bluuebunny/crossref_metadata_2025 huggingface dataset:
Scattering of electromagnetic plane waves by two parallel finite planes
Authors: Shimoda Michinari , Itakura Tokuya
Published: July 2007

A scattering problem of two parallel conducting plates of finite widths is analyzed by a new formulation. It was shown that an analysis of multiple scatterings by a system of parallel plates can be obtained formally by the representation of the scattered fields by one plate. The representation was derived for scattered waves using Wiener‐Hopf simultaneous equations which must be satisfied by each scattered field. Through an approximate integral by the saddle point method, we obtained numerically the diffraction patterns concretely for the far‐field diffracted waves. In a case where the distance between edges of parallel plates is almost or more than one wavelength, we showed that a system of conducting plates can be analyzed taking into account multiple scatterings by the present formulation.
Chase's second algorithm using received carrier level as CMI for decoding block codes in mobile data communication
Authors: Matsumoto Tadashi
Published: July 2007

In digital mobile radio, it is well known that the error control by block codes is effective for improving the code error performance in the multipath fading channel. Chase has proposed efficient soft decision decoding algorithms for block codes. In this paper, the word error rate performance of Chase's second algorithm using the received carrier level as CMI (channel measurement information) is described in the Rayleigh fading. First, the upper and lower bounds of the word error rate in the Rayleigh fading channel are derived theoretically assuming independent variations of received carrier level corresponding to each bit in a received block. The computer simulation results agree well with the theoretical results. Next, for the case where received carrier level variations are correlated, the word error rate performance is obtained by computer simulation using the Golay code as an example, and the bitinterleaving size required to make the variations of the received CNR statistically independent, and to randomize the errors occurring in a received block is calculated.
Delay and jitter property of mutually synchronized networks using complete digital plls
Authors: Luan Zaihua , Mori Shinsaku
Published: July 2007

This paper discusses the effect of delay propagation in the mutually synchronized network using completely digital PLL. A difference equation is derived with the risetime differences among nodes as the variables. The dynamical properties of the mutually synchronized network including the propagation delay, the steady‐state and the jitter characteristic are derived. As a result, the following properties are demonstrated. When the delay is less than half of the steady‐state period, the dynamical property and the jitter of the network are the same as those of the network, without delay. However, when it is larger than the half‐period, the dynamical property and the jitter of the network are affected by the delay. It is also shown that the jitter suppression of the N‐node mutually synchronized network is approximately proportional to the number of nodes N.
Quantities of higher‐mode generations in linearly tapered waveguides
Authors: Suga Takashi , Shirasaki Hirokimi , Ishihara Fujio
Published: July 2007

When the electromagnetic field method is used in analyses of tapered waveguides, solutions can be obtained with the same degree of accuracy inside or outside the cutoff regime. If the length of a taper is of the order of, or more than, the wavelength, we need to consider only the fundamental mode in practice. However, we cannot neglect the influence of higher‐order modes if the length is shorter than the wavelength. We must examine the quantities of higher‐order mode generations.
Fault recovery processing in a switching control multiprocessor
Authors: Yamada Takahiko , Ogawa Satoshi , Suyama Masato , Hori Yoshinori
Published: July 2007

For a switching system which must operate 24 hours a day with high reliability, the requirements are secure recovery from a fault and minimization of the effect of the fault recovery (i.e., system down time). On the other hand, when a multiprocessor system is employed, competition may be produced among processors, leading to complex and difficult problems in the fault recovery. Several techniques are shown in this paper concerning the following points: (1) local fault processing in the unit processor; (2) the upper‐level fault processing, realized by combining the local fault processing; and (3) improvement of reliability of the fault recovery by a hierarchical monitoring of the overall system. With regard to the effect of the fault recovery, the factors affecting the down time are analyzed. The relations among those factors, the performance of the processor, and the fault rate are modeled. The effect of the fault recovery is compared between the proposed system and the existing single‐processor control system. As the result of comparison, it is shown that the proposed multiprocessor control system can localize the effect of the fault, and is more desirable than the traditional single‐processor control system.
FDM‐FM interference evaluation on digital radio‐relay systems
Authors: Sango Jun‐Ichi
Published: July 2007

One of the factors determining the performance of the digital radio‐relay system is the interference from the existing FDM‐FM systems. Traditionally, the FDM‐FM interference characteristics have been evaluated by analyzing the effect on the error rate by the interference wave which is approximated by a sinusoidal wave. The method tends to underestimate the effect on the error rate in a digital system when the analysis is compared with the case where an interference wave is actually given. This paper proposes a method for evaluation in which the FDM‐FM interference wave is divided into the carrier and the sideband components. Based on the new method, the interference characteristics have been analyzed. It is found from a laboratory experiment that the present evaluation method is valid.
Malfunction of digital circuits caused by noise induced in breaking electric contacts
Authors: Uchimura Keiichi , Michida Junji , Nozu Shinji , Aida Teizo
Published: July 2007

