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The main problem of an indoor infrared (IR) wireless system via diffuse infrared link is bit error rate (BER) performance degradation due to intersymbol interference (ISI) induced by multipath distortion. In the previous study, only a rectangular pulse was employed as a transmitted pulse. However, multipath distortion tends to make the nondirected diffuse indoor IR channel have a low-pass frequency characteristic, and thus a rectangular pulse, whose spectrum has a form of sinc function, induces much ISI. In this paper, we analyze the BER performance of indoor IR wireless system via diffuse link employing different kinds of pulse waveforms, such as a Gaussian pulse and a raised cosine pulse, and consider the effect of ISI. Moreover, we analyze the BER performance employing a return-to-zero (RZ) pulse which has a guard interval in a slot. It is shown that the RZ Gaussian pulse is effective in mitigating the effect of ISI. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(9): 33–43, 2000 [ABSTRACT FROM AUTHOR]

Efficient handover during both mobile telephone and portable telephone communication is a technology essential m implementing ideal mobile communications. However, there exists the possibility of a transmission data slip during the process of circuit switching, which has become a problem in communication using terminal machines such as data modems and FAX machines connected to mobile telephones and portable telephones. In this paper, a transmission data slip accompanying route changes reside digital exchanges in a handover during telephone communications is assumed; it is shown on the basis of this assumption that a lag in synchronism occurs m the receiver terminal equipment. Then a sync lag of the receiver terminal modem during handover has been confirmed by tests using actual analog cellular phones and a transmission data slip has been shown on the basis of the results of the tests. In this paper, a synchronism control method minimizing the sync lag has been studied. The efficacy of this method has been confirmed as a result of applying the method to a mobile telephone FAX modem. [ABSTRACT FROM AUTHOR]

Following the growing digitalization of broadcasting, Integrated Services Digital Broadcasting for Cable (ISDB-C) digital broadcasting over cable TV networks has been increasingly adopted in Japan. Cable TV transmission technologies in Japan can be classified into three types: 1) the transmodulation system, which consists of retransmission of received broadcast signals after converting their modulation; 2) the pass-through system, consisting of retransmission of received broadcast signals without changing their modulation but converting only the frequency as required; and 3) the ReMux system, which consists of first demodulating the received broadcast signal, then combining services before retransmission. In this paper, we describe the multiple TS transmission system and TS division system standardized by the Japan CATV Engineering Association and Japan Cable Laboratories, as well as two-way operation and the headend in the sky service, which is a commercial program distribution service launched in Japan for cable operators. [ABSTRACT FROM AUTHOR]

Developing effective and fast data transfer system for the huge amount data between Europe and Japan is a critical issue for the ITER Remote Experimentation Center (REC). To implement the system, effective data transfer methods and wide bandwidth international network are required. This paper describes results of data transfer experiments. We have evaluated two data transfer methods: Packet Pacing and MMCFTP. By using Packet Pacing and 2.4 Gbps line, we achieved 2.2 Gbps data transfer from NIFS to IFERC. By using MMCFTP and 10 Gbps line, we achieved 2.5 Gbps data transfer from NIFS to Dublin, Ireland. Furthermore, by using MMCFTP and 100Gbps line, we successfully achieved the stable transmission of 1PB of data at approximately 84 Gbps, one of the world’s fastest transmission speeds. This paper also describes the upgrade plan of SINET (a Japanese academic backbone network), which is used for ITER and REC communications. SINET will be upgraded to the network based on 100-Gigabit Ethernet technology in April 2016. Furthermore, direct lines of 20 Gbps (10 Gbps × 2) between Japan and Europe will be introduced. These direct lines will reduce latency between Europe and Japan and will realize higher speed data transfer. [ABSTRACT FROM AUTHOR]

This 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 m readtime, is employed m 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 quadriphase-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/No 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. [ABSTRACT FROM AUTHOR]

