bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of narrowband FM receiver with delay‐flat IF filter for mobile radio communication
Authors: Shimizu Isao 
Published: July 2007

AbstractThis paper discusses the design of the IF filter for the mobile communication receiver, realizing narrowband and low‐distortion FM transmission characteristics. In the traditional mobile communication system with 25‐kHz channel spacing, a Chebyshev IF filter with a steep stop‐band roll‐off has been employed to prevent interference from adjacent channels. If the same design is applied to the narrowband mobile communication system with 12.5‐kHz channel spacing, the linear distortion due to the IF filter increases the demodulation distortion. First, this paper derives the expressions for the demodulation distortion and the adjacent channel selectivity in the narrowband FM transmission system, using the TBT filter as the model for the receiver. Then, based on the result, the condition for the narrowband IF receiver filter is derived to realize the low distortion and the required adjacent channel selectivity. Finally, a receiver was constructed experimentally on the breadboard, and it was verified that the theory and measurement are in good agreement.
Traffic analysis for token ring systems with limited service
Authors: Kimura George , Takahashi Yoshitaka 
Published: July 2007

AbstractThe token ring system is one of the typical LAN systems. In LAN, several kinds of traffic with different properties occur in bursts. The analysis has not been made for the case where the calls arrive in batch following the general distribution (GIx input). In the actual system, the buffer capacity is finite, and the analysis must consider such a property. This paper considers the asymmetric (i.e., the arrival process and the service time distribution are different for different stations) and single‐limitation (i.e., when the token arrives, only the first call is served) GIx/G/ 1 token system (where the suffix [X] indicates the batch arrival). The first half of the paper discusses the case where the buffer capacity of the station is infinite. The diffusion approximation is proposed using the elementary return as the boundary condition, and the quantitative expressions are given for the call distribution and mean waiting time for each station. The second half of the paper discusses the case where the buffer capacity in each station is finite. By combining the diffusion approximation used in the first half and the iteration, the blocking probability and the mean waiting time are derived quantitatively. For each case, simulation was made with the result indicating that the proposed approximation is reasonable.
Degradation of antenna pattern by snow accretion on radome
Authors: Shimba Minoru , Sato Kazuhiro , Koike Hiroo , Sato Takashi 
Published: July 2007

AbstractSheet radomes are used sometimes to prevent the degradation of antenna characteristics during snowfalls at simple Earth stations for satellite communication. If the snow accretion over the radome is uniform, the antenna has only a slightly lower level of signal reception. However, if the snow accretion over the radome is not uniform, there may be a large attenuation. In this paper we clarified the mechanism of the degraded antenna pattern due to a nonuniform accretion of snow over the radome. In the worst case, the antenna pattern is changed greatly and we showed that there was up to 40‐dB attenuation along the boresight of the antenna. We measured the process of changing the antenna pattern as the snow accretion changed with the passage of time. We clarified these processes.
Characteristic analysis of continuous‐service‐type multipacket transmission with restriction on number of packets in a frame
Authors: Komatsu Masaharu 
Published: July 2007

AbstractMultipacket transmission can achieve higher transmission efficiency because many packets are inserted into a frame and per‐packet overhead is small. However, in practice, too many packets cannot be inserted into a frame and too long a frame has higher probability of error. Therefore, the number of packets in a frame must be restricted. This paper analyzes the continuous‐service‐type multipacket transmission with restriction on the number of packets in a frame. Also, the distribution for the number of transmission waiting packets is derived along with the number of packets in buffer, z‐transform of the distribution for the number of packets in a frame, transmission efficiency, average queue length, and average packet delay time. From numerical examples, we examine the influence of the restriction on these performance measures.
Packet‐switched network design with constraints on the circuit discreteness
Authors: Kamimura Kunio 
Published: July 2007

AbstractThe packet‐switched network design problem can be formulated as a capacity and flow assignment problem (CFAP). The CFAP of an elementary network consisting of one tandem switch (TS) and n local switches (LSs) has been analyzed, and economical configurations shown in previous papers. This paper extends the study to include cases in which there are constraints on circuit discreteness. A large‐scale network usually employs a hierarchical structure with elementary networks used as structural units. In addition, the most economical structure of an elementary network in a hierarchical network is ascertained.The first assumption is that circuit speed is restricted to a predetermined discrete number (multiple of unit speed), and either one or no circuit can be installed per link. When the elementary network represents the entire small‐scaled network, economical regions of star, mesh and combined star/mesh are complicated. This is because effective traffic packing to a discrete capacity circuit sometimes yields more economical network configurations. When the elementary network is a structural unit in a large‐scale network, star occupies most of the economical region because a tandem circuit is always installed for carrying external traffic. The second assumption is that circuit speed is fixed. If a number of circuits can take real numbers, combined star/mesh is always the minimum cost topology in which internal traffic is assigned to the direct circuit, and external traffic through a tandem switch is assigned to the tandem circuit. When the number of circuits is a natural number, it is more economical in some cases to assign some part of the traffic to a tandem circuit because of the integrity of the number of circuits.
Design of audiographic teleconferencing terminal
Authors: Kotera Hiroshi , Sakai Yoshinori , Unemoto Kazuo , Arikawa Tomohiko , Tutt Timothy 
Published: July 2007

