bluuebunny/crossref_metadata_2025 huggingface dataset:
Traffic control architectures for integrated broadband networks
Authors: Ash Gerald R. , Schwartz Steven D.
Published: July 2007

Future broadband ISDN networks will provide a multiplicity of services on integrated transport networks. Switching nodes, interconnected by a flexible transmission network, provide connections for voice, data and broadband services. These connections are distinguished by estimated resource requirements, traffic characteristics and design performance objectives. This paper examines alternative traffic network architectures for integrated broadband networks, and provides integrated network routeing methods, bandwidth allocation strategies and traffic/routeing control plans for these networks. These architectures extend dynamic routeing control concepts to integrated broadband networks, and suggest perhaps radically different traffic architectures to which broadband networks might evolve. Strategies are examined for dynamic traffic routeing and dynamic trunk capacity routeing, which can adapt to load variations in customer requirements or to network resource failure conditions. Bandwidth allocation procedures are investigated which manage network bandwidth according to a virtual trunk concept, in which dynamic reservation controls are placed on the number of connections for each service category. We analyse the alternative traffic network architectures, for example broadband networks. The examples show that the architectures provide, to varying degrees, the advantages of increased network efficiency, improved customer service and increased network flexibility. Fully shared ring networks which integrate dynamic traffic and trunk capacity routeing yield many of these advantages and also provide greatly simplified network operation along with maximum flexibility to apportion network resources, especially when implemented with asynchronous transfer mode (ATM) technology. Such a traffic architecture provides a possible direction for future integrated broadband networks.
Multipoint connection routeing
Authors: Lee Kyoo J. , Gersht Alexander , Friedman Anda
Published: July 2007

Among other potential services envisioned for broadband ISDN networks, multipoint connnection services have drawn much attention from the standards arena as well as research communities. These services include conference calls, video lectures, etc. where more than two endpoint CPEs are involved in communication. In this paper we investigate representative multipoint connection routeing algorithms from a number of viewpoints: computational complexity, call set‐up complexity, dynamic reconfiguration, robustness to node failures and bandwidth efficiency. These algorithms are either known in the literature or a simple generalization of point‐to‐point routeing algorithms. An interesting conclusion of our study is that the use of multiple point‐to‐point connections for multipoint calls is a viable solution in many cases of interest. This solution would eliminate much of the additional call‐handling complexity that may be otherwise introduced by more sophisticated multipoint routeing algorithms.
A multichannel, bidirectional single‐wavelength, optical video link over a single fibre
Authors: Shklov Shane J.
Published: July 2007

Over the past year the Manitoba Telephone System, working with both Catel in California and Cabletel in Toronto has developed a unique optical architecture. In comparison to conventional fibre architectures, this structure has reduced the cost and complexity while increasing the reliability and capacity without sacrificing technical performance. This multinode, multichannel, bi‐directional, single wavelength video conference structure is in use between hospitals in the province of Manitoba. Details of this configuration along with its performance are discussed.
A survey of multistage interconnection networks in fast packet switches
Authors: Chen Xiaoqiang
Published: July 2007

This paper comprises a broad survey of multistage interconnection networks (MINs), which are incorporated into the underlying fabric of fast packet switches for use in broadband ATM networks. A general classification of MINs based on network functionality and blocking characteristics in the context of fast packet switches is presented in order to emphasize the fundamental principles which differentiate the network architectures. For each class of network, important theoretical results are given and the underlying design principles are explained with the best known explicit examples. Special emphasis is given to the implementation complexities and control strategies of individual approaches.
Multiserv: An ATM based residential SPN for the belgian broadband project
Authors: van Engelshoven Rob
Published: July 2007

The paper describes the ATM based MULTIserv subscriber premises network (SPN) intended for residential and small business use. The system is optimized for users requiring a low number of broadband connections and having a large demand for distributive services such as CATV. This SPN may be used whenever call acceptance is done according a peak bandwidth allocation policy.

Although the MULTIserv access system is extremely simple, both continuous and variable bit‐rate services are supported. Traffic calculation and simulations show that the services most susceptible to jitter, i.e. the synchronous, can be guaranteed for mean network access loads of up to 95 per cent, provided that traffic source shaping is performed.

Through the equal S and T interface the modular concept allows for star, bus and tree‐like topologies. The low functionality enables low‐cost solutions through high system integration.
Statistical multiplexing gain for variable bit rate video codecs in ATM networks
Authors: Heeke Helmut
Published: July 2007

Asynchronous transfer mode (ATM) broadband networks will support variable bit rate video codecs, which are capable of maintaining a constant picture quality. To demonstrate this capability, a prototype hardware video coder has been developed in the Siemens Central Communications Laboratories. The prototype uses interframe coding, combined with a discrete cosine transform, and is able to reproduce the original picture quality, independent of signal sources or picture material used.

A gain in transmission efficiency is expected when several video sources share a common ATM channel (‘statistical multiplexing’). This paper reports on a series of measurements that have been performed using this coder for a large variety of video sources to determine the possible gain in transmission efficiency.

