bluuebunny/crossref_metadata_2025_split huggingface dataset:
A method of designing communication service specifications using message sequence charts
Authors: Mizuno Osamu , Niitsu Yoshihiro 
Published: July 2007

AbstractA new specification design method for describing communication services is developed. This method describes service specifications in sequence charts and provides a user‐friendly man‐machine interface and specification conversion function. Applying this method to actual specification design showed that: (1) services such as call waiting or teleconference, normally impossible to represent with sequence charts, can now be described; and (2) the amount of specification description (the number of elements in sequence characters plus data required for specification conversion) for services frequently repeating the same signal elements is less than 30 percent of the number of steps in the corresponding service software. For services in which signal elements are not greatly repeated, this amount is still less than 40 percent of the number of steps if 20 percent of the signals can be shared between services.
A bit error and cell loss compensation method for atm transport systems
Authors: Iwase Ryoichi , Obara Hitoshi 
Published: July 2007

AbstractA bit error correction and cell loss recovery method is proposed to provide high‐quality virtual paths in an asynchronous transfer mode (ATM) transport system. This method arranges the cells into a two‐dimensional array and performs error correction coding along both dimensions of the array. The error correction code applied in the horizontal direction corrects bit errors and detects lost cell positions. The error correction code applied in the vertical direction restores lost cells. This compensation method requires no processing at the intermediate nodes of the transport system but can be performed after reception of the coded array at the virtual path terminating nodes. Performance estimates are given for this compensation method. It is shown that when a BCH code is used for the horizontal code and a (15, 14) parity code is used for the vertical code on one‐tenth of the virtual paths, then improvements of approximately seven and ten orders of magnitude are achieved in cell loss and bit error rates, respectively. In this case, the communication efficiency is reduced by 10 percent on those paths that employ error correction coding.
A method of protecting high‐priority packets in video packet transmission
Authors: Sakai Yoshinori , Yamamoto Satoru 
Published: July 2007

AbstractA method for protecting priority packets is proposed, and its effectiveness is confirmed. This method can be used with video packet transmission schemes for packetized video image signals that have been encoded using redundancy compression encoding. In general, during video packet transmission, the significant parts are transmitted as high‐priority packets. Between each originating and terminating node in the proposed method, a number of copy paths exist together with the main path. A copy packet of the high‐priority packet is generated by the originating node, and this copy packet is transmitted with low priority over a copy path. As a result, even when a sudden increase of packet information causes congestion on the main path, the copy packet arrives correctly at the terminating node. Since the copy packets have a low priority level, these packets also have little effect on the data on other paths. The results of analysis and computer simulation of this method clearly show a decrease in the transmission delay and in the probability of packet loss due to sudden increases in data.
Communication status analysis method
Authors: Watanabe Ichiro 
Published: July 2007

AbstractTo eliminate the effect to the line in the transfer of the optical fiber cable when the line is not used, i.e., when the communication is not conducted. To achieve the transfer during the noncommunication state, there must be a system that can discriminate the communication status of the line. To realize such a system, a principle must be established for discrimination as well as a design based on the characteristics of the transmission equipment.This paper discusses the method of discriminating the communication and noncommunication status, using the most general coded mark inversion (CMI) code as the code to be propagated in the optical subscriber line. First, properties of the code that are generated in the communication and noncommunication states are discussed. It is shown to be most effective to use the ratio of the average powers of the line spectrum at 1/THz and the signal light as the discrimination data, whereT[s] is the period of the transmitted information. Then the design method is shown based on the actual transmission equipment.Finally, the result of evaluation is presented for the experimentally constructed communication/noncommunication discrimination equipment. It is shown that the correct discrimination is achieved down to the minimum ‐41 dBm of the average signal optical power, propagating in the optical fiber; and the proposed method is well applied to the actual transmission equipment.
Picture degradation caused by motion detection disagreement on MUSE encoder/decoder
Authors: Gohshi Seiichi , Izumi Yoshinori , Ninomiya Yuichi 
Published: July 2007