In the conventional adaptive discrete cosine transform (ADCT) using the fixed length code, it is known that the source coding performance can be improved greatly by the combined use of the M-transform (MT). This method is called ADCT-MT. The purpose of this paper is w evaluate the effect of the combined use of MT from the viewpoint of the channel coding performance. In the conventional ADCT, as well as in the scene adaptive coding (SAC) using the variable length code, the damage in the reconstructed image due to the channel error often is manifested as the local block distortion. In ADCT-MT, the damage is diffused and distributed uniformly by the inverse MT over a large number of blocks, making the damage less noticeable. A subjective evaluation experiment is conducted (five-step score) assuming the binary symmetrical channel. A simple error-correcting code is applied to the coding data of the additional information and DCT dc component. When the bit-error rate is 10-3, the average score is approximately 3.5 for ADCT and 1.2 for SAC, while it is above 4.5 in ADCT. Thus, in ADCT-MT, the damage is little noticeable. [ABSTRACT FROM AUTHOR]

This paper considers a function to improve the efficiency of the operation administration and maintenance (OAM) of the virtual path (VP) in the AIM 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 piper, 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. [ABSTRACT FROM AUTHOR]

The 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 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. [ABSTRACT FROM AUTHOR]

This 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. [ABSTRACT FROM AUTHOR]

In general, an optimum quantizer which gives the minimum distortion at a given bit-rate is uniquely determined when the statistical characteristics of the source signal are given. This quantizer, however, is not optimum for the human visual characteristics; and a quantizer which is designed to minimize the estimated distortion (estimated noise) reflecting the human visual characteristics is more likely to be optimum. In the optimum quantization of orthogonal transform schemes, theoretical quantizer design schemes considering only the human visual characteristics of the spatial frequency direction have so far been reported. However, there is another human visual characteristic, that is, the noise-masking effect which is the difference in the detectability of noise, depending on the local variation of a video signal (activity). For this, only the quantizers which use this effect experimentally have been reported; and they have not been studied theoretically. In this paper, it is proposed, as the first step, that the visual sensitivity to noise be expressed on two axes, i.e., spatial frequency and ‘activity.’ A three-dimensional (3-D) structure quantization cube is then proposed which is obtained by minimizing the noise estimated by the visual sensitivity of the noise at the given bit-rate and the theoretical design scheme of this optimum quantization cube is described. Finally, the effectiveness of the quantization cube designed by this theoretical scheme is compared with that of the conventional quantization schemes by a computer simulation using real picture data. [ABSTRACT FROM AUTHOR]

This paper presents a data compression scheme which uses the statistical properties of ordered dither image by vector reputation. When a part of the dither image corresponding to n × n dithering matrix is described as a vector, it is observed that there is high correlation ratio between neighbor blocks for level information (the number of black pixels in the vector), the resolution information (the number of kinds of vectors) is a few, and their frequency distribution is very biased. Thus, if these two kinds of information on vector are coded separately by the variable length coding scheme, then high compression ratio can be attained for transmission and storage of dither image. [ABSTRACT FROM AUTHOR]

This paper proposes a novel direct sequence/spread spectrum communication system for use in power line data transmission where the transmission characteristic varies largely and rapidly. In the proposed system, two similar PN sequences are used, one of which is loaded with data and the other is used as a reference PN. Waveform distortion during transmission can be cancelled out by an appropriate process utilizing two PN sequences. Data can be recovered as the sign of correlations between two PN sequences at the receiver. Results of computer simulation show considerable improvement in the data error rote over the conventional DS/SS system. [ABSTRACT FROM AUTHOR]

This paper introduces the key technology of the Uplink Center facility for ISDB-S that provides HDTV based digital broadcasting services in Japan. It especially focuses on the unique aspects of the base-band signal processing, such as multiplexing, channel coding, and clock synchronization, as they relate to the ISDB-S transmission system. [ABSTRACT FROM AUTHOR]

The paper investigates the evolution of the successful mobile internet service i-mode in Japan, identifies the relevant explanatory factors, and provides implications for the further development of mobile data communications in Europe. In conclusion, the paper argues that there must be a balanced and efficient mix of industry coordination, service experimentation, and dynamic competition in order to provide a foundation for mobile data success in Europe. [ABSTRACT FROM AUTHOR]

Discusses the information and communication technology applied in the Japanese pharmaceutical industry. Safety information systems; Electronic transfer of safety reports; Process of regulatory submission.