The main results are: for realistic video phone scenes, up to about three times the number of signals can be transmitted compared to transmision with constant rate and the same picture quality, if the output signal of the coder has been smoothed over a period of one frame. Smoothing over shorter periods reduces the potential gain substantially. The statistical multiplexing gain increases with the duration of the picture sequences due to the criterion of constant picture quality. It varies very little with the acceptable packet loss rate.
A survey of research and standards in high‐speed networks
Authors: Li Victor O. K. , Chang Jin‐Fu , Lee Kuo‐Chun , Yang Tien‐Shun
Published: July 2007

This paper surveys research and standards in high‐speed networks. It first classifies high‐speed networks according to the area of coverage. Secondly, it discusses the switches. Then, it examines network management protocols: media access control, routeing, flow control and error control. Finally, it investigates current hig‐speed network standards: DQDB, FDDI, ATM, and SONET.
An efficient method for computing cell loss probability for heterogeneous bursty traffic in ATM networks
Authors: Jabbari Bijan , Yegenoglu Ferit
Published: July 2007

In this paper, we present an approximation for the probability of cell loss of heterogeneous bursty traffic in broadband integrated packet networks based on the asynchronous transfer mode. The sources considered here alternate between active and silent periods and are characterized by their peak and average transmission rates. The cell loss probability is obtained by considering only the number of active sources at a given time and computing the amount of traffic that exceeds the link capacity. Since the amount of buffered excess traffic is not considered in this computation, this approximation is actually an upper bound of the cell loss probability. The numerical efficiency of this bound enables it to be used as a measure based on which robust and simple resource allocation strategies can be developed for bursty sources. Comparison of this bound with the simulation results has shown that the bound is close to the actual loss probabilities especially for large burst lengths and high utilizations.
Optimized nested threshold cell discarding for ATM overload control
Authors: Petr David W. , Frost Victor S.
Published: July 2007

This paper deals with overload control in asynchronous transfer mode (ATM) networks via priority cell discarding mechanisms governed by a set of nested queue fill thresholds. Specifically, we address the problem of finding the optimal set of discarding thresholds, for an arbitrary number of priorities, under two different performance scenarios. In the first scenario, we minimize the expected discarding cost (a performance penalty) for a given offered load using stochastic dynamic programming. In the second scenario, we maximize the offered load subject to constraints on cell loss (discarding) probabilities using an efficient search technique developed specifically for this problem. Our results illustrate that nested threshold discarding systems can perform significantly better under either scenario than a system without discarding priorities. We characterize the performance advantage over ranges of system parameter values and briefly study the use of sub‐optimal, non‐adaptive thresholds.
An analytical technique for the derivation of the delay performance of ATM switches with multiserver output queues
Authors: Bruneel Herwig , Steyaert Bart , Desmet Emmanuel , Petit Guido H.
Published: July 2007

In this paper, a discrete‐time multiserver queueing system with infinite waiting room and general independent arrivals is considered. The delay performance of such a system, under a first‐come‐first‐served queueing discipline, is evaluated by means of a purely analytical technique. Specifically, explicit formulae are derived for such quantities as the probability generating function, the mean value and the variance of the delay. The results of the study are useful, for instance, in the context of fast packet switching with output queueing, where the switching elements have their output ports organized in groups, each group corresponding to a separate output queue.
Precise UPC scheme and bandwidth allocation methods for ATM‐based bisdn characterized by wide‐ranging traffic parameter values
Authors: Yamanaka Naoaki , Sato Youichi , Sato Ken‐Ichi
Published: July 2007

This paper proposes an ATM traffic management method that combines a deterministic source traffic descriptor, a deterministic usage parameter control (UPC) algorithm, and a conservative statistical bandwidth allocation method. The source traffic descriptor is based on sliding time interval‐type descriptors for both the peak‐rate and the average‐rate. A UPC method which combines a sliding‐window‐type circuit and a two‐phase credit‐window‐type circuit for widely‐ranging traffic parameter values is proposed. The method is precise and accurate, and requires only a small amount of hardware. The bandwidth allocation method uses the worst pattern that can be transmitted through the proposed UPC circuit. The proposed traffic management method not only guarantees the QOS of all connections, but also allows for large statistical multiplexing gain. The proposed method, therefore, makes it possible to create a more effective BISDN, one that can offer cost‐effective broadband VBR services.
Path enumeration and hot‐potato routeing analysis in multihop networks
Authors: Ayanoǧlu Ender , Caballero Richard J.
Published: July 2007

Using a labelling of the edges of the network graph for a multihop network and a Taylor series expansion of the transfer function of the resulting signal flow graph, we calculate the number of paths of a given length in the multihop network. The derivative of the transfer function and a fixed point algorithm yield the average delay as a function of the packet arrival rate.
A parametric optimization approach to admission control and bandwidth assignment in hybrid TDM networks
Authors: Aicardi Michele , Bolla Raffaele , Davoli Franco , Minciardi Riccardo
Published: July 2007

