bluuebunny/crossref_metadata_2025_split huggingface dataset:
An experimental TDMA transmission system using 1.5 GHz‐band π/4 shifted QPSK
Authors: Kubo Tokuro , Oishi Yasuyuki , Fukuda Eisuke , Takano Takeshi 
Published: July 2007

AbstractThe π/4‐shift QPSK transmission system with TDMA scheme is constructed and an experiment is conducted, aiming at the digital cellular automobile telephone system. Various detection methods are first compared and it is decided that differential detection is advantageous, considering the operation in TDMA system where the burst modulated wave must be demodulated. Then, by varying the bandwidth of the receiving filter in the differential detection demodulator, the biterror rate and the adjacent channel emission are examined using simulation. The optimal receiver bandwidth is determined.In the differential detection, the bit‐error rate depends greatly on the carrier frequency drift. A highspeed automatic frequency control (AFC) circuit is newly proposed to solve this problem.The post‐detection, two‐branch selection diversity demodulator is experimentally constructed and a satisfactory performance is obtained, with the deviation from the theoretical value being 2.3 dB under the static condition, and the diversity gain is 6 to 7 dB. Based on those results, it is experimentally verified that the π/4‐shifted QPSK differential detection with TDMA scheme is practically useful.
Approximate analysis for bulk arrival queueing system with bulk departure
Authors: Suzuki Muneyoshi 
Published: July 2007

AbstractA bulk arrival queueing model with bulk departure is presented for information and communication processing systems where each transaction requires different memory size; moreover, each transaction cannot be divided and is analyzed. This model is characterized by customers arriving in bulks to a system that consists of a finite number of servers and waiting rooms, and customers belonging to the same bulk are served by the same server. Further, whenever customers are being served, they reserve their waiting room until the service of all customers in the bulks is completed. For its exact analysis a system of 2N state equations need be solved, where N is the waiting room size. Hence, it is practically difficult to obtain exact solutions and we evaluate the steady‐state probabilities of the system by using successive approximation. Approximate values of the traffic characteristics are compared with simulation results. They agree well with each other.
A packet switch architecture with channel group virtual circuit scheme in high‐speed communication networks
Authors: Ohtsuki Kazuhiro , Okada Hiromi , Hasegawa Toshiharu 
Published: July 2007

AbstractThis paper discusses the channel assignment problem in the multichannel, high‐speed packet network. It is assumed that multiple channels exist between a pair of switches in the network. It is expected that by regarding those channels as a single channel group and executing the packet transmission, a more efficient high‐speed and large‐capacity transmission will be realized.This paper newly introduces, in contrast to the virtual circuit in the multichannel network, the concept of a channel group‐virtual circuit (CG‐VC) for the multichannel network, where the packets are assigned to the channels based on the concept of the overflow traffic. To realize the CG‐VC system in the high‐speed environment, a simple and practical switch structure is proposed. The switch uses optical fibering as the basic module and the system is constructed by superposing the basic modules.Each packet automatically selects an appropriate channel from the set of output channels belonging to the same channel group. It is shown as a result of performance evaluation that, compared to the conventional VC packet switching system, the proposed system greatly improves the transmission delay and utilizes efficiently the channel.
A realtime management system for optical fiber outside plants
Authors: Yamashita Katsuya , Furukawa Shin‐Ichi , Ishihara Koushi 
Published: July 2007

AbstractTraditional outside plant management for communication cables uses a concentrated database. Plant data are inputted manually when a new plant is introduced or the plant is modified. A problem then is the deterioration of the data through incorrect manual input and the manpower/cost issue for manual input. Another problem is that the realtime property is not provided in the database due to the data input/update scheme that made it impossible to know the state of the plant at any instant.This paper attempts to solve these problems. Included is a proposal for an outside plant management system in which data can be updated by a remote automatic execution in realtime and high‐level maintenance support information can be supported. Basic concepts and the construction of this proposed system is also described here.A prototype system was constructed as follows. The semiconductor memory is built into the outside plant. Plant information is automatically transferred and managed in realtime, using the dedicated compact communication device and the dedicated cable. By adding the core matching, terminal box environment monitor and cable test functions to such a system, the construction and maintenance of the outside plant can be supported. Thus, a high‐level system can be realized by integrating plant management and construction/maintenance.
Feasibility of dispersion‐shifted fiber to the home
Authors: Ohashi Masaharu , Kawase Masaaki 
Published: July 2007

