which effectively receives request signals from the vehicle. Performance of the protocol is analyzed by computer simulation. Reliable connections were achieved without losing high throughputs.
Traffic congestion control based on call density control
Authors: Tokunaga Hiroshi , Kawano Hiromichi 
Published: July 2007

AbstractAs a means to control traffic congestion in the communication system, it is most effective to control the traffic directed toward the congested switch, at the input of the network. From such a viewpoint, a method is employed in which a constant rate of traffic is controlled at the originating switch, according to the state of the switch congestion. However, the congestion recently observed frequently in ticket reservation and in other cases is difficult to be controlled completely by this method. From such a viewpoint, this paper proposes a control method based on the combination of the following two schemes: (1) the call number distribution, where the number of calls which can be processed in the congested switch is allocated individually to the originating switches; and (2) the call density control, where the number of connected calls (output call attempts) per unit time is controlled to within the specified value at the originating switch. The characteristics of the output call attempts at the originating switch are analyzed for the call density control. It is shown that the mean number of output call attempts is close to the ideal, but the variation coefficient of the output call attempts is somewhat large compared with the traditional call gap control. An extended call density control is proposed, where the number of output call attempts is adjusted in each time interval according to the state of connection, and it is shown that the mean number of output call attempts is close to the ideal. By employing the proposed scheme, the normal traffic can be secured, even if the control is started before the congestion arises, and the peak can be reduced when there is a sudden increase in originating calls.
Timing extraction and carrier estimation for PSK signal block demodulation system
Authors: Higashida Yasushi , Hagiwara Masafumi , Nakagawa Masao 
Published: July 2007

AbstractIn recent years, block demodulation systems have been proposed which store blocks of phase‐shift keying (PSK) signal and derive data by batch processing. In such systems the traditional method of realtime demodulation is not considered and block processing is applied after quasicoherent demodulation. Training signals required for traditional methods are not at all needed for this system. Therefore, the data transmission efficiency becomes very high. However, conventional block demodulators have a serious disadvantage–they cannot demodulate the signal without external timing information. This paper proposes a new timing extraction circuit not contained in a conventional block demodulator, which improves greatly practical applicability. Also, a method is proposed for accurate carrier estimation. According to computer simulation results, the permissible noise limit becomes 4 to 5 dB lower in comparison to the conventional method.
Radiation characteristics of cutoff‐waveguide applicators for hyperthermia
Authors: Sen Atsurou , Morita Nagayoshi , Kumagai Nobuaki 
Published: July 2007

AbstractThis paper is a detailed theoretical study of the basic radiation characteristics of a cutoff‐waveguide aperture antenna excited by a post when it is used as a hyperthermia applicator for heating tumors located deep inside the human body. The effect of the wave reflected from the body on the radiation characteristics is considered by an approximate evaluation of the reflected wave from a semi‐infinite lossy medium with electrical constants equivalent to those of a muscle placed in front of the antenna aperture. In the analysis, an equivalent problem is considered in which the aperture is closed by a conductor and unknown magnetic current sources are placed on both sides of this conductor. The integral equation derived from the continuity condition of the tangential magnetic field components at the aperture is solved by Galerkin's method. Extensive numerical data are presented for the relationship of the radiation power and the input impedance to the location of the lossy medium and the dimensions of various parts of the waveguide applicator. It is found that although the radiation power is generally larger if the distance between the lossy medium and the aperture is smaller, for a certain distance the radiation power can be smaller than the case without a lossy medium. It is also found that if the location of the excitation post is distanced somewhat from the aperture, the imaginary part of the input impedance is not affected by the location of the lossy medium.
Service choice behavior modeling of telecommunication users
Authors: Yamamoto Hisao , Inoue Akiya 
Published: July 2007

