When the multipath delay difference exceeds the guard interval (GI), the performance of MIMO-OFDM transmission suffers severely from both the inter-symbol interference (ISI) from the adjacent OFDM symbols and the inter-carrier interference (ICI) within the same symbol. This paper therefore proposes a MIMO-OFDM receiver employing the low-complexity turbo equalization. The proposed receiver initially separates the data streams and suppresses ICI by linear processing. In the iterative processing, it cancels the other data streams as well as ISI and ICI. The MIMO-OFDM turbo equalizer consists of an ISI canceller, an ICI canceller, an optimal detection filter, and a MAP detector. The proposed receiver can improve the transmission performance by exploiting the log-likelihood ratio that the decoding process produces for canceling both ISI and ICI and separating of the spatially multiplexed streams. Computer simulations, which apply the wireless LAN to MIMO, demonstrate that the proposed receiver can provide excellent performance in the severe multipath channels where the delay difference is greater than GI.

We present a method for binarization of degraded call number images. Based on the texture feature of the character stroke, the algorithm initially detects the character pixels to determine the size of the local area and compute the logical thresholding level. Experimental results prove the effectiveness of the method.

Novel microstrip lowpass filters are developed with reduced size and significantly improved stopband characteristics. After introducing quarter-wavelength open stubs, we get one or two transmission zeros in the stopband. By folding the high impedance microstrip lines, we reduce the size of the filter. Three-pole and five-pole lowpass filters are designed, and their measured frequency responses agree well with theoretical predictions.

This paper considers a neighborhood broadcasting protocol in undirected de Bruijn and Kautz networks. The neighborhood broadcasting problem(NBP) is the problem of disseminating a message from an originator vertex to only its neighbors. Our protocol works under the single-port and half-duplex model and solves NBP in 5log2(n+1) + O(1) time units on the undirected de Bruijn graph UB(n,d) with nd vertices and the undirected Kautz graph UK(n,d) with nd + nd-1 vertices, where 2n is the maximum degree of these graphs. This completion time is asymptotically optimal in this model.

In this paper, we present a noble pattern synthesis method of linear and planar array antennas, with non-uniform spacing, for simultaneous reduction of their side-lobe level and pattern distortion during beam steering. In the case of linear array, the Gauss-Newton method is applied to adjust the positions of elements, providing an optimal linear array in the sense of side-lobe level and pattern distortion. In the case of planar array, the concept of thinned array combined with non-uniformly spaced array is applied to obtain an optimal two dimensional (2-D) planar array structure under some constraints. The optimized non-uniformly spaced linear array is extended to the 2-D planar array structure, and it is used as an initial planar array geometry. Next, we further modify the initial 2-D planar array geometry with the aid of thinned array theory in order to reduce the maximum side-lobe level. This is implemented by a genetic algorithm under some constraints, minimizing the maximum side-lobe level of the 2-D planar array. It is shown that the proposed method can significantly reduce the pattern distortion as well as the side-lobe level, although the beam direction is scanned.

We regard the events of a Markov decision process as the outputs from a Markov information source in order to analyze the randomness of an empirical sequence by the codeword length of the sequence. The randomness is an important viewpoint in reinforcement learning since the learning is to eliminate the randomness and to find an optimal policy. The occurrence of optimal empirical sequence also depends on the randomness. We then introduce the Lempel-Ziv coding for measuring the randomness which consists of the domain size and the stochastic complexity. In experimental results, we confirm that the learning and the occurrence of optimal empirical sequence depend on the randomness and show the fact that in early stages the randomness is mainly characterized by the domain size and as the number of time steps increases the randomness depends greatly on the complexity of Markov decision processes.

An inverse-RZ modulation scheme for dense WDM systems is proposed. Inverse-RZ signals have tolerances to chromatic dispersion and optical bandwidth limitation. The strongly pre-filtered inverse-RZ signals can be adapted to ultra-dense WDM systems, in which the spectral efficiencies are over 1.0 b/s/Hz. We have confirmed the error-free transmission of pre-filtered and co-polarized 40-Gb/s inverse-RZ signals where the channel intervals were 37.5 GHz.

Isogeny for elliptic curve cryptosystems was initially used for efficient improvement of order counting methods. Recently, Smart proposed a countermeasure using isogeny for resisting a refined differential power analysis by Goubin (Goubin's attack). In this paper, we examine a countermeasure using isogeny against zero-value point (ZVP) attack that is generalization of Goubin's attack. We show that some curves require higher order of isogeny to prevent ZVP attack. Moreover, we prove that the class of curves that satisfies (-3/p) = 1 and whose order is odd cannot be mapped by isogeny to curves with a = -3 and secure against ZVP attack. We point out that three SECG curves are in this class. In the addition, we compare some efficient algorithms that are secure against both Goubin's attack and ZVP attack, and present the most efficient method of computing a scalar multiplication for each curve from SECG. Finally, we discuss another improvement for an efficient scalar multiplication, namely the usage of a point (0,y) for a base point of curve parameters. We are able to improve about 11% for double-and-add-always method, when the point (0,y) exists in an underlying curve or its isogeny.