The access to a multiservice synchronous TDM network is considered, where hybrid frames are used to carry two basic traffic types (a circuit‐switched isochronous and a packet‐switched asynchronous one), generated by several users. Each user is assigned a portion of the total available bandwidth, in terms of slots/frame, which is dynamically allocated between the two traffic types at the user premises, by means of a local randomized decision rule. The users' bandwidth shares (capacities) are allocated by a centralized agent, whose goal is to minimize a global cost function that accounts for packet delays and call blocking of the entire process. Parametric optimization problems for the central agent are defined and the application of suitable descent techniques is shown, with the cost function extending over a finite and an infinite time horizon, respectively. The specific nature of the optimization problems is discussed, and numerical examples and simulations are presented that illustrate the effectiveness of the method.
Performance evaluation of an adaptive GSM receiver with frequency‐selective fading and adjacent‐ and co‐channel interference
Authors: Luise Marco , Reggiannini Ruggero
Published: July 2007

This study represents the sequel and conclusion of a previous one already published in this Journal a few issues ago.1 In that article, we tackled the problem of evaluating theoretically the performance of an adaptive MLSE receiver for MSK signals on a frequency‐selective stationary radio propagation channel, and we validated the theoretical findings (in the form of upper and lower bounds to the BER of the receiver) by means of computer simulations. In the present paper, we report on the performance of the very same scheme of channel‐estimator‐plus‐Viterbi‐equalizer receiver for mobile communications in a more realistic operating environment. In particular, we completely encompass here the groupe spécial mobile (GSM) transmission format, based on the Gaussian minimum shift keying (GMSK) modulation scheme and on narrowband time‐division multiple access (TDMA) transmission. Also, we remove the assumption of a time‐invariant propagation channel, assuming the recommended standard GSM channels as benchmark transmission conditions. Finally, with the aid of extensive computer simulations, we analyse the sensitivity of the MLSE receiver to unwanted co‐channel and adjacent‐channel interference coming from other users of the mobile cellular GSM system.
On the non‐blocking conditions of self‐routeing multistage interconnection networks
Authors: Ferrari G. , Lenti M. , Pattavina A.
Published: July 2007

This paper studies the non‐blocking conditions of a genericN × Nmultistage interconnection network, such as an omega network or ann‐cube network, in which only one path connects any inlet to each outlet and different I/O paths can share interstage links. It is widely known that any of these networks is non‐blocking for a compact and monotone pattern ofk≤NI/O paths. Recently it has become very important to show the network non‐blocking property for permutation sets, wider than the compact and monotone, which are usually encountered in broadband ATM networks. By using a new approach based on the concept of distance between I/O paths, we show here that these networks are non‐blocking for a set of I/O paths obtained by shifting cyclically the inlets of a compact and monotone pattern of I/O paths by an arbitrary number of steps.
Coupling between tilted Gaussian beam and graded‐index multi‐mode fibre
Authors: Sun Z. J. , Jannson T.
Published: July 2007

This paper is a comment on the paper presented by Shimazu and Kikuchi,11 ‘A time and wavelength division fiber loop distribution system with acousto‐optic tunable filters’. Specifically, a number of assumptions made in their paper regarding channel loss and crosstalk make it difficult to apply to real‐world system evaluations.
On the effects of a spacecraft subcarrier unbalanced modulator
Authors: Nguyen Tien Manh
Published: July 2007

This paper presents mathematical models with associated analysis of the deleterious effects which a spacecraft's subcarrier unbalanced modulator has on the performance of a phase‐modulated residual carrier communications link. The undesired spectral components produced by the phase and amplitude imbalances in the subcarrier modulator can cause (1) potential interference to the carrier tracking and (2) degradation in the telemetry bit signal‐to‐noise ratio (SNR). A suitable model for the unbalanced modulator is developed and the threshold levels of undesired components that fall into the carrier tracking loop are determined. The distribution of the carrier phase error caused by the additive White Gaussian noise (AWGN) and undesired component at the residual RF carrier is derived for the limiting cases. Further, this paper analyses the telemetry bit signal‐to‐noise ratio degradations due to undesirable spectral components as well as the carrier tracking phase error induced by phase and amplitude imbalances. Numerical results which indicate the sensitivity of the carrier tracking loop and the telemetry symbol‐error rate (SER) to various parameters of the models are also provided as a tool in the design of the subcarrier balanced modulator.
Policing of realistic VBR video traffic in an ATM network
Authors: Rathgeb Erwin P.
Published: July 2007

