We propose a programming language, Flage, for building software systems which dynamically adapt to changing local situations. In our language, we construct applications by agents; concurrent mobile objects with the metalevel architecture. Metalevel programming facilities realize a self-control of an agent's actions and an autonomous adaptation to changes. We also introduce another kind of program element called field. A field represents a local situation around agents. For example, one field represents a virtual place to get local information in a network environment and another represents a virtual place where agents do cooperative works. If an agent enters a field, it gets programs and shared information in the field. By moving field to field, an agent can change its program composition by itself and it adapts to changing local situations. In this paper, we describe the language specification of Flage, the implementation of the platform for Flage programming and show some program examples.

Major problems of traffic control in ATM networks include how to decide whether a network accepts a new call or not in real time and how to select the best set of Dual Leaky Bucket (DLB) parameter values. To solve these problems, it is necessary to determine the amount of network bandwidth required by the call. In this paper, we present an analysis based on bounding technique to derive an upper bound on bandwidth requirement when the call is characterized by a set of DLB parameters. Consequently, a new definition of the upper bound on bandwidth requirement and simple formulae used for computing the upper bound have been obtained. To clarify the advantages of the derived upper bound, we demonstrate its two applications, one to select the best set of DLB parameter values from candidates for minimizing the amount of bandwidth to be allocated to the call and the other to establish a Connection Admission Control (CAC) scheme. The upper bound-based CAC scheme is fast enough to process in real time due to its simplicity and provides a significant improvement of network utilization compared to the peak rate-based CAC scheme.

We describe a new multiport memory which is called Shared DRAM (SHDRAM) to overcome bus-bottle neck problem in parallel processor system with shared memory. The processors are directly connected to this SHDRAM without conventional common bus. The test chip with 32 kbit memory cells is fabricated using a 1. 5 µm CMOS technology. The basic operation is confirmed by the circuit simulation and experimental results. In addition, it is confirmed by the computer simulation that the system performance with SHDRAM is superior to that with conventional common buses.

This paper presents a timing-driven global routing algorithm based on coarse pin assignment, block reshaping, and positioning for VLSI building block layout. As opposed to conventional approaches, we combine pin assignment and global routing problems into one problem. The proposed algorithm determines global routes, coarse pin assignments, and block shapes and positions so as to minimize the chip area and total wire length of nets under the given timing constraints. It is based on an iterative improvement paradigm and performs rip-up and rerouting, block reshaping, and positioning in the manner of simulated evolution taking shapes of soft blocks and routing congestion into consideration until the solution is not further improved. The Elmore delay model is adopted for the interconnection delay model. Experimental results show the effectiveness of the proposed algorithm.

In this paper we have introduced a new method for signature pattern recognition, taking advantage of some image moment transformations combined with fuzzy logic approach. For this purpose first we tried to model the noise embedded in signature patterns inherently and separate it from environmental effects. Based on the first step results, we have performed a mapping into the unit circle using the error least mean square (LMS) error criterion, to get ride of the variations caused by shifting or scaling. Then we derived some orientation invariant moments introduced in former reports and studied their statistical properties in our special input space. Later we defined a fuzzy complex space and also a fuzzy complex similarity measure in this space and constructed a new training algorithm based on fuzzy learning vector quantization (FLVQ) method. A comparison method has also been proposed so that any input pattern could be compared to the learned prototypes through the pre-defined fuzzy similarity measure. Each set of the above image moments were used by the fuzzy classifier separately and the mis-classifications were detected as a measure of error magnitude. The efficiency of the proposed FLVQ model has been numerically shown compared to the conventional FLVQs reported so far. Finally some satisfactory results are derived and also a comparison is made between the above considered image transformations.

Voice activity detection (VAD) is to determine whether a short time speech frame is voice or silence. VAD is useful in reducing the mean speech coding rate by suppressing transmission during silence periods, and is effective in transmitting speech and other data simultaneously. This letter describes a VAD system that uses a neural network. The neural network gets several parameters by analyzing slices of the speech wave form, and outputs only one scalar value related to voice activity. This output is compared to a threshold to determine whether the slice is voice or silence. The mean code transfer rate can be reduced to less than 50% by using the proposed VAD system.

This paper presents a new binding algorithm for a retargetable compiler which can deal with diverse architectures of application specific embedded processors. The architectural diversity includes a "non-orthogonal" datapath configuration where all the registers are not equally accessible by all the functional units. Under this assumption, binding becomes a hard task because inadvertent assignment of an operation to a functional unit may rule out possible assignment of other operations due to unreachability among datapath resources. We propose a new BDD-based algorithm to solve this problem. While most of the conventional methods are based on the covering of expression trees obtained by decomposing DFGs, our algorithm works directly on the DFGs so as to avoid infeasible bindings. In the experiments, a feasible binding which satisfies the reachability is found or the deficiency of datapath is detected within a few seconds.

