A workflow definition containing errors might cause serious problems for an enterprise especially when it involves mission critical business processes or inter-organizational interaction. So workflow definitions should be defined in a strict and rigorous way. In this paper, we develop a workflow definition language and analysis methods for the language to support strict and rigorous workflow definitions. Faults or mistakes causing communication deadlock, access conflicts, and improper exception specification in workflow definitions can be detected and notified automatically using the methods. The proposed workflow definition language borrows structured constructs of conventional programming languages because many good features of conventional programming languages also can be used effectively in expressing workflow processes. With slight modifications and scope restrictions, the developed analysis techniques in this paper can be used in any workflow definition languages and they can help workflow designers define workflow processes in much more safe and reliable manner.

Europe has initiated research activity to analyse and prepare the floor for mobile communication beyond 3G. Very recently, around the beginning of 2004, the European commission started together with the main partners in the relevant industry special projects to realize this plan. The key objective of the WINNER (Wireless World Initiative New Radio) project is to develop an innovative concept in radio access in order to address high flexibility and scalability with respect to data rates and radio environments. The future converged wireless world requires in the long-term perspective a ubiquitous radio system instead of disparate systems for different purposes (cellular, WLAN, short-range access etc.). This concept will be derived by a systematic investigation of advanced radio technologies with respect to predicted user requirements and challenging scenarios. The project will contribute to the global research, regulatory and standardisation communities and processes.

This investigation proposes a novel dual-mode patch bandpass filter (BPF) that uses defect ground structure (DGS) to suppress spurious response. The proposed dual-mode patch BPF has exhibits a wide stopband characteristic owing to that uses the bandgap resonant characteristic of DGS in the harmonic frequency of the dual-mode patch BPF. The novel proposed filter demonstrates the frequency characteristics with center frequency f0 = 2.2 GHz, 3-dB bandwidth (FBW) of 8% and wider stopband from 2.6 to 6 GHz at the level of -35 dB. The experimental and simulated results agree.

A random transmit power control (TPC) is applied to DS-CDMA/TDD packet mobile radio, which controls the transmit power so as to intentionally vary the received signal power in order to obtain the large capture effect. The uplink capacity with the random TPC in a frequency-selective fading channel is evaluated by computer simulation. The simulation results show that the random TPC provides larger link capacity than slow TPC.

In the road-to-vehicle communication (RVC) on intelligent transport systems (ITS), the frequent occurrence of shadowing caused by other vehicles deteriorates wireless transmission quality because of a small sized zone. However, a diffraction wave generated at the edge of vehicle can be utilized in applying adaptive modulation method with decreased modulation level. Therefore, it can be expected to keep communication only with a diffraction wave under shadowing. Hence this paper proposes an application of adaptive modulation for RVC system. This paper first reveals its improved effect in shadowing duration by computer simulation considering practical traffic flow, radio reflection and diffraction, and then shows that applying adaptive modulation can increase throughput performance largely.

Analytical derivation of bit error rates for multi-user coherent chaos-shift-keying (CSK) communication systems are presented in this paper. Nearly exact results are obtained by applying the central limit theorem of statistics to sums of independent variables. Based on χ2 distribution approximations, more viable but still very accurate results decrease complexity of the calculations. The χ2 approach is compared with the widely used Gaussian approximation approach to show its superiority in most cases. Bit error performance bounds for the multi-user CSK system from the approach are deduced as further contributions of this paper. The theoretical results obtained are entirely consistent with a range of simulations.

The scattering problem by metallic gratings has become one of fundamental problems in electromagnetics. In this paper, a thin metallic grating placed in conical mounting is treated as a lossy dielectric grating expressed by complex permittivity and thickness. The solution of the metallic grating by using the matrix eigenvalue calculations is compared with that of the plane grating by using the resistive boundary condition and the spectral Galerkin procedure, and the availability of the resistive boundary condition for thin metallic gratings in conical mounting is investigated. In order to improve the convergence of the solutions of thin metallic gratings, the spatial harmonics of flux densities which are continuous function instead of electromagnetic fields are used.

Propagation modeling and advanced channel characterization techniques represent integral parts of significant impact in advancing progress in enabling next generation wireless communication technology and realizing its much anticipated broader application and economic benefits. In this paper we describe advances in developing computationally efficient ray-tracing channel modeling procedures, and also describe recent results in characterizing challenging propagation environments including transmission through windows and propagation through walls of complex structures. The impact of these realistic propagation environments as well as the antenna mutual coupling effects on the estimation of channel capacity in a MIMO-based communication system is also evaluated. Significant difference between realistic and statistical channel models are identified and quantified for the special cases of the channels modeled in this study.

