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[Keyword] Q(6809hit)

601-620hit(6809hit)

  • Designing a Framework for Data Quality Validation of Meteorological Data System Open Access

    Wen-Lung TSAI  Yung-Chun CHAN  

     
    PAPER

      Pubricized:
    2019/01/22
      Vol:
    E102-D No:4
      Page(s):
    800-809

    In the current era of data science, data quality has a significant and critical impact on business operations. This is no different for the meteorological data encountered in the field of meteorology. However, the conventional methods of meteorological data quality control mainly focus on error detection and null-value detection; that is, they only consider the results of the data output but ignore the quality problems that may also arise in the workflow. To rectify this issue, this paper proposes the Total Meteorological Data Quality (TMDQ) framework based on the Total Quality Management (TQM) perspective, especially considering the systematic nature of data warehousing and process focus needs. In practical applications, this paper uses the proposed framework as the basis for the development of a system to help meteorological observers improve and maintain the quality of meteorological data in a timely and efficient manner. To verify the feasibility of the proposed framework and demonstrate its capabilities and usage, it was implemented in the Tamsui Meteorological Observatory (TMO) in Taiwan. The four quality dimension indicators established through the proposed framework will help meteorological observers grasp the various characteristics of meteorological data from different aspects. The application and research limitations of the proposed framework are discussed and possible directions for future research are presented.

  • The Shift-and-Add Property of m-Sequences

    Fanxin ZENG  Lijia GE  Xiping HE  Guixin XUAN  Guojun LI  Zhenyu ZHANG  Yanni PENG  Linjie QIAN  Sheng LU  

     
    LETTER-Information Theory

      Vol:
    E102-A No:4
      Page(s):
    685-690

    The shift-and-add property (SAP) of a p-ary m-sequence {ak} with period N=pn-1 means that this sequence satisfies the equation {ak+η}+{ak+τ}={ak+λ} for some integers η, τ and λ. For an arbitrarily-given p-ary m-sequence {ak}, we develop an algebraic approach to determine the integer λ for the arbitrarily-given integers η and τ. And all trinomials can be given. Our calculation only depends on the reciprocal polynomial of the primitive polynomial which produces the given m-sequence {ak}, and the cyclotomic cosets mod pn-1.

  • Toward Scalable Superconducting Quantum Computer Implementation Open Access

    Yutaka TABUCHI  Shuhei TAMATE  Yasunobu NAKAMURA  

     
    INVITED PAPER

      Vol:
    E102-C No:3
      Page(s):
    212-216

    In this paper, we briefly review the concept of superconducting quantum computers and discuss their hardware architecture. We also describe the necessary technologies for the development of a medium-scale quantum computer with more than tens of thousands of quantum bits.

  • A Simple Heuristic for Order-Preserving Matching

    Joong Chae NA  Inbok LEE  

     
    LETTER

      Pubricized:
    2018/10/30
      Vol:
    E102-D No:3
      Page(s):
    502-504

    Order preserving matching refers to the problem of reporting substrings in the text which are order-isomorphic to the pattern. In this paper, we show a simple heuristic which runs in linear time on average, based on finding the largest elements in each substring and checking their locations against that of the pattern. It is easy to implement and experimental results showed that the running time grows linearly.

  • Stochastic Channel Selection for UAV-Aided Data Collection

    Tianyu LU  Haibo DAI  Juan ZHAO  Baoyun WANG  

     
    LETTER-Communication Theory and Signals

      Vol:
    E102-A No:3
      Page(s):
    598-603

    We investigate the uplink channel selection problem of unmanned aerial vehicle (UAV)-aided data collection system in delay-sensitive sensor networks. In the studied model, the fixed-wing UAV is dispatched to gather sensing information from terrestrial sensor nodes (SNs) and they contend for uplink channels for transmission. With the goal of minimizing the system-wide delay, we formulate a resource allocation problem. Encountered with the challenge that the flight trajectory of UAV is unknown to SNs and the wireless channel is time-varying, we solve the problem by stochastic game approach and further propose a fully distributed channel selection algorithm which is proved to converge to a pure strategy Nash Equilibrium (NE). Simulation results are presented to show that our proposed algorithm has good performance.