The malfunction of a digital circuit has been investigated from the viewpoint of the IC as its constituent. However, little has been reported from the viewpoint of electrical contact which is one of the principal causes of the malfunction. In the research reported here, simple automatic measurement equipment has been developed which counts the malfunctions of a digital circuit. Measurement has been done with this equipment under various circuit conditions. As a result, it was found that malfunctions of digital circuits not only increase with the load circuit current, but may decrease when the circuit current exceeds a certain value depending on the parallel capacitance between contacts. As the parallel capacitance between contacts increases, the region in which malfunctions are likely to occur shifts toward a larger current side. It was found that these elements are related closely to the region of showering arc generation which is one of the discharge modes at the time electrical contacts open. Also, since the parallel capacitance between contacts is larger, the 0 percent malfunction rate is approached while the wiring spacing between the inductive and induced wires is closer. For this characteristic, the frequency spectrum of the dielectric breakdown region of the showering arc voltage waveform has been derived.
Accuracy of XPD measurement at the CS‐2 experimental earth station related to satellite tracking systems
Authors: Maekawa Yasuyuki , Chang Nion Sock , Miyazaki Akira , Segawa Tetsuro
Published: July 2007

The problems in measurement of the beacon wave XPD are pointed out when the satellite is tracked automatically by the step tracking method in the CS‐2 operation test station. Since the antenna is driven on a trial‐and‐error basis in the step tracking system so that the beacon receiving level always increases, measured values of the beacon receiving level and the XPD vary during the tracking operation. If the tracking operation is performed periodically at a constant time interval to avoid these unwanted variations, the pointing error of the ground station antenna to the satellite during this interval causes degradation of the antenna gain and the XPD. In this paper, the antenna pattern of the ground station antenna is measured. In addition, the characteristics of the location variation of the satellite on the elevation and azimuth angles are determined. The reduction of the maximum beacon receiving level and the XPD degradation are computed which are likely to occur if the tracking interval is 10 ‐ 210 min. It is pointed out that the satellite tracking must be done at least once every 50 – 90 min to perform the on‐propagation‐path XPD measurement in the satellite channel with an estimated accuracy of about 40 dB.
Reflector error of large deployable antennas and its effects on radiation characteristics
Authors: Takano Tadashi , Ui Masaaki
Published: July 2007

There is a need for large deployable antennas with diameters larger than 10 m for space‐VLBI satellites and mobile communication satellites. Several deployment mechanisms have been proposed, each of which uses determined lines and points on a smooth prototype reflector surface. The basic structure is to use the reflector surfaces which are located between them as meshes or films.

This paper examines types of mechanical errors of a deployable antenna and its relation with the radiation characteristics. Its effects on the radiation characteristics are shown numerically. As a result, it is shown that the gain reduction is less than 0.18 dB by subdividing the reflector surfaces by equilateral triangles whose side is about one‐eighth the radius for a 2‐GHz band tension‐truss type antenna of 15 m diameter. With a penalty of an additional 0.1 dB, the number of approximating triangles can be reduced by about 30 percent by subdividing the outer portion of the reflector twice as roughly as the interior portion. However, it is important to add phase offsets.

It is shown that grating lobes appear in the sidelobe characteristics due to the periodic errors. The relationship between mechanical error and the effective error of the reflector surface is also clarified.
An experimental system of two‐dimensional tat bandwidth compression for television signals
Authors: Tanimoto Masayuki , Kageyama Masahiro , Murakami Masayuki
Published: July 2007

In the TAT (time‐axis transform) picture bandwidth compression system the pixels are selectively utilized. Because of its high reproducibility of the details of a picture, an application is expected to the bandwidth compression of HDTV (high‐definition TV) and other pictures of high quality. In the one‐dimensional (1–D) TAT system, the pixels are reduced and interpolated along the horizontal direction. This paper reports on the two‐dimensional (2–D) TAT system which reduces and interpolates the pixels not only in the horizontal direction but also in the vertical direction. Using this system, a system for the color TV signal with 7–MHz bandwidth was constructed, which compresses the bandwidth to one‐half in real‐time. Compared with the 1–D system, the number of modes is reduced from 3 to 2, and the size of the block is increased from 8 to 16 pixels. Then the mode information is reduced to approximately one‐third the 1–D system. On the other hand, a faithful picture is obtained with little degradation of resolution both in moving and still pictures. Sometimes a flicker is observed due to the time‐variation of the mode in the reconstructed picture, which can be suppressed by the new mode decision scheme with a hysteresis.
Multiphase pulse counting FM demodulator
Authors: Sawahashi Mamoru , Yamao Yasushi , Murota Kazuaki
Published: July 2007

