bluuebunny/crossref_metadata_2025_split huggingface dataset:
A future traffic‐dimensioning method: A nonparametric approach for cell loss‐rate evaluation
Authors: Saito Hiroshi 
Published: July 2007

AbstractThis paper advocates the nonparametric approach and shows its application to asynchronous transfer mode (ATM) network dimensioning. The conventional dimensioning procedure, which is used in conventional dedicated and low‐speed networks, can cause the following problems in ATM networks and intelligent networks:(1) The need for a complicated arrival process model to describe high burstiness. As a result, elaborate modeling is necessary for each new service, which reduces flexibility in introducing new services.(2) The need for traffic measurement of higher moments of interarrival times. However, traffic measurement mechanisms cannot meet this requirement.(3) It is impossible to verify the arrival process model. The nonparametric approach dispenses with parametric modeling of arrival processes and derives performance measures directly from traffic measurement, thereby resolving the forementioned problems. This approach can be applied when the peak and average cell rates in ATM networks are known and provides an accurate measure of the cell loss rate.
Hierarchical video coding scheme with scalability and compatibility
Authors: Hanamura Tsuyoshi , Sekiguchi Shun‐Ichi , Kameyama Wataru , Tominaga Hideyoshi 
Published: July 2007

AbstractIn this paper, functional requirements for the MPEG 2 coding method are presented and, as an implementation method of these requirements, a hierarchical video coding scheme is proposed. In the proposed coding method, the prediction efficiency is increased by introducing spatial prediction in addition to temporal prediction as used in the MPEG 1 coding method. The hierarchical scheme is also characterized by the following features. (1) The input format is an output device‐independent noninterlaced video; (2) the coder has a hierarchical structure that permits the resolution level to be selected by the user; (3) by means of a small number of operations and a wide compensation area, the coder gives a motion‐detection method which detects motion vectors of each layer and a coding method of motion vectors; and (4) the proposed coding system introduces the use of down/up sampling processes with no phase distortion. Furthermore, the coding data description method is realized as an extension of that used by MPEG 1 and thus retains the compatibility. Simulation experiments show that this coding method satisfies the functional requirements without any obvious decrease in coding efficiency.
Adaptive virtual path capacity control in multimedia ATM networks
Authors: Watanabe Yutaka , Hadama Hisaya 
Published: July 2007

AbstractThe Virtual Path concept has several beneficial features to construct an economical and efficient Asynchronous Transfer Mode (ATM) network. The Virtual Path capacity control technique can increase network flexibility and improve transmission efficiency through statistical sharing of facilities.This paper presents an adaptive virtual path capacity control method which maximizes transmission efficiency under the condition of limited processing load. Evaluation shows that the proposed method successfully improves network transmission efficiency with a slight increase in processing load compared to the fixed virtual path capacity scheme.
Throughput analysis of pipelined protocol processors
Authors: Cardona Mario , Tsuji Shigeo , Satake Tadashi 
Published: July 2007

AbstractPipelined protocol processors are used in high‐speed networks such as FDDI for achieving high‐throughput data communications between end users. In this paper, we present a model for computing the maximum throughput that can be delivered by such processors.The parameters of the model are: input packet length, length of PDU (Protocol Data Unit) and SDU (Service Data Unit) headers, packet processing time of pipeline stages, capacity of the FIFO channels that interconnect stages, and average number of packets assembled/segmented at a stage.As an example, the maximum throughput of an idealized pipelined processor that executes the FDDI, LLC Class I, IP, and TCP protocols is computed. Also, we show that the formulas given in [1] and [2] are particular cases of the formulas presented in this paper.In a typical application of the proposed model, some desired, or measured, throughput characteristics of a protocol processor will be given, and the parameters of the processor will be computed.
Performance analysis of a slotted ring LAN by a single‐buffer model
Authors: Yamazaki Genji , Kobayashi Noboru , Takagi Hideaki , Wolff Ronald W. 
Published: July 2007

AbstractSlotted rings have been popular medium access control protocols for local area networks (LANs) since the early proposal of Cambridge and Owell rings. This paper provides a simple approximation technique for the performance analysis of a slotted ring based on a single‐buffer model in which at most one packet can be stored at each node. The technique produces approximate values of the network throughput by using an assumption which is valid for large networks and a solution of a quadratic equation whose complexity does not depend on the number of nodes in the network. It is shown by numerical examples that the present technique also gives accurate performance data for rather small networks to the extent that the relative error of the approximate throughput values is less than 0.3 percent of exact values. Since other performance measures for the single buffer model of a slotted ring can easily be calculated from the throughput, the proposed technique is very useful for evaluating the total performance of a slotted ring network.
FDTD analysis of two‐dimensional transient scattering of cylindrical wave via buried conducting objects
Authors: He Yiwei , Uno Toru , Adachi Saburo 
Published: July 2007