  • Passive Localization Algorithm for Spaceborne SAR Using NYFR and Sparse Bayesian Learning

    Yifei LIU  Yuan ZHAO  Jun ZHU  Bin TANG  

     
    LETTER-Digital Signal Processing

      Vol:
    E102-A No:3
      Page(s):
    581-585

    A novel Nyquist Folding Receiver (NYFR) based passive localization algorithm with Sparse Bayesian Learning (SBL) is proposed to estimate the position of a spaceborne Synthetic Aperture Radar (SAR).Taking the geometry and kinematics of a satellite into consideration, this paper presents a surveillance geometry model, which formulates the localization problem into a sparse vector recovery problem. A NYFR technology is utilized to intercept the SAR signal. Then, a convergence algorithm with SBL is introduced to recover the sparse vector. Furthermore, simulation results demonstrate the availability and performance of our algorithm.

  • Modification of Velvet Noise for Speech Waveform Generation by Using Vocoder-Based Speech Synthesizer Open Access

    Masanori MORISE  

     
    LETTER-Speech and Hearing

      Pubricized:
    2018/12/05
      Vol:
    E102-D No:3
      Page(s):
    663-665

    This paper introduces a new noise generation algorithm for vocoder-based speech waveform generation. White noise is generally used for generating an aperiodic component. Since short-term white noise includes a zero-frequency component (ZFC) and inaudible components below 20 Hz, they are reduced in advance when synthesizing. We propose a new noise generation algorithm based on that for velvet noise to overcome the problem. The objective evaluation demonstrated that the proposed algorithm can reduce the unwanted components.

  • A 6th-Order Quadrature Bandpass Delta Sigma AD Modulator Using Dynamic Amplifier and Noise Coupling SAR Quantizer

    Chunhui PAN  Hao SAN  

     
    PAPER

      Vol:
    E102-A No:3
      Page(s):
    507-517

    This paper presents a 6th-order quadrature bandpass delta sigma AD modulator (QBPDSM) with 2nd-order image rejection using dynamic amplifier and noise coupling (NC) SAR quantizer embedded by passive adder for the application of wireless communication system. A novel complex integrator using dynamic amplifier is proposed to improve the energy efficiency of the QBPDSM. The NC SAR quantizer can realize an additional 2nd-order noise shaping and 2nd-order image rejection by the digital domain noise coupling technique. As a result, the 6th-order QBPDSM with 2nd-order image rejection is realized by two complex integrators using dynamic amplifier and the NC SAR quantizer. The SPICE simulation results demonstrate the feasibility of the proposed QBPDSM in 90nm CMOS technology. Simulated SNDR of 76.30dB is realized while a sinusoid -3.25dBFS input is sampled at 33.3MS/s and the bandwidth of 2.083MHz (OSR=8) is achieved. The total power consumption in the modulator is 6.74mW while the supply voltage is 1.2V.

  • Optimization of Power Allocation for Chase Combining Hybrid ARQ

    Chen JI  Juan CAO  Guo'an ZHANG  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2018/08/29
      Vol:
    E102-B No:3
      Page(s):
    613-622

    This paper studies power allocation for Chase combining (CC) hybrid ARQ (HARQ) in block-fading channels, with causal channel state information (CSI) available both at the receiver and transmitter. A best-effort power allocation scheme is proposed to improve the average throughput of CC HARQ. The scheme is formulated as an optimization problem that, for each round, allocating the transmit power to maximize the average incremental information according to the HARQ retransmission status and CSI. By convex optimization, the solution is derived in simple analytical form. At the same time, the HARQ performance metrics including throughput and outage probability are computed by recursive numerical integral. With at most 4 transmission rounds, this best-effort method achieves about 75% of ergodic capacity in independent Rayleigh block fading channels.