A new pulse counting FM demodulator which requires no extra outer part and is suitable for monolithic circuit integration is proposed. Although a pulse counting FM demodulator composed of digital logic circuits is suitable for monolithic circuit integration, it is difficult to realize high demodulation sensitivity with a quadrature demodulator or a Foster‐Seeley demodulator. Considering the application to narrowband FM mobile radio communication, a new FM demodulator based on multiphase pulse counting (MPC) scheme is proposed. The proposed demodulator has demodulation sensitivity nearly equal to that of existing demodulators, requires no adjustment, and has a low distortion rate. Its mechanism and circuit configuration are described. Basic characteristics, especially the demodulation sensitivity improvement, are then theoretically analyzed. Demodulation sensitivity and demodulation SINAD characteristics are experimentally validated; finally, single‐chip monolithic circuit integration of the MPC‐FM demodulator is prefabricated and its feasibility is shown.
A new channel assignment scheme in demand‐assignment radio communications system
Authors: Tajima Jun
Published: July 2007

To make the utilization of radio frequencies more effective, a large number of investigations has been made from the viewpoints of frequency, space, and time. Among the forementioned investigations, relatively few studies are from the viewpoint of time, and thus a new approach is desired. At present, a multiplicity of services are provided; these include mixed analog‐digital communications, and the approach from this viewpoint should be emphasized more. With this as background, this paper discusses the effective utilization of the frequencies in the demand‐assignment radio communication system, and proposes a new control scheme for the radio channel assignment. The technique described here is based on the hand‐off (channel switching) technique in the mobile communication system. By applying the technique to “pack” the radio communication traffic, a drastic improvement in the frequency utilization efficiency is demonstrated. As typical demand‐assignment systems, the radio communication system with heterogeneous calls with the same transmission bandwidth, and the system with heterogeneous calls with different transmission bandwidth are considered. The application of the proposed technique to those systems, as well as the behaviors of the systems, are discussed in detail, both by theory and computer simulation.
Half duplex optical communication system using an LED as source‐and detector‐device
Authors: Enomoto Masayoshi , Nakano Minoru , Matsushita Kenji , Shimizu Eiji
Published: July 2007

Although optical fiber communication systems have recently been utilized in many fields, most of these have been realized by using a light source‐detector pair. Therefore, two fibers have been needed for bidirectional communication. Alternately, for small‐scale systems such as communication between personal computers and measuring systems, for which not too high a speed is required, a single‐fiber half‐duplex optical communication can be realized by using an LED as source and detector. However, the LED as source stores many excess charge carriers, and the LED as detector has a large depletion capacitance. Therefore, the transceiver must be constructed to minimize these effects for possible high‐speed communication.

This paper proposes a transceiver applied to a multivibrator, which has both functions of switching between transmitting‐ and receiving‐mode and modulating the data to FSK signal. The characteristics of trial system including the methods of data‐input and demodulation are investigated. Although the transmitting speed by the proposed method depends on the LED characteristics, we have established a transmitting speed of about 200 k‐bit/s in unidirection by the trial system.
Theoretical analysis of error sequence characteristics in digital land mobile radio channels
Authors: Sasaoka Hideichi
Published: July 2007

It is important to clarify error sequence characteristics in digital land mobile radio channels with memory for accurate performance evaluation of error control schemes such as error correction coding. This research deals with the theoretical analysis of error sequence characteristics in digital land mobile radio channels with very slow Rayleigh fading. First, the digital channel model is studied on the basis of the error generation mechanism in digital land mobile radio channels and the analytical model is simplified, assuming that the envelope fading effect is dominant and fading rate is very small. The quasi‐static approximation method is applied to simplify analysis. Numerical expressions of gap probability and joint gap probability, which are important in making the mathematical model of error process, are derived for binary PSK under the Rayleigh fading environment. The calculated result from the anlytical model and the experimental measured result from the laboratory experiment are shown to agree well when the effect of fading variation is small.
Lowpass type quasi‐optical diplexer by rectangular metallic patch array
Authors: Iwata Ryuichi
Published: July 2007

This paper investigates theoretically and experimentally a rectangular metallic patch array as a low‐pass quasi‐optical diplexer. By complementary principle and experiment, it is demonstrated that the brick arrangement of rectangles is also available for broadbanding. In a previous paper the author proposed such an arrangement for high‐pass quasi‐optical filters by rectangular mesh.

