We propose a unique word detection scheme having the correction of the phase ambiguity that remains in the output of a carrier recovery circuit for QPSK systems. The performance of the proposed scheme is analyzed by obtaining the probability generating function (PGF) for the output of the detector. The PGF is obtained from the z-transform of the probability density function (PDF) for each matched symbol with the reference symbol and by using the characteristics at this time that the random variables for matched symbols are independent and identically distributed. Then the total PGF for a unique word is obtained from powering the PGF for the individual symbol. From the total PGF, the length of a UW and the threshold value for detection can be obtained with a detection probability defined in a required system specification.

A new method of sequential control has been developed in order to increase the productivity and flexibility of production systems. This advanced sequential control (ASC) method is proposed for sequential control systems based on the autonomous decentralized system (ADS) architecture. The ADS defines the system software and message formats and makes it easy to expand the number of devices and software modules. The ASC method increases productivity because it minimizes the processing and adjustment times of production lines by adjusting the starting times of production processes automatically. Experimental evaluation results of the ASC method showed that it increases the productivity of production systems. It is also applied to an actual production system and the results are reported.

This letter proposes a new detection method of human faces in gray scale image with cluttered background using a face template and elliptical structure of the human face. This proposed method can be applicable even in the cases that the face is much smaller than image size and several faces exist in one image, which is impossible in the existing one.

A new current-mode (CM) multifunction filter with single input and three outputs (SITO) employing only three dual output current conveyors (DO-CCII) and four passive elements is presented. The proposed filter realizes three basic filter functions simultaneously all at high impedance outputs. No component matching is required and all the passive and active sensitivities are low.

As a preprocessor of the automatic speech recognizer in a noisy environment, a microphone array system has been investigated to reduce the environmental noise. In usual microphone array design, a plane wave is assumed for the sake of simplicity (far-field assumption). However, this far-field assumption does not always hold, resulting in distortion in the array output. In this report, the subspace method, which is one of the high resolution spectrum estimator, is applied to the near-field source localization problem. A high resolution method is necessary especially for the near-field source localization with a small-sized array. By combining the source localization technique with a spatial inverse filter, the signal coming from the multiple sources in the near-field range can be separated. The modified minimum variance beamformer is used to design the spatial inverse filter. As a result of the experiment in a real environment with two sound sources in the near-field range, 60-70% of word recognition rate was achieved.

Numerous scientific and engineering fields extensively utilize optimization techniques for finding appropriate parameter values of models. Various optimization methods are available for practical use. The optimization algorithms are classified primarily due to the rates of convergence. Unfortunately, it is often the case in practice that the particular optimization method with specified convergence rates performs substantially differently on diverse optimization tasks. Theoretical classification of convergence rates then lacks its relevance in the context of the practical optimization. It is therefore desirable to formulate a novel classification framework relevant to the theoretical concept of convergence rates as well as to the practical optimization. This article introduces such classification framework. The proposed classification framework enables specification of optimization techniques and optimization tasks. It also underlies its inherent relationship to the convergence rates. Novel classification framework is applied to categorizing the tasks of optimizing polynomials and the problem of training multilayer perceptron neural networks.

This paper presents the bit error rate (BER) upper bounds for trellis coded asymmetric 8PSK (TC-A8PSK) system using the Ka-band satellite in the rain fading environment. The probability density function (PDF) for the rain fading random variable can be theoretically derived by assuming that the rain attenuation can be approximated to a log-normal distribution and the rain fading parameters are calculated by using the rain precipitation data from the Crane global model. Furthermore, we analyze the BER upper bounds of TC-A8PSK system according to the number of states in the trellis diagram and the availability of channel state information (CSI). In the past, Divsalar and Simon has analyzed the BER upper bounds of 2-state TCM system in Rician fading channels; however, this paper is the first to analyze the BER upper bounds of TCM system in the rain fading channels. Finally, we summarize the dominant six factors which are closely related to the BER upper bounds of TC-A8PSK satellite system in the rain fading channel as follows: (1) frequency band, (2) rain intensity, (3) elevation angle, (4) bit energy to noise ratio, (5) asymmetric angle, and (6) availability of CSI.

