bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of two‐stage cascade FIR digital filters with coefficients of limited word‐length
Authors: Imai Satoshi , Fukuda Yutaka
Published: July 2007

It is shown that the two‐stage cascade construction is very effective in the realization of a digital filter with a sufficiently large attenuation in the stop‐band. A design method for the two‐stage cascade FIR filter with limited word‐length is described. Compared with the direct construction, the word‐length of the filter coefficient in the two‐stage cascade FIR filter is reduced to less than 60 percent. In general, compared with the direct construction, the word‐length of the filter coefficient is reduced in the cascade construction, while the order is increased. However, in the proposed method, the order of the two‐stage cascade construction need not be very large, compared with the case of direct construction, being 1.5 times in the worst case. By imposing less strict limitation on the word‐length of the filter coefficient, the order of the two‐stage cascade construction FIR filter never exceeds 4/3 times that of the direct‐type FIR filter. In the realization of a linear‐phase, two‐stage cascade FIR filter, lower‐order minimum‐ and maximum‐phase filters than the linear‐phase filter can be applied as subfilters. This is effective in further reducing the order of the two‐stage cascade FIR filter, thereby reducing the order to 0.8 to 0.9 times the case of the construction based on the linear‐phase subfilter.
Variable‐length‐code‐selective reversible predictive coding for multilevel images
Authors: Taniguchi Takayuki , Kamikura Kazuto , Itoh Susumu , Utsunomiya Toshio
Published: July 2007

To construct efficiently an image database system for high‐tone images, a variable‐length, code‐selective reversible predictive coding scheme with a high‐compression ratio is proposed. This coding scheme is based on application of the quantizer‐selective method in the DPCM coding [11] (previously proposed by the present authors) to an adaptive selection of a variable‐length code. This is an adaptive coding scheme in which a suitable code is selected from the pre‐designed variable‐length codes for each pel. This code selection method requires no additional information, since the code selection is carried out based only on information of pels for which the coding has already been completed. The predesigned variable‐length codes and the threshold values for the code selection are determined by a model of the probability distribution of transformed prediction‐error signals. The initial setting of coding parameters is constant and independent of the image to be encoded. This scheme has, therefore, much generality that is independent of any kinds of images. The coding rate of this scheme is improved by about 0.3 to 0.5 bit/pel compared with the optimal nonadaptive coding scheme using a single Huffman code. It was confirmed that the proposed scheme has the highest coding efficiency compared with several conventional representative reversible coding schemes.
Performance of a viterbi decoder using simplified digital metric calculation
Authors: Miyake Makoto , Fujino Tadashi , Fujiwara Ken‐Ichi
Published: July 2007

Recently, convolutional coding with Viterbi decoding has been used widely in digital satellite communication systems. This paper addresses the problem of simplifying the process of digital metric calculation in a Viterbi decoder to realize reduced hardware complexity and increased operating speed.

An analytical expression is introduced for the bit error rate (BER) performance of such a Viterbi decoder, and effects of the simplifications are evaluated for a typical convolutional code. It is shown that measured data agree well with theoretical curves, and that the simplifications can be introduced with no significant performance degradation. Finally, a method is proposed to design Viterbi decoders so that the degree of soft decision is increased and the number of bits for branch metrics is reduced to a specified value using a nonlinear transformation. For a constant number of bits for branch metrics, the BER performance realized by the proposed design method can be superior to that realized by the conventional design method. Results in this paper would be useful in designing simple Viterbi decoders for high‐speed applications.
Highly reliable subscriber cable network construction
Authors: Yamamoto Hideo , Oikawa Hisao , Iwashita Motoi
Published: July 2007

A cable network with high standards of reliability and cable usability is proposed. In a feeder cable system, Free Access Points (FAPs), in which all fibers can be cross‐connected, are set on each main feeder route; and loop cables are installed between adjacent FAPs. Using the cut‐set concept of graph theory, the relation between link addition and reliability improvement is shown and network constitution patterns for high reliability are shown. From the viewpoint of network availability, the optimum FAP location is determined to be the point which is about half the subscriber area radius from the center office. Finally, through the simulation of user demand increase it is shown that the proposed constitution system can improve the cable use efficiency more than the conventional individual cable distribution system. Thus, the high reliability as well as the high flexibility of the proposed system is shown.
Operational characteristics of a bistable laser‐diode memory for optical switching networks
Authors: Habara Keishi
Published: July 2007