An optical circulator function has been realized without using any magnetooptic effect by placing a multimode tapered bending waveguide made of passive material in rotational symmetry. The higher-order propagating mode components selectively radiate from a bend of a certain curvature, and the lower-order mode components pass through the bend and radiate from the tip of the taper. When the lower-order modes are launched into the waveguide, light radiates from the tip, and couples to the propagating higher-order modes of the next waveguide at its bending section. This phenomenon is accompanied by a change in the transmission mode distribution and an excess loss of at least 3 dB. However, if the evaluation is only by the transmitted power, the device exhibits the circulator function. This small and low-cost optical device is effective in a low-speed and short-distance bidirectional data communication system. In this paper, in order to confirm the basic principles, microwave simulation was carried out to examine in detail the radiation characteristics from the tapered bending waveguide with a resolution of one wavelength. An extinction ratio of more than 18 dB was realized when the distance between the adjoining waveguides was about one wavelength. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(7): 31–40, 2000 [ABSTRACT FROM AUTHOR]

Synchronous digital hierarchy (SDH) standardized in International Telecommunication Union-Telecommunication Standard Sector (ITU-T) applies a new multiplexing method using a pointer that indicates a tributary location in the SDH frame. The location of the SDH frame heads received from several lines is adjusted at interface circuits to facilitate the multiplexing process in the SDH equipment. Since the frame head locations of input signal differ from the output signal, pointer values are attached to the output signals. The pointer conversion of each tributary is performed independently of each other. Therefore the pointer values of tributaries transported on the same line might be different from each other after the conversion even if these values are the same. Hence large amounts of buffer memory would be required at the destination point to provide a transport service utilizing multiple virtual containers (VCs). This paper proposes a new pointer conversion method that keeps the pointer value differences unchanged between tributaries multiplexed in an SDH frame. This method allows multiple VC transport service to be provided. [ABSTRACT FROM AUTHOR]

This paper considers a new transmission method (quasisynchronous transfer mode, Q-STM), as a means to eliminate both the cell loss and the network delay fluctuation in an ATM network. The concept of time-switch in circuit switching is introduced into the ATM switching framework. A switching structure and the call establishment procedure are proposed. In the proposed method, the time-switch is introduced, which eliminates in principle the output port contention in the ATM switching fabric. By preparing a buffer with a certain capacity, cell loss due to buffer overflow in the output port of the ATM switch can be completely eliminated. The concept of subframe is newly introduced, which serves as the unit of time-switching. A three-layered structure is applied to the frame structure, composed of the frame, the subframe, and the slot. This helps to reduce delay due to time-switching, compared to the case in which the concept of subframe is not introduced, while maintaining the flexibility of bandwidth allocation. Additionally, the method is based on ATM switching, and the ordinary ATM cells not bound to the frame can be transmitted and ATM-switched by the idle slot in the frame. This enhances the features of ATM, i.e., effective use of the circuit by the statistical multiplexing effect. The basic characteristics concerning the quality of the ordinary ATM cell are analyzed by simulation. [ABSTRACT FROM AUTHOR]

