This paper proposes a new distributed connection establishment scheme involving several competing network providers in a multimedia telecommunications environment. This connection establishment scheme, which is based on the concept of open competitive bidding, enables mutual selection by users and network providers. By employing this proposed scheme, both network providers and users can pursue their own objectives, according to their own bidding and awarding strategies. In this paper, a simple bidding strategy for network providers is presented, and the effectiveness of this strategy is evaluated by means of computer simulation. It is shown that each network provider can improve its profit by adopting this strategy. In this paper, an example of utility functions for users is presented, and the effectiveness of the mechanism with which users can select a network provider is also evaluated by means of computer simulation. Each user can improve his/her utility by selecting an appropriate network provider based on this utility function.

Under a contamination of background sound noises, it seems difficult especially in a real working situation to evaluate various type statistics of only an objective sound signal fluctuation. In many cases of the noise evaluation, some signal processing method have been employed to eliminate the effect of background sound noises by first measuring emitted sound levels. In this study, a new evaluation method of sound level fluctuation is proposed in principle on the basis of the measurement of heterogeneous physical quantity other than sound pressures or sound levels to eliminate the effect of background sound noises. Though the theoretical analysis on acoustical emission caused by a mechanical vibration seems very difficult in a working situation, the sound noise fluctuation emitted only from an objective sound source can be effectively evaluated through its related vibration measurement by employing a fairly unified stochastic method proposed on the basis of a generalized regression analysis between sound and vibration. Here, the regression coefficients are determined by employing the least squares error method to minimize the mean square of estimation error to illustrate well the sound data by means of vibration data. Finally, the effectiveness of proposed method has been experimentally applied to the sound noise evaluation of a jigsaw.

For the improvement of software quality and productivity, the author aims at realizing a software development environment to develop software through utilizing the merits of group work. Since networking is necessary for collaborative software development, he has developed a software distributed development environment for collaborative software development. In this environment, discussions about software design are held through a communication network, and the contents of discussions are recorded as software design decisions and decision rationale. One feature of this environment is that the contents of discussions can be recorded in on-line real time and reused without reconstructing the information recorded through this environment. This paper clarifies the essential conditions for actualizing this environment and proposes an information structure model for recording the contents of discussions that actualizes the above-mentioned feature. The effectiveness of the proposed model is proved through an example of its application to software design discussions.

In the IETF, discussions on the authentication method of the Dynamic Host Configuration Protocol (DHCP) message are active and several methods have been proposed. These related specifications were published and circulated as the IETF Internet-Drafts. However, they still have several drawbacks. One of the major drawbacks is that any user can reuse addresses illegally. A user can use an expired address that was allocated to a host. This kind of "illegal use" of the addresses managed by the DHCP server may cause serious security problems. In order to solve them, we propose a new access control method to be used as the DHCP message authentication mechanism. Furthermore, we have designed and developed the DAG (DHCP Access Control Gateway) according to our method. The DAG serves as a gateway that allows only network accesses from clients with the address legally allocated by the DHCP server. This provides secure DHCP service if DHCP servers do not have an authentication mechanism, which is most likely to occur. If a DHCP server has such an authentication scheme as being proposed in IETF Internet-Draft, the DAG can offer a way to enable only a specific client to access the network.

The EMC-adequate design of microelectronic systems includes all actions intended to eliminate electromagnetic interference in electronic systems. Challenges faced in the microelectronic area include a growing system complexity, high integration levels and higher operating speeds at all levels of integration (chip, MCM, printed circuit board and system). The growing complexity, denser design and higher speed all lead to a substantial increase in EMC problems and accordingly the design time. EMC is not commonly accepted as a vital topic in microelectronic design. Microelectronic designers often are of the opinion that EMC is limited to electrical and electronic systems and the mandatory product regulations instead of setting requirements also for the integrated circuit they are designing. In this contribution a concept for an EMC-adequate design of electronic systems will be introduced. This concept is based on a generalized development process to integrate EMC-constraints into the system design. A prototype of an environment to analyse signal integrity effects on PCB based on a workflow oriented integration approach will be presented. Based on this approach the generation of user specific design and analysis environments including various set of EMC-tools is possible.