Also, the method of analysis for the dielectric multilayered patch array is presented, and the design method for the diplexer based on the analysis is described. The validity of the analysis and the design method are confirmed by experiment.
Multifrequency dipole antenna with closed‐spaced parasitic elements
Authors: Ebine Yoshio , Kagoshima Kenichi
Published: July 2007

It is shown theoretically and experimentally that a multifrequency dipole antenna can be realized by placing parasitic elements close to an excited element. Numerical data for two‐frequency and five‐frequency operations are presented. In the theoretical analysis, current distribution along both the excited and parasitic elements are calculated, and it is verified that large density current is induced on the parasitic element, as well as on the excited element.

It is also shown that the length of a parasitic element should be less than about 1/1.2 of the excited element to realize a new resonant frequency. Calculated results of the radiation pattern in the horizontal plane are also presented.
A microstrip antenna of circular polarization over wide angles using λ/4 short‐circuit patches
Authors: Chujo Wataru , Teshirogi Tasuku
Published: July 2007

In mobile communication using a satellite, it is required to use a mobile antenna which has a circular polarization with a good axial ratio over wide angles. If a conventional microstrip antenna is used as an element antenna, it is difficult to improve the axial ratio over a broad angle even if a good axial ratio is obtained in the boresight direction. This paper investigates a circularly polarized microstrip antenna with a good axial ratio over wide angles. A method is proposed in which a combination of λ/4 short‐circuit microstrip antennas and the principle of operation is confrimed experimentally. First, it is shown that a good axial ratio cannot in principle be obtained over wide angles, since the directivity is restricted by the permittivity in a conventional microstrip antenna.

Next, configurations and characteristics are presented for combinations of rectangular λ/4 short‐circuit microstrip antennas and circular λ/4 short‐circuit microstrip antennas suitable for obtaining a good circular polarization over wide angles. Conditions for a good axial ratio over wide angles are presented for both rectangular and circular structures. Further, experiments have been carried out for combinations of circular λ/4 short‐circuit microstrip antennas. Performance observed is the axial ratio less than 2 dB over wide angles of $60 degrees.
A broadband ATM switching system
Authors: Murakami Koso , Hajikano Kazuo , Abe Shunji
Published: July 2007

This paper proposes a switching system for the broadband integrated service digital network (B‐ISDN). The proposed system uses self‐routing and a multistage switching configuration. Asynchronously arriving information blocks are switched one by one at high speed. This configuration suppresses cell collision that can occur in asynchronous transmission. This paper describes the system configuration, a technique for designing the system's basic parameters, and system effectiveness.
Coding parameter optimization for the block truncation coding of still pictures
Authors: Ishibashi Satoshi
Published: July 2007

Block truncation coding is a highly efficient compression coding for the natural picture. It is useful in reducing the cost for storage and transmission of full‐color still pictures, such as those in the picture data base and the videotex. In the application of the highly efficient compression coding to the practical system, it is required to adjust the coding complexity and the picture quality, according to the cost and quality of the service provided by the system. From such a viewpoint, this paper discusses the control of the coding parameters, which determine the coding condition, and then the optimization of the coding parameters, to arrive at the coding complexity and the picture quality to meet the requirement.

First, the traditional adaptive block truncation coding is extended to improve the coding efficiency and to expand the realizable range of coding complexity and picture quality. Then the control of coding is discussed which determines the coding parameter values in an adaptive and automatic way, according to the required picture quality and the property of the object picture in the considered system, to arrive at the desired quality. It is shown that it is possible to realize the coding with the desired quality simply by specifying SNR, independently of the property of the object picture.
Significant digit requirement for fm demodulation using digital signal processing
Authors: Kondo Shoji , Hattori Masaaki , Akiyama Hideki
Published: July 2007

The effect of the number of significant digits on the demodulator output noise is analyzed and examined by a simulation in relation to the FM broadcasting system specification. The quantization noise Nq generated at A‐D conversion of IF signals is regarded as a white Gaussian noise similar to the thermal noise Nz fed to a receiver input. From the condition of C/Nz satisfying the broadcasting specification, Nq such that Nq Ni‐ 10 [dB] is obtained and then the quantization precision satisfying this condition (being translated into the precision at the output of a digital signal processing demodulator) is obtained. As a numerical example, it is shown that only 6‐ and 9‐bit precisions are necessary for monophonic and stereophonic reception, respectively. The simulation result agrees with the numerical result. Reduction in the number of filter taps at the demodulator with the introduction of a window function is also studied. Given the system specification, the obtained result is also applicable for digital FM demodulators of any use.
Network constructing algorithm based on link significance evaluation‐nable
Authors: Ikeuchi Noriyuki
Published: July 2007

