bluuebunny/crossref_metadata_2025_split huggingface dataset:
An optimum design of alternative routing system with trunk‐reservation scheme
Authors: Akimaru Haruo , Katada Hironori , Okuda Takashi 
Published: July 2007

AbstractThe trunk‐reservation scheme is employed to specify the individual call loss in the alternative routing system. The numerical solution of the state equation and the simulation has been used traditionally for the optimum design of such a system. This paper presents the optimum (in the sense of the minimum cost) design of the alternative routing system with the trunk‐reservation scheme, using the approximate expression for the individual call loss and its derivatives. A method is presented also to obtain the optimum integer number of trunks. By an example, it is shown that the presented method of the optimum design can reduce the computation time drastically and provides a good approximation compared with the past methods by state equation or simulation.
Electromagnetic wave propagation in two‐dimensional impedance tunnels with modified multicross‐junctions
Authors: Matsunaga Toshiaki , Uchida Kazunori , Noda Takeaki 
Published: July 2007

AbstractAs a model for the electromagnetic wave propagation in a tunnel‐shaped structure with branches and bends such as an underground shopping center and a street lined with buildings, a two‐dimensional tunnel with modified multicross junctions is studied both theoretically and experimentally for wave propagation. The basis of the theoretical analysis is to neglect the higher‐order multiple scattering effect and to consider the field as the cascaded connection of the results of the modified single‐cross junction. As the boundary condition of the tunnel wall, the surface impedance approximation is employed. The present results can be applied to special tunnels made of cascaded connection of the modified cross, step and T. In the experiment, a microwave simulation is carried out for a tunnel model made of concrete. It is found that the numerical results of the electric field intensity in the tunnel agree well with the experimental results.
Distortion in analog transmission for subsampled picture signals
Authors: Liu Fu‐Sheng , Tanimoto Masayuki 
Published: July 2007

AbstractIn sampled‐value transmission such as TAT where pixel values are transmitted, the transmission characteristics must be equalized so that the transmission distortion caused by the interference between sampled values is reduced below the detectable limit or tolerable limit. This paper considers the situation where the image signal bandwidth compressed by subsampling is to be transmitted by baseband or VSB transmission.The analysis and computer simulation for the transmission distortion are presented. The relation of the maximum transmission distortion to the deviation of the frequency characteristics or the deviation of resampling timing of the transmission system is examined quantitatively. The detectable limit and the tolerable limit of the distortion, for the case where the distortion spreads by the interpolation, are determined by subjective experiment. Their relation to the compression ratio and interpolation scheme is examined.The following properties were obtained. The maximum distortions are nearly the same for the transmitted and interpolated pixels, independently of the bandwidth compression ratio and the scheme of compression. The detectable limit and the tolerable limit become smaller with the extent of compression, imposing more severe requirements on the transmission characteristics. The effect of the interpolation scheme is small.
Delay performances of tandem go‐back‐n arq scheme
Authors: Hayashida Yukuo , Sugimachi Nobuyuki , Yoshida Yoshinori 
Published: July 2007

AbstractThe performances (throughput and transmission delay) of the Go‐back‐N ARQ scheme are affected greatly by the bit error rate of the link and the round‐trip propagation delay. This paper discusses the transmission delay of the tandem Go‐back‐N scheme, in which the round‐trip propagation delay can substantially be reduced. First, the generating function for the transmission delay distribution is derived, and then the result is applied to derive the average transmission delay. As a result, it is shown clearly that the performance of the tandem Go‐back‐N ARQ scheme is better than that of the standard Go‐back‐N ARQ scheme.
Mode partition of high‐definition television signals using adaptive subsampling
Authors: Sakurai Naoya , Kishimoto Ryozo 
Published: July 2007

AbstractIn the analog transmission of high‐definition television signal using satellites, the transmission must be performed within a limited band. For this purpose, an adaptive subsampling system is proposed and is used in the highly efficient transmission of the high‐definition television signal. One of the important problems in the adaptive subsampling for improving the picture quality is to partition the picture into as many subsampling modes as possible in an efficient way.This paper proposes an adaptive subsampling system with four different subsampling modes. The four modes are composed of three modes for the moving part and one mode for the still part. Discussions are made on the partitioning of three modes in the moving part, and the partitioning between moving and still parts. In the mode partitioning in the moving part, a method (histogram method) is proposed where the distortion over the whole picture is reduced, based on the histogram derived from the distortion for each subsampling block to determine the subsampling mode partitioning.The proposed method is compared with the traditional method by computer simulation, and it is verified that the SN ratio is improved by the proposed method. As to the partitioning between moving and still parts, a control method for the motion detection threshold is proposed, which seeks a balance between the distortions of still and moving parts. The performance of the control method is verified by a computer simulation for the picture data containing a scene change. Finally, the usefulness of the proposed method is verified by a simulation using motion pictures.
Coded continuous phase modulation combined with nonuniform mapping and multi‐h scheme
Authors: Itoh Toshiyuki , Sasase Iwao , Mori Shinsaku 
Published: July 2007