AbstractWith the open use of the communication activities and the diversified applications of services with various functions, a tendency to utilize the communication network in various ways and for various purposes is observed. There is an increasing need to realize network management based on the prediction technique for the communication activities of the user. This paper proposes a modeling for the choice behavior of communication services by applying the disaggregate behavioral model used in the field of urban engineering as a means of estimating commuter demand. The possibility of application to the communication network management is demonstrated. First, the decision‐making factors to be considered in the model are classified and then the general construction procedure for the model is presented. The qualitative and subjective decision‐making factors are represented numerically using the cardinal scaling based on paired comparisons, and are then used as factors of the model. Assuming a communication service providing 28 kinds of information data concerned with daily life activities, a model construction experiment was made. An examination is made based on actual survey data regarding user intention. It is shown that an excellent performance is obtained in the prediction of service choice, learning based on accumulated data, and the evaluation of service functions. Based on the realized performance, the application of the model to the management and operation of the communication network is discussed.
Application of the boundary‐element method to an infinitely long tunnel
Authors: Sakai Koichi , Koshiba Masanori 
Published: July 2007

AbstractA hollow waveguide or a tunnel made of a lossy dielectric material such as concrete is presumed. A method of analyzing the wave propagation inside the tunnel by the boundary‐element method is formulated. When the boundary‐element method is applied to an infinitely long tunnel or a tunnel containing a bend or a branch, it is necessary to truncate the tunnel at a finite length. In addition, an analytical matching condition similar to the one for a lossless metal waveguide must be provided at the fictitious boundary. In this paper, a tunnel with a surface impedance approximation as the boundary condition on the lossy dielectric wall (so‐called impedance tunnel) is considered. First, an analytical solution is derived for a uniform impedance tunnel. Next, a method is proposed in which the analytical solution and the boundary‐element method are coupled on the forementioned hypothetical boundary. The algorithm is described in detail. For a straight tunnel, it is confirmed that the results agree well with those by the Fourier integral even when the imaginary part of the relative permittivity is small. Problems of finding electromagnetic fields inside a semi‐infinite tunnel excited by a line current source or an infinitely long tunnel with an aperture are studied. It is pointed out that the present method is extremely useful for a hollow waveguide consisting of a lossy dielectric medium such as concrete. The difference from the case of a lossless metal waveguide is investigated.
Throughput analysis of adaptive ARQ schemes
Authors: Ishibashi Yutaka , Iwabuchi Akira 
Published: July 2007

AbstractMany ARQ error control schemes have been proposed in data transmission, including go‐back‐N and selective‐repeat schemes. In those schemes, most of the parameters affecting performance, such as the number of continuously transmitted data blocks and the data block length, are fixed. Consequently, the performance may be greatly degraded when there is a time‐variation in the bit‐error rate or when the bit‐error rate is difficult to estimate. This paper proposes a control scheme wherein the number of continuously transmitted data blocks and the data block length are adapted dynamically to the bit‐error rate. The throughput of the proposed scheme is analyzed for go‐back‐N and selective‐repeat schemes using the half‐duplex channel. The evaluations for the go‐back‐N and the selective‐repeat schemes are obtained as special cases of the result of analysis. The effects of various parameters on performance are discussed and the performances of various schemes are compared. The results show that the proposed scheme based on the adaptive control has a performance which is very close to the scheme with a fixed number of continuously transmitted data blocks and fixed data block length, where those parameters are set optimally in a static way.
A study of bit error model on digital subscriber transmission
Authors: Wataya Hideo 
Published: July 2007

AbstractIn digital transmission through a metallic subscriber line, burst bit errors are produced due to impulsive noise and other causes. It is important to investigate the actual properties of those bit errors. This paper presents the result of long‐term measurements using various kinds of cores concerning the bit error gap length in the time‐compression multiplex directional control transmission system. It is shown that the bit error rate can be characterized by three gap length ranges. A model is proposed which can represent accurately the features of those distribution patterns of gap length through a simple formulation. The model is compared with the actual characteristics, and the usefulness of the model is demonstrated. As an application of the model, several evaluation measures for the transmission quality (such as bit error rate and errored seconds) are discussed, and it is shown that a more detailed quality specification than in the past (the evaluation in a short‐term observation for 100 ms, for example) can be realized, based on the estimated distribution.
64 kbit/s video coding equipment using adaptive tree‐search vector quantization
Authors: Watanabe Hiroshi , Hoshino Ryohei , Kuroda Hideo , Hashimoto Hideo 
Published: July 2007