The Internet is a heterogeneous and rapidly evolving environment. New information services have been added, modified, and diversified, while legacy services have been abandoned. Users' requirements for services are also changing very quickly. It is becoming very difficult to find required information services from extremely huge amount of information in the Internet. It is necessary to design information service system, which can meet user's heterogeneous requirements for services, adaptability of services to cope with ever-changing situation and to provide assurance. Faded information field architecture and Push/Pull Mobile Agent (MA) technologies are proposed as basic components of autonomous information service system to achieve these goals. The system is proposed from users' and providers' point of view, therefore we present a technique for balancing users' and providers' communication cost based on `through rate' for faded information field realization. On the basis of this technique, autonomous information allocation algorithm is proposed, in which each node may determine information amount based on push/pull cost. The effectiveness of the proposed algorithm is shown through simulation.

In a typical indoor environment such as in a building, delay spread tends to be small, which causes frequency non-selective fading. Therefore resolvable paths at the RAKE receiver can not be obtained, and effective path diversity can not be achieved. This paper proposes an artificial path diversity system in which one or multiple sectors at the base station are pre-selected according to the channel conditions for transmitting data. Each sector's signal is delayed by several chips to create artificial paths which can then be combined by using a RAKE receiver at the mobile station creating a diversity effect for an indoor environment. Moreover, only pre-selected sector antennas transmit signals to reduce inefficient signal usage in the sectors whose paths are blocked by using all sectors, therefore the transmission power is used efficiently at the base station. As a result of sector selection, the better BER performance and the reduction of interference signals between different channels can be achieved by means of sector selection. The performance of the proposed system is analyzed and demonstrated by computer simulation in a Rayleigh and log-normal fading indoor environment.

Based on the partially-depleted, thin-film SOI/CMOS technology, the influence of reduced junction capacitance on the performance of the elementary gates and large scale gate array chip is reviewed. To further reduce the power consumption, SOI-specific device configurations, in which the body-bias is individually controlled, are effective in lowering the supply voltage and hence the power consumption while keeping the circuit speed. Two attempts are introduced: (1) DTMOS (Dynamic-Threshold MOS)/SOI to achieve ultra low-voltage and yet high-speed operation, and (2) ABB (Active-Body-Bias) MOS to enhance the current drive under the low supply voltage.

To provide cellular data services with differentiated QoS, a shared resource scheme, based on the optimization theory and LaGrange λ-calculus was developed. This scheme can generate a fair schedule for a diverse mix of traffic with diverse QoS requirements in a limited radio spectrum. We define the acceptance indication, AI, as the QoS measurement for the shared resource scheme. The experimental results show that this approach outperforms other existing schemes.

A novel adaptive algorithm based on pilot channel (PCA) for MMSE multiuser detection in downlink CDMA is proposed in this paper. This algorithm uses the information in pilot channel to compute the desired weight vector directly. Compared with conventional adaptive algorithms and blind algorithms, it does not require training sequences nor channel estimation. Analysis shows that the weight vector obtained by the PCA algorithm converges to the Wiener solution globally and its computational complexity is O(N2). Simulation results show that the PCA algorithm can adapt rapidly to the changing environment. The steady state performance can be enhanced by increasing the transmitted power in pilot channel, but is worse than that of conventional recursive least-square (RLS) algorithm in decision-directed mode. Also, performance of the adaptive MMSE detector is much better than that of conventional RAKE receiver.

In this paper, we present a low-power and area-efficient design method of embedded high-speed A/D converters for mixed analog-digital system LSI's. As the A/D converter topology, a 1.5 bit/stage interleaved pipeline A/D converter is employed, because the basic topology covers a wide range of specifications on the conversion frequency and the resolution. The design method determines the minimum DC supply current, the minimum device sizes and the minimum number of channels to meet the precision given by the specification. This paper also points out that the interleaved pipeline structure is very effective for low-power design of high-speed A/D converters whose sampling frequency is over 100 MHz.

