bluuebunny/crossref_metadata_2025_split huggingface dataset:
A variable bit rate video codec for ATM networks and its robustness against cell losses
Authors: Manabe Katsutoshi , Tanaka Tomoaki , Ohtsuka Sakuichi 
Published: July 2007

AbstractA video codec for ATM (Asynchronous data Transfer Mode), which is the transfer scheme in the era of B‐ISDN (broadband aspects of ISDN) is constructed and the performance is evaluated. The experimental equipment can realize the variable‐rate coded video transmission corresponding to CCIR 601 recommendation, through the experimental switching network. The periodic cyclic refresh, packeting of the coded information, and the interframe prediction DCT layered coding are employed, realizing a robustness against the cell loss which is the cause of a drastic image quality deterioration in ATM.As a result of the subjective evaluation experiment, the image quality of MOS 3.5 or above is obtained for the cell loss ratio of 10−6 using only the cyclic refresh and the packeting of the coded information, and 10−2 to 10−4 of low‐priority order information using the interframe prediction DCT layered coding.
Optimum dimensioning of circuit‐switched networks handling heterogeneous traffic with application to multiple bit‐rate network dimensioning
Authors: Shinohara Masaaki 
Published: July 2007

AbstractISDN network resources such as links and nodes can be shared by various classes of calls with different bit‐rate service quality, holding time characteristics, etc., raising expectations for economical design and efficient operation of the networks. Heterogeneous‐traffic network dimensioning is defined as a problem of determining each link size so as to minimize the total network cost while satisfying the individual loss probability specifications. This is formulated as a nonlinear programming problem and an iterative algorithm for solving it is proposed.The iterative algorithm is similar to the one used in single‐class traffic network dimensioning, but the optimality conditions are constructed by temporarily using the individual loss probability constraints for the traffic classes for which the equality is held in the preceding iteration. The algorithm then is applied to dimensioning networks serving multiple bit‐rate traffic, and its dimensioning examples are shown. The result shows design characteristics peculiar to a heterogeneous traffic environment, such as the possibility of two local minima, and network topologies with zero direct link size and nonzero direct link size are shown.
Novel automatic bias voltage control for LiNbo3 mach‐zehnder optical modulators using probe light
Authors: Kataoka Tomoyoshi , Hagimoto Kazuo 
Published: July 2007

AbstractLiNbO3 Mach‐Zehnder optical modulators, which are expected to be used for multi‐Gbit/s optical transmission scheme, have one problem which is a dc drift phenomenon. In order to operate this modulator for a long time, a control unit to adjust a bias voltage for such dc drift is therefore necessary. So far, a method to superimpose a control signal with a main signal has been commonly used. However, the control signal may influence the output signal in this method. A novel automatic bias voltage control scheme utilizing the feature of Mach‐Zehnder modulator with traveling‐wave electrodes is proposed in this paper. A dc drift can be detected with a probe light propagating along a direction opposite to that of a modulated voltage waveform, and therefore very little influence of the probe signal on the output signal would be expected. A theoretical discussion on a dc drift detection and control method is described. This method has been successfully demonstrated to work for a mark density of 1/4, 1/2, and 3/4.
Multiple differential detection with adaptive sequence estimation (MDD‐ASE)–‐mobile radio transmission performance in frequency selective fading environment
Authors: Nakajima Tatsuhiro , Horikoshi Jun , Fukawa Kazuhiko , Suzuki Hiroshi 
Published: July 2007