AbstractIt is important to know the scattering properties of objects buried underground so that the techniques of imaging the buried objects by electromagnetic waves may be established.This paper analyzes numerically the transient scattering characteristics by the finite difference time domain (FDTD) method where an infinitely long perfect conductor of arbitrary cross section is buried in the ground and an infinitely long current source is located above the ground surface parallel to the object. The calculation error resulting from the approximation of the scattering object by square mesh is decreased by introducing the field interpolation which satisfies the boundary conditions of the scattering surface.The spatial distribution of the electromagnetic field at each step of the calculation is shown. Moreover, the propagation characteristics of the wave near the ground surface and the scattering characteristics of various objects are studied and the presence of two types of waves, i.e., direct and lateral, is confirmed between the source and ground and between the object and ground.
Optical spectrum measurement system with very high resolution
Authors: Nagaki Yoshiro , Ooka Takao , Sonobe Youji , Kikugawa Tomoyuki 
Published: July 2007

AbstractSince the discovery of semiconductor‐optical fiber, the development of optical communication has been significant. In particular, a baseband modulation frequency in high‐speed communication has been increased up to the order of 10 GHz at the research level and of 1 GHz at the practical level. A factor which is the obstacle for further improvement is the bandpass width limitation for a transmitted signal caused by the spread of an oscillation spectrum of LD and also the wavelength dispersion of an optical fiber. For long‐distance and high‐speed transmission, it is important to determine accurately the spread of the LD spectrum for designing an optical transmission system.The objective of the present study is to clarify the condition required for a high‐resolution optical spectrum analysis system, which is essential for understanding the spectrum‐spread and chirping of the LD laser at a time of high‐speed modulation. A comparison of various measurement systems is made. A method of combining the diffraction grating system and the Fabry‐Perot etalon system is proposed, and the optimization of the system is discussed in detail.The present paper describes for the first time the optimization of the tandem configuration of a diffraction grating and Fabry‐Perot etalon systems. Based on those discussions, a prototype system has been constructed with which a maximum wavelength sweeping width of 200 MHz/div and resolution of 100 MHz were demonstrated.
Development of a breadboard model for the 22‐ghz band satellite broadcasting multibeam antenna
Authors: Shoki Hiroki , Kawabata Kazuaki , Nakatsuka Hirotaka , Tokunaga Kyoko , Orikasa Teruaki , Tsuzuku Aiichiro , Fukuchi Hajime , Ohmori Shingo 
Published: July 2007

AbstractThe multibeam antenna for the 22‐GHz band satellite broadcasting has been studied. The aim of this study is to meet future satellite broadcasting demands and advanced services such as high definition television (HDTV), digital broadcasting, and regional satellite broadcasting. The breadboard model of the 22‐GHz band multibeam antenna has been developed.Here, a new type of primary feed and a pattern synthesis method are proposed to achieve high gain and low sidelobe antenna performance which is required for the 22‐GHz band satellite broadcasting. The feasibility of the proposed antenna system and the design method have been verified numerically and experimentally.
Effect of compensation for rain attenuation on earth‐satellite links by onboard resource sharing using AMeDAS data
Authors: Matsudo Takashi , Karasawa Yoshio , Shiokawa Takayasu 
Published: July 2007

AbstractOnboard resource sharing (ORS) is a method wherein, for increasing effective isotropically radiated power, surplus satellite resources (radiated power or time slots in TDMA) are used to maintain communications quality in areas affected by rain attenuation. This paper analyzes simultaneous occurrence rates of rain over a wide area using Automated Meteorological Data Acquisition System (AMeDAS) data (1 hr rain rate data at approximately 1300 locations in Japan provided by the Japan Meteorological Agency).An ORS system is proposed using AMeDAS data as dynamic information for controlling satellite transmission power. Then a control simulation is performed by using actual reception intensities of satellite signals and rain rate information derived from AMeDAS data at corresponding times. The effect of the proposed ORS system is demonstrated in compensating for rain attenuation.From these results it was confirmed that the forementioned compensation provides a saving of about one‐third compared to the case where unavailable time is not compensated.
System testing architecture for a distributed switching system
Authors: Imagawa Hitoshi , Sakakibara Hajime 
Published: July 2007