In this paper, we propose a scalable service networking architecture as a TINA-like environment for providing flexibly various mobility services. The proposed architecture provides an environment that enables the advent of service providers and rapidly introduces multimedia applications, considering networks scalability. For supporting customized mobility services, this architecture adopts a new service component, which we call Omnipresent Personal Environment Manager (OpeMgr). In order to support mobile users who move between heterogeneous networks, for instance, between the TINA-like environment and the Internet environment, we propose a structure of a gateway. In addition, the proposed architecture uses the fixed and mobile agent approaches for supporting the user's mobility, and we evaluated their performances with comparing those approaches.

In this paper, we present CB-Power, a hierarchical power analysis and characterization environment of cell-based CMOS circuits. The environment includes two parts, a cell characterization system for timing, input capacitance as well as power and a cell-based power estimation system. The characterization system can characterize basic, complex and transmission gates. During the characterization, input slew rate, output loading, capacitive feedthrough effect and the logic state dependence of nodes in a cell are all taken into account. The characterization methodology separates the power consumption of a cell into three components, e.g., capacitive feedthrough power, short-circuit power and dynamic power. With the characterization data, a cell-based power estimator (CBPE) embedded in Verilog-XL is used for estimating the power consumption of the gates in a circuit. CBPE is also a hierarchical power estimator. Macrocells such as flip-flops and adders are partitioned into primitive gates during power estimation. Experimental results on a set of MCNC benchmark circuits show that the power estimation based on our power modeling and characterization provides within 6% error of SPICE simulation on average while the CPU time consumed is more than two orders of magnitude less.

Many network protocols for routing messages have been proposed for mobile computing environments. In this paper, we consider the query processing strategy which operates over these network protocols. To begin with, we introduce five fundamental location update methods based on ideas extracted from the representative network protocols. They are the single broadcast notification (SBN), the double broadcast notification (WBN), the single default notification (SDN), the double default notification (WDN), and the no notification (NN). As a network protocol, each method is strong in performance in some system enrivonment, but weak in others. In practical situations, where various kinds of applications are used for various purposes, however, it is required to use a single method. We therefore propose an adaptive query processing strategy where these five location update methods can be dynamically selected. Moreover, we analyze the performance of this adaptive query processing strategy via the Markov chain. We also use the statistical approach to estimate the traffic of individual hosts. Finally, we show the efficiency of our proposed strategy over a wide area of system environments.

This paper compares three cell transfer quality control schemes, namely HPS, DAS and ORS, which integrate a preventive congestion control and a reactive congestion control in ATM switch. Simulation results showed that ORS achieves the largest network utilization, and HPS provides enough large throughput compared with DAS only when many VBR connections are multiplexed.

This paper describes the effectiveness of stream-oriented data-driven scheme for achieving autonomous fault management of hyper-distributed systems such as networks based on the Telecommunications Information Networking Architecture (TINA). TINA, whose specifications are in the finalizing phase within TINA-Consortium, is aiming at achieving interoperability and reusability of telecom applications software and independent of underlying technologies. However, to actually implement TINA network, it is essential to consider the technology constraints. Especially autonomous fault management at run-time is crucial for distributed network environment because centralized control using global information is very difficult. So far many works have been done on so-called off-line management but runtime management of service failure seems immature. This paper proposes introduction of stream-oriented data-driven processors to the autonomous fault management at runtime in TINA based distributed network environment. It examines the features of distributed network applications and technology requirements to achieve fault management of those distributed applications such as effective multiprocessing of surveillance, testing, reconfiguration in addition to ordinary processing.