AbstractThis paper aims at the improvement of the transmission performance of the differential detection system in the mobile radio transmission channel in a frequency selective environment. The multiple differential detection with adaptive sequence estimation (MDD‐ASE) is proposed, and the performance is analyzed by a computer simulation. In MDD‐ASE, not only the differential detection by one‐symbol delay but also the differential detection by two‐ or more‐symbol delays are applied. The soft decision is applied to the output of the multiple differential detection, and the symbol sequence is estimated by Viterbi algorithm (VA).The bit error rate (BER) performance is improved by the extended observation time by the multiple differential detection and the sequence estimation. The number of states in VA and the processing complexity of the adaptive algorithm increases exponentially with the extension of the observation time. Consequently, the following method is proposed: (i) the number of parameters to be estimated is reduced; and (ii) the sequence candidates stored in each path of VA are fed back.In this paper, the configuration and operation of MDD‐ASE are described first and then the transmission performance of the 40 kbit/s QPSK modulation system is presented. As a result of analysis for the static and the dynamic performances of ADD‐MSE using one‐ and two‐symbol differential detection, it is shown that the improvement effect is almost the same as in coherent detection DFE.
A high‐accuracy positioning service for land‐based mobile communication systems using the DGPS method
Authors: Ishikawa Hiroyasu , Kobayashi Hideo , Mizuno Toshio 
Published: July 2007

AbstractThis paper proposes a high‐accuracy positioning service for terrestrial mobile communication systems which employs the global positioning system (GPS) with the differential method (DGPS). The proposed system provides a high‐accuracy navigation service to land‐based mobile communication users. The proposed system also provides a comprehensive vehicle control service to the transportation companies when both forward and return links are available in the terrestrial‐based mobile communication systems.This paper also assesses the performance of the DGPS method by computer simulations and a field experiment in an urban area to identify the viability of the proposed system under an actual environment. The relationship between average ranging time rate and the average visible number of satellites in various operating environments also is investigated.
An estimation method of buried pipe location by using zero‐crossed synthetic aperture
Authors: Nagashima Yuji , Yoshida Hirotaka , Masuda Jun‐Ichi , Komatsu Kouji 
Published: July 2007

AbstractIn the buried‐object search technique using a pulsed radar, the estimation method for the buried‐pipe location and the underground propagation velocity of the electromagnetic wave by means of a synthetic aperture method has been studied. In general, the electromagnetic wave attenuates as it propagates in the underground and the amplitude of the received signal often becomes extremely small. Therefore, it has been difficult in the signal processing using the amplitude value to recognize several buried objects at different depths by an identical discrimination standard.To resolve this difficulty, a new zero‐crossed synthetic aperture method is developed. In the underground cross‐sectional image, the waves reflected from a buried pipe form a hyperbolic pattern dependent on the underground propagation velocity of the electromagnetic wave. By evaluating only the edge of this hyperbolic pattern, the underground propagation velocity of the electromagnetic wave and the location of the buried object are estimated.First, to extract the edge, the amplitude value at the time when the observed signal has a “0” amplitude is replaced with “1” if the phase of the original waveform changes from minus to plus whereas with “‐1” if it changes from plus to minus. The amplitude at other time points is replaced with “0.” Subsequently, a synthetic aperture process (addition process) is carried out. Since the absolute value of the amplitude is 1 or 0, it is not necessary to consider the effect of the attenuation of the amplitude due to propagation of the electromagnetic wave as a discrimination reference in the estimation of the location of the buried pipe after the addition process. The location of the buried pipe can be detected accurately.
Widening the bandwidth of ferrite electromagnetic wave absorbers by attaching rubber ferrite
Authors: Naito Yoshiyuki , Mizumoto Tetsuya , Wakita Yuuichi , Takahashi Michiharu 
Published: July 2007