To realize a high‐speed time division optical switching network, optical bistability devices including optical memory are important. In this paper, a bistable laser‐diode memory made of an APD, an LD and an optical feedback circuit is studied from the point of low set power and high speed. To attain a low set power, the effect of spontaneous emission of an LD cannot be neglected. Therefore, the input and output characteristics of an optical memory are studied including the spontaneous emission coefficient. Next, the response speed at a low input power is studied and the relationship between the response speed and the optical memory design parameters is derived. The input‐output characteristics and the response speed are verified with an experimental circuit. Finally, a high‐speed optical memory with a low set power is fabricated. The results of operating experiments of optical memories in an optical switching network are described.
A transform coding for compression of offset‐sampled image data
Authors: Sawami Hideo , Morikawa Yoshitaka , Hamada Hiroshi
Published: July 2007

This paper derives a transform coding method for offset‐sampled image data. The method is based on the idea that the usual discrete‐cosine transform (DCT) as well as the symmetrical cosine transform (SCT) are regarded as discrete Fourier transforms for the signal sequences obtained by forming mirror images of the given signal sequence. The derived transform is composed of DCT and SCT, which have one‐half transform length of the ordinary square lattice DCT.

Using the proposed method which corresponds to the DCT with the block size of 8 lines × 8 pixels, the number of multiplications required in the transform is reduced drastically to approximately one‐fourth. The coding efficiency between the proposed method and the DCT is compared by a computer simulation, and it is shown that the proposed method has a higher coding efficiency. Especially, the following advantage should be noted.

The slope of the proposed method in the linear part of the rate‐SNR characteristic is steeper than the DCT (the slope of the proposed method is 1/0.64 of DCT) for the forementioned block size, resulting in a more remarkable improvement of the coding efficiency for higher rate coding. This improvement is the result of the gain due to sample reduction of a factor 2 per image area, and the loss due to the duplicate block partitioning.
A priority control method of burst multiplexing network with the feedback of delay quality
Authors: Su Jing , Sakai Yoshinori
Published: July 2007

In multimedia communication, where media data with various requirements for the delay quality are transmitted through the multinode network, it is desirable to apply a priority control method according to the nature of the media. This paper proposes a new priority control method whereby the delay quality of each medium is evaluated by the fuzzy satisfaction, and the priority is adjusted through the feedback of the delay quality. The performance of the system is examined by a simulation.

In the proposed system, the delay time is observed for each origination/destination pair at the destination node, and the fuzzy satisfaction of the delay quality is determined. The average satisfaction of the whole system is determined. Then the priority is renewed according to the difference between the satisfaction for each origination/destination pair and the average satisfaction of the system. It is shown that by the proposed method, the delay quality of the whole system is made almost uniform.
Design and performance of a repeater for CSMA/CD passive optical star network connection
Authors: Hakamata Yoshiro , Oguchi Kimio , Tokura Nobuyuki
Published: July 2007

One method to expand a network is to employ repeaters operating at layer 1. When networks using the optical passive star coupler are connected through repeaters with only a relaying function, there arises the problem of “self‐collision.” This problem occurs when the packet returned from the optical star coupler connected to the destination network is relayed unconditionally by the repeater to the originating network.

As a means to avoid the self‐collision, the authors have proposed a repeater with wavelength‐division multiplex technique and gate control [1]. Through the design of the wavelength filter, it is shown that a satisfactory performance is obtained [3]. This paper shows further the results of studies, from the functional viewpoint, for the transmission design of the repeater, the control method for the gate, and the relaying method for the code rule violation. The repeater is built into a system constructed experimentally for the star configured optical transmission system with the transmission rate of 32 Mbit/s. The result of measurement of the transmission performance and the functional operation are described. The design for the repeater, which is applicable to the connection of the passive star network, is now described clearly.
Performance evaluation of radio link control protocol using stop‐and‐wait arq in mobile radio systems
Authors: Hiroike Akira , Matsumoto Tadashi
Published: July 2007

In land mobile data transmission, the error control by FEC and ARQ generally is employed to improve the reliability of transmission. In the control signal transmission for the radio link control in the mobile communication system, the error usually is detected by FEC, and the reliability is improved by ARQ. Under the condition of motion velocity of 40 to 50 km/h and the tolerable transmission delay of several seconds, the transmission characteristics of ARQ depend greatly on the short‐term median variation of the received level of the retransmitted signal, together with the packet signal transmission characteristics under the instantaneous received level variation due to fading. No evaluation has been presented for the transmission characteristics of ARQ considering such a median variation.

This paper considers the stop‐and‐wait (SAW) ARQ where the number of retransmissions is limited to a finite value, and presents an evaluation of the transmission characteristics considering the correlation of the short‐term median variation of the retransmitted signal. Numerical examples are presented. Assuming that SAW‐ARQ is applied to the transmission protocol of the common control channel, the blocking probability is examined, together with numerical examples.
Revenue maximization control of a communication network by the use of hierarchical fuzzy system
Authors: Tanaka Yoshiaki , Miyakoshi Katsuyuki , Akiyama Minoru
Published: July 2007

The call‐wise control of a communication network, such as dynamic routing, is a very complex problem, although the extent of difficulty depends on the control target. Especially, the optimization of a communication network in a multiservice environment contains the difficulty of the choice of the state variables. The analytical method is limited in handling such a problem.