ATM has been accepted by CCITT as the transport mechanism for the future BISDN and will also be widely used in future customer premises networks. Networks based on the ATM principle are expected to provide a very flexible communications infrastructure allowing customers to make effective use of a wide variety of offered services. To provide this flexibility with an acceptable quality of service while operating the network in an economic way, elaborate traffic management functions will be necessary to control the traffic flows within the network. This paper will study one of these functions—the so‐called ‘usage parameter control’ or ‘policing’ function—in some detail to illustrate some of the problems that arise and point out possible solutions. The mechanisms chosen to implement the policing function will be the ‘leaky bucket’ mechanism, the ‘jumping window’ mechanism and the ‘moving window’ mechanism. The input streams used to assess the mechanisms represent different types of video communication—videophone, video conference and entertainment video—coded according to different variable bit‐rate (VBR) algorithms. In contrast to most of the previous studies, where artificial, statistical traffic sources have been used, the sources used in this paper are directly based on measured ‘real‐life’ video data. This ensures that all the statistical properties of the actual traffic stream are preserved and allows identification of the different factors that influence the dimensioning and the performance of the policing mechanism. The results of this study show that the uncertainty about the key parameters at call set‐up and the considerable impact of single scenes make the proper dimensioning of policing mechanisms difficult. Furthermore, it seems not to be practical to use the long term mean bit‐rate as the key traffic control parameter for these sources. Results indicating that the long‐term cell loss ratio is not a sufficient measure for the quality of service are also presented. A comparison of the mechanisms shows that from a performance perspective, the ‘leaky bucket’ mechanism is superior to the two window mechanisms. This work is relevant to evolving standards for both BISDN traffic management and variable bit‐rate video coding.
Identification of novel genes expressed during mouse tooth development by microarray gene expression analysis
Authors: Pemberton Trevor J. , Li Fang‐Yuan , Oka Shoji , Mendoza‐Fandino Gustavo A. , Hsu Ya‐Hsuan , Bringas Pablo , Chai Yang , Snead Malcolm L. , Mehrian‐Shai Ruty , Patel Pragna I.
Published: July 2007

To identify genes heretofore undiscovered as critical players in the biogenesis of teeth, we have used microarray gene expression analysis of the developing mouse molar tooth (DMT) between postnatal day (P) 1 and P10 to identify genes differentially expressed when compared with 16 control tissues. Of the top 100 genes exhibiting increased expression in the DMT, 29 were found to have been previously associated with tooth development. Differential expression of the remaining 71 genes not previously associated with tooth development was confirmed by quantitative reverse transcription‐polymerase chain reaction analysis. Further analysis of seven of the latter genes by mRNA in situ hybridization found that five were specific to the developing tooth in the craniofacial region (Rspo4, Papln, Amtn, Gja1, Maf). Of the remaining two, one was found to be more widely expressed (Sp7) and the other was found to be specific to the nasal serous gland, which is close to, but distinct from, the developing tooth (Vrm). Developmental Dynamics 236:2245–2257, 2007. © 2007 Wiley‐Liss, Inc.
Learning rules of neural networks for inverse systems
Authors: Maeda Yutaka
Published: July 2007

This paper considers on‐line learning of neural networks for an inverse problem. A neural network must learn an inverse system of a static unknown system on the basis of an evaluation function that is a squared error between an output of the unknown system and its desired value.

Usual learning methods need information about the sign of the sensitivity of the unknown system. This paper proposes learning rules that do not require the information about that sign. These rules utilize a perturbation signal. Rules with the perturbation on an input of the unknown system and a rule with it on each weight of the neural network are presented. The usefulness of these learning rules is confirmed via some numerical simulations.
Analysis of chaotic neuron models with information theory
Authors: Ishiyama Kunihiko , Itoh Susumu , Utsunomiya Toshio , Aihara Kazuyuki
Published: July 2007

A one‐dimensional mapping of a chaotic neuron model which generates deterministic chaos is analyzed from the viewpoint of the information theory.

First, the mutual information between the initial value and the value after iterations of the mappings is calculated, and it is shown that the information of the initial value decays almost exponentially. To examine the decaying behavior in detail, the dynamics of the chaotic neuron model is represented as the information flow of “0” and “1” in a bitwise space (register) and the behavior of the mutual information contained in each bit is examined. It is shown through this analysis that the information in the chaotic neuron model is maintained, being mixed and distributed among the bits. Moreover, the chaotic neuron model is compared with two typical chaotic dynamical systems with different information structures, i.e., the B‐Z mapping and the logistic mapping to clarify the information structure. Finally, it is shown for the system, where the chaotic neuron models are unidirectionally connected as a one‐dimensional network, that the information transmission is made possible by its peculiar information structure.
Reliability of maximum‐likelihood decoded codewords and its application to decoding of concatenated codes
Authors: Tanaka Hatsukazu
Published: July 2007

This paper attempts to improve the reliability of the maximum‐likelihood decoded codeword. The reliability function is defined anew based on the Euclid distance in the signal space and is derived for the case where the signal representation for the binary linear code is precisely specified. The traditionally well‐known Viterbi algorithm is modified to evaluate the reliability based on the proposed reliability function in parallel with the maximum‐likelihood decoding. This algorithm is called the modified Viterbi algorithm.