  • Quantum Information Processing with Superconducting Nanowire Single-Photon Detectors Open Access

    Takashi YAMAMOTO  

     
    INVITED PAPER

      Vol:
    E102-C No:3
      Page(s):
    224-229

    Superconducting nanowire single-photon detector(SNSPD) has been one of the important ingredients for photonic quantum information processing (QIP). In order to see the potential of SNSPDs, I briefly review recent progresses of the photonic QIP with SNSPDs implemented for various purposes and present a possible direction for the development of SNSPDs.

  • Bandwidth-Efficient Blind Nonlinear Compensation of RF Receiver Employing Folded-Spectrum Sub-Nyquist Sampling Technique Open Access

    Kan KIMURA  Yasushi YAMAO  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2018/09/14
      Vol:
    E102-B No:3
      Page(s):
    632-640

    Blind nonlinear compensation for RF receivers is an important research topic in 5G mobile communication, in which higher level modulation schemes are employed more often to achieve high capacity and ultra-broadband services. Since nonlinear compensation circuits must handle intermodulation bandwidths that are more than three times the signal bandwidth, reducing the sampling frequency is essential for saving power consumption. This paper proposes a novel blind nonlinear compensation technique that employs sub-Nyquist sampling analog-to-digital conversion. Although outband distortion spectrum is folded in the proposed sub-Nyquist sampling technique, determination of compensator coefficients is still possible by using the distortion power. Proposed technique achieves almost same compensation performance in EVM as the conventional compensation scheme, while reducing sampling speed of analog to digital convertor (ADC) to less than half the normal sampling frequency. The proposed technique can be applied in concurrent dual-band communication systems and adapt to flat Rayleigh fading environments.

  • Superconducting Digital Electronics for Controlling Quantum Computing Systems Open Access

    Nobuyuki YOSHIKAWA  

     
    INVITED PAPER

      Vol:
    E102-C No:3
      Page(s):
    217-223

    The recent rapid increase in the scale of superconducting quantum computing systems greatly increases the demand for qubit control by digital circuits operating at qubit temperatures. In this paper, superconducting digital circuits, such as single-flux quantum and adiabatic quantum flux parametron circuits are described, that are promising candidates for this purpose. After estimating their energy consumption and speed, a conceptual overview of the superconducting electronics for controlling a multiple-qubit system is provided, as well as some of its component circuits.

  • Quantum Query Complexity of Unitary Operator Discrimination Open Access

    Akinori KAWACHI  Kenichi KAWANO  Francois LE GALL  Suguru TAMAKI  

     
    PAPER

      Pubricized:
    2018/11/08
      Vol:
    E102-D No:3
      Page(s):
    483-491

    Unitary operator discrimination is a fundamental problem in quantum information theory. The basic version of this problem can be described as follows: Given a black box implementing a unitary operator U∈S:={U1, U2} under some probability distribution over S, the goal is to decide whether U=U1 or U=U2. In this paper, we consider the query complexity of this problem. We show that there exists a quantum algorithm that solves this problem with bounded error probability using $lceil{sqrt{6} heta_{ m cover}^{-1}} ceil$ queries to the black box in the worst case, i.e., under any probability distribution over S, where the parameter θcover, which is determined by the eigenvalues of $U_1^dagger {U_2}$, represents the “closeness” between U1 and U2. We also show that this upper bound is essentially tight: we prove that for every θcover > 0 there exist operators U1 and U2 such that any quantum algorithm solving this problem with bounded error probability requires at least $lceil{ rac{2}{3 heta_{ m cover}}} ceil$ queries under uniform distribution over S.

  • BER Performance of Human Body Communications Using FSDT

    Kunho PARK  Min Joo JEONG  Jong Jin BAEK  Se Woong KIM  Youn Tae KIM  

     
    PAPER-Network

      Pubricized:
    2018/08/23
      Vol:
    E102-B No:3
      Page(s):
    522-527

    This paper presents the bit error rate (BER) performance of human body communication (HBC) receivers in interference-rich environments. The BER performance was measured while applying an interference signal to the HBC receiver to consider the effect of receiver performance on BER performance. During the measurement, a signal attenuator was used to mimic the signal loss of the human body channel, which improved the repeatability of the measurement results. The measurement results showed that HBC is robust against the interference when frequency selective digital transmission (FSDT) is used as a modulation scheme. The BER performance in this paper can be effectively used to evaluate a communication performance of HBC.