In the measurement of actual random phenomenon, the observed data often contain the fuzziness due to the existence of confidence limitation in measuring instruments, permissible error in experimental data, some practical simplification of evaluation procedure and a quantized error in digitized observation. In this study, by introducing the well-known fuzzy theory, a state estimation method based on the above fuzzy observations is theoretically proposed through an establishment of wide sense digital filter under the actual situation of existence of the background noise in close connection of the inverse problem. The validity and effectiveness of the proposed method are experimentally confirmed by applying it to the actual fuzzy data observed in an acoustic environment.

Effective collaboration in ComputerSupported Collaborative Learning (CSCL) environments is nowadays an important research topic. It deals with two main problems: the configuration of an appropriate learning group and the intelligent task distribution in the practice of domain knowledge. In order to have effective collaboration in a CSCL environment, we have proposed a set of software agents that assist the learners to select their learning tasks, according to their capabilities and the possibilities of collaboration between them. In this paper the cooperation among software agents is presented as the key point for effective collaboration in CSCL environments. In this kind of environments the learner must have enough collaboration and learning possibilities, being motivated with the experience of social knowledge construction. We have been working on the problem of effective collaboration in CSCL environments, based on the cooperation between software agents developed for GRACILE, our Japanese Grammar CSCL environment. Before, we have proposed intelligent agents that assist the learners. Our next step has been the design of the cooperation between agents in order to create possibilities of effective collaboration in a virtual community of practice. In order to evaluate the performance of our agents we made several simulations. The results obtained from these simulations of diverse types of learning groups provided us with guidelines for the configuration of groups in CSCL environments, where effective collaboration is possible.

The intelligent tutoring system (ITS) enables students to learn knowledge deductively. However, students often become passive, because the ITS takes the initiative in their learning process. Also their knowledge is often superficial, beacause they can not understand different kinds of knowledge due to their limited experience. This paper presents a virtual learning environment (VLE) for discovery learning. The VLE has been built with virtual reality (VR) technology, and supports the student's discovery learning activity and fosters his/her creativity and adaptability based on a broad range of experience by using the functions of VR such as interactivity, direct manipulation interface, walk-through, the function to change view point freely. Also, the VLE connects the explorative training by means of VR with guided education by the ITS. The student model in VLE evaluates the student's level of understanding and adjusts the training accordingly. We have built an operator training system for the training of control activities of electric power plant using the conception of the VLE. The purposes of this system are the following: to aid students to acquire adequate knowledge and skills, and to aid them to gain confidence and experience through their learning activities. The student model evaluates the student's level of understanding for experiential knowledge connected that of skills in VR with that of knowledge in ITS.

Recently, various systems based on agent model architecture have been developed. In these systems, 'agents' with their own goals and functions are embedded, and perform their own tasks through collaboration among them by communication to achieve a goal as the system requires. Using this agent model for the construction of educational systems, adaptive configuration of the system is achieved. The purpose of this study is to propose a methodology for the design of an educational system based on agent model architecture. This paper describes the configuration of the agent model and the communication language and protocol used to represent collaboration among the agents necessary for performing a cooperative task. Moreover, we explain how to organize these agents as an educational system. As a case to show the organization of agents, we discuss the configuration of an intelligent learning environment to support C shell programming in UNIX and explain the collaborative behavior of embedded agents.

This letter shows an architectural approach for analyzing real-time aspects of distributed multimedia processing systems. The results of this letter are 1) to propose the concept real-time supporting environments which consist of real-time traffic management/control environment and real-time application environment and 2) to analyze the real-time requirements of such environments.

This paper proposes a new AFC (automatic frequency control) circuit employing a double-product type frequency discriminator to enable fast acquisition in very-low CNR (carrier to noise power ratio) environments. The frequency step responses of the proposed AFC circuit are theoretically analyzed. In addition this paper evaluates the performance of the proposed AFC circuit by computer simulation in very-low CNR environments. The simulation results confirm that click noise at the frequency discriminator causes large frequency tracking error and that this error can be improved by increasing the delay time of the double-product type frequency discriminator. The frequency error can be also reduced by introducing the proposed frequency discriminator to modify the frequency error detection performance. The acquisition time of the proposed AFC circuit can be reduced by about 100 symbols compared to the conventional cross-product type AFC circuit.