To verify the usefulness of the newly defined reliability, the difference between the reliability and the likelihood is examined. The block‐error rate when the algorithm is applied to the decoding of the concatenated code is compared to the block‐error rates of the various conventional decoding methods. As a result, the block‐error rate is improved drastically by the decoding which effectively utilizes the reliability function; and it has been shown to be useful to introduce the concept of reliability into the decoding process.
Design of two‐channel perfect reconstruction QMF
Authors: Ikehara Masaaki , Yamashita Akinobu , Kuroda Hideo
Published: July 2007

This paper proposes a design method for the FIR two‐channel perfect quadrature mirror filter (QMF) with the linear phase. The two‐channel perfect QMF can be designed by Vetterli's method, where a system of equations representing the condition for the perfect reconstruction of the signal is solved. The filter designed by this method, however, does not, in general, have good frequency characteristics.

This paper presents the design for the two‐channel QMF with a perfect reconstruction and a good amplitude characteristic. The method is based on Vetterli's method, and a constraint to approximate the amplitude characteristic in the frequency domain is added to the condition of perfect reconstruction in time domain. Then Remez' algorithm is applied to the derived system of equations.

The construction of the two‐channel perfect QMF, when the coefficient is quantized, also is discussed. Furthermore, a method is shown in which the two‐dimensional (2‐D) perfect QMF is designed by applying the McClellan transformation to the obtained 1‐D QMF. The condition for the McClellan transformation for the perfect reconstruction is derived.
Vibration analysis of length extensional mode quartz crystal resonator with plural vibration bars
Authors: Kawashima Hirofumi , Nakazato Mitsuhiro
Published: July 2007

A length extensional mode quartz crystal resonator of small size and good antishock performance and which functions at relatively low frequencies of 200 kHz to 1.536 MHz has been used in pagers and IC cards. An on/off repetition in quartz resonators of this type is common and therefore the start‐up transient performance becomes important.

This paper describes a length extensional mode quartz crystal resonator with plural vibration bars which has a short start‐up time. The objective of this paper is to clarify both theoretically and experimentally motional inductance L1, frequency characteristics and temperature dependence of resonance frequency, and also electric properties of the resonator.

Motional inductance L1 is derived first. Especially, L1 is found theoretically to be inversely proportional to the number of bars. Next, a vibration analysis of bars and supporters is made by taking into account the lateral motions based on an energy method and then a frequency equation is derived. The frequency characteristics, temperature dependence of resonance frequency, and electric properties are analyzed and compared with experimental results. The calculated results are found to be in agreement with the experimental ones. Finally, it is shown that a length extensional mode quartz resonator exhibits a short start‐up time, since L1 and R1 are compared to the single‐bar case. Such resonators are believed to be manufactured in a small form and also exhibit a good anti‐shock performance since vibrational and supporting portions can be made as one solid body by an etching method.
Measurement of leaky surface acoustic wave velocity using interdigital transducer in a layered structure composed of piezoelectric ceramic and fused quartz
Authors: Toda Kohji , Sawaguchi Akihiro
Published: July 2007

An ultrasonic system for measuring a leaky surface acoustic wave (SAW) velocity is described. A leaky SAW transducer consisting of a piezoelectric ceramic thin plate, an interdigital transducer (IDT), and a fused quartz plate is used in this system. A longitudinal wave which is reradiated from a test sample surface into a water layer is detected as electric signals having different delay times received at two different IDTs placed on a substrate surface. A phase difference between two delayed signals depends on the leaky SAW velocity. It is essential in this measurement method that an incident angle of an ultrasonic beam be nearly equal to the Rayleigh angle. The present method using a layered structure leaky SAW transducer has the advantage of a wider range of detecting SAW velocities, compared to a conventional single‐layer SAW one. Experimental results for a 128° rotated Y‐cut‐X propagation LiNbO3 plate and a glass plate are discussed. The layered structure leaky SAW transducer is useful for nondestructive evaluation of piezoelectric as well as nonpiezoelectric substrates.
Systematic consideration of the superiority of generalized linear interpolation approximation
Authors: Kida Takuro , Mochizuki Hiroshi
Published: July 2007

This paper considers the set of waveforms for which the weighted power‐of‐p(1 < p < +∞) integral of the Fourier spectrum is bounded. Since different weight functions can be used in different frequency bands, as long as they are positive, the restriction of the waveform by the power‐of‐pintegral is sufficiently general. It is assumed that the waveform belonging to such a set is added to several given linear time‐invariant filters. A theory of the optimum approximation of the original waveform is established using the sampling sequences of the corresponding outputs. The measure of the approximation error is defined as the upper limit of the absolute value of the difference between the original and the approximating waveforms when the original waveforms are changed one by one over the whole set of waveforms.

Considering the sampling points, which substantially affect the approximation at a fixed timet, a theorem is presented which indicates that there exists a waveform which has zero value at all such sampling points and has the absolute value of the approximation error which reaches the above upper limit. It is shown also that a similar result can be established for the multidimensional waveform.