  • An Iterative Decoding Scheme for CPM-QC-LDPC Codes Based on Matrix Transform

    Zuohong XU  Jiang ZHU  Qian CHENG  Zixuan ZHANG  

     
    PAPER-Fundamental Theories for Communications

      Pubricized:
    2018/09/06
      Vol:
    E102-B No:3
      Page(s):
    496-509

    Quasi cyclic LDPC (QC-LDPC) codes consisting of circulant permutation matrices (CPM-QC-LDPC) are one of the most attractive types of LDPC codes due to their many advantages. In this paper, we mainly do some research on CPM-QC-LDPC codes. We first propose a two-stage decoding scheme mainly based on parity check matrix transform (MT), which can efficiently improve the bit error rate performance. To optimize the tradeoff between hardware implementation complexity and decoding performance, an improved method that combines our proposed MT scheme with the existing CPM-RID decoding scheme is presented. An experiment shows that both schemes can improve the bit error rate (BER) performance. Finally, we show that the MT decoding mechanism can be applied to other types of LDPC codes. We apply the MT scheme to random LDPC codes and show that it can efficiently lower the error floor.

  • An Equalization of PN-DSTBC for Concatenating with Spectral Precoding

    Kanako YAMAGUCHI  Nicolas GRESSET  Hiroshi NISHIMOTO  Akihiro OKAZAKI  Hiroyasu SANO  Shusaku UMEDA  Kaoru TSUKAMOTO  Atsushi OKAMURA  

     
    PAPER-Mobile Information Network and Personal Communications

      Vol:
    E102-A No:3
      Page(s):
    544-552

    A diversity strategy is efficient to reduce the fluctuation of communication quality caused by fading. In order to further maintain the communication quality and improve the communication capacity, this paper proposes a two-dimensional diversity approach by serially-concatenating spectral precoding and power normalized-differential space time block coding (PN-DSTBC). Spectral precoding is able to take benefit from a frequency diversity effect without loss in spectral efficiency. In addition, PN-DSTBC is robust against serious phase noise in an extremely high frequency (EHF) band by exploiting a spatial diversity effect. However, there is a problem that a naive concatenation degrades the performance due to the imbalance of equivalent noise variances over transmit frequencies. Thus, we examine an equalized PN-DSTBC decoder as a modified approach to uniform equivalent noise variances over frequencies. The performance evaluation using computer simulations shows that the proposed modified approach yields the performance improvement at any modulation schemes and at any number of transmit frequencies. Furthermore, in the case of 64QAM and two transmit frequencies, the performance gain of the modified approach is 4dB larger than that of PN-DSTBC only at uncoded BER=10-4.

  • Sparse DP Quantization Algorithm Open Access

    Yukihiro BANDOH  Seishi TAKAMURA  Atsushi SHIMIZU  

     
    PAPER-Image

      Vol:
    E102-A No:3
      Page(s):
    553-565

    We formulate the design of an optimal quantizer as an optimization problem that finds the quantization indices that minimize quantization error. As a solution of the optimization problem, an approach based on dynamic programming, which is called DP quantization, is proposed. It is observed that quantized signals do not always contain all kinds of signal values which can be represented with given bit-depth. This property is called amplitude sparseness. Because quantization is the amplitude discretization of signal value, amplitude sparseness is closely related to quantizer design. Signal values with zero frequency do not impact quantization error, so there is the potential to reduce the complexity of the optimal quantizer by not computing signal values that have zero frequency. However, conventional methods for DP quantization were not designed to consider amplitude sparseness, and so fail to reduce complexity. The proposed algorithm offers a reduced complexity optimal quantizer that minimizes quantization error while addressing amplitude sparseness. Experimental results show that the proposed algorithm can achieve complexity reduction over conventional DP quantization by 82.9 to 84.2% on average.