AbstractThis paper considers the design and experimental result of an audiographic teleconferencing terminal which applies document and telewriting as media for teleconferences via 64 kbit/s transmission lines, in addition to voice. For an effective teleconference, it is desirable that the terminal realize common visual space and have a paperless facility. First, this paper shows that distributed memory allocation is appropriate to the file configuration and proposes a document retrieval method which uses visual information. Also input/output function and display function suitable for teleconferencing terminals are discussed. Next, human interface which is suitable for teleconferencing terminals is discussed, and a key design pattern and its operational characteristics are shown. Finally, the experimental result of a fabricated prototype is shown.
Performance evaluation for spread‐spectrum multiple‐access communication systems
Authors: Nishida Takeshi , Miyahara Hideo 
Published: July 2007

AbstractThe performance of the spread‐spectrum multiple‐access communication system is analyzed assuming that channel access from each terminal (station) is random. By distinguishing the retransmission traffic load from the freshly originating traffic load, a more accurate formula for message delay can be derived. By comparing the performance between this communication system and the FDMA, this system is shown to have higher usage efficiency of the channel bandwidth. Moreover, the processing gain optimizing the system performance is obtained as the function of the mean offered load. Using this fact, we consider the group random access scheme where all terminals are grouped according to their utilization forms if possible. Then each group uses the separate channel whose bandwidth is determined in accordance with the offered load, and its performance is evaluated.
Analysis of DC‐DC converter using voltage‐resonant switching mode
Authors: Onodera Toshihiro , Masuda Youichi 
Published: July 2007

AbstractThe frequency of switching dc‐dc converters has become higher when their size and weight must be reduced. When a higher frequency is chosen, some related phenomena become problems. These include the increase of the transition loss of the switching, the increase of magnetic energy in leakage inductances of a transformer, and high‐frequency noises. These problems can be solved at the same time by utilizing the resonance‐arc of the switching mode. Notably, a mode in which the applied switching voltage becomes the resonance‐arc is suitable for an increase of the frequency.This paper analyzes a dc‐dc converter, based on the concept of a class‐E power amplifier which is useful for solving the three forementioned problems. The design of the converter and its characteristics which are useful for understanding the behavior of the converter, are also given. As an inherent characteristic of the resonant switching mode, there is a period in which a part of the energy stored in the resonance circuit returns to its input. By using the duty ratio of the switch in this period, the switching characteristics, such as the transition of a mode and the input/output voltage ratio, were found.
Scattering of electromagnetic plane wave by an infinite plane grating on a dielectric slab for oblique incidence
Authors: Noda Takeaki , Uchida Kazunori , Matsunaga Toshiaki 
Published: July 2007

AbstractIn this paper, the problem of scattering for an obliquely incident electromagnetic wave by a planar grating on a dielectric slab has been analyzed accurately by the method in which the sampling theorem is applied to the Fourier transform. First, by means of the unknown surface current on the planar grating, the Fourier‐transformed functions of the scattered field are given analytically. Next, this current is expanded in terms of weighted Fourier series so that its Fourier transform is given. Finally, the sampling theorem is applied for the purpose of discretization to the relationship for the perfect conductor condition expressed in the Fourier transform domain so that simultaneous equations for the unknown expansion coefficients of the surface current are obtained. By means of the numerical calculations, accuracy of the method is confirmed and the numerical values are given for the transmitted and reflected powers and the surface current.
An image data compression method using extrapolative prediction‐discrete sine transform; in the case of two‐dimensional coding
Authors: Yamane Nobumoto , Morikawa Yoshitaka , Hamada Hiroshi 
Published: July 2007