We fabricated organic p-n heterojunction, p-i-n heterojunction and all-i-layer photovoltaic cells of a zinc phthalocyanine (ZnPc)/1:1 codeposition (ZnPc:C60)/C60 structure with Al cathode. We investigated the effects of the device structure and the cathode material on the photovoltaic properties. The thickness of the i-layer was changed as 0 nm (= p-n heterojunction), 10 nm (= p-i-n heterojunction) or 50 nm (= all-i-layer) with the total thickness of 50 nm. We also changed cathode materials from Al to low-workfunction Mg:Ag electrode. Photovoltaic properties, i.e., short-circuit current density, fill factor and power conversion efficiency, were strongly influenced by the device structure and cathode material. Finally, the power conversion efficiency showed a maximum (1.5%) with the p-i-n structure and a Mg:Ag cathode under Air Mass 1.5 global solar conditions.

This paper presents a novel ZVS bidirectional 1 kW class DC-DC converter used for a photovoltaic (PV) system. The proposed circuit is based on a boost&buckboost converter, which consists of a boost converter and a buckboost converter. Bidirectional soft switching is realized by using of coupled inductors and auxiliary switches in the circuit. From the analysis of the circuit operation, ZVS conditions of the switches are derived. In the experiment, the maximum efficiency of the proposed converter during forward power flow was 97.1% on output power of 320 W.

This paper proposes a post-layout transistor sizing method for crosstalk noise reduction. The proposed method downsizes the drivers of aggressor wires for noise reduction, utilizing the precise interconnect information extracted from the detail-routed layouts. We develop a transistor sizing algorithm for crosstalk noise reduction under delay constraints, and construct a crosstalk noise optimization method utilizing an analytic crosstalk noise model and a transistor sizing framework that have been developed. Our method exploits the transistor sizing framework that can vary transistor widths inside cells with interconnects unchanged. Our optimization method therefore never causes a new crosstalk noise problem, and does not need iterative layout optimization. The effectiveness of the proposed method is experimentally examined using 2 circuits. The maximum noise voltage is reduced by more than 50% without delay violation. These results show that the risk of crosstalk noise problems can be considerably reduced after detail-routing.

This paper presents a fuzzy model-based approach for synchronization of time-delay chaotic system with input saturation. Time-delay chaotic drive and response system is respectively represented by Takagi-Sugeno (T-S) fuzzy model. Specially, the response system contains input saturation. Using the unidirectional linear error feedback and the parallel distributed compensation (PDC) scheme, we design fuzzy chaotic synchronization system and analyze local stability for synchronization error dynamics. Since time-delay in the transmission channel always exists, we also take it into consideration. The sufficient condition for the local stability of the fuzzy synchronization system with input saturation and channel time-delay is derived by applying Lyapunov-Krasovskii theory and solving linear matrix inequalities (LMI's) problem. Numerical examples are given to demonstrate the validity of the proposed approach.

This paper presents optimum and sub-optimal designs of noise-shaping FIR filters for single- and multi-bit data converters. In the designs, only three parameters, the number of taps, oversampling ratio (OSR) and l1-norm of the filter coefficients are specified, and the in-band peak of the amplitude response is minimized under the specifications. The minimization problem is formulated with the overload-free condition, which guarantees the rigorous stability, and an overload-free converter generates no distortion in any output signals. In the optimum design, the minimization problem is directly and exactly solved, but the sub-optimal method solves this problem by iteratively utilizing the simplex method. The iterative sub-optimal method without the exact optimality is far faster and more efficient than the optimum method. In design examples, optimum and sub-optimal noise-shaping FIR filters for single- and multi-bit data converters are designed, and their optimal performance is revealed. For single-bit data converters with OSR 64, a noise-shaping FIR filter is designed and then shown to achieve a signal to noise and distortion ratio (SNDR) 107.6 [dB] in the band of interest.

Inter-domain communications on a chip require a synchronizer to resolve the timing problems between an input and a clock of a destination. This paper presents a parallel flop synchronizer and its interface circuit for transferring asynchronous data to the clock domain. The proposed scheme uses a bank of independent two-flops in parallel and supports a two-phase handshake protocol. Compared to the conventional two-flop synchronizer, performance analysis shows that the proposed scheme can reduce latency up to one and a half of clock cycles while retaining its safety to a tolerable level. All designs have been implemented in a 0.25 µm CMOS technology to verify performance analysis of the proposed synchronization.