There is increasing demand for corporate information systems that have a simple human interface and are easy to access via WWW browsers. This paper proposes WebBASE, which integrates the WWW and relational databases. Experimental evaluation shows that WebBASE offers superior performance compared to existing products. Field studies of actual WebBASE applications show that it can improve the productivity of software developers for intranet application development.

Hardware software codesign using various hardware and software implementation possibilities requires a cosimulation environment which has both flexibility and efficiency. In this paper, a hardware software cosimulation environment is developed using the backplane approach and optimized synchronization. To seamlessly integrate a new simulator, this paper defines and implements the backplane protocol for communication and synchronization between client simulators. Automatic interface generation facility is also devised for more effective cosimulation environment. To enhance the performance of cosimulation backplane, a series of optimized hardware software synchronization methods are introduced. Efforts are focused on reducing control packets between simulators as well as concurrent execution of simulators without roll-back. The environment is implemented based on Ptolemy and validated with a QAM example run on different configurations. With optimized synchronization method, we have achieved about 7 times speed-up compared with the lock-step synchronization.

A major topic in the field of network and telecommunications is doing business on the World Wide Web (WWW), which is called Electronic Commerce (EC). Another major topic is blending Artificial Intelligence (AL) techniques with the WWW. In the Ex-W-Pert Project we have proposed an agent model for EC components that blends the traditional expert systems' reasoning engine with a multi-layer knowledge base, communication and documentation engines. In this project, EC is viewed as a society of software agents, such as customer, search, catalog, manufacturer, dealer, delivery and banker agents, interacting and negotiating with each other. Each agent has a knowledge-base and a reasoning engine, a communication engine and a documentation engine. The knowledge-base is organized in three layers: skill layer, rule layer and knowledge layer (S-R-K layers). In this project, for each EC agent, we identify the class of problems to be solved and build the knowledge base gradually for each layer. We believe that using this multi-layer knowledge base system will speed up the reasoning and ultimately reduce the operation costs.

A fractal image coding scheme using classified range regions is proposed. Two classes of range regions, shade and nonshade, are defined here, A shade range region is encoded by the average gray level, while a nonshade range region is encoded by IFS parameters. To obtain classified range regions, the two-stage block merging scheme is proposed. Each range region is produced by merging primitive square blocks. Shade range regions are obtained at the first stage, and from the rest of primitive blocks nonshade range regions are obtained at the second stage. Furthermore, for increasing the variety of region shape, the 8-directional block merging scheme is defined by extension of the 4-directional scheme. Also, two similar schemes for encoding region shapes, each corresponding to the 4-directional block merging scheme and the 8-directional block merging scheme, are proposed. From the results of simulation by using a test image, it was demonstrated that the variety of region shape allows large shade range regions to be extracted efficiently, and these large shade range regions are more effective in reduction of total amount of codebits with less increase of degradation of reconstructed image quality than large nonshade range regions. The 8-directional merging and coding scheme and the 4-directional scheme reveal almost the same coding performance, which is improved than that of the quad-tree partitioning scheme. Also, these two schemes achieve almost the same reconstructed image quality.

In this paper we present two traffic control approaches, a circuit emulation traffic control (CETC) and an adaptive priority traffic control (APTC) for supporting voice services in ATM networks. Most voice services can be handled as CBR traffic, this causes a lot of wasted bandwidth. Sending voice through VBR (variable bit rate) may be a better alternative, because it allows the network to allocate voice bandwidth on demand. In CETC, the service discipline guarantees the quality of service (QOS) for voice circuits. Through mathematical analysis, we show that CETC features an adequate performance in delay-jitter. Moreover, it is feasible in implementation. We also present an APTC approach which uses a dynamic buffer allocation scheme to adjust the buffer size based on the real traffic need, as well as employs an adaptive priority queuing technique to handle various delay requirements for VBR voice traffic. It provides an adequate QOS for voice circuits in addition to improving the multiplexing gain. Simulation results show that voice traffic get satisfied delay performance using our approaches. It may fulfill the emerging needs of voice service over ATM networks.