In December 2001, the authors started two kinds of experiments on the meteor burst communication (MBC) in Antarctica to study the ability of MBC as a communication medium for data collection systems in that region. In the first experiment, a continuous tone signal is transmitted from Zhongshan Station. The signal received at Syowa Station (about 1,400 km apart) is recorded and analyzed. This experiment is aimed to study basic properties of the meteor burst channel in that high latitude region. On the other hand, the second experiment is designed to estimate data throughput of a commercial MBC system in that region. A remote station at Zhongshan Station tries to transfer data packets each consisting of 10 data words to the master station at Syowa Station. Data packets are generated with five minutes interval. In this paper, we explain the experiments, briefly examine the results of the first year (from April 2002 to March 2003), and put forward the plan for the experiments in the second and third year. From the data available thus far, we can see that 1) the sinusoidal daily variation in the meteor activity typical in middle and low latitude regions can not be clearly seen, 2) non-meteoric propagations frequently dominate the channel especially during night hours, 3) about 60% of the generated data packets are successfully transferred to the master station within two hours delay even though we are now operating the data transfer system only for five minutes in each ten minutes interval, etc.

This paper proposes a method of improving demodulation performance for chaotic synchronization based multiplex communications systems. In a conventional system, the number of data demodulated correctly is limited because transmitted chaotic signals interfere with each other. The proposed system uses a generalized inverse of a matrix formed from chaotic signals at the transmitter. Since this completely cancels the interference between chaotic signals, demodulation performance is greatly improved. The proposed system has the following features: A simple correlation receiver suitable for small terminals can be used; The magnitude of the correlator output is constant for binary data transmission; Analog information data can also be transmitted. Two methods to reduce the peak-to-average power ratio of the transmitted signal are presented.

The hardware implementation of a neural network model using stochastic logic has been able to integrate numerous neuron units on a chip. However, the limitation of applications occurred since the stochastic neurosystem could execute only discrete-time dynamics. We have contrived a neuron model with continuous-time dynamics by using stochastic calculations. In this paper, we propose the circuit design of a new neuron circuit, and show the fabricated neurochip comprising 64 neurons with experimental results. Furthermore, a new asynchronous updating method and a new activation function circuit are proposed. These improvements enhance the performance of the neurochip greatly.

Various effective and draft legislations and rules in Europe (WEEE--Waste Electrical and Electronic Equipment ROHS--Restrictions on the use of certain substances and ELV--End of life of vehicles) and Japan (Recycling Law for Home Electric Appliances) have either targeted restrictions or fully banned on the use of lead, to be enforced from 2001, 2003 and 2006 onwards. Up to now, mainly tin-lead alloys have been used in electronics. The process temperatures usually applied have been in the range of 230. All currently discussed lead-free alternatives for professional electronics need process temperatures which are at least 20 higher. In addition, the process duration is significantly longer. The combination of higher process temperatures and longer duration results in significant thermal stress on electromechanical devices. In particular the precision mechanics of electromechanical relays must withstand the solder process with maximum process temperatures of 255 without dimensional changes. During the transition from tin-lead to lead-free solder processes all combinations of component surfaces and solder must be possible. The selection of pure Sn100 or SnCu0.7 as terminal surface allows mixed assemblies with tin-lead as well as lead-free solders. All tested combinations of terminal surface, PCB surface and solder showed good results. From these results it can be concluded that mixed assemblies are possible during the transition time without any negative impact on the reliability of the electronic devices.

We propose a novel handover initiation algorithm based on available bit rate and timing constraint criterion for multimedia capable cellular systems. Computer simulations are performed to evaluate the handover rate and handover initiation delay. Numerical results show that handover must be initiated at different positions for different services to maintain the required quality of service requirements.

This paper proposes an alternative learning algorithm for a stereophonic acoustic echo canceller without pre-processing which can identify the correct echo-paths. By dividing the filter coefficients into the former/latter parts and updating them alternatively, conditions both for unique solution and for perfect echo cancellation are satisfied. The learning for each part is switched from one part to the other when that part converges. Convergence analysis clarifies the condition for correct echo-path identification. For fast and stable convergence, a convergence detection and an adaptive step-size are introduced. The modification amount of the filter coefficients determines the convergence state and the step-size. Computer simulations show 10 dB smaller filter coefficient error than those of the conventional algorithms without pre-processing.