In this paper, it is shown that the proposed method of linear approximation is better than any other approximation using the same sample values, including the nonlinear signal processing, as long as the forementioned set of waveforms and the measure for the approximation error are considered.
A least‐squares adaptive filter with complex coefficients for ill‐conditioned adaptive equalization
Authors: Shimamura Tetsuya , Suzuki Jouji
Published: July 2007

This paper presents a least‐squares adaptive equalizer that provides good performance even in an ill‐conditioned environment where the channel distortion is rather severe. Using complex‐valued tap coefficients and halving the order of the transversal equalizer result in a substantial reduction in the condition number of the input correlation matrix composed of input signals to the equalizer. The input and output signals for the equalizer are transformed into analytic signals. Then a sampling operation of decimation by a factor of two is performed. Adaptive filtering is performed based on complex arithmetic. Compared with commonly used real‐valued adaptive equalizers, accuracy of the estimation of tap coefficients is improved substantially and the computational burden per time is reduced. Computer simulations will show the effectiveness of the proposed adaptive equalizer.
Deriving the complete weight distribution of reed‐solomon codes
Authors: Tokiwa Kin‐Ichiroh , Tanaka Hatsukazu
Published: July 2007

The weight distribution of a code usually is investigated on the basis of Hamming weight. For such non‐binary codes as Reed‐Solomon (RS) codes, therefore, all nonzero components of codewords are regarded as identical. To describe the structure of nonbinary codes in more detail, each nonzero component should be distinguished from the other. This requirement can be met by the complete weight distribution (CWD).

Recently, Blake and Kith and the present authors derived independently the CWD for a special class of RS codes. However, the derivation of the CWD for general RS codes remains a difficult problem. This paper discusses the problem of obtaining the CWD for general RS codes. To make this process easier, three unique sets of codewords which should be examined are defined first. Then it is shown that the CWD can be derived from such unique sets of codewords. Finally, a relationship between the CWD for RS code of dimension k and that of dimension k + 1 is considered.
Floating‐electrode‐type SAW unidirectional transducers using leaky surface waves and their application to low‐loss filters
Authors: Takeuchi Masao , Yamanouchi Kazuhiko , Murata Kenji , Doi Kenji
Published: July 2007

To realize surface acoustic wave (SAW) filters with low‐loss and wide bandwidth for mobile communications, a floating‐electrode‐type unidirectional transducer (FEUDT) using internal reflection is discussed. The proposed structure for FEUDT has an advantage of manufacturability and also for high‐frequency performance exhibiting a second harmonic operation better than a fundamental mode.

This paper describes both a theoretical and experimental result. A leaky surface acoustic wave (LSAW) of SH‐wave type using 41 °YX LiNbO3substrate, the velocity of which is much faster than that for a usual Rayleigh wave and has a largeK2is used. A second harmonic FEUDT suitable for this wave is obtained theoretically by using the Green function method. The result is in good agreement with experiment.

An SH‐type LSAW is more sensitive to a surface boundary condition of a substrate compared to the usual Rayleigh wave and thus the boundary condition for a low‐loss filter is very important. This is discussed both theoretically and experimentally. It is found that an open grating is the best for a propagation path if one considers the mode conversion of LSAW excited by a transducer. A prototype filter has been fabricated. The insertion losses of 2.6 dB and 2.8 dB at the center frequency of 360 and 700 MHz, respectively, are obtained successfully.
High‐frequency IIR switched capacitor filter using parallel cyclic‐type circuit with low‐power consumption
Authors: Hirata Yoshinori , Takahashi Nobuaki , Kato Kyoko , Takebe Tsuyoshi
Published: July 2007

FIR transversal filters have been proposed using a parallel cyclic‐type circuit configuration which alleviates the performance degradation at higher frequencies due to the finite gain‐bandwidth product of op amps in switched capacitor filters. A parallel cyclic‐type circuit realizes the delay and weighting of the input signal with switches and capacitors without op amps. It is also of low‐power consumption because it requires only one op amp for its adder.

This paper describes a method to implement direct form I IIR filters using a parallel cyclic‐type circuit. The performance degradation caused by the finite gain bandwidth product of the op amp and by parasitic capacitances is analyzed, both for the canonical circuit with the delay element using op amps and for the parallel cyclic‐type circuit. Also, a parallel cyclic‐type circuit is proposed for high‐frequency operations containing multiple adders. This circuit incorporates a novel feedback scheme using the “Look Ahead” calculation method. Finally, through experiments, the performance improvement by the parallel cyclic‐type circuits over the canonical and biquad circuits is demonstrated.
Signal propagation timing check system in multilevel sequential circuits
Authors: Nakamura Yatsuka , Nishiyama Takaya , Fuwa Yasushi
Published: July 2007

This paper presents the concept of the timing vector as well as the related techniques which are useful in checking the synchronization and the timing in the multistage sequential circuit. In each of the sequential circuits, the output period where the output is unstable and the sense period where the input must be stable are considered. The proposed method is based on the property that, if the output period of the preceding stage in the cascaded circuits overlaps with the sense period of the succeeding stage, the signal cannot be propagated properly. The existence/nonexistence of such an overlap is checked.

