We designed a CMOS image sensor capable of capturing variably smoothed images. This sensor uses a negative-feedback technique to set photodiode (PD) capacitance in the pixel circuit to any intermediate voltage during charge accumulation and it provides a neighboring-pixel operation by using their average value when resetting the PD capacitance. Smoothing-filter coefficients are changed by adjusting timing of the pixel-readout and neighboring-pixels operations. The performance of the proposed sensor was evaluated by SPICE simulation and numerical analysis.

Orthogonal Frequency Division Multiple Access (OFDMA) allows multiple users to make use of the same bandwidth as the single-user OFDM for data transmission and is a promising candidate to be used for future cellular systems. A key issue at hand is the rate-adaptive resource allocation problem. In this paper, we propose two basic subcarrier allocation schemes with low complexities based on the magnitude of the channel frequency responses. The proposed algorithms ensure a fair resource allocation in terms of the number of subcarriers with affordable bit-rates. Through extensive discussions and Monte Carlo simulations, a comprehensive comparison with previously derived subcarrier allocation schemes is performed which depicts the pros and cons of our proposed algorithms.

Pulse-shaping OFDM is well-known that it performs well in a mobile environment compared with conventional OFDM. However, in a highly mobile environment intersymbol and intercarrier interferences (ISI/ICIs) increase and can no longer be neglected. These ISI/ICIs deteriorate the performance of the systems. Proper channel equalization is needed for further improvement of the systems. In this paper, a more general case, namely Biorthogonal Frequency Division System based on Offset QAM (BFDM/OQAM) is considered. We propose a multi-input multi-output (MIMO) transversal filter to equalize the time-frequency dispersive channel. Tap weights are calculated using the zero-forcing (ZF) algorithm. We also propose maximum-likelihood channel estimator and its low-complexity version. The proposed system can significantly improve the performance of BFDM/OQAM systems in the highly mobile environment.

The output limits of the power system stabilizer (PSS) can improve the system damping performance immediately following a large disturbance. Due to non-smooth nonlinearities from the saturation limits, these values cannot be determined by the conventional tuning methods based on linear analysis. Only ad hoc tuning procedures have been used. A nonlinear least squares method, which is the Gauss-Newton optimization algorithm, is used in this paper. The gradient required in the Gauss-Newton method can be computed by applying trajectory sensitivities from the hybrid system model with the differential-algebraic-impulsive-switched (DAIS) structure. The optimal output limits of the PSS tuned by the proposed method are evaluated by time-domain simulation in a multi-machine power system (MMPS).

Martucci's Zero-tree Entropy (ZTE) coding algorithm exploits the advantages of discrete wavelet coding to improve the video quality of inter-frame coding. In this algorithm the wavelet tree is coded into three different tables, type, valz and valnz. Subsequently these three tables are arithmetic coded. However, the statistical variation of the distribution of the values and types are not considered in this categorization. We propose to decompose the zerotree such that this variation is taken into account. In our representation, values and the types are reorganized into hierarchical structures according to the sub band and the orientation. Our test results show that the proposed algorithm can reduce the bit rate per frame up to 73% over the Martucci's algorithm and performs better than EBCOT at higher bit rates.

Since the control input of a feedback linearizable system depends on the diffeomorphism, the transient behavior of the controlled system is different. In this paper, we propose a switching rule for selecting a diffeomorphism so that the transient behavior is improved and the switched system is stable. Specifically, we show the sufficient condition for the exponential stability and the exponential upper bound of the trajectory of the switched system.

We have developed a code-division-multiplexing (CDM) transmission scheme for future road-vehicle communication systems, which uses cyclic shifted-and-extended (CSE) codes generated from a basic code with superior auto-correlation characteristics. This paper proposes to use a Quasi-Orthogonal (QO) sequence as the basic code. Its auto-correlation values are zero except at zero and middle shifts. When the CDM transmission is performed by the CSE codes based on the QO sequence, a desired correlation value is, at a receiver, interfered by the auto-correlation value at middle shift. Therefore, an elimination technique for the interfered correlation value is proposed and realizes zero cross-correlation characteristics within the cyclical shift interval. The new CDM transmission scheme based on the proposed scheme is evaluated by computer simulations in terms of the bit-error-rate performance.

This paper overviews the high-speed power-line communication (PLC) technology, and the related standardization and regulatory activities are described. PLC modems of 200 Mbps class become a practical use stage in the West, and the standardization activity is active now. The discussion for deregulation is being continued in also Japan, and regulation values have been proposed. Another topic in this paper is a sensor network application of PLC, which is an indoor fine-grained localization system by acoustic Direct-Sequence Code Division Multiplexed (DS-CDM) signals. The obtained average accuracy of the localization in a 4 m2 plane was 1 cm if there was no obstacle. To realize the localization system, some novel ideas, such as PLC speakers, a synchronization method based on the zero-crossing timing of the mains frequency, and integrated wired/wireless PLC, are introduced.

This paper presents a design method to minimize energy of both functional units (FUs) and an interconnection network between FUs. To reduce complexity of the interconnection network, data transfers between FUs are classified according to FU types of operations in a data flow graph. The basic idea behind reducing the complexity of the interconnection network is that the interconnection resource can be shared among data transfers with the same FU type of a source node and the same FU type of a destination node. Moreover, an efficient method based on a genetic algorithm is presented.

In this letter, a blind frequency offset estimation algorithm is proposed for OFDM systems. The proposed method exploits the intrinsic phase shift between neighboring samples in a single OFDM symbol, incurred by a frequency offset. The proposed algorithm minimizes a novel cost function, which is the squared error of the candidate frequency offset compensated signals from two different observation windows. Also, the solution of the proposed algorithm is given by an explicit equation, which does not require any iterative calculation. It is shown that the performance of the proposed method is better than those of the conventional methods, especially in the presence of multipath channels. This is due to the fact that the proposed method is insensitive to inter-symbol interference (ISI).