This paper discusses the application of the fuzzy system by extending the range of search for the optimal solution for the communication network control from the analytic single expression to the description by the combination of several rules. The usefulness of the idea is demonstrated by a simulation. Then aiming at the full utilization of the descriptive power of the fuzzy system, the modularization of the control system corresponding to network installations, as well as the hierarchical structure corresponding to the data abstract level, is proposed. Further, this paper considers the revenue maximization control of the communication network as an example, and the usefulness of the hierarchical fuzzy system is demonstrated through a simulation. By applying the proposed method, it is made possible to cope with a range of problems not previously handled by the analytical method.
Propagation characteristics for mobile reception of satellite broadcasting in urban areas
Authors: Ito Yasuhiro
Published: July 2007

When various broadcasting radio waves in the 12‐GHz band from a geostationary satellite such as a broadcasting satellite are received in an urban area by a mobile receiver, transmission and reception systems such as a temporal diversity system often are designed. In such instances, it is necessary to evaluate quantitatively the mobile receiving characteristics such as the areal visibility on an urban street. When driving on an urban street, one finds that the waves from satellites frequently are disturbed by buildings. The degree of disturbance depends on the direction of the street, the density, height and width of the building.

This paper describes first characteristics of measured satellite areal visibility on a road using an airscape photographed at a time when the apparent locations of the satellite and the sun coincide. The histogram of the visibility length is modeled by a log normal distribution. Second, from these distributions and the measurement and analysis of the actual velocity characteristics of automobiles in the Tokyo metropolitan area, the histogram of the visibility duration time is estimated. Third, an estimation method of the satellite areal visibility on a road is proposed in which the statistical data are published by a governmental agency on the building distributions and on the road. The results obtained by these measurement and estimations can provide quantitatively the mobile receiving characteristics of satellite broadcasting at 12 GHz so that they can be effective guidelines in the design of various transmission and reception systems.
Electromagnetic wave excitation in a rectangular tunnel with impedance walls
Authors: Matsunaga Toshiaki , Uchida Kazunori , Noda Takeaki
Published: July 2007

This paper analyzes the problem of excitation of an electromagnetic wave inside a rectangular tunnel by means of the waveguide modes. As the boundary condition, the surface impedance approximation will be used. It is assumed that the separable solution can be adopted. For the excitation by a waveguide, the Wiener‐Hopf solution of the two‐dimensional problem is assumed to be applied. Although the results obtained are approximate, future applications are expected since an analytical expression is provided. For instance, the solution may be applied to the problem of electromagnetic wave propagation in a three‐dimensional tunnel with branches and bends. In the experiment, a microwave simulation is carried out with a model of the tunnel made of concrete. It is found that the computed results and the measured results agree rather well for the electric field intensity distribution inside the tunnel.
Theoretical analyses of a capacity controlled digital microwave radio transmission
Authors: Komaki Shozo
Published: July 2007

Capacity‐controlled digital microwave radio systems that can improve the traffic throughput by adapting the transmission capacity according to the level of traffic are described. Calculated throughput values for the 22n‐QAM and Mphase‐PSK modulation technique in the presence of Rayleighan fading are compared with the Shannon limit. The results suggest that throughput improvement by a factor of 1.5 to 3 can be achieved.
Trellis coded modulation for mobile‐satellite communication using space diversity
Authors: Umeda Masatoshi , Murata Masashi , Morinaga Norihiko
Published: July 2007

Most of the past studies concerning the decoding performance of trellis coded modulation (TCM) in a fading channel have been based on time diversity using interleaving/deinterleaving. One problem with time diversity is that a large decoding delay is produced due to the interleaving/deinterleaving which depends on the fading interval. This paper considers TCM signals using space diversity which can drastically improve the decoding delay and analyzes the decoding characteristics in Rice fading channels. An analysis is also made of the effect of the Euclidean distance (ED) and the Hamming distance (HD) of the trellis code on the average bit error rate (BER), and it is shown that a code design considering those two distance structures is needed in a channel with severe fading.