A computational cost reduction scheme for a post-distortion type nonlinear distortion compensator of OFDM signals is proposed, and compared with the conventional sub-optimum detection scheme. The proposed scheme utilizes the principle that a complex OFDM signal can be demodulated with not only both I-phase (real part) and Q-phase (imaginary part) components, but also either of them. Usually each phase of an OFDM signal exhibits different signal envelope and they are distorted differently by the nonlinearity of a power amplifier. Consequently, three output sequence patterns can be obtained at the receiver. By comparing these outputs, we can know the erroneous positions of these sequences to some extent. By the aid of this comparison, we need to evaluate only a limited number of replicas for the compensation process of the post-distortion type nonlinear distortion compensator, which results in the computational cost reduction. We have proposed four new compensation schemes based on this idea and derived their performance in terms of the bit error rate and the average number of calculations.

The explosive increase of traffic in computer communications is a clear sign that we have entered the multimedia information age. To cope with this ever increasing need, economical optical access networks that support burst traffic such as in the Internet are expected to be developed. The ATM-PON is considered to be a promising candidate for such a network, and vigorous efforts in this direction are being promoted worldwide. This paper focuses on accommodating burst traffic in the ATM-PON. In order to do this, a mechanism to transport bandwidth requests from the ONU to the OLT and an algorithm to support dynamic bandwidth allocations based on ONU requests are needed. We have performed a comparative study on bandwidth request methods and bandwidth allocation algorithms, including bandwidth request dependence on time interval and correlation and/or impact between system design parameters. The results of computer simulations are useful in determining how to accommodate burst traffic efficiently in the ATM-PON.

In this paper, we propose and evaluate the performance of Wireless ATM MAC layer protocol to support efficiently various ATM traffics, such as CBR, VBR, ABR and UBR, in wireless ATM network environments for reverse and forward link. The proposed MAC protocol could extend efficiently the service discipline of ATM traffics from wired network to wireless ATM network environments. Thus, available bandwidth, which is remained except the bandwidth for CBR and VBR traffics, could be effectively allocated to ABR and UBR traffics. Especially, in view of reverse link, two-phase scheduling algorithm supports successfully variable characteristics of VBR traffic. And, in view of forward link, 'Wireless Dynamic Weighted Earliest Deadline First' scheduling algorithm minimizes the mean cell delay and required buffer size. Simulation results show that proposed method provides effective performance in wireless ATM environments.

The recently proposed modified PML (MPML) absorbing boundary condition is extended to three dimensions. The performance of the MPML is investigated by FDTD simulation of a typical microstrip line and a rectangular waveguide. The dominant and higher order modes of the microstrip line and the waveguide are excited separately in the computation. In all of the cases of excitation, the reflection properties of the MPML boundaries are examined for the side walls and the end walls, respectively. Various values of the permittivity and permeability of the MPML medium are tested in the computation, and the variation behavior of reflection from the MPML boundaries is examined. The numerical results reveal that by choosing appropriate values of the permittivity and permeability of the MPML, we can realize efficient absorption of both evanescent waves and propagating waves over a wide frequency band.

A decision-directed carrier phase recovery scheme for high-speed satellite communications is proposed. Since the estimation is performed in complex domain from the baseband signal, the scheme has fast acquisition performance, unlike the conventional PLL. This merit makes it applicable for various wireless systems such as wireless local area networks (LANs), wireless asynchronous transfer modes (ATMs) and local multipoint distribution systems (LMDSs) that need high-speed burst signal communications. Also, this scheme can be implemented easily because low pass filters (LPFs) are utilized in filtering the estimates in order to suppress the noise within the carrier recovery loop. Moreover it does not require any divider or voltage-controlled oscillator (VCO). The performance is analyzed through analytical methods and simulation.

The productivity of developing software for switching systems and the effects of using advanced software development methods were evaluated and analyzed. Productivity was found to be improved by using automatic code generation, simulator debugging, a hierarchical object-oriented software structure, and software-development-support tools. The evaluation showed that the total productivity was improved by about 20%, compared with a case where these efforts were not introduced. It also showed each effect of these methods and tools by evaluating their manpower saving ratios. These results are expected to benefit the development of various types of communication-switching and multimedia service systems. Also, our development-support tools and methods are expected to be the basis for attaining higher software development productivity.

A novel image improving algorithm for compressed image sequence by merging a reference image is presented. A high quality still image of the same scene is used as a reference image. The degraded images are improved by merging reference image with them. Merging amount is controlled by the resemblance between the reference image and compressed image after applying motion compensation. Experiments conducted on sequences of JPEG images are given. This technique does not need a prior knowledge of compression technique so it can be applied to other techniques as well.

The problem of electromagnetic scattering caused by inductive discontinuities locate in parallel-plate waveguides, in particular when dealing with discontinuous conductors of finite thickness, is analyzed using the modified residue-calculus method, the equations suitable for a numerical calculation are derived. The incident wave is taken to be the dominant mode, and the reflection and transmission properties of a symmetrical inductive iris are discussed.