In this paper, the interpolation line search (ILS) algorithm to find the desirable step length in a numerical optimization method is investigated to determine the optimal saturation limits with non-smooth nonlinearities. The simple steepest descent algorithm is used to illustrate that the ILS algorithm can provide adequate reductions in an objective function at minimal cost with fast convergence. The power system stabilizer (PSS) with output limits is used as an example for a nonlinear controller to be tuned. The efficient computation to implement the ILS algorithm in the steepest descent method is available by using the hybrid system model with the differential-algebraic-impulsive-switched (DAIS) structure. The simulation results are given to show the performance improved by the ILS algorithm.

This paper introduces a block based motion estimation algorithm based on projection with adaptive window size selection. The blocks cannot match well if their corresponding 1D projection does not match well, with this as foundation 2D block matching problem is translated to a simpler 1D matching, which eliminates majority of potential pixel participation. This projection method is combined with adaptive window size selection in which, appropriate search window for each block is determined on the basis of motion vectors and prediction errors obtained for the previous block, which makes this novel method several times faster than exhaustive search with negligible performance degradation. Encoding QCIF size video by the proposed method results in reduction of computational complexity of motion estimation by roughly 45% and over all encoding by 23%, while maintaining image/video quality.

This paper proposes a new codec design method based on JPEG for face images and presents its application to face recognition. Quantization table is designed using the R-D optimization for the Yale face database. In order to use in the embedded systems, fast codec design is also considered. The proposed codec achieves better compression rates than JPEG codec for face images. In face recognition experiments using the linear discriminant analysis (LDA), the proposed codec shows better performance than JPEG codec.

A family of sequences with zero correlation zone, which is shortly called a ZCZ set, can provide CDMA system without co-channel interference nor influence of multipath. This paper presents two types of ZCZ sets of non-binary sequence pairs, which achieve the upper bound of family size for length and zero correlation zone. One, which is produced by use of a perfect complementary pair and an orthogonal code, can change zero correlation zone, while the upper bound is kept. The other, which is generated by use of a newly defined orthogonal pair and an orthogonal code, can offer such CDMA system as a binary ZCZ set seems to be used.

Synchronous sampling allows alternating current (AC) quantities, such as the root mean square (RMS) values of voltage and power, to be determined with very low uncertainties (on the order of a few parts of 10-6 [1]). In this paper, a mathematical expression for estimating measurement uncertainties in nonideal synchronization with fundamental frequency AC signals is presented. The obtained results were compared with those obtained by measurements with a high-precision instrument used for measuring basic AC values.

A high efficiency SiGe HBT differential power amplifier with an open collector adaptive bias was successfully demonstrated. A novel linearizer consists of an open collector heterojunction bipolar transistor bias circuit and an MOS feedback diode was proposed, which achieved better power added efficiency (PAE) than that of traditional adaptive bias circuits. The size effect of linearizer was investigated and the impedance ratio (R1/R2) between the linearizer and the main amplifier was optimized by the factor of 3. The measured differential power amplifier achieved an output 1-dB compression point (P1 dB) of 18.7 dBm with PAE of 31.2%, the output second order intermodulation point (OIP2) of 59 dBm, and third-order intermodulation point (OIP3) of 28 dBm. Compared to traditional adaptive bias technique, the proposed linearizer power amplifier effectively improved the PAE. The fabricated die size including pads is less than 0.925 mm2 and suitable for highly integrated linear drive amplifier.

The purpose of this research is to propose an effective color metric which can predict the perceptual image quality for Retinex method. In this paper, we first give a brief introduction of three kinds of typical single Retinex methods to improve the color reproduction. And then, we state the process for obtaining the observer rating value from the subjective evaluation experiment performed under the sRGB illumination condition. Next, we introduce the S-CIELAB metric and propose a new metric on the basis of S-CIELAB metric that considers the gazing information. The average S-CIELAB color differences with and without the consideration of gazing information were calculated as the objective image quality measures. The correlations between the observer rating values and the objective image quality measures were calculated. The result shows that all of the average S-CIELAB color differences based on the gazing information are better correlated to the observer rating value than the average S-CIELAB color difference over the whole area. The average S-CIELAB color difference weighted by the gazing frequency over the gazing area shows the strong correlation with the observer rating value.

We give necessary and sufficient conditions for a 1-D DBCNN (1-dimensional discrete-time binary cellular neural network) with an external input to be stable in terms of connection coefficients. The results are generalization of our previous one [18],[19] in which the input was assumed to be zero.

In this paper, given an integer e and n such that e|n, and a prime p, we propose a method of constructing optimal p2-ary low correlation zone (LCZ) sequence set with parameters (pn-1, pe-1, (pn -1)/(pe -1), 1) from a p-ary sequence of the same length with ideal autocorrelation. The resulting p2-ary LCZ sequence set can be viewed as the generalization of the optimal quaternary LCZ sequence set by Kim, Jang, No, and Chung in respect of the alphabet size. This generalization becomes possible due to a completely new proof comprising any prime p. Under this proof, the quaternary case can be considered as a specific example for p = 2.

This paper considers the universal coding problem for stationary ergodic sources with countably infinite alphabets. We propose modified versions of LZ77 and LZ78 codes for sources with countably infinite alphabets. Then, we show that for any source µ with Eµ[log X1]<∞, both codes are asymptotically optimum, i.e. the code length per input symbol approaches its entropy rate with probability one. Further, we show that we can modify LZ77 and LZ78 codes so that both are asymptotically optimal for a family of ergodic sources satisfying Kieffer's condition.