AbstractWith a view to increasing the bandwidth of ferrite electromagnetic wave absorbers, the reflection characteristics were studied for an absorber made of sintered ferrite loaded with rubber ferrite via an appropriate dielectric layer.First, by means of calculations, it is shown that this structure has a bandwidth wider than that for the sintered ferrite single‐layer absorber. Also, the bandwidth of the absorber increases as the permittivity of the dielectric material inserted in between is lower. By loading an appropriately thick rubber ferrite plate via an air layer on a sintered ferrite plate, an absorber can be constructed for which the reflection is less than ‐20 dB over the frequency range from 30 to 1830 MHz. By loading another air/rubber ferrite pair, an even further increase of the bandwidth is possible. For an existing ferrite single‐layer absorber, it is effective for increase of the bandwidth to load the air/rubber ferrite by attaching a sheet resistance on the ferrite surface.Finally, by an experiment, it is shown that a broader bandwidth can be obtained than the ferrite single‐layer absorber by loading a rubber ferrite via a low‐permittivity layer.
Application of modulation level‐controlled radio system to ATM networks
Authors: Ohuchi Mikihiro , Lee Hee‐Jin , Komaki Shozo , Morinaga Norihiko 
Published: July 2007

AbstractThis paper considers the application of the modulation level‐controlled variable capacity radio channel to asynchronous transfer mode (ATM) networks and analyzes the cell loss characteristic. A system is proposed in which the transmission capacity of the overall system can be enlarged by controlling the number of modulation levels. This helps to enhance the absorption effect for the traffic variation in ATM networks. Therefore, the proposed system can reduce the cell loss probability.As a result of quantitative analysis of the system, it is shown that the cell loss improvement is by the factor of several hundreds to several thousands compared to the virtual path fixed‐capacity transmission system and several to several thousands compared to the virtual path capacity control system proposed up to present.
capacity assignment algorithm for packet switching network with different grades of service
Authors: Sugano Masashi , Murata Masayuki , Miyahara Hideo 
Published: July 2007

AbstractA multimedia communication network is expected to treat various kinds of information, e.g., voice, image, and data which have different demands of grade of service. Furthermore, in new high‐speed networks, end‐to‐end delay distributions or packet‐loss probabilities rather than average delays become more important performance measures.This paper presents a new heuristic design algorithm for packet switching communication networks in which the end‐to‐end delay distribution and packet‐loss probabilities are adopted as design constraints. It is shown that, while the total cost is increased slightly when compared with the former approach, end‐to‐end delays and packet‐loss probabilities between every two end‐nodes can satisfy predefined constraint as expected.
Two‐dimensional interpolation in the wavenumber domain for radar image reconstruction
Authors: Furusawa Akira , Wakayama Toshio , Sato Toru , Kimura Iwane 
Published: July 2007

AbstractIn the two‐dimensional radar image reconstruction using diffraction tomography, missing data become a significant problem if the observation direction and the scan range are restricted. A method is proposed in which these missing data are interpolated in the wavenumber domain. As an object image, a collection of the point targets is assumed. By means of a method which minimizes repetitively the square residual of the observed values and the reconstructed image in the wavenumber space, it is shown by simulation that a good image reconstruction is possible even if the missing rate is as high as 50 percent.As a method to provide the initial value for the repetitive method, an interpolation method using the autocorrelation function is proposed. It is shown that this scheme works well in a stable manner even for a high missing rate and a poor SN ratio. Further, an objective discrimination criterion is proposed for estimation of the number of targets. It is shown that the true target can easily be discriminated if the SN is good and that a stable estimation is still possible even if the SN is poor and the extraction of a weak image is difficult.
High‐frequency analysis of electromagnetic fields on variable radius of concave‐conducting boundary
Authors: Ishihara Toyohiko , Goto Keiji 
Published: July 2007

