bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adaptive karhunen‐loeve transform coding and its design method
Authors: Ohzeki Kazuo 
Published: July 2007

AbstractSpecific models have been conventionally used to switch between various Karhunen‐Loève (KL) transform matrices to adapt to local characteristics of nonstationary images. Here, the superior characteristic of the KL transform (mean square error minimization) is extended over all parts of the design process as an evaluation criterion. Further, by using actual images as training data, a design process is established that reflects the nature of real images. In order to compare the adaptive matrix‐switching KL transform coding method with previous simple discrete cosine transform (DCT) coding methods, a transform is proposed that does not cause mean value separation. the effectiveness of this type of adaptive transform is determined by computer simulation. Also, since the resulting coding characteristics do not depend on the training images, it is estimated that the construction of a system that includes common nonstationary characteristics has been achieved. Examination of intermediate steps of this design process show that, in fact, all generated eigenvalues are practically positive and the stability of the design process is guaranteed.
Rate control strategies for high‐priority data in two‐layer packet video transmission
Authors: Kawashima Masahisa , Inoue Masahiro , Tominaga Hideyoshi 
Published: July 2007

AbstractTo transmit the video image with the two‐layer transmission by utilizing the priority cell control of the ATM network, the required bandwidth varies depending on the rate control scheme for the high‐priority information. Therefore, several high‐priority rate control schemes can be considered such as the scheme in which the ratio of the high‐priority bit rate to the entire bit rate is kept constant or the scheme in which the peak rate is specified for the high‐priority information. Therefore, for these two schemes, the optimum layering parameters will be derived in order to keep the minimum bandwidth requirements and to compare the bandwidth requirements by using the optimum layering parameters. As the result of the comparison, it was concluded that the peak rate control is superior when the number of multiplexed video sources (terminals) in the network is low and when the bandwidth requirements for the low‐priority information is not strict. It was concluded also that the scheme to keep the ratio of the high‐priority information fixed is superior when the number of multiplexed video sources in the network is high and when the bandwidth requirements for the low‐priority information is strict.
Single‐reflector‐type wide beam‐spacing multibeam antennas
Authors: Naito Izuru , Makino Shigeru , Furuno Takayoshi , Katagi Takashi 
Published: July 2007

AbstractJapanese commercial communications satellites (CSs), which are 50 to 60 degrees from the Japanese broadcasting satellite (BS), have begun direct broadcasting service. Simultaneous reception of broadcasting from CSs and BS requires a multibeam antenna with wide beam‐spacing. an optimum reflector for a single‐reflector‐type wide beamspacing multibeam antenna is presented on the basis of wave aberration analysis of defocus‐fed reflector without restrictions on reflector symmetry and feed displacement amount.
A spread spectrum cordless telephone
Authors: Tanaka Kiyoshi 
Published: July 2007

AbstractThe United States industrial, scientific, and medical (ISM) band has been released for spread spectrum communication, and various applications for it are being proposed. A spread spectrum cordless telephone set has been developed for domestic use as one of its applications.In this paper, the design outline and its characteristics are explained. the direct sequence spread spectrum technique with spreading ratio of 16 in the 902‐ to 928‐ MHz ISM band is used. to solve the near‐far problem in the mobile radio communication channel, the frequency division multiple access‐time division duplex (FDMA TDD) technique is adopted where different frequencies can be assigned to each channel. Compact size and low power consumption is achieved by developing a chip in which spread spectrum processing and transceiver multi plexing can be handled on a single ASIC chip.The voice codec uses ADPCM and provides better voice quality compared to the conventional analog cordless phones. Wider talking range compared to the conventional 46/49 MHz cordless phone is obtained by increasing the amount of transmitted power. Moreover, since the ISM band is used, interference from other sources can be avoided by changing the channel frequencies.
Source‐radiation field analysis in scalar waves‐ electromagnetic scattering in conducting circular cylinder
Authors: Tokumaru Shinobu , Ohgake Ken‐Ichi 
Published: July 2007

AbstractTo enlarge the range of applications of integral equation methods in wave fields, a new source‐radiation field analysis is proposed. In this method, in addition to the conventional Huygens integral representation deriving the radiation field from the source, the Huygens‐Fresoel integral representation deriving the source from the source and the radiation field by means of the conjugate Green's function is added. These two integral equations are solved simultaneously for the source and the radiation field. the source‐radiation field solutions in the scalar waves are formulated. As the simplest example to demonstrate the effectiveness of this method, electromagnetic plane wave scattering by a perfectly conducting circular cylinder is solved.
Errors and correction factors for schelkunoff's shielding effectiveness formula
Authors: Nagao Hiroshi , Nishikata Atsuhiro , Shimizu Yasutaka 
Published: July 2007