A new network design algorithm called “NABLE” (network constructing algorithm based on link significance evaluation) is proposed for constructing future circuit‐switched telecommunications networks. First, this algorithm creates synthetically a backbone network by utilizing a new concept called “link significance.” Then it adds other links to the created network. The flowchart for constructing a network based on this concept is explained. Design examples on digital 64 kbit/s and high‐speed/ broadband circuit‐switched networks show that NABLE is a powerful heuristic algorithm for total network optimization. NABLE can be used in practice for the long‐range planning of various types of networks.
Design and implementation of protocol conversion equipment for layered protocols
Authors: Ideguchi Tetsuo , Nonmember Yuuji Koui, , Tsuchida Mitsuru , Nonmember Yukio Ushisako, , Ishizaka Michihiro
Published: July 2007

In the information communication system it is necessary to establish the protocol conversion, network connection and media conversion techniques to realize communications among computers and terminals with different communication protocols. This paper considers the hierarchical protocol defined based on the OSI basic reference model, and discusses the protocol conversion method together with its realization. A versatile method is introduced in the proposed hierarchical protocol conversion system, in which a protocol conversion can be made from PAD function for various terminals as well as from the nonprocedural level to the personal computer communication protocol recommended by the Ministry of Posts and Telecommunications. The protocol conversion equipment developed based on the proposed idea is demonstrated, and its usefulness is indicated.
Test sequence generation method for systems‐based finite automata–single transition checking method using w set
Authors: Sato Fumiaki , Munemori Jun , Mizuno Tadanori , Ideguchi Tetsuo
Published: July 2007

When testing communication systems, it is necessary to select the test sequence from the specification. Since the test sequence must be selected manually, the confidence in the testing is low and the testing cost is high. Therefore, we are studying a tool to generate the test sequence automatically from the state table, based on a finite state machine (FSM) model.

The PW method and the DS method are presently used to generate a sequence that has a great error detection capability. However, both the PW method and the DS method have disadvantages.

This paper presents a new method for the generation of the test input sequence for a system based on an FSM. The method is called the SW method (single transition checking method using W set), and uses the state transition checking approach and the characterization set (W set) for state distinction. This paper also presents an evaluation of this method in terms of its generated test sequence length, its error detection capability, and its general applicability. The results of the evaluation show that the SW method improves some of the weak points of the existing PW and DS methods.
Theoretical analysis of optical fiber strength by bending test
Authors: Tachikura Masao
Published: July 2007

The bend strength of an optical silica fiber tested by deforming fibers in a U‐shape in a pair of parallel plates has been analyzed theoretically by considering the dynamic fatigue of fibers. By assuming that the fiber initial strength follows Weibull distribution, the following results are obtained:

The bend strength follows Weibull distribution but the Weibull exponent is different from that of the tensile strength.

The fatigue constant n of fibers can be evaluated by using the bending velocity dependence of the bend strength.

The distribution of the bend strength can easily be translated into the tensile strength by an approximate calculation without integration.
Automatic pursuit routing for mobile communications network
Authors: Nakajima Akihisa , Yamamoto Koji , Sawada Hiroshi
Published: July 2007

This paper describes an automatic pursuit routing capability necessary for a public land mobile network because mobile stations move freely through service areas. The purpose of pursuit routing is to automatically deliver calls to the called mobile station through the best route. Callers can dial without knowing the actual location of the called mobile station. Automatic pursuit routing requires three logical functions of the mobile communication control center (MCC): the gateway MCC, the home MCC, and the visited MCC. The charging method, numbering plan, and the signaling architecture for implementation are also described, and the effects of the APR and the MCC logical function capabilities are discussed.
Survey on traffic control in atm networks based on traffic theory
Authors: Murata Masayuki , Miyahara Hideo , Oie Yuji
Published: July 2007

This paper presents a survey on the result of researches on the traffic control in the ATM network, together with future problems. In the ATM network, all data are transmitted, being divided into fixed‐length blocks of several tens Bytes called cells. Consequently, a new traffic model is required which is different from the conventional models.

As the traffic model suited to the ATM network, this paper discusses first the model which considers the burstiness of the traffic. The purpose in constructing an ATM network is to provide an efficient channel for various media with diversified traffic patterns, from the low speed to the high speed, in the multimedia environment by utilizing the effect of the statistical multiplexing.

Next, the traffic multiplexing effect is discussed considering the burstiness of the traffic. Finally, as the traffic control required in the ATM network to satisfy the “communication quality depending on each medium,” a control method is discussed which considers more than one processing class.
Cell loss protection using hierarchical coding in video packet communication
Authors: Katto Jiro , Yasuda Yasuhiko
Published: July 2007

As a promising means of realizing broadband ISDN, the ATM (asynchronous transfer mode), which is based on fast packet switching, is considered interesting. In video communication by ATM, the constancy and improvement of picture quality by variable rate coding is expected, while the quality deterioration by cell loss is a serious problem.