To measure the arc motion in interruption process of low voltage molded case circuit breakers (MCCBs) more precisely, a set of novel 2-D optical fiber system is developed. To improve the spatial resolution of optical fibers, lens with inhomogeneous dielectric is fixed on the top of each fiber. Furthermore, the full hardware control logic facilitates the real-time, synchronous and high-speed processing and breaks through the restricted bus operation frequency range and data stream capacity of microprocessor. The Publisher-Subscribe behavioral design pattern is applied to the software and the loosely coupled relationship between glyph and experimental data is once established, the graphic configuration can be implemented for simulation analysis, and the flexibility and applicability of the whole system are obviously improved. It demonstrates that the system provides a better research technique especially for new generation MCCB with gas driven arc.

In this paper, we present a group communication protocol that achieves total ordering message delivery for mobile computing systems with multiple overlapping groups. Our mechanism is an efficient adaptation of the propagation-tree technique to the mobile computing environments. It takes advantages of the capability of stationary mobile support stations to overcome the deficiencies associated with mobile devices. We construct the propagation tree based on the stationary stations, rather than the mobile hosts. As a result, mobile hosts are relieved of the excessive load of forwarding messages and communications on wireless channels are confined to transmitting messages to destination processes. This is important considering that the bandwidth of the wireless channels is limited. Moreover, the proposed protocol employs a mechanism to synchronize transmissions within a wireless cell. This serves to avoid redundant transmissions of a message in a wireless network in an attempt to achieve better utilization of the network bandwidth. Our mechanism relies on a handoff operation to deal with mobility of mobile devices. The handoff procedure ensures a smooth integration of a mobile host into a new cell, while preserving reliability of communication and the total ordering property of message delivery.

The proposed DOA (Direction Of Arrival) estimation method by integrating the frequency array data generated from microphone pairs in an equilateral-triangular microphone array is extended here. The method uses four microphones located at the apices of regular tetrahedron to enable to estimate the elevation angle from the array plane as well. Furthermore, we introduce an idea for separate estimation of azimuth and elevation to reduce the computational loads.

This paper presents a new automatic-frequency control (AFC) configuration capable of removing wide range frequency offsets (up to about 0.625 fs, where fs is signal symbol rate). The new configuration consists of an AFC that removes frequency offsets between 0.125 fs and another AFC that detects the frequency offset range coarsely between 0.625 fs. This paper describes the principle of the new AFC configuration. The proposed AFC configuration employs four correlators to enhance the acquisition range. It also adopts the reverse modulation scheme to decrease the acquisition time. The performance of the new AFC configuration is confirmed via computer simulations. It is shown that the proposed configuration can accommodate wide range frequency offsets as well as reduce the acquisition time.

We have developed a code-division-multiplexing (CDM) transmission scheme for future cellular communication systems, which uses cyclic shifted-and-extended (CSE) codes generated from an M-sequence to enable seamless communication in highly mobile environments. Because the correlation characteristics of CSE codes are determined by the M-sequence, the cross-correlation values are accumulated as a result of combining transmitted signals with opposite polarities in parallel channels. The accumulated cross-correlation values significantly degrade transmission performance, especially with multi-level modulation schemes such as quadrature amplitude modulation (QAM). We thus propose a cancellation technique to eliminate the accumulated cross-correlation values. We have evaluated the transmission performance of the CDM transmission scheme with the proposed technique by computer simulation. The new scheme enables high-quality data transmission in fast-fading channels.

Smart or adaptive antennas promise to provide significant space-time communications against fading in wireless communication systems. In this paper, we propose multiple-input multiple-output (MIMO) beamforming for frequency-selective fading channels to maximize the Signal-to-Noise and Interference Ratio (SINR) based on an iterative update algorithm of transmit and receive weight vectors with prior knowledge of the channel state information (CSI) at both the transmitter and receiver. We derive the necessary conditions for an optimum weight vector solution and propose an iterative weight update algorithm for an optimal SINR reception. The Maximum Signal-to-Noise (MSN) method, where noise includes the additive gaussian noise and interference signals, is used as a criterion. The proposed MIMO with M N arrays allows the cancellation of M + N - 2 delayed channels. Computer simulations are presented to verify our analysis. The results show that significant improvements in performance are possible in wireless communication systems.