AbstractThis paper presents the error of the resistive film approximation and that of Schelkunoff's equation with respect to the rigorous solution. Both of these approximate equations cause errors for the planar shield for which either an infinitesimal electric dipole or an infinitesimal magnetic dipole is the source. Hence, the four types of planar shield with different directions and types of dipole source are investigated.Next, the conditions for causing the error is studied. When Schelkunoff's equation and the resistive film approximation are rewritten, they become functions of three dimensionless parameters. However, the numerical analysis reveals that only two error‐causing parameters are sufficient if the choice is carefully made. With these two parameters, the correction factors are derived with which the rigorous value is obtained from Schelkunoff's equation or the resistive film approximation. the rigor ous solution is a complicated equation including integral calculation. On the other hand, Schelkunoff's equation is relatively simple. If this correction value is used, a solution equivalent to the rigorous solution can be obtained from Schelkunoff's equation or even simpler resistive film approximation.
Performance of differential parallel combinatory spread spectrum communication systems
Authors: Sasaki Shigenobu , Kikuchi Hisakazu , Zhu Jinkang , Marubayashi Gen 
Published: July 2007

AbstractThis paper proposes differential parallel combinatory spread spectrum (DPC/SS) communication systems; one of the parallel combinatory spread spectrum (SS) communication systems the authors have been studying so far. the parallel combinatory SS system is a spectral efficient SS system in which the system transforms sever al bits of data into a combination of pseudonoise (PN) sequence with modulation of positive and negative signs and transmits them.The proposed DPC/SS system applies differential encoding to the positive or negative sign modulation of the PN sequences, and then they are transmitted. In the receiver, the combination of a transmitted sequence set is estimated by noncoherent detection and the coded sign is demodulated by differential detection. Thus, the receiver does not need to regenerate the phase of the carrier frequency. the proposed systems will be applicable to a mobile cellular system in which a large phase variation interferes with the communications.This paper evaluates the error performances. of the DPC/SS systems in additive white Gaussian noise (AWGN) channels and frequency‐nonselective, slowly Rayleigh fading channels. It also evaluates the effect of diversity in the Rayleigh fading channels.In the AWGN channel, the DPC/SS system is superior by I dB to the differential phase‐shift keying (DPSK) system and to the BPSK system in terms of required signal‐to‐noise ratio at 10‐8 bit error rate (BER) at the same spectral efficiency. In the Rayleigh fading channel, diversity reception in the DPC/SS system gains more improvement in the BER performance, as the number of branches increases, than that obtained in a direct‐sequence spread spectrum system with DPSK.
A signal design method for block‐coded modulation in multipath fading channel
Authors: Okada Minoru , Hara Shinsuke , Morinaga Norihiko 
Published: July 2007

AbstractThis paper considers the block‐coded modulation system in the multipath fading environment and derives the upper bound expression for the bit error rate considering the effects of the interleaving size and the space diversity. Then a signal design is proposed. Here, the set of signals minimizing the upper bound expression is sought using the quasi‐Newton method, which is known as an iterative solution method for the nonlinear progrmming problem. the bit error rate for the signal sequence derived by the proposed signal design is evaluated by a computer simulation, and the effectiveness of the proposed signal design is demonstrated.
Noise augmentation and signal‐to‐noise ratio degradation in in‐line amplifier systems due to the nonlinear refractive index of optical fibers
Authors: Saito Shigeru , Naka Akira 
Published: July 2007

AbstractOptical noise enhanced by the nonlinear refractive index of optical fibers is one of the major factors limiting the system performance of in‐line amplifier transmission. This paper derives an analytical expression of noise enhancement taking into account group‐velocity dispersion of optical fibers. Evolution of the in‐phase and quadrature‐phase noise field components is expressed by a simple matrix describing the transmission characteristics of optical noise through the basic section composed of an optical amplifier and a transmission fiber. This enables minute investigation of noise evolution in in‐line amplifier systems; approximate characteristics can be learned as well. A noise increase proportional to the third power of a number of amplifiers is verified in the normal dispersion regime while an exponentially rising noise peak is found in the anomalous dispersion regime.Based on these results, signal‐to‐noise ratios at the receiver and allowable transmission distances are discussed in terms of the dispersion parameter and the amplifier number. From the noise evolution point of view, the longest transmission distance is achieved in the normal dispersion regime.
A new method of designing telecommunications networks using time‐series traffic data
Authors: Matsumoto Kimihide , Nojo Satoshi 
Published: July 2007