AbstractA large‐scale switching system composed of distributed modules requires a system testing architecture that automatically tests for verification of call connections normality and determines the fault position when a system fault occurs.This paper proposes a system testing architecture for high‐speed testing of the entire system and wide‐area tests in the system. In the proposed, the distributed modular switching system is divided into upper and lower level modules. The upper level has a system testing function for executing tests of the lower level in parallel. The lower level is provided with various kinds of test equipment and test execution control functions. Similarly, test control functions and test execution control functions, respectively, are provided to the upper and the lower function units composing the module.Compared to the existing sequential test control architecture, the test execution time for verification of the system operation normality of the entire switching system is reduced to 1/[(number of modules) × (number of function units composing a module)]. Testing started by maintenance personnel and diagnosis automatically executed by the switching system itself in the case of a fault can share the test agent for controlling the testing. Then, not only the fault position analysis but also the verification of call connection normality can be realized through the originating and terminating connection testing.
Stochastic amplitude fluctuation in coherent optimal time domain reflectometry and its reduction technique
Authors: Izumita Hisashi , Koyamada Yahei , Furukawa Shin‐Ichi , Sankawa Izumi 
Published: July 2007

AbstractWhen the coherent detection technique is employed in optical time domain reflectometry (OTDR) (C‐OTDR), enhancing the dynamic range is expected to be an effective means of improving the minimum detectable signal level to that of shot noise. In C‐OTDR, however, there are fluctuations in the OTDR trace, and the problem is the degradation of the resolution of the loss measurements. The main reasons for such amplitude fluctuations are: (1) scattering light‐power jags due to the interference between Rayleigh backscattered lights; (2) variations of the heterodyne detection efficiency due to rotations of Rayleigh backscattering polarization; and (3) variations of the detection efficiency due to phase fluctuations of Rayleigh backscattering light.In this paper, such fluctuations are evaluated stochastically, and the techniques for their reduction are proposed. With regard to cause (1), the amplitude fluctuations can be reduced by integration over the frequency of light, while with regard to cause (2), the improvement can be achieved by polarization diversity detection or integration over the polarization. In case (3), phase diversity detection or phase integration is effective in reducing the amplitude fluctuations. Experimental investigations with regard to cause (1) are conducted in detail, and it is shown that the amplitude fluctuations can be reduced by about 3 to 7 times as a result of integration in the frequency domain compared to those without such integration.
A laser diode transmitter for optical intersatellite communications
Authors: Nohara Mitsuo , Inagaki Keizo , Fujise Masayuki 
Published: July 2007

AbstractDevelopment of a laser diode (LD) transmitter that has such characteristics as high power, fast frequency response, and good beam profile is essential to a realization of broadband optical intersatellite communications. Both an LD collimator to achieve a good wavefront quality and an LD driver to achieve a fast frequency response are designed for use with an LD operated at a wavelength of 0.83 μm.Also developed is an LD transmitter using an LD collimator and an LD driver. The objective of the LD collimator design was an acceptable degree wavefront aberration with a minimum number of lenses, by applying aspheric lens technology. As a result, a three‐lens configuration for the collimator was obtained. As for the LD driver, two high‐speed LD‐driver GaAs‐ICs are fitted in parallel. Their outputs are combined and fed to an LD. The parallel‐feed configuration enabled a fast frequency response at a high current.For fabrication results, a circularly collimated output beam 5 mm in diameter, with an output power of 60 mW, a transmission rate of 2.5 Gbit/s, and a wavefront aberration of λ/16 was obtained. The result satisfies the system requirements for optical intersatellite link between satellites in low earth orbits.This paper presents an LD transmitter design and data on its test samples, followed by discussions of further improvements.
On‐board large mesh antenna reflector with high surface accuracy
Authors: Ueba Masazumi , Tanaka Hiroshi , Kawakami Yoichi , Ohtomo Isao 
Published: July 2007

AbstractAn increase in the size of on‐board antenna reflectors is a key technology in providing economical services by miniaturized portable equipment in future mobile satellite communication systems. In practice, a mesh antenna can be used as the on‐board antenna. However, since the reflector surface of this antenna is supported by the cable and the mesh, and its size is larger, the surface is subject to larger thermal deformation in orbit than is the solid antenna reflector. Conventional compensation methods such as passive thermal control or rotation of the antenna reflector cannot maintain the required antenna performances. Various methods have been reported to compensate for the deterioration of antenna performance by thermal deformation.This paper describes a static shape control system for a 10‐m diameter antenna which actively compensates for the deformation by using a shape‐measuring sensor and shape‐compensation actuator. The configuration of the sensor and the experimental results by a functional model are described to confirm the design validity. The shape‐compensation method by the actuator was confirmed to be useful in achieving a required surface accuracy.
Use of concentrators to obtain an asymmetric broadcast ATM switching network
Authors: Tanaka Yoshiaki , Tsuchiya Hirofumi 
Published: July 2007