AbstractThe convolutional coding combined with continuous phase modulation (CPM) has been shown as a good tradeoff between coding and bandwidth. This paper proposes the coded CPM with the nonuniform signal constellation and the multi‐h scheme to achieve further coding gains over the conventional uniform mapping single‐h coded CPM. Using the minimum Euclidean distance, the number of merge events up to a certain depth in the state trellis and the average bandwidth as estimated criteria, the performance of the non‐uniform multi‐h coded CPM is analyzed. It is found that the nonuniform multi‐h coded CPM achieves larger Euclidean distance and diminishes the number of merge events without expanding the bandwidth.
Development and performance evaluation of highly efficient retransmission scheme for high‐speed data transfer via satellite
Authors: Nakamura Tsutomu , Sasaki Ryooichi , Fujikura Nobuyuki , Morita Hiroshi 
Published: July 2007

AbstractSatellite communication has the following problems. The propagation delay is larger than in the terrestrial channel. When the carrier frequency exceeds 10 GHz, the bit‐error rate tends to increase due to the effect of rain and snow, which degrades the transmission efficiency. To cope with such problems, a highly efficient error control protocol has been proposed to prevent the degradation of the transmission efficiency.This paper describes a new large‐capacity, highly efficient retransmission scheme for satellite communication (extended SREJ scheme), which was devised considering the compatibility to the terrestrial network. The method is based on the SREJ (selective reject) scheme, which is specified in the HDLC (high‐level data link control) protocol, employed widely in terrestrial data transmission. To evaluate quantitatively REJ, SREJ and extended SREJ schemes, a satellite communication control equipment was developed.The result of the data transmission experiment is described in detail, indicating that the extended SREJ scheme is efficient. Then, through the discussion of practical usefulness, it is shown that the extended SREJ scheme has no problem from the viewpoint of the number of buffers in transmitting and receiving stations. Furthermore, to realize the efficient processing as far as possible, even if the bit‐error rate is higher than 1.0 × 10−4, the extended SREJ/REJ scheme is discussed by combining the proposed scheme with the REJ scheme.
Development of a location system for tv ghost sources and its serviceability
Authors: Miyazawa Hiroshi , Itoh Hironobu 
Published: July 2007

AbstractA practical system was developed which locates the origin of reception interference (the so‐called ghost interference) by the reflection of a wave incident on a building which is a major factor for electromagnetic interference in television broadcasting. One of the authors has already developed a prototype system in which the location of the ghost source can be detected by measuring the delay time and the direction of arrival of the reflected wave (so‐called ghost wave) with respect to the direct wave at the measurement point. In this method, the ghost wave is separated at each delay time while the measurement antenna is rotated and the receiving pattern of each ghost wave is obtained so that the location of the ghost source is detected.A system of locating the ghost sources was developed. In this system, a small computer is combined with the PDUR measurement system for measurement and analysis of the ghost wave. As a result, the portability is increased to be useful at the location of the electromagnetic interference by means of size reduction and reduced power consumption. From the examples of measurement of actual ghost interference and the direction‐finding accuracy at the measurement site, the measurement accuracy was studied for the reflection location of the ghost wave in the VHF and UHF broadcasting bands so that the serviceability of the system was confirmed.
An adaptive two‐stage image coding scheme using dpcm and vector quantization
Authors: Itoh Susumu , Naitoh Ichiroh , Kishidas Kouji , Utsunomiya Toshio 
Published: July 2007

AbstractThis paper proposes a two‐stage coding scheme, whereby a reduced image for retrieval is sent at the first stage, as a highly efficient coding scheme for images and other databases. In the first stage, the reduced image is encoded by block adaptive DPCM. In the second stage, the interpolative error component is encoded using adaptive vector quantization. In this scheme the number of quantization levels is easily determined from the standard deviation of the prediction error signals calculated for each subregion and the rate‐distortion characteristic of the scalar or vector quantizers, using the same method for either of the two stages. By designing the quantizers for typical probability distributions of the predictive error signal, a highly versatile coding scheme is realized.The proposed method has a better overall coding performance than a vector quantizer with the same block size (4 × 4 pixels), which has been designed in an optimal way in the original signal space. Compared with adaptive discrete cosine transform vector quantization [16] and adaptive predictive error vector quantization of the prediction error signals [7], which are also highly versatile, the proposed method exhibits a better characteristic when the coding rate exceeds a certain level. There is little degradation due to the two‐stage coding process. It has also been verified that the proposed method is effective for coding color images.
Routing algorithms of multiple‐destination telecommunication services
Authors: Tanaka Akira , Mizusawa Jun‐Ichi 
Published: July 2007