AbstractTo introduce the optical fiber into the subscriber network, economy, immediate response, reliability and other factors must be considered. A 1.3‐μm zero‐dispersion single‐mode fiber is investigated as the transmission medium for fiber to the home (FTTH) because of its broadband, low cost, and easy connection. In the trunk transmission line system, on the other hand, a dispersion‐shifted fiber is commercially used. There have been four investigations into the application of dispersion‐shifted fiber to the subscriber network.This paper describes the feasibility of a unified trunk and subscriber network through the use of dispersion‐shifted fiber and problems related to the application of dispersion‐shifted fiber to subscriber networks. Particular attention is paid to the requirements for splice loss and a quantitative investigation of the tolerance of the fiber parameters. First, a fiber parameter design with a mode field diameter 2 W and a cutoff wavelength λce is presented as a model for the subscriber network. Second, using the results of the foregoing applications of dispersion‐shifted fiber to the 1.5‐μm band, 1.3/1.55‐μm wavelength multiplex systems are discussed and problems of application are presented.
Analysis on squeezing properties of degenerate parametric amplifier for quantum communication
Authors: Koyano Hidenori , Uyematsu Tomohiko , Yoshida Norihiro , Hirota Osamu 
Published: July 2007

AbstractIn this paper, characteristics of degenerate parametric amplifiers are analyzed and are expected to be useful as a generator of a squeezed state or a noiseless amplifier for an optical wave. Especially, when a degenerate parametric amplifier is used as a noiseless amplifier or a squeezed‐state generator (squeezer), the depletion of the pumping light which has been neglected affects the quantum noise characteristic of the squeezed light. This effect is analyzed in this paper. Further, when the incident light does not satisfy the phase matching condition, the effect of this phase shift on the gain and quantum noise characteristics of the degenerate parametric amplifier is studied.On the other hand, when a degenerate parametric amplifier is used as a preamplifier for the receiving side of the communication system, the phase noise of the pumping light can be a cause of degradation of the communication system performance. The phase noise of the pumping light is classified as the phase shift and the phase fluctuation caused by the quantum noise and then the effects of these phase noises on the quantum noise characteristics of the squeezed light are analyzed.Further, in the BPSK optical coherent communication system, the effect of the phase noise on the bit error rate is analyzed. A quantitative evaluation is made to determine how small the phase noise of the pumping light should be in order not to degrade the error rate.
The radiation field from the dielectric‐rod antenna with two‐layered, rectangular cross section
Authors: Marumoto Tsunehisa , Kuroda Michiko , Kasai Yutaka , Soejima Teruzane 
Published: July 2007

AbstractIt is difficult to operate a single‐layered dielectric waveguide for the millimeter‐wave frequency range in a single mode with a small dielectric loss while the electromagnetic field is sufficiently trapped in the guide. On the other hand, this becomes possible in a two‐layered dielectric waveguide if the dimensions of the core and the clad are appropriately well chosen.In this paper, the electric field distributions of the amplitude and phase on the truncated plane and the radiation pattern of a two‐layered dielectric rod antenna with a rectangular cross section are analyzed theoretically. By the “generalized effective dielectric constant method” [2], the electromagnetic field distribution on the truncated plane of the waveguide cross section is derived. The boundary conditions at the discontinuity are Fourier transformed in the x and y directions. The results are multiplied to compute the electromagnetic field distributions.In comparison with the two‐dimensional Fourier transformation, this method has an advantage in that the computation time is shorter and the method can be applied to more complicated geometries. The results are compared with the assumption that the electromagnetic field on the cross section is identical to the one propagating in the waveguide.As for the electromagnetic amplitude distribution, the discontinuities of the electric field amplitude distributions are smaller at the boundary between the core and the clad in the present method. In regard to the phase distribution, the variation of the phase is smaller near the center axis so that the effect on the radiation pattern is negligible. The present method can be applied to analyze the problem of the discontinuities and truncations of a multilayered dielectric waveguide in the millimeter‐wave and submillimeter‐waves and of the radiation from an optical source.
Study of rotary mechanical optical fiber switch
Authors: Kobayashi Hideo , Shimizu Masatoshi 
Published: July 2007