This paper proposes a video coding method introducing hierarchical coding to cope with the cell loss problem. The proposed hierarchical coding extracts the low‐frequency components of the image by iterating the hierarchical processing based on the spatial filter. Then it is possible to suppress the effect of the quality deterioration caused by cell loss, as long as the low‐frequency components are retained.

First, the configuration of the proposed system is discussed. Simulations are executed to observe the effect of the cell loss and the coding characteristics, demonstrating the effectiveness of the proposed method in coping with the cell loss. Then discussions are made on the optimal number of hierarchical processings to cope with the cell loss and the protection level for hierarchical information. Furthermore, it is shown that a new type of video communication can be realized by introducing hierarchical coding.
Design of a nondissipative lc snubber in a forward converter
Authors: Ninomiya Tamotsu , Tanaka Tetsuro , Harada Koosuke
Published: July 2007

A snubber circuit protects semiconductor switches in a dc‐dc converter from voltage stresses. The snubber composed of a resistor and a capacitor, namely theRCsnubber, is used widely for protection circuit, although the power dissipation inRCsnubbers deteriorates the power efficiency of converters. To remedy this drawback, a nondissipativeLCsnubber composed of an inductor, a capacitor and diodes has been developed.

TheLCsnubber is not only nondissipative in principle but also has a feature to reduce the switching power‐loss in semiconductor switches. As for the design of the snubbers, for theRCsnubbers the power dissipation in the snubber circuit is the point to be considered; and for theLCsnubber, the power loss in the semiconductor switch is taken as a criterion from its features.

In this paper, the design procedure of theLCsnubber in a forward converter is discussed in the following order: First, the operation of a forward converter with theLCsnubber is examined. Next, the energy loss in a switching transistor is evaluated, and the condition to minimize this energy loss is provided. As a result, the procedure to determine the optimum values of the snubber capacitor and snubber inductor is reported.
Properties of linearly steep tapered cutoff waveguide filters
Authors: Suga Takashi , Shirasaki Hirokimi , Ishihara Fujio
Published: July 2007

The properties of linearly steep, tapered cut‐off waveguide filters are analyzed by the eigenmode expanding method. Coupling from higher modes to the fundamental mode and coupling between higher modes have been taken into account in order to get exact results. The numerical results of the reflectional loss are in good agreement with the experimental results over a wide range from one‐wavelength tapered waveguides to a step‐connected waveguide. The effect of higher modes is marked in asymmetric waveguides and very steep waveguides, and is shown by the down shifting of the first resonant frequency.
Satellite and terrestrial link switching control method using high‐speed time‐division multiplexer
Authors: Shinnai Kohsuke , Nakamura Tsutomu , Suzuki Michio , Sasaki Ryoichi , Takahashi Hiroaki , Matsuura Akio
Published: July 2007

The mixed media network including the terrestrial and the satellite communication links is considered, aiming at the realization of a highly reliable information network. This paper proposes a method of physical level switching control in the highspeed multiplexer between the terrestrial and the satellite links.

The following three aspects of the physical level switching control method are described. The high‐speed digital network management system instructs the link switching to the high‐speed multiplexer according to detected faults. The high‐speed multiplexer has a function to handle equally the high‐speed digital link and the satellite link.

The Earth station has the interface function which enables the high‐speed multiplexer to switch the master clock. This paper outlines the switching control method at the physical level using the high‐speed multiplexer in the transmission network. It discusses also the technical issues as well as their solutions in the implementation, such as the loss of paths for managing information, management of intermittent faults and switching of the master clock.

The link switching experiments actually are made between the earth and the satellite in the “pilot study for use of satellite,” underwritten by the Min. Post & Telecomm. The time from the fault detection to the complete link switching in the proposed network management system is within 30 s, indicating the effectiveness of the proposed switching control method.
An approximate analysis of a queueing system with markov‐modulated arrivals
Authors: Takahashi Haruhisa , Wang Li‐Sheng
Published: July 2007

This paper presents an excellent two‐moment approximation via an N‐environment diffusion model of a queueing system with Markov modulated Poisson process (MMPP) arrivals and general service time distribution. By choosing residual workload as a performance criterion, an approximation error of less than 3 percent can be achieved.

We give a closed form solution for all moments of the waiting time distribution with two‐state MMPP arrivals. We also propose an algorithm for the approximate solution of single server queueing systems with n‐state MMPP arrivals. The proposed sufficiency condition for the existence of a stationary solution has not been proved for the n‐state case with n ≥ 3.
Small‐signal dynamic analysis of class e resonant dc‐dc converter regulated by an auxiliary switch
Authors: Gu Wen‐Jian , Harada Koosuke
Published: July 2007

Small‐signal dynamic analysis of a class E resonant dc‐dc converter is presented where voltage regulation is done by an auxiliary switch without changing the switching frequency. This converter is suitable for high‐frequency operation because both the main and the auxiliary switches can be turned ON/OFF at zero voltage level and the switching loss is very low.