For Nakagami-Rice fading environment which seems to become a principle propagation environment in the next generation wideband and high-capacity mobile systems such as personal communications, we have previously proposed an approximated evaluation scheme for wideband digital transmission characteristics such as errors due to intersymbol interference of multipath waves. We called the scheme 'Equivalent Transmission-Path (ETP) Model.' In this paper, through a discussion about more general equivalent propagation channel expressions, we clarify a theoretical foundation of the ETP model and extend the model to have an ability of expression of instantaneous fading condition varying with time. Also the appropriateness of the instantaneous expression is examined by a computer simulation analysis. Based on this model, statistics of link quality and service availability in Nakagami-Rice fading environments are discussed.

We develop a simulation environment for designing and examining a neural network model at the network level. The aim of our research is to enable researchers investigating neural network connective models to save time by being equipped with a graphical user interface and database of the network models. This environment consists of three parts: (1) the kernel of the simulation system, (2) NNDBMS (Neural Networks DataBase Management System), and (3) a system for displaying simulation results in various ways.

Distributed shared memory is an attractive option for realizing functionally distributed computing in a wide area distributed environment, because of its simplicity and flexibility in software programming. However, up till now, distributed shared memory has mainly been studied in a local environment. In a widely distributed environment, latency of communication greatly affects system performance. Moreover, bandwidth of networks available in a wide area is dramatically increasing recently. DSM architecture using high performance networks must be different from the case of low speed networks being used. In this paper, distributed shared memory models in a widely distributed environment are discussed and evaluated. First, existing distributed shared memory models are examined: They are shared virtual memory and replicated shared memory. Next, an improved replicated shared memory model, which uses internal machine memory, is proposed. In this model, we assume the existence of a seamless, multi-cast wide area network infrastructure - for example, an ATM network. A prototype of this model using multi-thread programming have been implemented on multi-CPU SPARCstations and an ATM-LAN. These DSM models are compared with SCRAMNetTM, whose mechanism is based on replicated shared memory. Results from this evaluation show the superiority of the replicated shared memory compared to shared virtual memory when the length of the network is large. While replicated shared memory using external memory is influenced by the ratio of local and global accesses, replicated shared memory using internal machine memory is suitable for a wide variety of cases. The replicated shared memory model is considered to be suitable particularly for applications which impose real time operation in a widely distributed environment, since some latency hiding techniques such as context switching or data prefetching are not effective for real time demands.

A trained sparse conjugate codebook is proposed for improving the speech quality of CELP-based coding in a noisy environment. Although CELP coding provides high quality at a low bit rate in a silent environment (creating clean speech), it cannot provide a satisfactory quality in a noisy environment because the conventional fixed codebook is designed to be suitable for clean speech. The proposed codebook consists of two sub-codebooks; each sub-codebook consists of a random component and a trained component. Each component has excitation vectors consisting of a few pulses. In the random component, pulse position and amplitude are determined randomly. Since the radom component does not depend on the speech characteristics, it handles noise better than the trained one. The trained component maintains high quality for clean speech. Since excitation vector is the sum of the two sub-excitation vectors, this codebook handles various speech conditions by selecting a sub-vector from each component. This codebook also reduces the computational complexity of a fixed codebook search and memory requirements compared with the conventional codebook. Subjective testing (absolute category rating (ACR) and degradation category rating (DCR)) indicated that this codebook improves speech quality compared with the conventional trained codebook for noisy speech. The ACR test showed that the quality of the 8 kbit/s CELP coder with this codebook is equivalent to that of the 32 kbit/s ADPCM for clean speech.