First, the output period and the sense period of the sequential circuit are modeled in a form which does not depend on the frequency and the duty‐ratio of the clock given to the circuit. In the check process, this clock information is given to the circuit model. A timing belt is constructed where the output and sense periods of each circuit are developed on the real time‐axis, and it is checked whether or not an overlap exists in each circuit. The feature of the method is that the timing check of the cascaded sequential circuit can be executed completely with a high speed. Using the program constructed based on the proposed method, the sequential circuit actually is checked and the usefulness of the method is verified.
Dynamic measurement of nonlinear constants of PZT ceramics
Authors: Cho Yasuo , Matsuno Fumihiko
Published: July 2007

The dynamic measurement technique of adiabatic nonlinear constants in piezoelectric materials used in elastic devices is discussed. The present technique deals with the FM wave whose frequency varies corresponding to a physical quantity which changes sinusoidally. Using this method, measurements of a change in velocity and dielectric constant due to an applied ac electric field and also of a change in dielectric constant due to sinusoidally applied stress are made. In this method one can measure physical quantities depending on their orders responding to an applied field separately and can obtain constants of the orders (third of fourth order). Also, this technique can distinguish a change in velocity and dielectric constant due to temperature variation from those resulting from a nonlinear effect. Using this unique feature, measurements of velocity and dielectric constants with electric field at various temperatures were made. The temperature dependence of linear and nonlinear constants of the third and fourth order in PZT ceramics was discussed.
A class of fixed‐point problems on graphs and iterative solution algorithms
Authors: Tamai Tetsuo
Published: July 2007

A family of well‐known problems on graphs including the shortest‐path problem and the data flow analysis problem can be formulated as a fixed‐point problem. The lattice is used to represent the algebraic structure of information and the problem is formulated with fixed‐point equations where unknown variables that label vertices of the graph take values over the lattice.

Then a practical solution algorithm based on the iterative approach that solves the unified problem is given. When applied to the shortest‐path problem, the algorithm is equivalent to the well‐known potential method but its validity for the generally formulated problem is not trivial. The correctness and termination of the algorithm within a general framework is proved.

Finally, the formulation is compared to other formulations and the most fundamental structure of the problem is discussed. The relation between the general algorithm and various existing methods for each specific domain are analyzed and it is shown that for the data flow problem, the general algorithm practically is improving existing iterative methods such as Kildall's and that of Hecht and Ullman.
Delta function model analysis of SSBW spurious responses in SAW devices
Authors: Hashimoto Ken‐Ya , Yamaguchi Masatsune
Published: July 2007

This paper considers the characterization of surface skimming waves (SSBW) by two newly defined parameters, i.e., effective electromechanical coupling factor and critical length. The parameters are estimated easily by the effective permittivity and are directly applicable to the delta function model analysis. Experiments on a TV‐IF SAW filter agreed well with the analysis. In addition, these parameters for SO2/36° KY‐LiTaO3structure were estimated. It is shown both theoretically and experimentally that the SSBW responses can be suppressed by depositing SiO2with appropriate thickness.
Narrow‐gap and multiphase interdigital transducer using anodic oxidation
Authors: Odagawa Hiroyuki , Meguro Toshiyasu , Doi Kenji , Yamanouchi Kazuhiko
Published: July 2007

A method of fabricating a narrow‐gap interdigital transducer and of a multilevel interconnection using anodic oxidation is discussed, which is a key technology for SAW devices with high performance. This process can cope with the two problems of its high‐frequency application and fabrication of an advanced electrode structure. As an example, this method is applied to a group‐type unidirectional transducer (GUDT). The process for a high‐frequency performance by having a narrow‐gap structure and no loss without meander‐line electrodes is proposed.

A prototype filter with GUDT has been fabricated by using this method and a good result of an insertion loss of 2 dB at a center frequency of 700 MHz was obtained. This result has confirmed that GUDT is useful for low loss and with very small ripple where no meander‐line electrode is used. The present method has demonstrated its high applicability.
A note on performance improvement of Ziv‐Lempel code
Authors: Ise Koutarou , Tanaka Hatsukazu
Published: July 2007

The Ziv‐Lempel (ZL) algorithm is well known as an efficient universal source coding algorithm to encode a data string by replacing with codewords given by substrings in a fixed‐size buffer. However, the original ZL algorithm contains considerable redundancy on how to give a codeword for each substring because the same substring appears in some different places in the buffer.

