bluuebunny/crossref_metadata_2025_split huggingface dataset:
An output‐buffered ATM switch in the multichannel bandwidth allocation environment
Authors: de Zhong Wen , Onozato Yoshikuni 
Published: July 2007

AbstractIt is desirable in the high‐speed broadband communication network to satisfy the high‐level requirements for the communication quality for various communication services while efficiently utilizing the communication network resources. From such a viewpoint, Pattavina proposed a multichannel bandwidth allocation scheme and constructed an input‐buffered multichannel ATM switch based on the forementioned scheme. This paper follows his idea and discusses the construction of a multichannel ATM switch with buffers at both the input and the output, a well as with the buffer only at the output.A periodic channel assignment algorithm is proposed, aiming at the balanced load allocation among the channels of the same output channel group. The proposed algorithm helps to share efficiently the resources (buffer and channel) of the same output channel group and to realize an economical use of the buffer. The performance evaluation is made for the case where the buffer is provided only on the output side. It is shown as a result that the cell loss probability and the buffer size required to satisfy the specified loss probability are greatly reduced with the increase of the group size. It is shown also that a better throughput‐delay performance is obtained than that of the input‐buffered multichannel ATM switch.
The helical loaded monopole antenna
Authors: Nakamura Kotaro , Nakamura Tetsuo 
Published: July 2007

AbstractMedium‐wave radio broadcasting in Japan has been disturbed by jamming from neighboring countries. To deal with this problem, consideration should be given to the use of numerous low‐power broadcasting stations, each with a rather narrow service area. A helical loaded monopole antenna is recommended for use in such stations. A field experiment was conducted using a model one‐tenth the size of the actual antenna. The antenna impedance was almost identical to the theoretical and the apparent efficiency was 32 percent at an antenna height of 0.1 wavelength.
Characteristics of CMA adaptive array for selective fading compensation in digital land mobile radio communications
Authors: Ohgane Takeo 
Published: July 2007

AbstractThis paper considers CMA adaptive array for the high‐speed TDMA transmission system using GMSK, which is the most ordinary constant‐envelope modulation system in the digital mobile land communication. A computer simulation is executed for the case where a four‐element adaptive array is applied to cope with the selective fading. CMA is employed as the array control algorithm, which is suited to the compensation of the constant‐envelope modulated signal. Assuming a model with two arriving waves, the convergence and the BER performances of CMA are evaluated. It is shown that the BER is improved greatly up to the limit that no more error can be reduced, compared to the case without an adaptive array. It is seen also that the error rate is improved better when the delay difference between the two arriving waves is large. Thus, the proposed method is shown to be an effective technique to cope with selective fading.
An efficient coding for Bi‐level facsimile images with dynamic arithmetic coding
Authors: Ohsawa Hidefumi , Kato Shigeo , Yasuda Yasuhiko 
Published: July 2007

AbstractIn the conventional coding of the facsimile signal, codes such as modified Huffman (MH) and modified Reed (MMR) codes have been used, where the statistical properties of the image are assumed as known and the image is assumed as stationary. In practice, however, it is not always adequate to represent the probabilistic structure of the image data by a single model. It is desirable to employ a code whose coding parameters can be adjusted according to the variation of the statistical properties. The arithmetic code can realize independently the symbol coding and the probability estimation, and the dynamic modification of the coding parameters is easy.From such a viewpoint, this paper proposes a new dynamic adaptive coding based on the arithmetic code. In the proposed method, the effective probability of the less probable symbol, which is the coding parameter of the arithmetic symbol, is selected from the values obtained by the approximation using a polynomial sum of the powers of 2. The algorithm of transition in each coding parameter is determined by considering both the static and the dynamic coding characteristics. In addition, a method is presented in which the decision about the stationarity is included, and the convergence from the initial value is improved by controlling the number of transition steps. As a result of simulation, it is seen that the proposed method can reduce the number of bits of the coded output by 27.2 percent on the average, compared to MMR coding.
An input buffer‐type ATM switching system using schedule comparison
Authors: Fan Ruixue , Akiyama Minoru , Tanaka Yoshiaki 
Published: July 2007