AbstractIn the multiple sub‐Nyquist sampling encoding (MUSE) system, stationary areas and moving areas of an image are processed differently from each other. These two processings are switched in accordance with the motion detection pixel by pixel. Since this motion detection is carried out independently on the encoder and the decoder, motion detection disagreement may occur between them [“motion detection disagreement”] due to transmission channel noise or particular image patterns.In this paper, the degradation of picture quality caused by the forementioned motion detection disagreement is analyzed. The analysis has made it clear that decoding an image which was encoded as a static image would generate picture degradation accompanied by flicker. However, when a static input image which was encoded as a moving image is decoded as a static image, the decoded image would only generate resolution degradation in its stationary areas but it would not produce any picture degradation through aliasing.This analysis conforms with the results of tests using the MUSE encoder and decoder. Thus, a prototype of a simplified encoder equipped with only a moving image processing was made. This prototype was combined with a MUSE decoder and images of good quality were obtained. The simplified encoder resolution in the stationary areas is somewhat inferior to that of conventional encoders. However, since it helps to reduce the machinery size by a third, or even smaller than that of conventional MUSE encoder, it may be used in consumer Hi‐Vision cameras if most of its devices are replaced with LSIs.
Optimum design of yagi‐uda antenna for millimeter‐wave imaging
Authors: Uehara Kazuhiro , Nishimura Hiroshi , Yonekura Takeshi , Natsume Ken‐Ichiro , Mizuno Koji 
Published: July 2007

AbstractA millimeter‐wave imaging array is proposed in which many Yagi‐Uda antennas are placed on a dielectric lens. By changing the dimensions of these antennas, the impedance matching with the detector is optimized. At the same time, a radiation pattern matched to the incident beam from the focusing optics is realized. The crosstalk between the adjacent detectors on the array is measured. An optimum spacing is derived and a good imaging property is realized. The present imaging array is suitable for MMIC and is applied in practice for plasma measurement for nuclear fusion research.
Jitter reduction for asynchronous network application of synchronous digital hierarchy
Authors: Rokugo Yoshinori , Yoshida Norio 
Published: July 2007

AbstractThe synchronous digital hierarchy (SDH) architecture has been recommended by C.C.I.T.T. to establish a synchronous digital network. Although the network is inherently synchronous, it must also accommodate conventional asynchronous mode applications. In the asynchronous mode applications, tributary signals are transported using the frame transfer technique which is performed by AU or TU pointer adjustment at each network entity. At the final network entity stage, however, these tributary signals are regenerated with strong low‐frequency phase jitter, which might cause substantial transmission quality degradation.This paper describes the operation of the AU frame transport system employing pointer adjustment. Next, jitter caused by pointer adjustment and subsequent signal degradation are analyzed. Then a new method of suppressing the jitter to an allowable level is proposed. This jitter is caused by a frequency difference in reference clocks used in pointer generating and pointer adjustment operations. Therefore, this jitter can be suppressed theoretically by carrying out the demapping at the identical reference clock frequency used during the mapping process. The proposed method uses a frequency analyzer that directly calculates the moving average of the positive/negative justifications to regenerate the mapping frequency.
Long‐distance propagation in a stratified atmosphere with an even power n profile
Authors: Kawaguchi Yoshinari 
Published: July 2007

AbstractThe propagation characteristics of the radio wave were analyzed in a nonuniform atmosphere in which there exist an inverted layer with an even power profile of a height under a standard atmosphere and the lowest layer with a linear profile. If the modified index of refraction obtained by introduction of the earth‐flattening approximation has a 2n power profile of the height, the solution of the wave equation cannot be given by a closed form function. Hence, the rigorous solution was obtained by a series representation in accordance with the method by Frobenius. This series solution is found effective even if the wave equation has two turning points close to each other. The function value can be obtained within a time shorter than the one required for the numerical solution such as the one by the Runge‐Kutta method.By continuation of the analytic solutions for each atmospheric model layer, the wave function was derived and the received electric field at a far distance was obtained by the mode theory. It was found that the received electric field depends strongly on the order n of the 2n‐th power N profile as the atmospheric layer near the zero of the index of refraction slope is increased.
Multiple‐feedback‐loop synchronization control scheme for SS‐TDMA
Authors: Okada Kazuyasu , Kawai Makoto 
Published: July 2007