AbstractTelecommunications networks are designed and managed based on statistical traffic data including basic traffic obtained at peak traffic hours. Network links are also designed based on the basic traffic. the network is designed so that the quality of services (network blocking) is at a certain level when basic traffic is applied to the network and the network is managed so that quality of services is maintained for the basic traffic. This conventional method is universal and simple because the required data for design and management are very small. On the other hand, recent telecommunication systems have the ability to measure and collect detailed traffic data.This paper proposes a new network design method in which time‐series traffic data rather than statistical traffic data is used for network design. Combining the time‐series traffic data and the tariff data for each hour, we can design a network based on total revenue. Unlike the conventional method, the proposed method makes it possible to estimate revenues, costs, and damages. Using time‐series traffic data obtained for every hour of the year, a method is devised that optimizes the number of circuits (i.e., for optimizing network blocking) and thus maximizes profits. This paper also presents a new methodology for traffic data and a new network structure that effectively uses the proposed method.
Design of an asymmetric parabolic cylinder antenna with high aperture efficiency
Authors: Asai Kikuo , Kojima Masayoshi , Misawa Hiroaki , Ishida Yoshio , Maruyama Kazuo , Yoshimi Naohiko , Wakasa Masaaki , Karakida Masue 
Published: July 2007

AbstractWith respect to the asymmetric cylindrical parabola antenna constructed for radio astronomical observation at 327 MHz, the design method and the verification of the design values are reported. The present antenna placed emphasis on the improvement of the receiving sensitivity and is designed to increase the aperture efficiency as much as possible.To carry out an optimum design of the primary feed made of a dipole array with a corner reflector, the structural parameters of the primary feed have been studied. It was found that there exist optimum values. The reduction of the efficiency due to the transmission loss and the phase error loss of the reflector surface made of stainless wires was derived. The overall aperture efficiency was estimated to be 75.9 percent. In an actually constructed antenna, the aperture efficiency measured with a celestial radio source as the standard radio source was 71 ± 5 percent. It was confirmed that the aperture efficiency derived from the computation and the optimum design values are reasonable.
Path planning for low‐altitude flight by fuzzy reasoning
Authors: Nomoto Kohei , Kameda Hiroshi , Mano Seiji , Tachibana Yasuo 
Published: July 2007

AbstractThis paper discusses flight‐path planning for an aircraft flying at low altitude while avoiding terrain crashes. In a past study, several algorithms based on exploratory procedures have been proposed; however, they do not generate practical paths that take into account aircraft inertia. This paper proposes a new algorithm to generate a flight path taking account of the aircraft's inertia; this algorithm does not generate the flight path directly, but determines the aircraft's steering acceleration at every point along the way and then generates the flight path based on the steering acceleration. This algorithm extracts feature parameters representing a relation between the aircraft and the terrain, determines steering acceleration by fuzzy reasoning using the feature parameters, and updates state variables of the aircraft. Furthermore, this paper also proposes a learning algorithm to design the membership values in the fuzzy reasoning from reference flights since it is difficult to optimize them by trial and error. The flight‐path planning by the proposed algorithm is compared with that based on the exploratory procedure. The learning algorithm of the membership values is validated through computer simulations.
Moving target detection by quadrature mirror filter
Authors: Ehara Naoki , Sasase Iwao , Mori Shinsaku 
Published: July 2007

AbstractFor pulse radars, coherent moving target indication processes and discrete Fourier transform‐based Doppler filter banks are used to separate moving targets from stationary objects and clutter. These processes utilize the Doppler frequency shift of the moving target. Because the moving target indication processes and Doppler filter bank processes are performed with the pulse repetition period as a unit, several pulses are required to obtain output from the filter bank. If the search radar considered here uses an electronically scanned antenna, the fact that several pulses are required for one steered beam means that search capability is limited (e.g., the searchable region is narrowed). A method is proposed here that uses the quadrature mirror filter with a range cell as the process unit for the Doppler filter process for high‐speed target Doppler separation to reduce the number of pulses required for each beam. The quadrature mirror filter is a filter that performs the orthogonal wavelet transform. This original signal can be separated without wasting information in the time‐frequency domain. Long transmitted pulses are used in computer simulations to show that the number of pulses needed in the Doppler filter bank can be reduced using this method.
A study on introduction of power spectrum density model for field merged signal and its analysis
Authors: Shishikui Yoshiaki 
Published: July 2007

AbstractThis paper describes a theoretical model of the power spectrum density (PSD) for a field‐merged frame signal and compares the efficiency between the field‐based coding and frame‐based coding which uses the fieldmerged signal. The field‐merged signal has also been used recently as an input signal to the spatial coding process for the coding of interlaced‐scanned television signals. However, the nature of PSD, which is an important basis for high‐efficiency coding, is not sufficiently understood in the area of field‐merged signal. For instance, optimality of the conventional techniques applied to the field‐merged signal is not assured. A theoretical PSD model for the field‐merged signal has been introduced and its properties have been clarified in relation to the motion of the image. The performance of frame based‐coding is calculated using this model.
Radar clutter suppression using notch filter bank in multibeam radar
Authors: Kondo Michimasa , Fujisaka Takahiko , Iwamoto Masafumi , Okada Takamitsu , Tachibana Yasuo 
Published: July 2007