AbstractAn input buffer‐type, high‐capacity ATM switching system using schedule comparison is proposed for a high‐speed ATM switching system whose internal link speed is equal to trunk speed. Its throughput, delay, and loss characteristics are evaluated. The schedule of the input buffer to send cells and that of the output to receive cells are compared to decide the timing to send a cell so that there exists only one cell bound for the same output line.The maximum throughput (outgoing trunk efficiency) is more than 0.9, and the mean delay is less than 10 cell times. Moreover, if a doubled transfer network is used, higher throughput can be achieved and the delay characteristic is almost equal to that with an ideal output buffer type.A comparison of the proposed scheme with the output buffer‐type system under the same cell loss probability 10−5 reveals that the delay is almost the same and the required buffer size is one‐third. This characteristic holds even if the system size is extended to 4096 lines; hence, a super high‐capacity, high‐speed switching system can be configured with the proposed system.
Parallel processing scheme of the received data based on OSI protocols
Authors: Ishizaka Michihiro , Tsuchida Mitsuru , Ideguchi Tetsuo 
Published: July 2007

AbstractThis paper studies a parallel processing scheme for the OSI protocols in session layer and below to achieve high‐speed processing for the received data. First, technical issues are extended to exploit parallelism based on the layered structure of the OSI reference model. A basic parallel processing model including the distribution function for the received protocol data units (PDUs) and the synchronization mechanism is presented to make each microprocessor assigned to a layer execute the protocol processing for the received data in parallel.Next, the configuration of the distribution function is discussed with a particular emphasis on reassembling of segmented PDUs. Then a distribution processing scheme is proposed and algorithm is selected from the consideration on the separation processing corresponding to the concatenation of PDUs. Here, the issues are examined relating to execution of the proposed algorithm, such as the prevention of the disorder of the data unit sequence induced by the reassembling process.Finally, the characteristics of the parallel processing scheme are presented based on the proposed algorithm by comparing the communication performance with that of the ordinary sequential processing scheme by computer simulations.
Design of log‐periodic two‐stacked circular loop antenna
Authors: Korekado Toshikazu , Okuno Kiyoshi , Kurazono Sadao 
Published: July 2007

AbstractBy taking into consideration the high gain characteristics of a circular twin‐loop antenna and by distributing this antenna in a log‐periodic arrangement, an antenna with a wide bandwidth was proposed. Equivalent circuits for the loop part and its transmission line part were established to perform a numerical analysis. After examining its properties, data to design such an antenna were obtained. In particular, the reason why this antenna had a high gain and wide bandwidth through its current distribution was clarified.Based on the design data of this paper, an antenna was constructed and its performance was measured. As a result, its half‐power bandwidth was about 80 deg for the E‐plane and 45 deg for the H‐plane with a sharp directivity. Over a wide bandwidth of about 360 MHz for the 3‐dB bandwidth, VSWR was less than about 2.2 and the directivity gain was more than about 10 dB. From these data, the validity of the present design method was confirmed. Thus, at present, the proposed antenna is a wideband antenna with a structure that has the highest gain.
Slotted aloha with PCT (power control during transmission) scheme using capture effect
Authors: Mutsuura Kouichi , Okada Hiromi , Tezuka Yoshikazu , Ohtsuki Kazuhiro 
Published: July 2007

AbstractThis paper proposes two new access protocols, wherein the power control during transmission (PCX) scheme attempts improvement of the throughput by capture effect; this scheme is applied to s‐ALOHA. Either method solves the problem of contradiction between the packet transmission time difference required in PCT scheme and the synchronized transmission as the basic requirement in PCT scheme and the synchronized transmission as the basic requirement in s‐ALOHA.The first protocol is the s‐ALOHA with capture interval (s‐ALOHA/CI), which is concerned with the fixed‐length packet format. A capture interval is provided in the first part of the slot, wherein the transmission time is selected at random to provide the transmission time difference.The second protocol is s‐ALOHA with tail synchronization (s‐ALOHA/TS), which is concerned with the variable‐length packet format. Utilizing the variable‐length property, the tail of the packet is synchronized to the tail of the slot and the packet is transmitted. Then the packet length difference produces the transmission time difference. It is verified through evaluation by analysis and simulation that the throughput performance of traditional s‐ALOHA is greatly improved in either protocol by the capture effect. Especially, in contrast to the deterioration of the effective throughput of the traditional s‐ALOHA due to the slot loss, it is verified that the performance of s‐ALOHA/TS is better than that of the fixed‐length packet scheme. These high‐performance protocols will serve as a powerful means of realizing the effective operation of VSAT network, etc., with the synchronization function.
A new pulse echo fault location method using waveform pattern matching for paired subscriber cables
Authors: Takeda Kazutoki , Kawashima Makoto , Koga Hiroaki , Hayashi Akira 
Published: July 2007