This paper considers the major application of the proposed method to be digital voice transmission in mobile communication via satellite. Consequently, a simulation is made for the second‐order space diversity decoding performance for the trellis coded 8‐PSK signal. The optimal trellis coding at the transmitter is discussed for BER = 10−4.
A digital signature scheme on a document for MH facsimile transmission
Authors: Tanaka Kiyoshi , Matsui Kineo
Published: July 2007

This paper proposes a digital signature scheme for a facsimile document which embeds a signature directly onto the document. The scheme modifies each run of white or black pixels with a single bit of the signature data. It is designed to be compatible with CCITT G3 facsimile standards and to protect the document from the insertion, modification, replacement, overwriting or deletion of characters. Furthermore, the total amount of data to be transmitted is about the same as that of the original facsimile document. In this paper, an authentication scheme is shown with a prototype model under a one‐key encryption system.
A study on subscriber optical line‐switching networks
Authors: Imai Michitaka , Sankawa Izumi , Furukawa Shin‐Ichi
Published: July 2007

In subscriber optical line networks, it is necessary to take measures to accompany the reliability improvements to efforts concerning the increases in the speed of information communications and the diversity of the services.

In this paper, in regards to the structure of the line switching of the loop networks, the optimized settling method of the switch and its structure are investigated. The efficient switching method, in case of a failure, also is shown.

Finally, the results of the trial manufacturing of the switch with the required functions are discussed. As the network structure, the one with its feeder lines pulled into many loop lines in one central office is modelled. In such network structures, exclusive protection lines are accommodated, taking into account the circuit failure ratio and the efficiency of line usage, etc.

The switching is possible at the branching points of the feeder and the distribution lines between the service and the protection lines. By attaching the switching possibility at the feeding and crossing points to the protection lines, failure of one loop network is shown to be relieved effectively. Finally, the four‐terminal switch possessing the required functions in regards to the present line‐switching networks is proposed and compared against the usual 1 × 2 and 2 × 2 switches. It is shown that it is possible to realize the line‐switching networks with considerably reduced number of switches. Then, from the trial manufacturing results, the possibility of realization of high‐speed and low‐loss switches is indicated.
Performance evaluation of large‐scale data flow‐controlled switching systems
Authors: Yamada Shigeki , Ito Toshio
Published: July 2007

The performance of data flow‐controlled switching systems with processing elements (PEs) on the order of 100 to 1000 is evaluated by software simulation.

For the large‐scale simulations, a simplified model is proposed to reduce the required number of computer resources, similar to memories and CPU times.

The simulations show that a very large‐scale data flow switching system is feasible by separating mutual exclusion processing PEs from general processing PEs. The performance results are compared with calculations of an approximate model. These results help us to establish the optimum design parameters for the system.
Mobile propagation loss prediction for arbitrary urban environments
Authors: Sakagami Shuji , Kuboi Kiyoshi
Published: July 2007

This paper describes the estimation of the propagation loss in an urban environment important for channel design of land mobile communication. Conventional methods for estimating the propagation loss in an urban environment gives a representative value of the propagation loss in the urban environment or the propagation loss (median value) within a 500 m × 800 m area obtained by introducing an area factor of occupied buildings. Such a method is not suitable for estimation of the propagation loss depending on the situation near the mobile station.

In this paper, the relationship of the measured data of the propagation loss in the Tokyo Metropolitan area at 813 and 1433 MHz with the urban environment parameters such as the base station antenna height, distance, frequency, width of the street where the mobile station exists, direction, average building height, building height on the street side is derived by the multiple regression analysis method.

A prediction formula for the propagation loss (median value in the section of about 80 m) including these parameters is derived. The parameter dependencies of the propagation loss, such as the antenna height dependence and the average building height dependence, are described. In addition, the distance dependencies of the propagation loss in this prediction formula and conventional method are compared with the measured values. The prediction formula is expressed in terms of the sum of simple functions of the foregoing parameters. Hence, the estimation of the propagation loss can be carried out easily, taking into consideration the urban environments such as the height of the buildings and width of the streets.
An evaluation of test sequence generation methods for communication protocols
Authors: Nakahara Akiko , Aida Hitoshi , Saito Tadao
Published: July 2007

In the conformance test of the communication protocol, it is desired from the viewpoints of strictness and efficiency to generate automatically the test sequence, based on the formal description. Several methods have been proposed for this purpose. All of these methods are based on the two formal descriptions which can be the basis for the test‐sequence generation: one is the description based on the order of the input/output events, and the other is the description based on the finite‐state machine model.

This paper attempts to compare the applicability of the two description methods to the conformance test. Also, it evaluates the error‐detection capability which actually generates the test sequences for the following two cases.

(1) The test sequence is generated directly from the specification based on the order of events.

(2) The test sequence is generated from the finite‐state machine model, which is obtained from the description of (1). In the evaluation, a simulation technique is employed which uses as a testing object a finite‐state machine containing random errors.