In this paper, a new algorithm to remove such redundancy is proposed to improve the coding efficiency for any kinds of strings. The algorithm requires search matched strings in the decoding process. A modified algorithm also is proposed to decode without searching matched strings.
A new cut for torsional mode quartz crystal resonators of tuning fork type
Authors: Kawashima Hirofumi , Nakazato Mitsuhiro
Published: July 2007

This paper proposes and describes a new cut torsional quartz resonator which is designated “TT‐Cut,” and clarifies its frequency characteristics, frequency temperature behavior, and electrical equivalent circuit parameters.

First, in the analysis procedure, an equation of motion is derived from an energy method. Next, by solving the equation of motion under the boundary conditions of “free‐free bar” or “clamped‐free bar,” the frequency equations are derived as a function of thicknessz0, widthx0, and lengthy0.

Furthermore, from the frequency equation a relationship of frequency constant (f.y0) versus thickness‐to‐width ratioRzx(=z0/x0) and a relationship between thickness‐to‐width ratioRzxand cut angles (ϕ, θ) where the first‐order temperature coefficient α reaches zero are derived theoretically. As a result, numerous relationships where α reaches zero are found to exist between thickness‐to‐width ratioRzxand cut angles (ϕ, θ). Especially, the second‐order temperature coefficient β has a small value of ‐1.16 × 10−8/°C2whose absolute value is approximately one‐third of the well‐known flexural mode quartz crystal resonator. The value of β then is‐compared with the measured data of ‐1.29 × 10−8/°C2, so that both results are found to agree sufficiently well.

Finally, series resistanceR1and a quality factorQof a tuning‐fork‐type resonator are examined. Consequently, it is shown that a tuning‐fork‐type torsional quartz crystal resonator is obtained with a smallR1of 2.2 to 14.4 k° and a largeQvalue of 276, 000 to 378, 000 in frequency range of 385 to 444 kHz.
Knowledge‐based requirements specification and definition method for computer communication system design
Authors: Kinoshita Tetsuo , Sugawara Kenji , Shiratori Norio
Published: July 2007

The requirements specification and definition is one of the important and difficult tasks in the design and implementation of systems which realize various user requests.

This paper proposes a knowledge‐based requirements specification and definition method for computer communication system design. In the proposed method, a framework for representing and utilizing various design knowledge of the requirements specification and definition is introduced based on a knowledge‐based design methodology for a computer communication system. According to the proposed method, the requirements specifications of logical functions of a computer communication system can be derived systematically from the users' requests and also represented in the formal descriptions called knowledge models of the requirements definition task.
Two‐dimensional adaptive state‐space filters using LMS method
Authors: Muneyasu Mitsuji , Hinamoto Takao
Published: July 2007

This paper considers the construction of two‐dimensional (2‐D) adaptive state‐space filters using the least mean squares (LMS) method. The approach is based on the Roesser local state‐space model. First, the relation between the coefficient sensitivities and the intermediate transfer functions is investigated. Then, after introducing new systems for generating the gradient vectors, an adaptive algorithm is developed using the LMS method.

Next, a 2‐D adaptive state‐space filter with separable denominator is introduced to reduce the amount of computation in the adaptive process. Finally, a numerical example is given in which the 2‐D adaptive state‐space filters are used to design 2‐D digital filters in the spatial domain.
A layout description system using C language
Authors: Shigehiro Yuji , Shirakawa Isao , Harashima Katsumi , Kambe Takashi
Published: July 2007

With the rapid progress of VLSI microfabrication technology, the functional cell library must be updated frequently. Then it is important to develop a functional cell generation technique. For this purpose, the study of technique is considered interesting, which represents the layout pattern efficiently and independently of the process technology, using a language.

This paper discusses the layout language based on the general‐purpose C language and the processing system. The layout pattern is described using C language and newly defined functions for layout description. Then the layout data are generated automatically from the description.

First, the assumed layout pattern structure is considered. Then the proposed layout description technique, as well as the realization of the processing system, are discussed. Finally, the processing system actually is constructed and it is demonstrated that the layout pattern is generated automatically from the layout description.
Digital filters with hypercomplex coefficients
Authors: Ueda Kazuhiro , Takahashi Shin‐Ichi
Published: July 2007

This paper considers digital filters with hyper‐complex coefficients. Filters of this type can reduce the order of filters to one‐fourth the one with real coefficients. It is reported that the first‐order digital filter with hypercomplex coefficients can realize the fourth‐order digital filter with real coefficients which can be expressed by a second‐order all‐pass filter with complex coefficients.

This paper considers also generalization including the foregoing special case and shows that the first‐order digital filter with hypercomplex coefficients can realize an arbitrary‐order digital filter with real coefficients less than 4.

Arbitrary higher‐order digital filter with real coefficients can be realized by parallel connection or cascade connection of first‐order digital filters with hypercomplex coefficients. This paper considers the following three different realizations: (a) realization by parallel connection; (b) realization by cascade connection of real part; and (c) realization by cascade connection. We find that case (b) is the most low sensitive. Finally, stability criteria of hypercomplex digital filters of first‐order are suggested.