In an asynchronous transfer mode (ATM) network, various calls with different transmission quality requirements ranging from tow bit-rate data signals to high bit-tare motion picture signals are applied. Therefore, it is important to determine how to allocate network resources to those calls and to judge whether those calls can be accepted. This paper proposes a can admission control scheme based upon a data table that holds the relationship between average bit-rate and needed bandwidth for aggregated signals in each quality class obtained beforehand by simulation. This proposed scheme assumes broadband services where the aver-age bit rate and burstiness of aggregated signals can be estimated clearly with predictable value ranges. This proposed scheme uses a conventional scheme for service quality class control. The following characterizes this proposed scheme: (1) it is suitable for real time call processing because it has small table search processing and a simple table search algorithm; (2) it realizes more accurate control due to a decreased data volume requirement and more precise data preparation than is the case for some of the conventional schemes; (3) it can be expanded easily to handle increases in the number of quality classes; and (4) it provides control in terms of statistic multiplexing effects between each quality class (also found in some of the conventional schemes). [ABSTRACT FROM AUTHOR]

Integrated train access protocol for a high-speed ring network is proposed in this paper. Using the concept of the train, synchronous and asynchronous traffic is integrated. To consider the fundamental performance, the periodicity of the channel activity is found in the steady state, and the cycle length is derived. On the basis of this cycle length, the tram length, channel utilization, and access interval of each traffic are derived. To characterize the proposed protocol more clearly, it is compared with fiber distributed data interface (FDDI), which uses the timed token scheme. As a result, it is shown that the proposed protocol and FDDI have the same high channel utilization. On the mean access interval of the asynchronous traffic, FDDI shows the increase character with the target token rotation time (TTRT), while the proposed protocol shows the decrease character with the number of asynchronous frames contained in the train γ. [ABSTRACT FROM AUTHOR]

In the ATM network, which handles such multimedia services as voice, video, and data, a traffic control technique must be established to cope with various requirements of the media for transmission quality. From such a viewpoint, this paper discusses the multiplexing control method which can control the quality. Through the discussion, a control method is proposed which multiplexes the multimedia with various quality requirements and the details of the method are presented. The proposed multimedia multiplexing method contains two control schemes: the polling control for the number of queueing cells with an offset; and the control by monitoring the queue length. The two control methods are switched according to the number of waiting cells of the medium in the severest condition so that the cell delay and the cell loss are controlled. Using the proposed design, the optimal hardware configuration can be derived from the input model the requirements. Based on the designed optimal hardware configuration, the multiplexing performance of the proposed control method is evaluated by a simulation. It is verified that the multiplexing performance meeting the requirement of each medium is obtained, and a higher throughput is obtained than the polling control without an offset or the queue length monitoring control, indicating that the proposed method is an excellent multiplexing control method. [ABSTRACT FROM AUTHOR]

Kron's Diakoptics is well known as a solution method of large-scale network problems by tiering. It interconnects all tiered subnetworks with tiered branches simultaneously by one step. We introduce Multistep Diakoptics (MSD), which interconnects tiered subnetworks partially with subsets of tiered branches step-by-step, and completes interconnections by multiple steps. By using the parallel computation method, the MSD algorithm uses less computation time than is the case with the standard Diakoptics algorithm. This paper introduces the MSD algorithm and the program that is executed by each computer in a multiple computer system and solves only a tiered subnetwork problem. We also explain the contents of data which must be transmitted to other computers. Furthermore, computation complexity, communication complexity, and organization of block data used in each computer for simulation of large-scale nonlinear networks are discussed, and a simple method for applying MSD in practice is introduced. It is concluded that, characteristically, MSD reduces the computation time in accordance with the number of computers if the data transmission time can be neglected. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the recent development of a gigabit data transmitter for the Belle-II pixel detector (PXD). The PXD is an innermost detector currently under development for the upgraded KEK-B factory in Japan. The PXD consists of two layers of DEPFET sensor modules located at 1.8 and 2.2cm radii. Each module is equipped with three different ASIC types mounted on the detector substrate with a flip-chip technique: (a) SWITCHER for generating steering signals for the DEPFET sensors, (b) DCD for digitizing the signal currents, and (c) DHP for performing data processing and sending the data off the module to the back-end data handling hybrid via Kapton flex and 12–15m twisted pair (TWP) cables. To meet the requirements of the PXD data transmission, a prototype of the DHP data transmitter has been developed in a 65-nm standard CMOS technology. The transmitter test chip consists of current-mode logic (CML) drivers and a phase-locked loop (PLL) which generates a clock signal for a 1.6Gbit/s output data stream from an 80cm reference clock. A programmable pre-emphasis circuit is also implemented in the CML driver to compensate signal losses in the long cable by shaping the transmitted pulse response. The jitter performance was measured as 25ps ( distribution) by connecting the chip with 38cm flex and 10m TWP cables. [Copyright &y& Elsevier]