AbstractThis paper proposes a high‐efficiency coding algorithm realization of a 64 kbit/s video coding equipment. A prototype equipment constructed shows a high quality performance for video conferencing and videophones. For high efficiency coding for video conferencing a coding algorithm combined with motion‐compensated interframe prediction and the orthogonal transform coding or vector quantization is usually employed. It is known theoretically that the latter has an excellent characteristic which approaches the rate‐distortion bound. However, another coding system is desired which not only has a high coding efficiency, but a small‐scale hardware and easy control of information generation. This paper proposes an adaptive tree‐search vector quantization in which the size of a code book can be varied according to the local property of an image. The improvement of the coding efficiency due to this idea is demonstrated by a computer simulation compared with a conventional system with a fixed size code book. A 64 kbit/s video‐coding system having the resolution of 384 (horizontal) × 240 (vertical) pixels per frame was constructed. Using the coding system with the proposed algorithm, a temporal resolution of 5 to 7.5 frames/s was obtained, confirming the satisfactory results for practical applications such as video conferencing and videophones.
Performance of the multisampling digital tanlock loop and its extension
Authors: Hagiwara Masafumi , Nakagawa Masao 
Published: July 2007

AbstractOne kind of digital PLL (DPLL), i.e., nonuniform sampling DPLLs, can control the sampling intervals. As a result, they can be used for timing extraction circuits and carrier extraction circuits in PCM and PSK systems, etc. The present authors have already proposed a new nonuniform sampling DPLL, the multisampling digital tanlock loop (MSDTL), which can handle more than two samples in each time period of the input sinusoid. The MSDTL can satisfy the sampling theorem because of the multisampling scheme. Therefore, a system with the MSDTL can easily utilize higher digital signal processing technologies. However, the performances of the MSDTL have not been reported yet. This paper presents detailed analyses of the MSDTL and shows its superior performances. In addition, the range (phase detection characteristic) extended MSDTL (RE‐MSDTL) is proposed.
A coding control algorithm for motion picture coding accomplishing optimal assignment of coding distortion to time and space domains
Authors: Kato Yoichi , Mukawa Naoki , Okubo Sakae 
Published: July 2007

AbstractIn high‐efficient motion picture coding such as systems to compress moving image information below several 100 kbit/s, some visible spatial and temporal distortions are unavoidable. The spatial distortion is perceived by humans as a spatial degradation or noise on the image. On the other hand, the temporal distortion, which is caused by frame dropping, occurs as unnaturalness of motions in the processed image sequence. Here, spatial and temporal distortions are in a trade‐off relationship. Finding the visually best point from this trade‐off is a key feature of good codecs. This paper describes a newly developed coding control algorithm aimed at keeping spatial and temporal distortions in a good balance. In the algorithm, the trade‐off relationship is calculated first from generated information amount vs. the SNR characteristics of the current input frame. Next, an optimal distribution is determined from the viewpoint of human perception. Finally, a coding parameter set is chosen for realizing the distribution and reproduces visually good images. This paper shows the principal of the coding control algorithm and describes an application of the algorithm to an MC‐DCT coding system and simulation results.
Passive telemetry using radar reflectors with controllable reflectivity
Authors: Hasebe Nozomu , Hanabusa Mikio , Kaneita Akihiro , Takahashi Yoshihiro 
Published: July 2007