AbstractSatellite‐switched time‐division multiple access (SS‐TDMA) is investigated as a multiple‐connection scheme to be applied to the multibeam satellite communication system, aiming at a large‐capacity satellite link and small‐sized earth station equipment. When the traditional single‐feedback loop scheme controlling the frame/burst synchronization of traffic stations by a single reference earth station is applied to SS‐TDMA, however, problems arise when the number of traffic stations in the system is increased. In other words, the transmission capacity of the beam, including the reference station, is decreased drastically and a data burst region is produced where the access to a particular beam cannot be achieved even if there is an idle channel.To remedy this problem, this paper proposes the multiple‐feedback‐loop scheme, where the receive timing at the traffic station is synchronized to the reference station; but the burst synchronization is controlled by the synchronization control stations provided for each beam. The proposed scheme has the following advantages.(1) The transmission capacity of the beam including the reference station, which decreases drastically in the single‐feedback loop scheme, is maintained as the same as that of other beams.(2) Even if the number of beams is increased, the usage efficiency of the reference station beam is kept constant and the same frame structure can be applicable.(3) The data burst region in which the access becomes impossible between particular beams is not produced.(4) The frame/burst synchronization accuracy is the same as that of the traditional scheme.
A burst mode all‐digital high‐speed clock recovery circuit and block clock recovery scheme
Authors: Matsumoto Yoichi , Morikura Masahiro , Kato Shuzo 
Published: July 2007

AbstractThis paper is focused on an all‐digital implementation of the high‐speed burst mode demodulator for time‐division multiple access (TDMA) satellite communication. A clock recovery scheme in a preamble‐less burst recovery demodulator is considered which is an item of research and development in recent years.A burst clock recovery scheme is proposed which can be operated at a speed twice higher than the symbol rate. The deterioration due to the error in the clock phase estimation in the burst clock recovery scheme is regarded as a stochastic process, and the effect of the burst signal on the bit error rate is evaluated by the computer simulation.It is shown, as an example, that when the burst clock recovery scheme is applied to the TDMA satellite communication with a burst length of 800 symbols and transmission filter roll‐off factor of 0.4, the burst probability is 1 ± 10‐6 times/burst for the degradation of 0.2 dB of Eb/N0. In other words, the proposed system affects only slightly the burst loss probability required in the TDMA system.
Circularly polarized energy flux densities
Authors: Tokumaru Shinobu , Tanaka Rie 
Published: July 2007

AbstractAs one of the methods to understand electromagnetic wave propagation and radiation mechanism of antennas, it is useful to use streamlines of electromagnetic energy flux densities. However, the Poynting vector, as an electromagnetic energy flux density, does not include any information about polarization.In this paper, the circularly polarized energy flow is explained in light of the circularly polarized electromagnetic energy flux densities proposed recently. As the most fundamental example, fields of circularly polarized cross dipoles are drawn by using the circularly polarized electromagnetic energy flux densities. Then, radiation characteristics of circularly polarized antennas are explained by newly defined circularly polarized radiation efficiency and directivity. Moreover, the conventional delta source excitation model for linear antennas is unable to explain the circularly polarized wave radiation from a conical spiral antenna composed of thin conductor.
Overview of the theory of adaptive antennas
Authors: Takao Kazuaki 
Published: July 2007

AbstractThe problem of control methods as the basics of the adaptive antenna is discussed. First, the general concept of the guiding principle and control algorithm is introduced. Next, the relationships between the guiding principles and corresponding control algorithms are explained for the LMS method, H‐A method, DCMP method, and CMA method. With respect to the first three methods, the control characteristics of the optimization systems by the feedback based on the steepest descent method are analyzed. Several factors governing the convergence speed are pointed out. The use of several algorithms intended to improve the convergence characteristics, where they came from and where they will develop are discussed.
Noise theory of distributed optical amplifiers and its application to fiber amplifiers
Authors: Yamashita Shinji , Okoshi Takanori 
Published: July 2007

AbstractUsually, noise characteristics of optical amplifiers are described by the theory of Shimoda, Takahashi, and Towns (STT theory). This theory deals only with lumped amplifiers whose noise parameters are spatially uniform. However, it is not the case with fiber amplifiers.In this paper, first, a novel noise theory of three‐dimensionally distributed amplifiers based on the STT theory is presented and the fundamental equations for calculations of the gain and noise characteristics of a fiber amplifier and systems with fiber amplifiers are obtained. Next, this noise theory is applied to a practical fiber amplifier and an example of the gain and noise characteristics is shown. The backward propagated spontaneous emission is shown to degrade the noise characteristics severely, and the total noise characteristics are shown to be better at 1.553 μm than at 1.530 μm.Finally, a low erbium‐doped fiber system whose gain is balanced with the background loss of the system fiber is analyzed as the system optimizing the signal‐to‐noise ratio. Nearly ideal characteristics are shown to be realized in this system with the bi‐directional pumping.
Evaluation of end‐to‐end performance for data traffic in ATM networks
Authors: Baba Ken‐Ichi , Murata Masayuki , Miyahara Hideo 
Published: July 2007