Finally, this paper notes the handling of the undefined transitions contained in a large number in the actual protocol and considers the class of errors pertinent to the actual protocol, such as the redundant state errors or the replicated state errors.
Degradations of bit‐error ratio due to echo in optical OOK communication systems
Authors: Yoshino Takayuki , Abe Mayumi , Hirano Nobuo
Published: July 2007

Echoes, which are transmission waves arriving at a receiver later than the principal wave, arise from multiple reflections at discontinuous points, such as connectors, on a transmission line and cause intensity fluctuations onto a laser light to be received. The intensity fluctuations and its effect on bit‐error ratios in binary on/off‐keying (OOK) optical fiber communication systems are analyzed theoretically here.

Analysis features and principal results are as follows: (i) a general theory is developed, including the case of short time delay; and it is shown that the bit‐error ratio degradation decreases when the time delay is shorter than the coherence time of a laser light; (ii) the analysis has no restrictions to amplitude ratio of the echo to the principal wave, so that a critical value of an echo amplitude for floor effect and its corresponding floor values can be evaluated; and (iii) since bit‐error ratios are obtained directly from the probability density function of intensity fluctuations, rigorous results are obtained. This paper considers PIN diodes in detail. Only results for the avalanche photodiode (APD) are presented.
Edgeworth series expansion of apd output current and its application to the evaluation of bit‐error ratio in optical communication systems
Authors: Yoshino Takayuki , Abe Mayumi , Hirano Nobuo
Published: July 2007

The use of a probability density function expanded into Edgeworth series of an APD output current instead of a Gaussian density function aids in the development of a theory of an APD behavior that is both more rigorous and practical. The determination procedure for both the optimum multiplication factor and the optimum symbol decision level is described through application of the theory to bit‐error‐ratio evaluation in optical communication systems.

The results reveal that the bit‐error ratios are evaluated about two orders lower when Gaussian approximation is employed. The theory of an APD behavior with the series is used to estimate the bit‐error‐ratio degradations and floor effects on bit‐error‐ratio curves that result from echoes on the transmission lines of the forementioned communication systems. Finally, general results are obtained without any restrictions to echo amplitude or delay time.
Null beam forming by phase control of selected elements in phased‐array antennas
Authors: Chiba Isamu , Mano Seiji
Published: July 2007

In phased‐array antennas, nulls of the radiation pattern can be formed in the direction of undesired wave by controlling only the phase excitation without affecting the main beam. However, the computation time becomes very large when an antenna with a large number of elements is analyzed and it becomes very difficult to counteract the variation of wave boundary instantly.

Here, based on the exact calculation of phase value by the method of plane‐wave synthesis, the foremen‐tioned elements are selected which contribute more to the null formation, and the method of controlling only the phase of the selected elements is presented. Using this method, the computation time can be reduced. Moreover, the depth of nulls and the gain of the main beam obtained in this way is the same as that produced by controlling the phase of all the antenna elements.

As a result of numerical simulation and experiments of null forming in the phased‐array antenna using a 5‐bit phase shifter, deep nulls with the level of less than ‐40 dB could be formed without decreasing the gain of the main beam.
Design support for the communication service specification by utilizing petri nets
Authors: Hasegawa Haruo
Published: July 2007

This paper describes a support system which designs a complete and error‐free service specification from ambiguous user requirements in a communication system. Each of the user requirements, defined as a combination of terminal operation and a reaction of a switching system to it, is converted into an individual service graph (ISG); and all ISGs are integrated into a total service graph (TSG) which is the final service specification. TSG is verified by three methods: a semantical one, a logical one, and a prototyping one. Then TSG is converted into SDL representation so that it can be used to design communication software.
A limited retransmission CSMA/CD system
Authors: Yamaguchi Takao , Fujiwara Chikato , Okumoto Takaaki
Published: July 2007

In the CSMA/CD LAN system, such as Ethernet, the throughput and the delay characteristics are greatly deteriorated by the increase of the traffic, and several remedies have been proposed.

This paper proposes a limited retransmission CSMA/CD system which can achieve a high throughput and easily realizes the retransmission algorithm. Also, the performance of the limited retransmission nonpersis‐tent CSMA/CD system is analyzed and evaluated, among limited retransmission CSMA/CD systems. The validity of the analysis is demonstrated by a simulation. Then the performances are compared among the limited retransmission CSMA/CD system, including the limited retransmission 1‐persistent CSMA/CD system, the traditional nonpersistent and 1‐persistent CSMA/CD systems, as well as an Ether‐type CSMA/CD system.