A moment matrix analysis (MMA) method can derive macroscopic statistical properties such as moments, response time, and power spectra of non-linear equations without solving the equations. MMA expands a non-linear equation into simultaneous linear equations of moments, and reduces it to a linear equation of their coefficient matrix and a moment vector. We can analyze the statistical properties from the eigenvalues and eigenvectors of the coefficient matrix. This paper presents (1) a systematic procedure to linearize non-linear equations and (2) an expansion of the previous work of MMA to derive the statistical properties of various non-linear equations. The statistical properties of the logistic map were evaluated by using MMA and computer simulation, and it is shown that the proposed systematic procedure was effective and that MMA could accurately approximate the statistical properties of the logistic map even though such a map had strong non-linearity.

Digital cinema will continue, for some time, to use image signals converted from the density values of film stock through some form of digitization. This paper investigates the required numbers of quantization bits for both intensity and density. Equations for the color differences created by quantization distortion are derived on the premise that the uniform color space L* a* b* can be used to evaluate color differences in digitized pictorial color images. The location of the quantized sample that yields the maximum color difference in the color gamut is theoretically analyzed with the proviso that the color difference must be below the perceivable limit of human visual systems. The result shows that the maximum color difference is located on a ridge line or a surface of the color gamut. This can reduce the computational burden for determining the required precision for color quantization. Design examples of quantization resolution are also shown by applying the proposed evaluation method to three actual color spaces: NTSC, HDTV, and ROMM.

The orthogonal function approach is developed in this paper to solve the Takagi-Sugeno (TS) fuzzy-model-based dynamic equations. The new method simplifies the procedure of solving the TS-fuzzy-model-based dynamic equations into the successive solution of a system of recursive formulae only involving matrix algebra. Based on the presented recursive formulae, an algorithm only involving straightforward algebraic computation is also proposed in this paper. The computational complexity can therefore be reduced remarkably. An illustrated example shows that the proposed method based on the orthogonal functions can obtain satisfactory results.

This paper presents a novel self-excited ZVS half-bridge converter. This converter including a self-oscillating control circuit is very simply constructed. The converter achieves excellent efficiency, low voltage stress across the switches and low EMI noise by using zero-voltage-switching technique. This converter stores not only magnetic energy in the primary winding of the transformer but also electrostatic energy on the resonant capacitor during the on-periods, so that the converter realizes the miniaturization of the transformer, the reduced conduction losses and the low current stress in the switch. This paper analyzes the behavior of static characteristics by using an extending state-space-averaging method and presents design equations. Based on the analysis, two prototype converters are designed for a 120 W output and a 350 W output. Experimental results are given for two converters and they confirm the validity of the theory. The proposed converters have displayed excellent performance.

This paper introduces an efficient affine projection algorithm (APA) using iterative hyperplane projection. The inherent effectiveness against the rank deficient problem has led APA to be the preferred algorithm to be employed for various applications over other variety of fast converging adaptation algorithms. However, the amount of complexity of the conventional APA could not be negligible because of the accomplishment of sample matrix inversion (SMI). Another issue is that the "shifting invariance property," which is typically exploited for single channel case, does not hold ground for space-time decision-directed equalizer (STDE) application deployed in single-input-multi-output (SIMO) systems. Therefore, fast adaptation schemes, such as fast traversal filter based APA (FTF-APA), becomes impossible to utilize. The motivation of this paper deliberates on finding an effective algorithm on the basis of APA, which yields low complexity while sustaining fast convergence as well as excellent tracking ability. The performance of the proposed method is evaluated under wireless SIMO channel in respect to bit error rate (BER) behavior and computational complexity, and upon completion, the validity is confirmed. The performance of the proposed method is evaluated under wireless SIMO channel in respect to bit error rate (BER) behavior and computational complexity, and upon completion, the validity is confirmed.

The design, manufacture, and test results are presented for a 90polarization-rotating Van Atta array reflector with suppressed scattered field for the 1.27-GHz band. The reflector consists of 48 element antennas, half for horizontal polarization and half for vertical polarization. It receives a horizontally or vertically polarized wave and retransmits a vertically or horizontally polarized wave, respectively. The measured cross-polarized radar cross section of the reflector was 15.8 dBm2 on average, which agreed well with a theoretical prediction. Although the suppression of the scattered field was limited to about -20 dB relative to the retransmitted field, we could suppress more the scattered field by accurate positioning and careful characteristics adjustment of element antennas. Theoretical calculations showed that total phase errors of the element antennas including positioning errors and impedance characteristics errors have to be within 7.5to suppress the scattered field by less than -30 dB.