AbstractThis paper considers the highly efficient coding of the gray‐level image. The extrapolative prediction‐discrete sine transform scheme, which was previously proposed by the authors for the case of one‐dimensional coding, is extended to the case of two‐dimensional coding. In the proposed method, the image is partitioned into square blocks. The correlations among blocks are eliminated by applying the two‐dimensional extrapolative prediction for each block from the restored boundary pixel. The correla‐in the block is eliminated by applying the orthogonal transformation to the prediction errors. In this paper, the correlation function of the image is assumed as the isotropic exponential function, and a two‐dimensional extrapolative prediction method is derived, which can be realized as a simple manipulation. The transformation of the prediction errors is performed by the variable‐separation type two‐dimensional extrapolative prediction‐discrete sine transform, where the one‐dimensional extrapolative prediction‐discrete sine transform is applied to rows and columns. Then the rate‐distortion characteristic is calculated, indicating that the proposed method is useful. It is shown that the proposed method with 4 × 4 block size has almost the same coding efficiency as the discrete cosine transform coding with 16 × 16 block size. A computer simulation was made for the actual image, leading to a result validating the theoretical estimation. The proposed method requires less computation per pixel, compared with the discrete cosine transform coding. The method is especially useful from the viewpoint of hardware implementation, since the block size is as small as 1/16.
Low temperature optical loss‐increase for optical fibers in compound‐filled cable splice closure
Authors: Sasaki Jun 
Published: July 2007

AbstractTo completely protect optical fibers from external water and chemicals, the development of compound‐filled cable splice closure was planned. To this end, the optical loss mechanism at low temperatures in an optical fiber placed in a compound such as epoxy or polyurethane has been investigated. In this paper, as the optical loss generating source in an optical fiber in a compound‐filled cable splice closure at a low temperature, the conventional bucking model of the fiber in a fiber jacket and a new bucking model of the entire jacketed fiber in the compound are considered. It is demonstrated that a phenomenon corresponding to either model appears depending on the kind of compound or jacketed fiber configuration. Next, an experimental equation is derived which shows the relationship between the optical loss and the average rate of curvature of a bucked and sinusoidally bent GI fiber. The optical loss in a GI fiber placed in a compound at a low temperature was estimated and compared with the experimental results. It is found that the experimental and theoretical values agree well even if the compound and the jacketed fiber are replaced. This implies that the two models are valid. Quantitative understanding of the optical loss after bucking is now possible.
Analysis of demand‐assignment schemes with adaptive reservation on bus‐type LANs for integrated communications
Authors: Tokinaga Shozo 
Published: July 2007

AbstractIn the demand assignment scheme on a bust‐type LAN for the integrated communications, the priority using the transmission reservation information is introduced and adaptive channel capacity allocation algorithm is proposed. Data traffic to be transmitted is classified into class 1 (voice), class 2 (data), and class 3 (file). In the usual transmission, higher priority is assigned to class r with smaller r, but in the case where the waiting time of the packet in buffer grows more than a threshold, then the class lower than r obtains a higher priority, instantaneously. As a result, while maintaining the voice packet discard rate below a certain threshold, the excessive delay of the other data traffic can be avoided. This paper proposes adaptive packet transmission prioritization algorithms for each of the four basic DAMA systems–RAM, ADAM, TPAM, and SDAM–and evaluates their performance by numerical calculation. It is shown that by adaptive prioritization excessive waiting time for data and file packets are avoided for the channel speed around 1 Mbit/s.
Improvement on singular value decomposition vector quantization
Authors: Saito Takahiro , Komatsu Takashi , Harashima Hiroshi 
Published: July 2007

AbstractFor high‐efficiency image compression, previously, an SVD (singular value decomposition)‐based coder was developed using vector quantization, called SVD‐VQ. This paper proposes an improved quantization SVD‐VQ scheme. For every input subblock, the SVD‐VQ coder scalar‐quantizes a singular value and vector‐quantizes two singular vectors, separately. The SVD‐VQ decoder reproduces a subblock as the product of these quantization outputs, but does not necessarily produce a reconstruction with the minimum distortion in an image space. This paper develops a quantization scheme where the minimum‐distortion reconstruction is always provided in the original image space and presents its design algorithm. The improved SVD‐VQ shows A/N performance improvement of 0.5 ‐ 1.0 dB over the conventional SVD‐VQ, and is similar in performance to the adaptive DCT (discrete cosine transform) coder.
Evaluations on the common application protocols in osi
Authors: Shiroshita Teruji , Nomura Masayuki 
Published: July 2007

AbstractFor the OSI message exchange protocol, the MHS (message handling system) was recommended in 1984 by CCITT. The implementation of this protocol is being considered by network service enterprises and computer manufacturers in various countries. MHS is constructed as an application of OSI common application protocol. ROS (remote operations service) and RTS (reliable transfer service), specified by MHS, and performing the acknowledgement of send/receive of application data and the interruption/recovery, can also be used in common with other applications of OSI. This paper presents an analysis and evaluation of ROS and RTS from the viewpoint of the number of transmitted/received packets and the transfer time. The relation between the window size and the transfer efficiency in RTS is derived. For the system combining ROS and RTS, the method for controlling the window size corresponding to the response time, as well as the method for setting the session data length corresponding to the interruption rate, are presented. As to the method of combining ROS and RTS, it is shown that a large amount of application data can be transferred in a stable way, even if the interruption rate is large, by applying RTS to ROS.
Experimental studies on fading reduction by four‐direction antenna pattern diversity reception with variable multithreshold switching strategy
Authors: Takeuchi Tsutomu , Ikegami Fumio , Yoshida Susumu 
Published: July 2007