AbstractA pulse echo wave tester can locate a fault in paired cables. However, when a paired cable comprises branched cables and different types of wire gage along a length, the pulse echo tester cannot detect faults because of complicated pulse echo waves.This paper describes a new pulse echo tester which can locate a fault by the correspondence between measured and calculated pulse echo waves in case of such complicated cable structures.First, we derive a calculation method of pulse echo waves in complicated cable structures. The fault is located by the condition that the difference between measured and calculated pulse echo waves becomes the minimum value. Next, location errors and the distance limitation of a fault location are described considering variations of cable parameters. It is clarified that the distance limitation of a fault location depends mainly on a pulse period. In the experiment, the fault is located in a 2‐km paired cable with a branched cable. As a result of this test, a fault location error is about 10 m.
Topologies and characteristics of DC‐DC converters using class E resonant switch
Authors: Gu Wen‐Jian , Harada Koosuke 
Published: July 2007

AbstractA class E resonant switch is developed from the conventional class E resonant converter. Using the class E resonant switch instead of the PWM switch, a new family of class E resonant converters is proposed. Assuming the current flowing through the tuned network of the converter is a pure sinusoidal waveform, the characteristics of the converters are analyzed using Fourier series expansion. As a result, it is known that a class E resonant converter can convert a constant voltage to a constant current or vice versa and the output regular can be accomplished over a narrow band of switching frequency. The operation principle and the analysis are verified by experiments on 2‐MHz converters.
A construction of optimum vector quantizers by simulated annealing algorithm
Authors: Kodama Hideo , Wakasugi Koichiro , Kasahara Masao 
Published: July 2007

AbstractVector quantization is known widely as a highly efficient coding for image and speech signals. The algorithm proposed by Linde, Buzo, and Gray (the LEG algorithm) is the most fundamental design procedure for this kind of quantizer. However, the LBG algorithm usually gives only the local minimum of the distortion measure based on the quantization error.With such a background, this paper introduces the simulated annealing procedure into the design of the vector quantizer based on the LBG algorithm, which is known as the effective method for the NP‐complete probabilistic combinational optimization problem. The widely employed mean‐square error is adopted as the distortion measure. Various approaches are considered to derive the global minimum of the measure.In other words, this paper is based on the LBG algorithm and presents a design procedure for the vector quantizer (more generally, the vector quantizer considering the channel error) by introducing simulated annealing. By this approach, a vector quantizer with a better performance than the traditional design as well as a more ideal highly efficient coding is realized. A simulated experiment is executed for the standard image data (SIDBA), and it is demonstrated that the simulated annealing is useful in the design of the vector quantizer.
An approximate solution of electromagnetically coupling microstrip dipole arrays
Authors: Kominami Masanobu , Yakuwa Naoki 
Published: July 2007

AbstractIn the computer‐aided design of an electromagnetically coupled (EMC) dipole array, approximate methods are very important for high‐speed and accurate evaluation of mutual coupling between the feed line and the dipole or in between the dipoles.In this paper, using the approximate moments method which is based on equivalent permittivity determined by quasi‐static analysis of a microstrip line, the EMC dipole array is analyzed and methods of evaluating various characteristics are studied.Moreover, the validity of this method is confirmed by comparing the results for the open end conductance of the microstrip line, the equivalent shunt impedance of the EMC dipole and the radiation pattern of the seven‐element EMC Chebyshev array, with the measured values and with the exact values obtained by full‐wave analysis. With the help of this method, the dynamic analysis, which includes the radiation coupling, can be performed with high speed. Thus, this method is effective to analyze the EMC dipole array with a large number of elements.
Convolutional coded continuous phase modulation with modified phase‐pulse signals
Authors: Ito Toshiyuki , Sasase Iwao , Mori Shinsaku 
Published: July 2007

AbstractThe continuous phase modulation method (CPM) has the property that the phase of the modulated signal changes continuously. This modulation method requires smaller bandwidth and is useful in satellite communication. In the partial response CPM, the signal is modulated by overlapping a number of phase‐pulse signals with longer pulse length than the symbol interval. This results in an advantage wherein the phase of the modulated signal changes more smoothly, resulting in a smaller bandwidth than the full‐response CPM. On the other hand, the phase of the modulated signal is given as the synthesis of more than one pulse. This makes the signal easily affected by the noise, and a coding is required to improve the error rate.This paper considers a convolutional coded CPM and discusses the effects of the waveform of the phase‐pulse signal on the error rate and the bandwidth, aiming at the determination of the trellis coded partial response CPM with excellent error rate and bandwidth performances.First, the effect of the waveform of the phase‐pulse signal in the convolutional coded CPM on the minimum Euclid distance and the 99‐percent bandwidth are examined. Then the trade‐off between the minimum Euclid distance and 99‐percent bandwidth of the proposed method is compared with other methods, including the traditional methods using L REC and L RC. The waveform of the phase‐pulse signal with excellent error rate and the bandwidth performances is indicated. Then the effect of the waveform of the phase‐pulse signal on the state trellis of CPM is discussed, in general, and the conditions for the phase‐pulse signal to improve the error rate are presented.
Underlying concept for network architecture
Authors: Hoshi Motoo , Sato Fumito , Inoue Yuji 
Published: July 2007