AbstractA novel mechanical optical fiber switch by rotation has been proposed; the dynamic and switching characteristics have been studied. The structure, operational principle and analysis of the mechanical property, e.g., switching torque, have been evaluated.To characterize dynamic motion, the rotational transfer response time of switching and the transfer function were investigated. It was theoretically and experimentally confirmed that the optical switch has an internal feedback mechanism. The connection loss between multimode fibers caused by deviations of the rods, balls, and optical fibers has also been theoretically and experimentally investigated. In the test optical switch, the switching connection loss was 0.68 dB and the rotational transfer response time in 1 × 6 switching was 134 ms. These experimental results agree with the theoretical results.
Use of signal processing techniques to improve the dynamic range of coherent OTDRs
Authors: Nakamoto Hiroshi , Ohta Norihisa , Koyamada Yahei 
Published: July 2007

AbstractIn the development of OTDRs, which are indispensable in the conduction of highly accurate cable supervisions of optical subscriber systems, the loss increases of the lines due to introduction of optical branches and improvements of the resolution become problems. In optical subscriber systems presently under investigation, one‐way dynamic ranges in excess of 40 dB are required so the increase of the dynamic range of 20 dB must be realized.In this paper, both the average and the correlation techniques are employed in the heterodyne detection of OTDRs. The bipolarity correlation processing and the average processing methods exploiting the phase and the amplitude of the optical signals are proposed and the relationships between the source spectral linewidth and the improved minimum detectable optical power due to both schemes are clarified.Finally, taking the presently required and the future characteristics of the source linewidth into account, the configuration of the wide dynamic range OTDR is proposed and the improvement of the dynamic range is explained quantitatively. As a result, the maximum improvement is obtained when the combined bipolar correlation and the average processes are employed in the heterodyne detection method. It is shown that achievement of more than 40 dB one‐way dynamic range is possible even at the present source linewidth.
Design of a perfect reconstructive subband image coding scheme
Authors: Irie Kazunari , Kishimoto Ryozou 
Published: July 2007

AbstractThe Broadband Integrated Services Digital Network (B‐ISDN) is being designed to support multimedia signals. Nationwide image‐signal transmission systems will be constructed to offer high‐quality and reliable services to customers. The largest users of image transmission systems will be broadcasting stations. The transmission of image signals within and between studios or broadcasting stations requires the ability to multiply encode/decode signals without visible degradation. The ideal system would be free of quantization noise.A subband coding scheme is presented which can achieve distortion‐free encoding. It is provided that the required entropy can be reduced by using two‐tap filters for subband splitting; the original picture quality is maintained. A new short‐kernel subband filter architecture is proposed which can further reduce the entropy of subband signals.Experimental results show that four‐band splitting with adaptive DPCM coding is the most promising of the various subband configurations. This subband DPCM coding scheme has higher performance than full‐band DPCM coding.
A low‐intermodulation, high‐efficiency harmonic‐controlled amplifier for high‐power applications in mobile communications satellites
Authors: Dooi Yoshikazu , Iso Akio , Sekine Kenji , Okubo Naofumi , Hunaki Haruhiko 
Published: July 2007