Small‐signal dynamic characteristics are determined by an averaging model obtained by the use of Fourier series expansion where the terms higher than second order have been neglected. Experiments are performed on a 1‐MHz switching converter and the applicability of this analysis is verified.
A token‐passing scheme in a time‐division multiplexed local area network and its performance evaluation
Authors: Ishizaka Michihiro , Shikama Toshihiro
Published: July 2007

This paper considers an access scheme to realize a packet switching function using the time‐division multiplexed frame which circulates on a ring‐type backbone LAN. A slotted token‐passing scheme is proposed which enables a long packet transmission by concatenating the time‐division slots available by dividing the frame. Its access control algorithm and the recovery mechanism from ring failure are shown, along with the numerical analysis of the mean transfer time of the proposed scheme by comparison with the token ring access scheme of ISO (ISO 8807/5). The communication performance is evaluated from the viewpoints of the number of stations, packet length, transmission rate, etc. As a result, it is demonstrated that the slotted token passing scheme proposed as the packet switching function for the time‐division multiplexed ring is effective for high‐speed LANs having heavy traffic loads with a large number of stations and a long transmission line.
High‐performance unidirectional bus lan in the case of large‐sized network
Authors: Asano Hitoshi , Masuda Takao
Published: July 2007

A new unidirectional LAN called SURVIVALNET, suitable to high‐speed integrated (HSI) LAN, is proposed. It has a function of controlling transmission by sensing a carrier not only on the outbound as in the case of DAMA but also on the inbound channel. Therefore, high channel utilization and short packet delay can be realized even if the network size becomes large.

This paper describes first the principle of SURVIVALNET. Second, its channel utilization is discussed analytically under both light and maximum load and analyzed numerically under medium load using computer simulation. Finally, it is shown that the SURVIVALNET is applicable to HSI LAN.
A numerical method to evaluate frequency modulation/demodulation limit of phase‐locked loop
Authors: Takahashi Yutaka , Bamba Eiichi , Kinemura Kazuhiro
Published: July 2007

A method is presented in this paper to determine the FM modulation/demodulation limit by numerical calculation. This is the synchronization limit when a phase‐locked loop is used as an FM modulator or demodulator. It is shown that the same differential equation can be used both for modulation and demodulation to describe the behavior of the phase‐locked loop for the FM signal. An algorithm is shown which solves the derived equation, which is nonlinear in general, by the harmonic analysis, and derives the periodic solution with the same period as that of the modulating signal by a numerical calculation. The limit of existence for the stable periodic solution is the limit of synchronization.

A method is presented which can determine the limit. A phase‐locked loop with a sinusoidal phase comparator and an adequate loop filter is considered as an example. The periodic solution is actually calculated and the FM modulation/demodulation limit is determined from the limit of stability. The obtained result can be accounted for qualitatively and agrees with the experimentally obtained result.
Error rate analysis in mdpsk and mcpsk with a pilot on satellite‐aircraft multipath channel
Authors: Miyagaki Yoshiya
Published: July 2007

The multipath channel between a satellite and an aircraft is modeled as direct wave + mirror reflected interference wave + scattered interference wave + receiver thermal noise. The symbol error rate in the channel is analyzed theoretically by strict and approximate methods for the case where the multiphase phase‐modulated wave is received by delayed detection (MDPSK) and for the case where the pilot wave is added and synchronous detection is made (MCPSK). As a result, it is seen that MDPSK is better when the direct wave‐to‐noise power ratio is less than 20 dB and MCPSK is better when it is larger than 20 dB.
Overlapping block discrete cosine transform coding and its fast algorithm
Authors: Sawami Hideo , Morikawa Yoshitaka , Hamada Hiroshi
Published: July 2007

The discrete cosine transform (DCT) method is well known for a highly efficient coding for still images. A problem in this method is that the block distortion is observed in low‐rate coding. The overlapping block transform (OBT) has recently been proposed, aiming at the reduction of the block distortion. OBT is derived as a frequency analyzer/synthesizer with the origin of the spatial coordinate at the mid‐point between the sampling points and the main processing operation results in a DCT of unordinary type. This increases the computational complexity compared to the ordinary DCT.