AbstractThe telecommunications network environment is moving toward rapid development of diverse services in response to several factors; for example: user needs; the introduction of advanced and efficient operations, maintenance and administration (OAM); the coexistence of multiple carriers as a result of telecommunications industry liberalization; and the use of telecommunications systems from multiple vendors driven by the increased strategic role played by the telecommunications and information industry. To enable telecommunications networks to evolve in an orderly manner under this changing environment, it has become necessary to establish network architecture.This paper presents the basic concepts used in network architecture, a framework of architectures (each representing various aspects of networks), and technologies that can be applied.
Recent research and development activities on spread spectrum communication systems
Authors: Marubayashi Gen 
Published: July 2007

AbstractThis paper reviews recent worldwide activities concerning research and development for spread spectrum communication technologies. Included are various novel proposals, results of analysis, and experimental results concerning spreading code, synchronization, device, system construction, and applications to consumer and mobile communications.For the spreading code, however, two invited papers are presented in this special issue and hence only a brief explanation is made here. Instead, considerable space is devoted to the recent progress toward development of CDMA public land mobile telecommunication systems in the United States.
Spread spectrum communication demodulator using SAW devices
Authors: Takehara Kazuyuki 
Published: July 2007

AbstractSpread spectrum communication is a system suited to a communication system with deteriorated transmission quality. Recently, its application to a simplified wireless communication system has been considered for consumer communication and in other areas. The demodulation of the spread spectrum signal, in general, is complex due to the requirement of establishing the accurate synchronization for PN code in low S/N condition. A technical problem in spread spectrum communication is to realize those circuits with as simple a configuration as possible.This paper presents a simplified configuration to solve this problem by employing two SAW devices as the matched filter and the delay line in the demodulator. The synchronization capture time also is reduced. First, the design and the result of experimental construction for the SAW matched filter which plays the core role in the demodulator are discussed. Then the construction of the small‐sized demodulator using this SAW device is discussed. Finally, a discussion is presented of the synchronization capture performance, BER performance with the thermal noise and the interference immunity performance against the interference by CW and other spread spectrum signals of the proposed demodulator. It is shown that the low‐cost demodulator for spread spectrum communication can be realized and is also applicable to packet communication.
Extraction and reinjection‐type interference canceller
Authors: Watanabe Kazuji , Murase Takehiro , Matsue Hideaki 
Published: July 2007

AbstractIn conventional interference cancellers, an auxiliary antenna has been used to obtain only an interference signal whose amplitude and phase was then adjusted to cancel out the interference in the signal received by the main antenna. In fact, however, conditions under which an auxiliary antenna can be used to receive such an interference signal necessary for cancellation are limited; and in all other cases, interference cannot be cancelled.In the interference canceller proposed in this paper, a signal consisting of the desired and the interference signal is received by both the main antenna and the auxiliary antenna, and the interference signal is extracted from the received signal using both antennas; interference is then cancelled using this extracted signal.First, the theory behind the operation of this canceller is presented and its configuration is described. Then the results of an experiment using a 16‐QAM signal as the desired signal and an FM (CH 3600) signal as the interference signal are presented. An improvement of about 17 dB has been obtained with regard to interference which cannot be cancelled out by conventional cancellers, thereby validating the operational principles of the proposed canceller.
An equalizer with carrier‐acquisition‐during‐training (CAT) algorithm for mobile radio
Authors: Yoshino Hitoshi , Ueda Takashi , Suzuki Hiroshi 
Published: July 2007

AbstractThis paper investigates an adaptive equalizer with carrier frequency offset compensation for digital mobile radio transmission over several tens kbit/s. The performance of conventional adaptive equalizers for mobile radio severely degrades for receiving signals having carrier frequency offset which is caused by local oscillator frequency offset due to misadjustment, temperature dependence, and aging.Carrier frequency offset compensation for TDMA burst signaling requires both accurate and short‐time measurements. However, both requirements have a tradeoff relationship and must be optimized.This paper proposes the carrier‐acquisition‐during‐training (CAT) algorithm for transmissions allowing a training signal. First, two basic configurations and their equivalence are discussed. Next, computer simulations and real‐time experiments with one‐chip DSP show the effectiveness of CAT by demonstrating training convergence, optimum parameter characteristics, and average BER performance under two‐path selective fading with one‐symbol delay difference and independent Rayleigh components.