AbstractRecently, research and development of mobile communications satellites has progressed in every country, and the key technologies for improvement have increased the output power and efficiency of solid‐state power amplifiers used in high‐output transponders for satellite payloads and decreased intermodulation distortion during multicarrier amplification.This paper describes the design method and experimental results for a harmonic‐controlled amplifier (HCA) having a theoretical efficiency more than 20 percent higher than existing solid‐state power amplifiers (SSPAs) and with nearly the same amount of intermodulation distortion.The HCA is a new type of SSPA which uses the harmonics to produce an amplifier with high efficiency in low‐distortion operation. Its operation is analyzed theoretically and experimentally, and new design methods are clarified. The HCA's output power is designed to be below saturation, and the output circuit is designed so that power‐added efficiency is maximum in the intermodulation distortion region. Experimental results show that at 69‐W output power in the UHF band, power‐added efficiency was SI percent. At 110‐W output power in the S band, power‐added efficiency was 42.5 percent, intermodulation distortion was 20 dBc in the UHF band, and 23 dBc in the S band (output back‐off 3‐dB point).
Reduction of lower sidelobe levels in a large deployable mesh reflector antenna as a means of decreasing the effective mass of communication equipment
Authors: Sato Shin‐Ichi , Iso Akio , Orikasa Teruaki , Sugimoto Toshio , Dooi Yoshikazu 
Published: July 2007

AbstractReducing sidelobe levels and lowering the effective mass of the equipment are important measures in the design of large deployable mesh reflector multibeam antennas used for mobile communication satellites with frequency reuse.In this paper, a method of converting from sidelobe levels to effective mass is described. Then the effects produced by the sidelobe level on the mass of the mesh reflector and the communication equipment are analyzed in the case of a cluster‐fed offset parabolic mesh reflector antenna. The surface density of the mesh reflector decreases with an increase in the aperture diameter, and the output efficiency of the solid‐state power amplifier decreases with an increase in output power.Next, assuming one transponder for each beam and using the EIRP of all the beams as a parameter, the relations between the sidelobe level, the minimum communication equipment mass, and the antenna aperture are described. The relation between the gain and the number of beams when the communication equipment mass is minimum is derived and the ratio of mesh reflector mass to the total mass of communication equipment is determined.
Throughput analysis of HDLC‐based data link protocols in a bridged network
Authors: Ikegawa Takashi , Motomura Kota 
Published: July 2007

AbstractThis paper presents an approximate analysis of the maximum throughput of an HDLC‐based data link protocol for a bridged network. To model an end‐to‐end data link connection, which is connected across multiple transmission lines and bridge processors, a specific server, denoted as a bottleneck server, is defined. This is identified as the server (i.e., transmission line or processor) which gives the largest service time (i.e., transmission time or processing time) among all the servers over the connection.The interval of receipt of information (I) frames at the receiver to that of the departure of corresponding I‐frames at the bottleneck server is approximated. This approximation enables an analytical throughput expression to be derived by observing the bottleneck server only.Compared with simulation results, analytical results obtained are in fairly good agreement if I‐frames are discarded at the bridges located between the bottleneck server and the receiver. However, they are relatively overestimated if I‐frames are discarded at the bridges located between the transmitter and the bottleneck server. It is shown also that the optimum window size is obtained as the smallest integer not less than the minimum acknowledgement delay over the service time of the bottleneck server.
Receiving system for the voyager‐2 neptune occultation experiment
Authors: Takano Tadashi , Yamamoto Zenichi , Hirosawa Haruto , Hayashi Tomonao , Yamada Mitsuo , Kawashima Nobuki , Mizuno Eiichi , Oh‐Hashi Seiichi , Tsuchiya Makio 
Published: July 2007