  • Robust Multimodulus Blind Equalization Algorithm with an Optimal Step Size

    Liu YANG  Hang ZHANG  Yang CAI  Hua YANG  Qiao SU  

     
    LETTER-Digital Signal Processing

      Vol:
    E102-A No:3
      Page(s):
    576-580

    A class of multimodulus algorithms (MMA(p)) optimized by an optimal step-size (OS) for blind equalization are firstly investigated in this letter. The multimodulus (MM) criterion is essentially a split cost function that separately implements the real and imaginary part of the signal, hence the phase can be recovered jointly with equalization. More importantly, the step-size leading to the minimum of the MM criterion along the search direction can be obtained algebraically among the roots of a higher-order polynomial at each iteration, thus a robust optimal step-size multimodulus algorithm (OS-MMA(p)) is developed. Experimental results demonstrate improved performance of the proposed algorithm in mitigating the inter-symbol interference (ISI) compared with the OS constant modulus algorithm (OS-CMA). Besides, the computational complexity can be reduced by the proposed OS-MMA(2) algorithm.

  • Design Optimization of Radar Absorbent Material for Broadband and Continuous Oblique Incidence Characteristics

    Yuka ISHII  Naobumi MICHISHITA  Hisashi MORISHITA  Yuki SATO  Kazuhiro IZUI  Shinji NISHIWAKI  

     
    PAPER-Electromagnetic Compatibility(EMC)

      Pubricized:
    2018/08/21
      Vol:
    E102-B No:2
      Page(s):
    216-223

    Radar-absorbent materials (RAM) with various characteristics, such as broadband, oblique-incidence, and polarization characteristics, have been developed according to applications in recent years. This paper presents the optimized design method of two flat layers RAM with both broadband and oblique-incidence characteristics for the required RAM performance. The oblique-incidence characteristics mean that the RAM is possible to absorb radio waves continuously up to the maximum incidence angle. The index of the wave-absorption amount is 20dB, corresponding to an absorption rate of 99%. Because determination of the electrical material constant of each layer is the most important task with respect to the received frequency and the incidence angle, we optimized the values by using Non-dominated sorting genetic algorithm-II (NSGA-II). Two types of flat-layer RAM composed of dielectric and magnetic materials were designed and their characteristics were evaluated. Consequently, it was confirmed that oblique-incidence characteristics were better for the RAM composed of dielectric materials. The dielectric RAM achieved an incidence angle of up to 60° with broadband characteristics and a relative bandwidth of 77.01% at the transverse-magnetic (TM) wave incidence. In addition, the magnetic RAM could lower the minimum frequency of the system more than the dielectric RAM. The minimum frequency of the magnetic RAM was 1.38GHz with a relative bandwidth of 174.18% at TM-wave incidence and an incidence angle of 45°. We confirmed that it is possible to design RAM with broadband characteristics and continuous oblique-incidence characteristics by using the proposed method.

  • A Novel Four-Point Model Based Unit-Norm Constrained Least Squares Method for Single-Tone Frequency Estimation

    Zhe LI  Yili XIA  Qian WANG  Wenjiang PEI  Jinguang HAO  

     
    PAPER-Digital Signal Processing

      Vol:
    E102-A No:2
      Page(s):
    404-414

    A novel time-series relationship among four consecutive real-valued single-tone sinusoid samples is proposed based on their linear prediction property. In order to achieve unbiased frequency estimates for a real sinusoid in white noise, based on the proposed four-point time-series relationship, a constrained least squares cost function is minimized based on the unit-norm principle. Closed-form expressions for the variance and the asymptotic expression for the variance of the proposed frequency estimator are derived, facilitating a theoretical performance comparison with the existing three-point counterpart, called as the reformed Pisarenko harmonic decomposer (RPHD). The region of performance advantage of the proposed four-point based constrained least squares frequency estimator over the RPHD is also discussed. Computer simulations are conducted to support our theoretical development and to compare the proposed estimator performance with the RPHD as well as the Cramer-Rao lower bound (CRLB).

601-620hit(6809hit)