AbstractWhen data traffic communications are serviced in ATM networks, a packet from the transmission source is divided into cells to be transmitted. Therefore, the assumption of the Poisson arrival of data packets used widely in the past is unreasonable and the bursty nature of data traffic must be considered. Furthermore, the end‐to‐end packet loss rate rather than the cell loss rate becomes more important in data traffic and retransmission due to packet loss must be considered in evaluating the packet transmission delay.In this paper, communications of data traffic in an ATM environment are considered by analyzing transmission of data traffic over a number of switching machines using a queueing network model allowing performance characteristics such as the end‐to‐end packet loss rate and the average delay of data traffic.
Adaptive carrier tracking (ACT) demodulation for QPSK mobile radio transmission
Authors: Saito Shigeki , Takami Tadao , Yamamoto Haruo 
Published: July 2007

AbstractA new QPSK demodulating scheme (adaptive carrier tracking (ACT)) enabling high‐speed carrier tracking has been developed for application to digital mobile communications demodulators. The ACT demodulating scheme, unlike the conventional detection tracking which extracts the carrier by averaging the phases, establishes the phase synchronization and frequency synchronization independently, without using phase‐averaging techniques. This method enables high‐speed tracking of the carrier phase, thereby improving demodulation characteristics of burst signals and demodulation characteristics under Rayleigh fading to the same degree as those of differential detection. In addition, by adopting the digital oscillator of the new scheme, frequency synchronization of a higher speed than coherent detection that allows avoidance of the false lock has been achieved.A new phase likelihood comparison (PLC) diversity comparing the accuracy of the data obtained from the signal reception phase has been developed, thereby improving the sensitivity and characteristics of detection with respect to co‐channel interference over those of conventional coherent detection and differential detection using the reception level comparison diversity. The ACT demodulation LSI with the diversity implemented by an entirely digital circuit yields good demodulating characteristics and a low power consumption of less than 9 mW, which corresponds to about 1/20 of the conventional differential detection circuit. The foregoing results confirm the practicability of the ACT demodulation method.
Region segmentation coding of color images based on uniform hvc color space
Authors: Horita Yuukou , Miyahara Makoto 
Published: July 2007

AbstractThere are two aspects to the region segmentation coding and the model‐based coding which extract and encode the structure and features from image information. They are the “technique for compression of image information” and the “technique for structural description of image information.” If the image information is described structurally, not only is the highly efficient coding realized but also a new image can be constructed by a local manipulation of the original image.This paper combines the region segmentation of the image based on Munsell color space and the region merge based on the hue difference between the regions. Then a new region segmentation coding based on the result of the forementioned region segmentation is proposed. It is assumed that an object consisting of the color image corresponds to a region of almost the same hue. The hue information within the region is coarse‐quantized based on the memory colors, and the shape information is coded using the chain code.For the value information which contains the information for the shape, shade, etc., of the object, the adaptive cosine transform coding is applied. For the chrome information, the region is approximated by a polynomial function and its coefficients are encoded. The proposed coding method is applied to several standard images which are portraits of relatively simple structures with different face sizes.The color information is transmitted with a relatively high efficiency, occupying approximately one‐fourth of all the transmitted information; and the usefulness of the region segmentation proposed in this paper is demonstrated. Compared to the traditional waveform coding, the method has the advantage that the local manipulation of the image is easier, although the total transmitted information is slightly larger.
An ultrahigh‐speed optical waveform measurement method based on optical sampling with sum‐frequency generation
Authors: Takara Hidehiko , Kawanishi Satoki , Yamabayashi Yoshiaki , Saruwataris Masatoshi 
Published: July 2007

AbstractTo realize a future high‐speed and ultralarge‐capacity optical transmission, it is indispensable to analyze the ultrahigh‐speed transmission characteristics of the entire system as well as functional circuits, devices and materials comprising the system. Evaluation of such a transmission characteristic requires ultrahigh‐speed optical waveform measurement method.In this paper, a new optical waveform measurement method called the sum frequency generation (SFG) optical sampling method is proposed. In this method, the SFG which is a second‐order nonlinear optical effect is used for all‐optically sampling the optical waveform to be measured (at the optical stage) by means of an ultrashort optical gate pulse. Hence, the bandwidth limitation of the optical receivers and the electronics can be eliminated.By means of this technique, accurate measurement without waveform distortions can be realized while high time resolution and high S/N ratios are maintained. In this paper, the theoretical performance of the present measurement technique is discussed and the measured results by the present method are presented.