We have developed a new method to improve cooperation in concurrent systems for distributed control by using multi-agent (MA) functions. Since field terminals (FTs) work concurrently, cooperation among them is essential to the effectiveness and efficiency of the overall system. When FTs are modeled as agents, it is easy to explicitly deal with the interactions among them because those interactions can be modeled naturally as communication among agents with cooperation and negotiation. In conventional central control systems, the host computer supervises and controls all FTs in accordance with a pre-installed control algorithm. Our method instead uses intelligent field terminals (IFTs) that can evaluate the diverse information from devices of other IFTs autonomously. In the work reported here, we have evaluated the effectiveness and efficiency of our cooperative control method experimentally and have developed a system using this method to control various kinds of water delivery systems. The IFT providing MA functions that can evaluate the control parameters (CPs) and conditions of the other IFTs. If turn-around time is to be shortened, the conflicts that occur when the data processed by different IFTs is inconsistent or irregular must be resolved autonomously. Each IFT therefore cooperates with diverse functional agents (FA)s of other IFTs by using priority levels, conditions, and evaluation points in order to maintain the continuity of water delivery.

Optical logic gates for OR, AND, NOT, and NOR operations in waveguides consisting of nonlinear material are numerically investigated by means of FD-BPM (Finite Difference Beam Propagation Method). The proposed devices are designed utilizing the self-routing characteristics of nonlinear X-crossing structures when they are operated with one input beam or two. The numerical simulations show that the proposed structures can favorably be applied to optical data processing and computing as fundamental logic gates.

An 1 V, 50 MHz, 16-bit DSP core was developed using a 0.25-µm Dual Vt library, SRAM, and Mask ROM tailored for 1 V operation. The core speed was 41% enhanced using an alternate MAC and 2-stage execution pipeline. A 1.0 V to 1.5 V voltage up converter with 59% power efficiency and a 450 ps 1 V to 2.5 V level converter were implemented. An new long wire delay estimation method enhanced the synthesis. The measured power consumption at 0.9 V was 8.7 mW, which was 40% less than the power of the normal library's at 1.3 V, when the PSI-CELP CODEC firmware was run at 40 MHz.

In this paper, we consider the coherent radar detection of rapid fluctuating signals in the Gaussian noise. This problem has been previously solved by employing the GLR technique, but we use the ALR to improve the detection performance. So, after deriving an approximate ALR detector, we compare the new detector with the GLR and Square-law detectors and we show its superiority.

This paper describes a Variable Threshold-voltage CMOS technology (VTCMOS) which controls the threshold voltage (VTH) by means of substrate bias control. Circuit techniques to combine a switch circuit for an active mode and a pump circuit for a standby mode are presented. Design considerations, such as latch-up immunity and upper limit of reverse substrate bias, are discussed. Experimental results obtained from chips fabricated in a 0.3 µm VTCMOS technology are reported. VTH controllability including temperature dependence and influence on short channel effect, power penalty caused by the control circuit, substrate current dependence at low VTH, and substrate noise influence on circuit performance are investigated. A scaling theory is also presented for use in the discussion of future possibilities and problems involved in this technology.

Recently we have studied the performance of the VS/VD behavior for two binary feedback congestion control schemes, FECN and BECN, when they are applied to multicast ABR services. It is shown that the VS/VD schemes alleviate the problems of consolidation noise and consolidation delay, which are two major design issues in multicast congestion control. To complement, we further explore the VS/VD behavior for the explicit rate feedback control scheme in this letter. Through an efficient rate estimation method, it is again observed that VS/VD behavior performs better than the traditional end-to-end schemes.

With the rising innovative antigens (such as intruders and viruses) through Internet, reliable security mechanisms are required to perceptively detect and put them down. However, defense techniques of the current host system over Internet may not properly analyze Internet antigens, because trends of attacks are unexpectedly shifted. In this paper, we introduce an Antibody Layer that mediates proper security services based on the biological mechanism to rapidly disclose and remove innovative antigens. The proposed Antibody Layer also employs a new topology called antibody cooperation protocol to support real-time security QoS for one host as well as host alliance.