AbstractA new clutter suppression method is proposed for a multibeam radar with which the profile of the input signal can be estimated with a statistically high accuracy. In this method, the suppression filter is selected adaptively from the discrete notch filter bank on the basis of the estimated clutter bandwidth. As the selection method, the concept of selection probability linked to the bandwidth estimation accuracy is introduced so that the selection algorithm is derived. To evaluate the performance of the system based on this algorithm, the conventional improvement factor is improved by defining the performance function taking into consideration the filter selection probability and the desired detection probability. Based on these factors, a configuration example of a notch filter bank is presented for the model radar.The system performance is evaluated by the figure of merit (FOM) defined here. The results obtained are: (1) there exists an optimum maximizing the FOM in the clutter bandwidth estimation accuracy and the filter distribution spacing; and (2) if the estimation accuracy is increased in response to the distribution spacing of the filter bank, the FOM is improved as the distribution spacing is reduced.
Performance of an asynchronous transfer mode local area network switch with backpressure function‐maximum throughput analysis
Authors: Ohsaki Hiroyuki , Wakamiya Naoki , Murata Masayuki , Miyahara Hideo 
Published: July 2007

AbstractAs an effective traffic control mechanism of the asynchronous transfer mode (ATM) local area network (LAN) which has been getting attention as the next‐generation high‐speed LAN, the reactive congestion control is considered. In this paper, to obtain such a traffic control mechanism, a scheme to add the function of backpressure to an ATM switch having buffers in both the input side and the output side is evaluated. Also in this paper, the maximum throughput of an ATM switch with backpressure function for burst traffic is analyzed mathematically. Further, a uniform traffic load and a mixture of such traffic occupying the bandwidth in a peak rate as voice and video are analyzed. Moreover, with some numerical data examples, the effect of the output buffer size and the burstiness of the arriving traffic on the system performance is analyzed.
Analysis of characteristics of a cross‐product frequency discriminator in four‐phase‐shift keying systems
Authors: Osuga Katsumi , Miyauchi Kazuhiro 
Published: July 2007

AbstractCharacteristics of a cross‐product frequency discriminator and the responses of an automatic frequency control (AFC) closed loop using the discriminator are analyzed theoretically in this paper for practical four‐phase‐shift keying (4PSK) transmission systems that have band‐limiting filters in their transmitters and receivers. The general expressions for the characteristics and the responses are derived when these filters are assumed to have arbitrary characteristics and three types of 4PSK, i.e., QPSK, offset QPSK, and π/4‐shift QPSK, are assumed.The expression for a deterministic component and the autocorrelation functions for random components are obtained first in the case of an open loop. Those results then are used to obtain the power spectral densities, and the expression for variance of frequency fluctuation is shown. The variance is used to calculate frequency jitter in an AFC closed loop.The variance of frequency fluctuation consists of three components. The components yielded from a product of noise and noise and a product of noise and signal are independent of the modulations. The component from a product of signal and signal, on the other hand, depends on the modulations. The components for quadra‐phase‐shift keying (QPSK) and for π/4‐shift QPSK are equal, but the component for offset QPSK is larger than that for the others.
Characteristics of mobile communication traffic in a two‐way band‐shaped service area
Authors: Kabasawa Tatsuya , Sengoku Masakazu 
Published: July 2007

AbstractIn a cellular mobile communication system, a service area is divided into many cells for efficient use of channels. It is necessary to take into consideration intercell vehicle movement for teletraffic performance evaluation of such cellular mobile communication systems. Its performance evaluation has been done for a one‐dimensional band‐shaped area, e.g., a highway, assuming that vehicle movement is one way.This paper presents a theoretical performance evaluation of a one‐dimensional band‐shaped area, assuming two‐way vehicle movement. First, whether steady‐state performance for the traffic offered to each cell is constant is analyzed and then the transient characteristic for the case in which traffic varies with time is analyzed. Through a comparison of theoretical and simulation results, the validity of the theoretical result is demonstrated.
Fundamental characteristics of multiple‐access schemes for satellite communication networks
Authors: Onozato Yoshikuni , Saito Miki , Teruya Ken 
Published: July 2007

AbstractIn multiple‐access schemes for digital satellite communication, a collective arrangement is needed in which all the uncoordinated users may share a single satellite channel. The slotted ALOHA scheme is basically a random access scheme where the time axis is slotted and each earth station transmits packets at random.In this paper, the stability issues of the slotted ALOHA scheme and its useful limits are discussed first. This gives the useful range of a basic type of random access scheme. Next, the instance conflict scheme is explained where multiple access according to the demands of various users is possible. This scheme can satisfy the basic requirements of the satellite channel according to the demand of various users.