AbstractA radar reflector with controllable reflectivity has been proposed by one of the present authors. This reflector is capable of electrically controlling its radar cross section. By using this reflector as a target, information including an identification code at a reflector site can be sent to a radar site by the modulation of reflected echoes. Thus, we can build up a passive telemetry system consisting of radar, the reflectors and a demodulator device.Since the reflector is a passive device, it does not interfere with other communication systems. Furthermore, the system at the reflector site uses little power because it has no transmitter. Experiments on the ground and on the sea have been conducted successfully.This paper presents a method of acquiring data in the case of a rotating radar antenna, transmission codes which eliminated the inverting effect of the reflection on the sea, and a type of demodulation process. The evaluated result of this system from outdoor experiments is also presented.The reflector was put into practical use as a traffic monitoring system and tested over a long period. From the experimental results it was discovered that the demodulation method using automatic threshold selection based on the probability distribution was the most successful. Hence, from the foregoing, we are able to conclude that the system using the radar reflector with controllable reflectivity is useful in passive telemetry.
Characteristics of a planar inverted‐F antenna on a rectangular conducting body
Authors: Sato Kazuo , Matsumoto Kazuhiro , Fujimoto Kyohei , Hirasawa Kazuhiro 
Published: July 2007

AbstractCharacteristics of a planar inverted‐F antenna attached to a rectangular conducting body are analyzed. The rectangular conducting body is modeled by wire grids and the moment method is applied so that the impedance characteristics and the radiation patterns are obtained. They are compared with the measured data. The element values are found for the equivalent circuit using a parallel resonance circuit seen from the feedpoint impedance and the antenna Q is found. The relationship between the relative bandwidth and the variation of the equivalent circuit parameter vs. the dimensions of the rectangular conducting body is investigated. Variations of the current distributions on the body and the radiation pattern are studied.
Experimental studies and improvements on the accuracy of the indoor random field measurement method for obtaining the radiation efficiency of electrically small antennas
Authors: Maeda Tadahiko , Morooka Tasuku 
Published: July 2007

AbstractThe indoor random field measurement (RFM) method is useful for measuring the radiation efficiency of a small built‐in antenna operating in the vicinity of electric gear and the human body. In this paper we report on the first experimental check of the accuracy of the indoor RFM method. We introduce the DDD value as a figure of merit for the measurement site. A new method of using radiowave scatterers is also proposed to improve the accuracy of the measurement. We find that the new indoor RFM method is effective for measuring the radiation efficiency of a small antenna.
Analysis and design methods of planar array antennas with slotted waveguides taking into account mutual coupling
Authors: Konishi Yoshihiko , Mizutamari Hitoshi , Sato Shin‐Ichi , Mano Seiji , Katagi Takashi 
Published: July 2007

AbstractThis paper described analysis and design methods for planar array antennas with slotted waveguides consisting of shunt slots as antenna elements which are cut on the wider surface of a rectangular waveguide. A matrix was shown for the mutual coupling among shunt slots. Also, another matrix was used relating the input and output waves at the array feeder point and the input and output waves between the shunt slots and free space. Through these two matrices the input reflection characteristics and excitation distribution of the array considering the mutual coupling of the total array with the feeder system could easily be obtained. Utilizing the variation of the mutual coupling among the shunt slots when sizes and displacements of the shunt slots from the guide axis were varied to be small, a simple algorithm with fast convergence was presented. Through experimental measurements the validity and effectiveness of the present analysis and design methods were confirmed.
Image restoration for complementary subsampling system
Authors: Tanimoto Masayuki , Yamada Akio 
Published: July 2007

AbstractWhen the sampling points of an image are divided into two complementary subsampling points, an image with low resolution is restored from one set of subsampling points, and the image with full resolution can be restored using both sets of subsampling points. In such a complementary subsampling system, either of the two restored images contains aliasing distortion. This paper discusses the restoration of subsampled values, in which the high‐frequency components are lost due to the prefiltering. A method is presented in which the subsampled value is restored by utilizing the other complementary subsampled values, which preserves the highfrequency components as the aliased components. The condition for the restoration by the proposed method is described. Based on the derived properties, a new complementary subsampling system is proposed. This new system can restore without distortion both the image with low resolution and the image with high resolution simultaneously. The usefulness of the method is verified by experiment. The method is useful in the realization of the HDTV system, which contains a high compatibility to the present TV system.