AbstractMultiple‐destination telecommunication is one of the new services in circuit switching. The telephone conference service, which is already in practical use in Tokyo 03 area, is an example of such a service. This paper assumes the use of a network control data base, and proposes a routing algorithm which is required in the realization of wide‐area multiple‐destination communication by placing a large number of bifurcations (bridges) in the network. It is required that the algorithm should not only suppress the circuit utilization cost for the determined route but also should determine the route in a sufficiently short time to cope with the immediate call.Five kinds of algorithms are proposed, including the search of the “minimum‐spanning tree,” which generally is considered as the basic connection configuration for the multiple‐destination communication. The two foregoing items are used as the items for evaluation, and a connection algorithm is presented which is the optimal for the given mumber distribution and the bridge placement. It is shown as a result that there exists an algorithm which is better than the “minimum‐spanning‐tree” search algorithm.
Studies on realization of information retrieval service function by fiber optic broadband distribution system
Authors: Yamagata Jun , Takemoto Kenji 
Published: July 2007

AbstractAs one approach to the realization of post 64 kbit/s ISDN, studies have been made on the optic broadband distribution system, based on the fiber optic transmission by tree (or bus) trunk line and star subscriber line. To realize a more versatile C‐E communication system, however, not only must the service functions such as distribution of multichannel video information, character, still picture and data be provided, but also the information retrieval function with random access such as videotex.This paper discusses theoretically the realizability of the information retrieval service by the optic broadband distribution system from the viewpoint of whether or not a sufficient number of subscribers can be accommodated.
Post‐detection combining diversity improvement of four‐phase dpsk system in mobile satellite communications
Authors: Hara Shinsuke , Morinaga Norihiko 
Published: July 2007

AbstractIn mobile satellite communications with a wide service area, the largest problems in composing the system are the Rician fading, where the direct wave component and the random time‐varying scattered wave component interfere with each other, as well as the low received power due to the propagation for a long distance.This paper considers diversity as a means to overcome these problems. The four‐phase DPSK system is considered, and a theoretical analysis is made on the error rate improvement by the post‐detection combining diversity. The characteristic functions of two orthogonal delayed detection outputs of the branches are used in the derivation of the error rate. Three communication systems of satellite/aircraft, satellite/land mobile and satellite/ship are considered as the models. Theoretical expressions are derived to evaluate the improvements. The error rate is also evaluated for the selective diversity. The result is compared with the case of combining diversity, together with the discussion for the difference between the two schemes.
Heating of deep—seated tumors by te wave irradiation
Authors: Ikeda Takuji , Morita Nagayoshi 
Published: July 2007

AbstractAs an applicator for heating deep‐seated tumors in the human body in a non‐invasive manner, a multiapplicator system radiating TE wave is proposed. In addition, it is shown that a hot zone can be formed deeply inside the human body if a method for good adjustment of the amplitude and phase of each applicator element is used. As an actual example, a homogeneous two‐layered cylindrical human body model is used for the cross section of the adrenal‐kidney level. Numerical calculations are carried out for the case where several line sources are placed around this model. It is confirmed that a hot zone is formed near the center. It is also demonstrated that the FD‐TD method is effective for the analysis of the electromagnetic scattering of a TE wave by an inhomogeneous cylindrical model which is the most important in the algorithm in the present method.
Analysis of electromagnetic field distribution in tunnels with partition walls
Authors: Sakai Koichi , Koshiba Masanori 
Published: July 2007

AbstractA method of formulation based on the boundary element method is provided for the electromagnetic field in a two‐dimensional impedance tunnel with partition walls excited by the fundamental mode. The impedance boundary condition used often for the analysis of the electromagnetic scattering problem from a lossy dielectric and of the wave propagation in a tunnel is based on the characteristic impedance for an infinitely thick medium. Since there is no provision on the transmitted wave behind the dielectric plate, this boundary condition cannot be applied directly if the dielectric plate used is thinner than the skin depth.This paper derives first a new boundary condition in which the values of the electromagnetic field in the region opposite to the wall surface are considered. In the case of a plane wave (TE wave) incidence on an infinitely wide than dielectric plate, the computed values by the boundary element method with the new boundary condition are compared with the rigorous solutions. It is found that the results agree with each other for both the reflection and transmission coefficients so that the impedance boundary condition introduced here can be used as the boundary condition for a thin dielectric plate. Further, assuming a tunnel with a thin partition wall, we carried out a microwave simulation experiment with a Bakelite plate so that the validity and usefulness of the present method are confirmed.
Tree configuration of n:1 multiconnection nonblocking switching networks
Authors: Tanaka Yoshiaki , Sezaki Kaoru , Akiyama Minoru 
Published: July 2007