Finally, the limited retransmission 1‐persistent CSMA/CD system is considered as an example, and a modified limited retransmission algorithm is shown, by which the variance of the message transmission delay can be reduced. The extent of the improvement is demonstrated by a simulation.
0.78‐μm digital transmission characteristics using 1.3‐μm optimized single‐mode fiber for a subscriber loop
Authors: Suto Ko‐Ichi , Yoneda Etsugo , Hayakawa Tadahiko , Tuchiya Toshiyuki
Published: July 2007

The transmission characteristics of digital systems comprised of 1.3‐μm zero dispersion, single‐mode fibers (1.3‐μm SMF) and 0.78‐μm band laser diodes (LD) are investigated. The problems encountered in such systems are the degradation of the transmission bandwidth due to the modal noise and the dispersion.

This paper describes the transmission‐distance limitations due to the mode dispersion and the range of suitability of short wavelength sources in conjunction with the 1.3‐μm SMFs is clarified. It is shown from the measurement of the long‐term bit‐error rate that the self‐pulsation LDs are useful. It is shown also that the bandwidth‐distance product is limited to 111 MHz km due to the maximum delay difference of 3 ns/km between LP01 and LP11 modes of 1.3‐μm SMFs fabricated by the VAD method. Finally, the selection rules of the optical sources are described taking into account the degradations due to the modal noise.
Topological design of corporate communication networks
Authors: Watanabe Atsushi , Ohmae Yoshitsugu
Published: July 2007

Recent construction of corporate communication networks with the use of high‐speed digital links, etc., is becoming popular. Economical and reliable networks must be designed. Few papers have been published on the design of corporate communication networks. Moreover, some need improvement.

This paper proposes a new topological design algorithm for efficiently constructing economical and reliable corporate communication networks. This algorithm achieves effective network design by utilizing the correct network information. The triangle network configuration, which provides higher reliability than two‐connected networks with only a small additional cost, is proposed. Moreover, this paper proposes a new idea at a lower cost (cost lower bound) that evaluates the results obtained by various heuristic algorithms. Superiority of the proposed algorithm is verified by means of this cost lower bound.
MS synchronization networks using digital signal processing PLL with different phase error averaging number in each slave level
Authors: Hayashi Minobu , Luan Zaihua , Sasase Iwao , Mori Shinsaku
Published: July 2007

When the scale of a network is expanded in the master‐slave synchronization system, a problem occurs in that the jitter produced in the upper‐level station propagates and accumulates in the lower‐level station.

This paper proposes a master‐slave synchronization network, where the digital signal processing PLL averaging different phase errors is used at each level, with the number of averaging depending on the level. The network in which the number of averaging increases linearly from the upper to the lower level, as well as the network in which the number of averaging increases nonlinearly according to the accumulation of the jitter are considered.

It is shown that the jitter characteristic for the whole network is improved for the same acquisition time compared to the network with the uniform number of averaging. With regard to the two networks considered, the optimal increment is derived for the linearly increasing case. It is shown that the improvement is more remarkable in the second network than in the first, and the improvement is more remarkable in either network with the increase of the network scale.
Experimental verification of real‐valued orthogonal PN sequence applied to pulse compression sonar
Authors: Tanada Yoshihiro , Yoshida Hiroshi , Nagasawa Yoji
Published: July 2007

In the pulse compression sonar, the code with a sharp autocorrelation function is used as in spread spectrum communication, and they share many common technologies. In this paper, the real‐valued orthogonal pseudo‐noise (PN) sequence that can be used in both over a broad frequency range including dc is applied to the pulse compression sonar. By adapting digital correlation processing, a high performance close to the theory has been obtained. The codes are generated from a binary orthogonal PN sequence with a length of 127 and a multivalue orthogonal PN sequence with a length of 256 and are sent into an acoustic transmission path at a frequency of about 40 kHz. The correlation operation of the received code and the transmitted code is carried out on a personal computer. The multiple echo is detected at a low noise while the Gaussian noise and the locked sinusoidal wave can be suppressed with a processing gain close to the one predicted by the theory.
Detection of objects by synthetic aperture FM‐CW radar
Authors: Yamaguchi Yoshio , Mitsumoto Masashi , Kawakami Atsushi , Sengoku Masakazu , Abe Takeo
Published: July 2007

The frequency‐modulated continuous‐wave (FM‐CW) radar is suitable for detecting objects placed in the near range compared to the pulse radars. This paper considers the principle of the synthetic aperture technique for the conventional FM‐CW radar and presents the fundamental detection results of objects placed in the free space. A laboratory measurement is carried out to detect a metallic plate and a pipe in an anechoic chamber using an explored radar system operative in the microwave X‐band. This demonstrates the high resolution detection in azimuth direction in the Fresnel region. It is shown that the radar has a potential ability in imaging objects placed in the near range.
Applicability of OSI directory to universal personal telecommunication (UPT)
Authors: Obana Sadao , Horiuchi Hiroki , Kato Toshihiko , Suzuki Kenji
Published: July 2007

The universal personal telecommunication (UPT) is expected as one of the future advanced telecommunication services, which enables telecommunication among subscribers while allowing personal mobility. In UPT, the database (UPT name server) is indispensable, which provides such information as address information and service profile, which are needed by the network in routing, switching control, and service control.