AbstractAn antenna pattern diversity reception system was constructed experimentally as a means to cope with multipath fading in mobile communication, where the four‐direction antenna is used as the diversity branches, which themselves have the fading reduction effect. The variable threshold switching method is employed as the output scheme from the diversity branches. The switching algorithm for the four‐branch multithreshold reception is discussed. From the computer simulation based on the actually measured fading data, the optimal values for the parameters of the branch switching control algorithm are determined.A field experiment is made using the experimental system, and it is verified that the short‐term fading is improved in the actual multipath environment with the value close to the theoretical value, for the selection switching by four receivers using uncorrelated branches with Rayleigh distribution.
Circuit simulation analysis of power dissipation in the main switch of a forward converter
Authors: Yamasaki Mikio , Murakami Naoki 
Published: July 2007

AbstractOptimum conditions for the on‐resistance and output capacitance of a power MOSFET used as the main switching element of a single‐ended forward converter are derived by circuit simulation. In the simulation, a device model of the power MOSFET suitable for analysis of a switching power supply is introduced, enabling analysis of the factors contributing to generation of main switch loss. First, the simulation clarifies that the power considered to become a loss in the conventional concept is partly recovered. A new evaluation method is proposed for the main switching loss, taking this phenomenon into account. Next, the main switch loss is analyzed by using as an independent variable the on‐resistance or the output capacitance, which have high device sensitivity to the main switch loss. The results are shown by an equi‐loss diagram. Finally, this diagram is used to derive the optimum on‐resistance and output capacitance with the largest CR product to make fabrication easiest within the allowable main switch loss.
Medical data transmission using mobile satellite communication
Authors: Murakami Hajime , Shimizu Koichi , Yamamoto Katsuyuki , Mikami Tomohisa , Hoshimiya Nozomu , Kondo Kimio 
Published: July 2007

AbstractA “mobile telemedicine” is attempted where the mobile satellite communication and remote medicine are applied. This study aims at improving emergency care in a ship on the ocean or in an aircraft flying an international route. The problem has several special points which differ from the usual data communication or telemedicine. These points must be overcome to realize the system.This paper presents first the analysis, investigation and design for mobile telemedicine, and indicates its feasibility. Based on these results an experimental transmission system is constructed. The fundamental transmission characteristics are measured through the satellite link. By the measurement, the threshold of operation for this system for deteriorated C/N0 is determined, and it is verified that even an experimental system can realize a reliability which is sufficient in practice. Then a transmission experiment is made from a ship navigating close to the shore of Japan, and the basic operation as the mobile telemedicine is verified.
Delay performances of tandem stop‐and‐wait arq scheme
Authors: Sugimachi Nobuyuki , Hayashida Yukuo , Yoshida Yoshinori 
Published: July 2007

AbstractThis paper considers the stop‐and‐wait ARQ scheme, which is the most fundamental error control method. The scheme is applied to the satellite tandem communication system composed of two links, and the average transmission delay is investigated.First, the tandem system with relay retransmission buffer with a finite capacity is considered, and the generating function for the transmission delay is derived. Using the obtained result, the effect of the buffer size of the relay node and the round‐trip propagation delay on the average transmission delay is investigated. It is shown as a result that the tandem‐type stop‐and‐wait ARQ scheme is better also in terms of the average transmission delay than the standard scheme without the relay‐retransmission buffer. The delay improving factor (the ratio of the average transmission delay to the average transmission delay providing the limit of the improvement with the infinite buffer size) is defined. A design principle is proposed for the buffer size, where not only the throughput but also the average transmission delay are considered.
Triplate‐type planar antenna and its array
Authors: Haneishi Misao , Matsui Akinori , Nakayama Masao , Saito Sakuyoshi 
Published: July 2007

AbstractA new type of electromagnetically coupled planar antenna made of a shielded triplate transmission line is studied and its design method is investigated. To this end: (1) studies are made on the radiation characteristics of the present planar antenna which are important when it is used as an array element. It is found that this planar antenna is sufficiently available as a linearly and circularly polarized array element. (2) The radiation characteristics are studied theoretically and experimentally for the array made of linearly polarized planar antenna elements. It is proven that this type of antenna system can be a useful form for a new type of linearly polarized array. (3) A method of configuration is studied for a circularly polarized array made of this type of planar antenna element. An antenna system is realized which has a broadband characteristic with about 5 percent bandwidth for the axial ratio of less than 3 dB.