A CMOS ultra-wideband impulse radio (UWB-IR) transceiver was developed in 0.18-µm CMOS technology. It can be used for 1-Mb/s data communications as well as for precise range finding within an error of ±2.5 cm. The power consumptions of the transmitter and receiver for data communication are 0.7 and 4.0 mW, respectively. When an LNA operates intermittently through bias switching, the power consumption of the transceiver is only 1 mW. The range for data communication is 1 m with BER of 10-3. For ranging applications, the transmitter can reduce the power to 0.7 µW for 1k pulses per second, and the receiver consumes little power. The transceiver design, all-digital transmitter, and intermittent circuit operation at the receiver reduce the power consumption dramatically, which makes the transceiver well suited for applications like sensor networks. The electronic field intensity is lower than 35 µV/m, and thus the UWB system can be operated even under the current Japan radio regulations. [ABSTRACT FROM AUTHOR]

The communication network of wide‐area protection may be interrupted because of the severe environment or artificial damage. The delay of communication will increase so much that the wide‐area protection cannot work normally in some severe cases mentioned above. That is one of the factors which affect the application of wide‐area protection. A reconstruction algorithm including different circuitous modes for different situations is proposed to maintain the transmission of the data on the interrupted channel. On the one hand, a single‐path circuitous mode is proposed when the data in the shut path is small. In this situation, the best circuitous path can be found out by Floyd considering the several reference factors affection. On the other hand, a multi‐paths circuitous model is proposed to solve the congestion which is caused by detouring under single‐path circuitous mode. The available margin of the bandwidth of the weakest channel called the short‐board channel in each circuitous path is the focus of the algorithm. In this situation, the optimal shunt coefficients are determined according to the bandwidth margin ratio of the short‐board channel. Then the data on the interrupted channel is divided into several streams based on the shunt coefficients. Therefore, the balance of the communication network can be ensured after the interrupted channel is divided. Finally, with OPNET communication simulation software, the IEEE14 nodes network is built. Delay and balance of system based on this reconstruction algorithm are tested. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In the videotex communication service system, a new matrix function is planned. The drawing pad may be used in writing the mail, where handwritten patterns can be accepted. However, this type of mall is composed of geometric information, and the conversion to pattern information (G/P conversion) is required in the communication device to produce the output processing in the communication device in the low-level terminal. This paper proposes a G/P conversion method (successive conversion), which suffers less delay in the start of the display and preserves the order of writing. In the successive conversion, the expansion of a geometric primitive and the transmission of the result of expansion are executed alternately. Only the rectangular region containing the part for which the expansion has been made is sent as the pattern data. The proposed method is applied to the drawing mail. It is shown that the processing required in the conversion is twice that of the straight system, where the result is sent after expanding all geometric primitives. It is also shown that the adequate speed of display for the character is 2.7 character/s, if it is displayed following the writing order. [ABSTRACT FROM AUTHOR]

This paper presents an outline of a prototype intelligent link system proposed to combine ‘data transmission’ and ‘data processing’ and its software system. The generative program and its processing scheme are reported in detail. The intelligent link is n pairs of a general-purpose pipe- line processing system. It is an n-stage one- dimensional line of segments which consists of a transmission line and a processor. Each segment processes received data by the programs which tag along with its data. In order to decrease the system processing time and the processor idle time, fewer bits are employed to represent a program for the information transmission. Here we use a transition matrix method to describe transition of the operations in a program. Firsts, we introduce the matrix properties and discuss applications of the matrix representation for generative programs. Secondly, we study how fewer bits can be used to represent a matrix and, as a result, find that less than 70% of the bits required to represent a matrix didrectly suffices in the proposed method. [ABSTRACT FROM AUTHOR]