AbstractA radio science experiment was carried out when the deep‐space probe Voyager‐2 travelled behind Neptune. This paper describes the receiving and recording systems which were developed for the experiment and gives a summary of the experiment itself. The object of the experiment was to detect the very small fluctuations in the phase and amplitude of the radiowave carrier as it passed through the atmosphere and rings of Neptune.To achieve this, a 64‐m diameter antenna and high‐performance maser amplifiers were used together and a high G/T value was obtained. The heterodyne receiver was controlled by open loops and the local signal was changed with continuous phase to match the predicted Doppler value, stabilizing the signal within the bandwidth. A local frequency generator with stable frequency and phase and a signal bandwidth filter were developed.Also, to counter antenna distortion caused by changes in the elevation angle, a method of compensation was introduced which kept the phase stable and suppressed gain reduction.
The T‐vector and generalized optical theorems
Authors: Hosono Toshio 
Published: July 2007

AbstractThe energy relationship is discussed for an arbitrary polarized plane wave. A representation with a clear physical meaning in a dispersive medium is provided to the energy portion of the 7‐vector discussed by Tokumaru. Next, using the formulas obtained by Tokumaru, the optical theorem is extended to include circularly polarized waves. Further, a quaternionlike representation of the electromagnetic fields is proposed to discuss deeper relationships between the Poynting vector and the T‐vector.
Distributed cooperative multiagent model for intelligent telecommunication networks
Authors: Kishimoto Ryozo 
Published: July 2007

AbstractThis paper treats the high‐functionality layer as a large‐scale distributed cooperative computing system and proposes a distributed cooperative multiagent model for intelligent telecommunication network. The intelligent telecommunication network is viewed from the distributed cooperative computing environment, and the five‐viewpoint model is proposed by viewing the functions of the intelligent telecommunication network from five aspects.Finally, as a practical application example, the idea of the distributed cooperative multiagent is applied to the distributed cooperative control of the virtual path network in the ATM network. Through such discussions, it is indicated how the intelligent network can be constructed by the distributed cooperative computing techniques and how the communication network is impacted upon by those techniques. Thus, the future direction of research concerning the telecommunication network is indicated.
Traffic characteristics of a free access network with selective circuits: Influence on channel mismatch
Authors: Shikata Yoshiaki , Funakawa Kimitoshi , Shimada Katsunori , Nakura Masamitsu 
Published: July 2007

AbstractWhen the blocking probability of the traffic between nodes is to be estimated in the free access network with selective circuits, the loss generated by the channel mismatch between the originating/terminating node and the circuit group must be considered.This paper proposes a method of estimating the mismatch probability, considering the properties of the free access network construction. The estimation method is proposed with the following features: (1) the effect of mismatch on the joint connection distribution for the circuit group and all nodes is considered; (2) the number of simultaneous connections and connection probability on more than one circuit is considered; and (3) the different mismatch probability is considered for each originating and terminating node pair.Based on the actual result of estimation, the effects of the network construction conditions (number of time slots, number of circuits, and the number of access devices) as well as the time‐slot selection method in channel assignment are examined. The effect of the mismatch for the case of multitraffic is evaluated by traffic simulation. A method is proposed to improve the blocking probability for the high‐speed calls, considering the mismatch condition. The effect also is evaluated by the traffic simulation.
Approximate analysis for delay queueing systems with two different classes of quasi‐random input
Authors: Hoshiai Takashige 
Published: July 2007

AbstractMultidimensional traffic models where calls of more than two classes of different properties share the same resource are very important as basic models for tightly coupled multiprocessor systems, etc. Thus,‐ this type of research has long been actively performed. So far, some papers on finite‐source loss models have been presented. However, neither finite‐source delay models nor their approximate analyses have been investigated much.As an approximate analysis method of delay queueing model with two different classes of quasi‐random input (M1, M2/M1, M2/S/N1, N2 model), this paper proposes a method which approximates combination states of waiting calls of each call class by the ratio of numbers of waiting calls of each call class. Moreover, by comparing numerical results of this approximate analysis with exact solutions and simulation values, it is shown that this approximate analysis method has very good accuracy.