AbstractBy extending the electromagnetic field representation on a cylindrical concave boundary with a constant radius of curvature, two types of representations are proposed for analysis of high‐frequency electromagnetic field on a concave boundary in which the radius of curvature depends on the location. They are: (1) a combination of the ray‐tracing method and the adiabatic whispering gallery (WG) mode; and (2) a combination of the ray‐tracing and the modified integral‐type interference waves. The limitations of the application of these field representations also are presented.Especially, the adiabatic WG mode is obtained by an approximate analysis of a parabolic equation in a curvilinear coordinate system under the condition that the radius of curvature changes slowly. A transformation equation is obtained from the lower‐order WG modal solution on a cylindrical concave boundary to the adiabatic WG mode.The foregoing transformation which is similar to the one proposed in the problem of diffraction of a creeping wave on a convex boundary is applied to an integral‐type interference wave and subsequently a modified integral‐type interference wave is derived which can be applied to the case where the radius of curvature changes as an adiabatic approximation. Further, a ray‐tracing algorithm is proposed for determination of the geometrical rays arriving at an arbitrary observation point within a concave surface and its usefulness is clarified.
Transmission power control for TDMA satellite communication systems
Authors: Kazama Hiroshi , Sakata Tetsu , Kato Shuzo , Saka Tsutomu 
Published: July 2007

AbstractThis paper aims at solving the problem of channel quality deterioration due to the reduced D/U and C/N by the rain attenuation. A method is proposed to improve the control accuracy in the transmission power control method. In the proposed method, the feedback‐loop control is applied to control the traffic earth station, and the set‐back closed‐loop control is applied to the control of the reference earth station. The site diversity is employed in the reference earth station, and the reference of the transmission power control is determined independently of the TDMA synchronization reference.It is verified as a result of computer simulation and RF set‐back experiment for the proposed method that the control error for the reference earth station in Ku and Ka bands is within ±2.5 dB, and the control error for the traffic earth station is within ±2.0 dB, which is an excellent performance. The proposed method is applied to the actual system, and an excellent performance is obtained in the control through a satellite.
A modular cable‐mesh deployable structure for large‐scale satellite communication antennas
Authors: Meguro Akira , Mitsugi Jin , Ando Kazuhide 
Published: July 2007

AbstractThis paper describes a concept and key technologies for a modular mesh deployable antenna. A modular concent is suggested. The advantage of the modular concept and the influence of alignment errors on the surface accuracy are estimated quantitatively. The antenna reflector consists of a mesh surface, a cable network, and deployable truss modules. The cable network comprises three kinds of cables–surface, tie, and back cables. Adjustment of tie cable lengths improves the surface accuracy. Synchronous deployment truss structures are considered as a supporting structure. Their design method, bread board models, and deployment analysis are explained.
Evaluation of acknowledgement methods for high‐speed data transmission
Authors: Saito Tadao , Aida Hitoshi , Tomiyama Tadahiro , Fu Hong 
Published: July 2007

AbstractThe protocol in the open system interconnection (OSI) basic reference model is specified as a system with a multilayer structure. The performance of the network is related closely to the network configuration and the protocol parameters. The authors have been attempting to evaluate the transmission efficiency of the network using the multilayered protocol, with the transmission speed, the window size, and the transmission delay as the parameters.It is assumed in the studies that the acknowledgement is returned at the end of each window. On the other hand, it is seen that the throughput of the network in the high‐speed transmission is affected greatly by the acknowledgement method. This paper notes this point and evaluates the relation between the acknowledgement method and the transmission efficiency. To achieve the desired transmission speed, the conditions for the window size, the acknowledgement method, and the protocol processing time are presented.
Virtual path test function and its mechanism for ATM transport networks
Authors: Matsunaga Haruhiko , Uematsu Hitoshi , Kanayama Yukiharu , Ueda Hiromi 
Published: July 2007

AbstractThis paper considers a function to improve the efficiency of the operation administration and maintenance (OAM) of the virtual path (VP) in the ATM network. A VP test method is proposed which can test the connectivity and performance at new VP establishment and locate the fault point at VP failure. The implementation of the method is discussed. The feature of proposed method is that the number of error bits, the number of lost cells, and the number of misdelivered cells can be measured by transmitting and receiving the test OAM cell in any test section of VP.In this paper, the purpose and requirements for the VP test system are described first. Then the mechanisms in the proposed system and the allocation of test functions are considered. A transmission performance measurement algorithm is proposed for the test OAM receiver so that the bit error, the cell loss, and the cell misdelivery can accurately be counted. The structure of the VP test OAM cell to realize the proposed algorithm is presented. Finally, the system parameters of the proposed method are evaluated quantitatively.
Ranging and positioning experiments for an aircraft using a geostationary satellite–the effect of a flight route and orbit elements
Authors: Ito Ken 
Published: July 2007