This paper aims at the efficient and economical realization of UPT and discusses the application of the existing OSI Directory standard to the UPT name server. First, the functions needed in the UPT name server are systematically categorized and classified. Five mapping rules are proposed, which maps those functions to the OSI Directory functions. Based on those mappings, a prototype for the UPT name server is constructed. The performance and the file volume are examined experimentally, and the applicability of the OSI Directory to the UPT name server is demonstrated.
Architecture of an optical subscriber loop cable network
Authors: Tanifuji Tadatoshi , Kawase Masaaki
Published: July 2007

The configuration of future optical subscriber loop networks supplying broadband services is discussed. In proceeding from the present analog telephone services using metallic cables to Broadband Integrated Services Digital Networks (BISDN), the single‐star (SS) network, and the double‐star (DS) network in the form of multiplexed subscribers used to reduce the cost or a mixture of them are employed. In multiplexed subscribers, the passive double star (PDS) using star couplers and active double star (ADS) using central terminal‐remote terminal (CT‐RT) connections are employed.

In this paper, first the required functions in operation and maintenance of subscriber networks using ribbon shape optical fiber cables are defined. Next, by separating these functions into the common and individual ones, it is shown that a mixture of SS, PDS, and ADS architectures is possible and the assignments for transition to BISDN according to SS also is discussed. Finally, the exchange system structure for operation and maintenance of the network with the possibility of its automation is proposed.
In‐orbit electrical performance evaluation of large satellite‐borne antenna
Authors: Itanami Takao , Kumazawa Hiroyuki , Kondo Akira , Ohata Kohei
Published: July 2007

The satellite‐borne antenna is large due to the requirement for a high gain and a multibeam operation. The construction is soft to reduce the weight as much as possible. Therefore, it is difficult to carry out the performance evaluation test on the ground with the configuration in the orbit.

This paper presents a method for accurate evaluation of a large antenna in orbit. First, the electrical test results on the ground with a weight deformation made as small as possible is compared with the numerical results based on the measured values of the manufacturing errors so that the evaluation error is obtained. Next, the performance in orbit is obtained by adding the evaluation error to the values computed from the measured fabrication error and assembling error and thermal deformation analysis value. The present procedure was applied to a Ka‐band multibeam antenna with an aperture diameter of 3.5 and 2.5 m on board the ETS‐VI satellite. It is shown that the evaluation can be done with sufficient accuracy.
ATM communications quality control with provision for multinode transfer
Authors: Tanaka Yoshiaki , Ueno Tomoyuki , Akiyama Minoru
Published: July 2007

In an ATM network, calls are transmitted through several nodes. At this time, quality control over multiple nodes is considered to be better than quality control for each node independently. In view of such considerations, this paper proposed two control methods regarding discard (loss) quality and call level delay over nodes by carrying quality information in the call.

In controlling delay quality, a call delayed at a node is given a higher priority in the next node to recover the delay. Since a cell can remain in one node for a long time, the buffer length of each node is lengthened. This leads to a decrease in the discarding rate. In addition, in discard quality control, the variations in the discard quality of each call can be minimized by performing discard of cells inside a buffer on the basis of the discard quality information of previous nodes when the buffer is full. The effect of these control methods is illustrated by simulation.
Analysis of intrinsic bearing error in doppler VOR
Authors: Yamamoto Kazuo
Published: July 2007

Of the Doppler VHF omnidirectional range (DVOR), the DSB‐type DVOR has begun to be used widely as a standard system in Japan. The objective of this paper is to derive an analysis method for quantitative prediction of the inherent directional error of the DSB‐type DVOR. The main emphasis is the error caused by the mutual coupling of the DVOR antenna elements.

First, from the combination of the antenna elements, the two types of mutual coupling are considered. A method is presented which can derive experimentally the amount of induced currents on the antennas. The analysis method for the error caused by the induced current is investigated. By combining the method with the conventional analysis of the errors caused by the counterpoise and distributers, a total analysis method is constructed. To evaluate the accuracy of the obtained analysis method, the results are compared with the experimental results obtained by the DVOR test stations.