In order to solve the problem of low accuracy in indoor positioning, a system based on ultra‐wideband and optimized time difference of arrival (TDOA) is designed. The optimized algorithm of TDOA is adopted to solve the problem of synchronization between anchors and improve the positioning accuracy. The use of LoRa technology for wireless data transmission between anchors improves the flexibility of anchor layout. According to the test, the system can work stably in corridors, rooms, warehouses and other scenarios, and the positioning error is controlled at about 13 cm. The positioning accuracy is 10 times that of the positioning system using WiFi and Bluetooth technology, which can meet the requirements of accurate mobile positioning in complex indoor environment. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

A classification‐based control approach is proposed for wireless networked control systems with lossy multipacket transmission. This approach takes advantage of a state reconstruction process to deal with the distinct feature of partial failure of data transmission caused by multipacket transmission, and then classifies the difference of the latest received system states and reconstructed ones to design a classification‐based controller. The closed‐loop stability of the system is proven using the switched systems theory. By considering more communication characteristics of multipacket transmission, the proposed approach is shown to give rise to a better system performance by a numerical example. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The article discusses Japan's telecommunications policy changes in the 1980's. In 1982 Japan's Public Telecommunications Law was amended and an important ordinance by the Ministry of Posts and Telecommunications (MPT) was issued. Interconnection of private and leased circuits to the public switched networks was authorized. The ordinance allowed privately-owned virtual area network (VAN) services, as long as they linked closely affiliated groups of small or medium-sized users. By 1984 Japanese firms reached technological equivalence with U.S. firms in telecommunications.

Recently serious natural disasters such as earthquakes, tsunamis, typhoons, and hurricanes have occurred at many places around the world. The East Japan Great Earthquake on March 11, 2011 had more than 19,000 victims and destroyed a huge number of houses, buildings, loads, and seaports over the wide area of Northern Japan. Information networks and systems and electric power lines were also severely damaged by the great tsunami. Functions such as the highly developed information society, and residents? safety and trust were completely lost. Thus, through the lessons from this great earthquake, a more robust and resilient information network has become one of the significant subjects. In this article, our information network recovery activity in the aftermath of the East Japan Great Earthquake is described. Then the problems of current information network systems are analyzed to improve our disaster information network and system through our network recovery activity. Finally we suggest the systems and functions required for future large-scale disasters. [ABSTRACT FROM PUBLISHER]

This article examines determinants of Electronic Data Interchange (EDI) adoption and integration in 76 U.S. and 93 Japanese automobile suppliers. The article constructs several hypotheses based on the transaction-cost and resource-dependence approaches and tests these hypotheses by data from these suppliers. Our study showed: (1) U.S. firms were more EDI-integrated with their customers, while Japanese firms adopted more EDI with their suppliers; (2) the resource-dependence approach seemed more effective in explaining EDI adoption, while the transaction-cost approach seemed more effective in explaining EDI integration; (3) the transaction-cost approach seemed more suited to the U.S. context, while the resource-dependence approach seemed more suited to the Japanese context; (4) EDI adoption had a positive impact on EDI performance in the U.S., suggesting the higher validity of our framework in the U.S. [ABSTRACT FROM AUTHOR]