AbstractA ranging and positioning system using a geostationary satellite has been developed and its performance has been evaluated using an aircraft. This system can be applied to oceanic air traffic control and can be used at a ground station to determine positions of aircraft. An experimental system consists of a geostationary satellite, a ground station, an aircraft, and a pseudo‐satellite, which is installed inside the ground station and used as the substitute for another geostationary satellite. The Engineering Test Satellite V (ETS‐V) of Japan was used in the experiment.It is known that the positioning error increases as a user approaches the equator in a positioning system using two geostationary satellites. This fact has been confirmed in this paper by experiment. It has also been shown that positioning errors can be decreased by using relative positioning in which the position of the ground station is used as a reference station. The use of old orbit elements increases the error of the predicted position of the geostationary satellite and therefore increases the positioning error of the aircraft. This has also been confirmed in the experiment. Furthermore, it has been shown that, in relative positioning, positioning errors do not increase much even with old orbit elements and the epoch of orbit elements does not have much influence on positioning errors.
Design of large‐circle rogowski coil for measuring lightning current in building columns and girders
Authors: Sato Masaji , Kuramoto Shoichi , Matsuoka Koichi , Ohta Minoru , Takemoto Koji 
Published: July 2007

AbstractWhen observation of a direct lightning strike to a building is performed or in an experiment for applying lightning using a building, one needs current sensors that can measure the current in building columns, girders, and walls. As the current sensor, the Rogowski coil commonly is used. The coil is placed around the object to be measured, and the inductive voltage is obtained. Although there are many commercially available units, these sensors are too small for measuring building columns and girders.This paper studies Rogowski coils which are long enough to encircle the building columns and girders and flexible enough to set up the structure according to the practical situation. First, the coil and the integrator are described by their lumped element equivalent circuits. In addition, the target values were set for the frequency bandwidth and the sensitivity. A structure optimum for these characteristics was found. From the results, a hollow core coil using a vinyl pipe was fabricated. A Rogowski coil 1 to 10 m long was realized which has a frequency of 300 kHz and a current‐voltage conversion factor of 1/100. Further, the position dependence of the current to be measured was observed. Sufficiently practical characteristics were obtained with the present coil with a long structure.
A hyperdistributed switching system architecture for B‐ISDN
Authors: Tanabe Shiro , Sakurai Yoshito 
Published: July 2007

AbstractThe broadband integrated services digital network (B‐ISDN) is expected to realize a high‐speed network. Information with diversified classes of quality must be transmitted on the network, from the 64‐kbit/s voice signal to the several tens Mbit/s video signal. Another aspect is that the voice and the video signals are sensitive to the delay, and severe requirements are imposed on the data error. For the switching system in B‐ISDN, an architecture is required which fully utilizes the advantages of the asynchronous transfer mode (ATM) communication system, where the effective use of the network is considered by multiplexing the multimedia.This paper proposes the hyperdistributed architecture to be applied to such a broadband communication environment. In the proposed system, front‐end processing modules (FPM), which are independent ATM nodes with the call processing functions, are placed according to the scale of system. The central switching module (CSM) with the single‐stage distributed ATM switch to connect FPM is provided only with the self‐routing function based on the routing information in the ATM cell header. For the proposed hyperdistributed architecture, the design for the communication channel based on the ATM nonblocking condition, as well as the transfer route determination, are discussed. Then the allocation of the quality class control using the shared buffer ATM switch is discussed which can construct an efficient network satisfying the diversified quality requirements.