From such a viewpoint, this paper first derives the overlapping block DCT (OBDCT) with the same main processing as that of the ordinary DCT, by placing the origin of the spatial coordinate at the sampling point. OBDCT has the same coding efficiency as that of the traditional OBT, and OBDCT with the transform length 8 has the same coding efficiency as that of DCT with the transform length 16. A fast OBDCT algorithm is derived by integrating and simplifying the proposed OBDCT and the transform processing. Finally, it is shown that the fast OBDCT with the forementioned transform length can be executed by 55 percent of multiplications of the fast OBT and 67 percent of the fast DCT.
An estimation formula of received power space correlation coefficient using three‐ray model
Authors: Sasaki Osamu , Satoh Akio , Hosoya Yoshio
Published: July 2007

This paper derives an estimating equation for the received power space‐correlation coefficient needed for the design of a space diversity receiving system for improved transmission performance of a microwave relay system as a semiempirical equation based on the theoretical investigation, with corrections by measured data, from a three‐ray model in which the received wave consists of the direct wave, reflected wave, and duct refractive wave. This equation is determined from the amplitude statistics of the three waves, the propagation conditions such as the distance and the transmitter and receiver heights, the frequency and the radio meteorological statistics. This model contains the two‐ray model method intended for a propagation path with a strong reflection (strong reflection link) and the Makino‐Morita method which assumes Rayleigh fading for a propagation path with a weak reflection (weak reflection link). The measured results of the spatial‐correlation coefficient of the received power in about 30 links measured in Japan, including both the strong and weak reflection links, are found to agree well with the estimated values based on the present equation. Hence, the effectiveness of the estimation equation proposed in this paper is confirmed.
Analysis of a planar inverted‐f antenna by spatial network method
Authors: Taga Tokio , Tsunoda Kikuo
Published: July 2007

By means of the spatial network method, the characteristics of a planar inverted‐F antenna on an infinite ground plane are analyzed. The electric field between the planar element and ground plane and the surface current distribution on the antenna for different values of the width of the short‐circuit plate are found. In addition, by Fourier transform of the impulse response of the antenna, the resonant frequency and the bandwidth are derived. The relationship between the width of the short‐circuit plate and the path length of the antenna current flowing on the planar element, short‐circuit plate and ground lane also is studied. An approximate formula is investigated for the resonant frequency as a function of the width of the short‐circuit plate, dimensions of the planar element and antenna height. Further, by comparison with the measured results, the validity of the analysis results is confirmed.
Interference canceling characteristics of diversity reception with least‐squares combining—MMSE characteristics and ber performance
Authors: Suzuki Hiroshi
Published: July 2007

This paper discusses theoretically several characteristics of diversity reception with least‐squares combining. Least‐squares combining minimizes the combined signal error from a reference signal by the least‐squares method. Values of complex coefficients and resulting minimum mean‐square error (MMSE) are derived first on the assumption that the desired and interference signals are mutually independent. The general solutions are applied to two‐branch diversity reception, and an explicit formula that determines the CNR of the combined signal is obtained.

The diversity performance is discussed from two aspects: signal combining and interference canceling. The discussions show that: (i) maximal ratio combining is achieved if there is no interference; (ii) if there is a single interference source, the interference can be canceled completely and one branch signal reception performance is obtained; and (iii) if there are two or more interference sources, the interference cannot be canceled completed and the diversity performance degrades severely. Furthermore, computer simulations determined the instantaneous CNR distribution functions and average BER performance characteristics.
Validation method for telecommunications protocol with internal events
Authors: Wakahara Yasushi , Kakuda Yoshiaki
Published: July 2007

This paper proposes a new method for efficient validation of the telecommunication protocol, containing the internal events, including those for the timer and resource management. The proposed validation method first converts the protocol containing the internal event into the equivalent protocol not containing the internal event. Then the original protocol is validated by applying the already‐proposed validation method for the protocol not containing the internal event to the result of conversion.

This paper discusses mainly the principle and the algorithm of the protocol equivalent conversion. The features of the proposed validation method are that the protocol is validated with the minimum processes and signals, which reduces the processing time and the memory capacity needed in the validation and also improves the efficiency.
HDTV/TV compatible coding based on intrafield/interframe adaptive LOT and its characteristics
Authors: Jozawa Hirohisa , Watanabe Hiroshi , Hashimoto Hideo
Published: July 2007

This paper describes an HDTV/TV compatible coding method based on lapped orthogonal transform (LOT). With this method, TV signals are obtained by performingN/2‐point inverse LOT to low‐orderN/2 coefficients. It is shown that the LOT domain decimation reduces the aliasing noise in TV images more efficiently than the DCT‐based method. In addition, intrafield/inter‐frame adaptive LOT coding is examined. The experimental results show that the coding efficiency of intrafield/interframe adaptive LOT coding is higher than that of intrafield/interframe adaptive DCT coding. LOT coding improves the SNR by 1 dB in fixed bit rate HDTV coding at 130 Mb/s. By using LOT as a decimation filter as well as a bit rate reduction algorithm in compatible HDTV coding, the quality of the TV images and the coding efficiency are better than with the DCT‐based method.