This analysis method is found to predict accurately the inherent error in the DSB‐type DVOR as well as to express accurately the errors in the SSB system. The sources of the error are different in the two systems. It is found that the main source of the error in the SSB system is the counterpoise whereas in the DSB system it is the mutual coupling between the carrier and sideband antennas.
Superdirective cascaded dipole array
Authors: Nakamura Takashi , Miyagawa Shin‐Ichi , Yckokawa Senji
Published: July 2007

With a view to realizing a superdirective antenna, an endfire array consisting of parallel dipole elements is analyzed. As a feeding method, a cascaded connection of all elements by transmission lines is proposed. A possibility of a superdirectivity and a basic design guideline are found for the case where an element spacing and the characteristic impedance of the connecting transmission lines are set arbitrarily. As the element spacing is reduced, the antenna becomes smaller and the gain increases, although the feeding becomes more difficult. Hence, the case of a finite‐element spacing is discussed.

First, it is demonstrated that the maximum gain as a superdirective antenna is obtained by adjustment of the element lengths and the lengths of the connecting transmission line. Further, it is shown that the optimum element length for the maximum gain is near the half‐wavelength even if all elements have an identical length for ease of design and that such a structure works as a superdirective antenna. Based on the findings, a quarter‐wavelength spacing, three‐element array is designed. The validity of the present method is demonstrated since the experimental results for the input impedance, gain, and directivity agree well with the theoretical prediction.
Identification of Material Parameters for Inelastic Constitutive Models Using Stochastic Methods
Authors: Harth Tobias , Lehn Jürgen
Published: July 2007

The parameters of a constitutive model are usually identified by minimization of the distance between model response and experimental data. However, measurement failures and differences in the specimens lead to deviations in the determined parameters. In this article we present our results of a study of these uncertainties for two constitutive models of Chaboche‐type. The models differ only by a kinematic hardening variable. It turns out, that the kinematic hardening variable proposed by Haupt, Kamlah, and Tsakmakis yields a better description quality than the one of Armstrong and Frederick. For the parameter optimization as well as for the study of the deviations of the fitted parameters we apply stochastic methods. The available test data result from creep tests, tension‐relaxation tests and cyclic tests performed on AINSI SS316 stainless steel at 600OC. Since the amount of test data is too small for a proper statistical analysis we apply a stochastic simulation technique to generate artificial data which exhibit the same stochastic behaviour as the experimental data. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification and estimation of constitutive parameters for material laws in elastoplasticity
Authors: Kreißig R. , Benedix U. , Görke U.‐J. , Lindner M.
Published: July 2007

The paper summarizes the comprehensive experience of the authors in the numerical identification and estimation of parameters for anisotropic elastoplastic material laws analyzing inhomogeneous mechanical fields. Generally, the constitutive model under consideration represents a system of differential and algebraic equations. It distinguishes itself by a strictly thermodynamically consistent foundation, and an identical structure in case of small as well as finite deformations. Different rules for the evolution of internal variables describing various hardening effects are proposed. The nonlinear inverse problem of the identification of material parameters is solved with deterministic optimization methods. Basically, the least squares type objective function contains several local and global variables for the comparison of experimental and numerical data. Within this context, the numerical values of the comparative quantities are calculated either using the local integration of the initial value problem at suitably chosen material points or analyzing the entire initial‐boundary value problem (e.g. with the Finite Element Method). In order to obtain the gradient of the objective function within the framework of a sensitivity analysis a semianalytical approach based on the implicit differentiation of the equilibrium conditions and the discretized constitutive relations is presented. The numerical algorithms for the direct as well as the inverse problem are implemented into in‐house Finite Element codes. Some examples based on real and numerical experiments analyzing selected constitutive approaches are presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Haplotype inference using a Bayesian Hidden Markov model
Authors: Sun Shuying , Greenwood Celia M.T. , Neal Radford M.
Published: July 2007

Knowledge of haplotypes is useful for understanding block structure in the genome and disease risk associations. Direct measurement of haplotypes in the absence of family data is presently impractical, and hence, several methods have been developed for reconstructing haplotypes from population data. We have developed a new population‐based method using a Bayesian Hidden Markov model for the source of the ancestral haplotype segments. In our Bayesian model, a higher order Markov model is used as the prior for ancestral haplotypes, to account for linkage disequilibrium. Our model includes parameters for the genotyping error rate, the mutation rate, and the recombination rate at each position. Computation is done by Markov Chain Monte Carlo using the forward‐backward algorithm to efficiently sum over all possible state sequences of the Hidden Markov model. We have used the model to reconstruct the haplotypes of 129 children at a region on chromosome 5 in the data set of Daly et al. [2001] (for which true haplotypes are obtained based on parental genotypes) and of 30 children at selected regions in the CEU and YRI data of the HAPMAP project. The results are quite close to the family‐based reconstructions and comparable with the state‐of‐the‐art PHASE program. Our haplotype reconstruction method does not require division of the markers into small blocks of loci. The recombination rates inferred from our model can help to predict haplotype block boundaries, and estimate recombination hotspots. Genet. Epidemiol. 2007. © 2007 Wiley‐Liss, Inc.