AbstractAs the broadband integrated services digital network (B‐ISDN) become more available for home use, it is expected that the demand for broadcast services, e.g., video distribution from a center to end terminals, will increase. Thus, in the local switching system, the number of output subscriber lines is much larger than the number of input trunk lines. Therefore, an asymmetric broadcast ATM switching network is needed for this service. However, most of the switching networks already proposed are symmetric.In this paper, an asymmetric switching network is realized by partitioning the output and by using existing symmetric switching networks. Furthermore, the size of symmetric switching networks which are used as parts is reduced by placing concentrators in the front. This decreases the total amount of hardware. Since excessive concentration invites cell loss, the relation between the hardware‐reduction effect and the cell‐loss characteristic also is studied.
A multicast hybrid ARQ scheme with stored error recovery
Authors: Sakakibara Katsumi , Kasahara Masao 
Published: July 2007

AbstractA multicast error control scheme which takes advantage of both MDS codes and GMD decoding is proposed and analyzed. The proposed scheme is characterized as follows:1. The sender does not retransmit data frames. The frames to be retransmitted consist of the redundant symbols obtained by encoding the previously transmitted data frames.2. Each receiver stores erroneous frames not greater than the prearranged number and decodes them all of a lump using the retransmitted frames of the fixed number.Numerical results show that the proposed scheme yields higher throughput not only for the case where the bit error rate is very large but also for the case where the number of VSATs is very large.
Interference cancelling characteristics of DFE transversal‐combining diversity in mobile radio environment–comparisons with metric‐combining schemes
Authors: Yoshino Hitoshi , Suzuki Hiroshi 
Published: July 2007

AbstractThis paper considers the decision feedback transversal‐combining (TC) diversity reception system in the digital mobile communication, and describes experimentally the interference cancelling characteristics of decision feedback equalizer‐type (DFE) TC diversity reception through laboratory tests. Three kinds of interference signals are considered: the intersymbol interference (ISI), the cochannel interference (CCI), and the adjacent channel interference (ACI). The exponentially weighted RLS, which executes the least‐square method in realtime, is employed in the adaptive control of the combining coefficients.It is shown first that the method for equalization and diversity combining can be classified into the TC and the metric combining (MC), among which TC has the linear interference cancelling effect. By 40 kbit/s quadri‐phase‐shift keying (QPSK) transmission experiments under Rayleigh fading condition, the following properties of TC are shown compared to MC: (1) In ISI, dominant condition in double path model, the average BER performance for average Eb/N0 values over 20 dB; (2) For CCI, dominant condition BER performance of TC is better than that of MC by 5 dB in average CIR at average BER of 10−2.
Method of Estimating Deterioration of Lead‐Acid Batteries Using Pulse Discharge and Charge Characteristics
Authors: Ogata Tsutomu , Takano Kazuo , Kohno Masaru , Yoshida Kazuki 
Published: July 2007

AbstractLead‐acid batteries have been used as emergency back‐up power supplies for communication systems. These batteries usually are charged and provide power to communication systems when a power blackout occurs. If the communication system is out of order during the blackout, the problems can be enormous. Therefore, NTT has been serious about the maintenance of the lead‐acid batteries.Since it takes longer than 20 hours to check the capacity of a battery, some other convenient battery evaluation method must be established. In this paper, the degradation mechanism of the lead‐acid battery was studied and it was concluded that the degradation of the internal resistance is related strongly to the capacity degradation. By measuring the internal resistance, the charge/discharge characteristics were evaluated for a short period of time.It was confirmed also that the internal resistance measured by measuring the charge/discharge characteristic for a period shorter than 500 ps is related strongly to the battery capacity. Using the forementioned relationship, the battery degradation was determined.
Facsimile image high‐speed coding and decoding processor
Authors: Horie Hitoshi , Ozaki Tohru , Shirai Hideyuki , Iizuka Yasuo 
Published: July 2007

AbstractThis paper describes a very high‐speed coding and decoding processor Image Pipeline Codec (ImPC, MN86063), which can be applied to bi‐level image, focusing on the architectural design and performance evaluations. An application example for a facsimile apparatus also is presented.The ImPC integrates basic functions required for an advanced facsimile such as two‐channel encoding and decoding, resolution conversion, and direct memory access (DMA) transfer functions. The ImPC includes the redundancy reduction coding algorithms modified Huffman (MH), modified READ (MR), modified MR (MMR), and an original coding scheme. A line of 4096 alternating black and white pixels can be encoded or decoded in 0.84 ms with 100‐ns cycle time. A typical A4 size office document is processed in 0.17 s. The ImPC chip is fabricated using 1.2 μ CMOS technology, integrating approximately 480,000 transistors on a 98‐mm2 die.