AbstractWith the widespread use of broadband communication, the nonblocking N:1 multiconnection switching network is required in video distribution and in other applications. In most of the N:1 multiconnection nonblocking switching networks, some rearrangements or simultaneous origination of multiconnection calls must be assumed. For the switching network which is nonblocking for any N:l multiconnections under no conditions, only a few studies have been made on the three‐stage switching network.This paper proposes an efficient method of constructing a switching network which can realize arbitrary nonblocking N:1 multi‐connections. First, the construction of a d:1 connection network is shown which serves as the fundamental component of the proposed structure. Then it is shown that by connecting several d:1 connection networks an N:1 multiconnection switching network which can realize arbitrary N:1 connection can be constructed. The number of crosspoints required in the switching network is calculated.
A performance comparison of link level connection schemes in csma/cd networks
Authors: Tasaka Shuji , Hirota Masaya 
Published: July 2007

AbstractThis paper considers the logical link control (LLC) sublayer in the CSMA/CD local area network, and compares analytically the performance of connection‐oriented (CO) and connectionless (CL) protocols. As the medium access protocol, slotted nonpersistent CSMA/CD with a priority assigned to some types of frames is employed. In comparison, the overhead for connection establishment/release in the CO‐LLC protocol, and the receiver‐buffer overflow in the CL‐LLC protocol are especially considered, and the two kinds of protocols are compared.In the CO‐LLC protocol, a connection is established corresponding to a message. Employing the technique of equilibrium point analysis, the throughput and the average response time of the two kinds of LLC protocols are derived. To compare the performance of the two kinds of protocols, the receiver‐buffer size is kept constant, and the average number of data frames in a message is varied. As a result, it is shown that the CL‐LLC protocol is better than the CO‐LLC protocol when the average number of data frames is sufficiently less than the receiver‐buffer size, but the order is reversed when the average number of data frames is increased.
A new access scheme for pure aloha using capture effect by time‐varying power control
Authors: Mutsuura Kouichi , Okada Hiromi , Tezuka Yoshikazu , Ohtuki Kazuhiro 
Published: July 2007

AbstractThe advent of VSAT (very small aperture terminal) has made it possible to consider a new utilization of satellite communication. This paper proposes a new access protocol v‐ALOHA, which is matched to the characteristics of the packet switching network based on VSAT. p‐ALOHA is used as a means to cope with the requirement for simplification. To complement its disadvantage of low through‐put, a new control scheme is combined based on the new utilization. The performance is improved by the capture effect.The basic idea of the control scheme is to vary the power with time while transmitting packets. The difference in the transmission‐start time is converted into the power difference and produces the capture effect, thereby improving the performance. Thus, an access protocol is realized which improves the low throughput of p‐ALOHA while preserving its simplicity.This paper describes the basic idea of this v‐ALOHA and the protocol structure, indicating qualitatively its features. Then the throughput performance is formulated through a quantitative analysis. It is shown from the numerical results for the fixed‐length packet that the performance of the proposed scheme is better than other capture schemes, approaching sufficiently the performance of s‐ALOHA. For the case of the variable‐length packet, there is no slot loss as in s‐ALOHA, and the proposed scheme is shown, using an example, to be better sometimes than s‐ALOHA.
Diffusion approximation for queueing systems with nonexhaustive cyclic service
Authors: Yanagiya Masayuki , Takahashi Haruhisa 
Published: July 2007

AbstractThe nonexhaustive cyclic service queueing system is a performance evaluation model for various communication systems. In this queueing model, a specified maximum number of jobs in the queue, denoted by K, will be served upon the arrival of a server. Although the analysis for K ≥ 2 is difficult, recently Fuhrmann et al. [12] and Everitt [13] have proposed approximations for mean waiting time on the basis of pseudo‐conservation law.This paper presents an approximation method for deriving the mean waiting time of GI(x)/G/1 system with nonexhaustive cyclic service, using diffusion approximation and an iterative method. Here, [x] denotes the batch arrival. By use of the proposed method, some performance for nonsymmetrical cases with arbitrary K can be evaluated. Here, “nonsymmetrical” means that arrival process and service time distribution at each queue can be different. Numerical results are shown and compared with existing results such as by Fuhrmann et al. [12] and also by computer simulation.