Recent progress in single flux quantum (SFQ) device technologies in Japan is described, mainly focusing on those developed in the NEDO ‘Superconductors Network Device Project’ which includes developments of both LTS and HTS devices. The advanced Nb process which consists of a planarized structure with nine Nb layers and 10 kA/cm2 Josephson junctions (JJs) has been developed. This enables fabrication of chips including 100,000 JJs and operating frequency up to 80 GHz. We have also developed the CAD tool by which one can generate SFQ circuit layouts including about 400,000 JJs from logic descriptions. For demonstration of a small-scale switch system, a 4 x 4 switch chip, a 117 Gbps multi- chip-module (MCM) technology, and a packaging technology with 32-ch 10 Gbps I/Os to an MCM have been developed. By using the multilayer process with three HTS epitaxial layers and interface- engineered ramp-edge JJs, we demonstrated operation of SFQ circuits with up to 200 JJs. A variety of elementary SFQ circuits such as a T-FF and a 1:2 switch required for an A/D converter front-end circuit have been designed based on a new layout method, and their operation at 30-50 K has been confirmed. A prototype sampler system is being developed for demonstration of bandwidth over 100 GHz for optical input signals. [ABSTRACT FROM AUTHOR]

A simple and efficient available-bit-rate (ABR) control algorithm is described that fairly allocates bandwidth to each virtual channel (VC) in large-scale networks. In ABR control, the peak cell rate (PCR) and minimum cell rate (MCR) are specified at call set-up, and the cell-emission rate of each VC is controlled between them based on the explicit rate (ER) calculated from the traffic conditions at the ATM switches. Conventional control algorithms that do not use per-VC accounting allocate the same ER to all VCs. Therefore, if there is a VC with a PCR lower than the allocated ER, the control algorithm may not utilize the bandwidth effectively. A VC with an MCR higher than the allocated ER may suffer persistent congestion. Furthermore, algorithms that do not use per-VC accounting cannot achieve weighted bandwidth allocation. However, it is hard to implement algorithms that do use per-VC accounting in large-scale networks. The described ABR control algorithm makes it possible to maintain high throughput under PCR/MCR constraints and to achieve weighted bandwidth allocation based on the traffic conditions, without using per-VC accounting. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(9): 44–56, 2000 [ABSTRACT FROM AUTHOR]

In this article, we propose an orthogonally polarized multicarrier modulation system called orthogonal polarization and frequency division multiplexing (OPFDM) that transmits by making use of orthogonal polarizations in the orthogonal multicarrier modulation system called orthogonal frequency division multiplexing (OFDM). Since the adjacent subchannels are placed to the orthogonal polarizations in the proposed system, the main lobes of the frequency spectra within the same polarization do not overlap each other. Hence, the adjacent subchannel interference caused by random FM noise and frequency offset can be reduced. In this article, adjacent subchannel interference caused by random noise is derived by theoretical analysis. Further, by means of theoretical analysis and computer simulation, error-rate characteristics are obtained in order to evaluate the effectiveness of the proposed system. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(9): 57–66, 2000 [ABSTRACT FROM AUTHOR]

In spite of its low loss and superior power handling capability, the waveguide filter cannot have broad bandwidth due to the strong frequency dependence of the reactance values for coupling of the cavity resonators and the guide wavelength. To achieve a broadband design of the iris-coupled waveguide bandpass filter with the Chebyshev function as the transfer function, the susceptance value of the inductive iris is optimized by specifying the ideal zero frequency of the reflection. Based on this method, a diplexer is trial fabricated and a broadband diplexing characteristic is realized. In addition, agreement with numerical results is demonstrated, confirming the effectiveness and validity of the method. The tested diplexer has a VSWR of less than 1.24 and an isolation of more than 53 dB at passband bandwidths of 32 and 7% relative to the wavelength. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(7): 59–67, 2000 [ABSTRACT FROM AUTHOR]

A 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 sad decodes them all of a lump using the retransmitted frames of the fixed number. Numerical remits 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. [ABSTRACT FROM AUTHOR]

The article reports on the announcement of Alcatel-Lucent that research teams from the U.S. and France has successfully transmitted 25.6 Terabits per second of optical data over a single fiber strand using Wavelength-Division Multiplexed channels. The breakthrough in data transmission capacity adds to the company's list of terrestrial and submarine optical networking research milestones, including the first terabit transmission experiment. Involved in the research were scientists from the National Institute of Information and Communications Technologies in Tokyo, Japan.