IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Online ISSN : 1745-1337
Print ISSN : 0916-8508
Advance online publication
Displaying 1-50 of 79 articles from this issue
  • Xiuping PENG, Mingshuo SHEN, Hongbin LIN, Shide WANG
    Article type: LETTER
    Article ID: 2021EAL2105
    Published: 2022
    Advance online publication: May 26, 2022
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    This letter provides a direct construction of binary even-length Z-complementary pairs. To date, the maximum zero correlation zone ratio of Type-I Z-complementary pairs has reached 6/7, but no direct construction of Z-complementary pairs can achieve the zero correlation zone ratio of 6/7. In this letter, based on Boolean function, we give a direct construction of binary even-length Z-complementary pairs with zero correlation zone ratio 6/7. The length of constructed Z-complementary pairs is 2m+3 + 2m+2 + 2m+1 and the width of zero correlation zone is 2m+3 + 2m+2.

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  • Yohei WATANABE, Takeshi NAKAI, Kazuma OHARA, Takuya NOJIMA, Yexuan LIU ...
    Article type: PAPER
    Article ID: 2021EAP1163
    Published: 2022
    Advance online publication: May 25, 2022
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    Searchable symmetric encryption (SSE) enables clients to search encrypted data. Curtmola et al. (ACMCCS2006) formalized a model and security notions of SSE and proposed two concrete constructions called SSE-1 and SSE-2. After the seminal work by Curtmola et al., SSE becomes an active area of encrypted search.

    In this paper, we focus on two unnoticed problems in the seminal paper by Curtmola et al. First, we show that SSE-2 does not appropriately implement Curtmola et al.'s construction idea for dummy addition. We refine SSE-2's (and its variants') dummy-adding procedure to keep the number of dummies sufficiently many but as small as possible. We then show how to extend it to the dynamic setting while keeping the dummy-adding procedure work well and implement our scheme to show its practical efficiency. Second, we point out that the SSE-1 can cause a search error when a searched keyword is not contained in any document file stored at a server and show how to fix it.

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  • Tongwei LU, Hao ZHANG, Feng MIN, Shihai JIA
    Article type: LETTER
    Article ID: 2022EAL2008
    Published: 2022
    Advance online publication: May 24, 2022
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    Convolutional neural network (CNN) based vehicle reidentificatioin (ReID) inevitably has many disadvantages, such as information loss caused by downsampling operation. Therefore we propose a vision transformer (Vit) based vehicle ReID method to solve this problem. To improve the feature representation of vision transformer and make full use of additional vehicle information, the following methods are presented. (I) We propose a Quadratic Split Architecture (QSA) to learn both global and local features. More precisely, we split an image into many patches as "global part" and further split them into smaller sub-patches as "local part". Features of both global and local part will be aggregated to enhance the representation ability. (II) The Auxiliary Information Embedding (AIE) is proposed to improve the robustness of the model by plugging a learnable camera/viewpoint embedding into Vit. Experimental results on several benchmarks indicate that our method is superior to many advanced vehicle ReID methods.

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  • TongWei LU, ShiHai JIA, Hao ZHANG
    Article type: LETTER
    Article ID: 2022EAL2010
    Published: 2022
    Advance online publication: May 24, 2022
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    At this stage, research in the field of Few-shot image classification (FSC) has made good progress, but there are still many difficulties in the field of Few-shot object detection (FSOD). Almost all of the current FSOD methods face catastrophic forgetting problems, which are manifested in that the accuracy of base class recognition will drop seriously when acquiring the ability to recognize Novel classes. And for many methods, the accuracy of the model will fall back as the class increases. To address this problem we propose a new memory-based method called Memorable Faster R-CNN (MemFRCN), which makes the model remember the categories it has already seen. Specifically, we propose a new tow-stage object detector consisting of a memory-based classifier (MemCla), a fully connected neural network classifier (FCC) and an adaptive fusion block (AdFus). The former stores the embedding vector of each category as memory, which enables the model to have memory capabilities to avoid catastrophic forgetting events. The final part fuses the outputs of FCC and MemCla, which can automatically adjust the fusion method of the model when the number of samples increases so that the model can achieve better performance under various conditions. Our method can perform well on unseen classes while maintaining the detection accuracy of seen classes. Experimental results demonstrate that our method outperforms other current methods on multiple benchmarks.

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  • Hangjin SUN, Lei WANG, Zhaoyang QIU, Qi ZHANG
    Article type: LETTER
    Article ID: 2022EAL2014
    Published: 2022
    Advance online publication: May 24, 2022
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    The Nyquist folding receiver (NYFR) is a novel analog-to-information architecture, which can achieve wideband receiving with a small amount of system resource. The NYFR uses a radio frequency (RF) non-uniform sampling to realize wideband receiving, and the practical RF non-uniform sample pulse train usually contains an aperture. Therefore, it is necessary to investigate the aperture impact on the NYFR output. In this letter, based on the NYFR output signal to noise ratio (SNR), the aperture impact on the NYFR is analyzed. Focusing on the aperture impact, the corresponding NYFR output signal power and noise power are given firstly. Then, the relation between the aperture and the output SNR is analyzed. In addition, the output SNR distribution containing the aperture is investigated. Finally, combing with a parameter estimation method, several simulations are conducted to prove the theoretical aperture impact.

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  • Li SHEN, Jiahuan WANG, Wei GUO, Rong LUO
    Article type: LETTER
    Article ID: 2022EAL2016
    Published: 2022
    Advance online publication: May 23, 2022
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    To mitigate the interference caused by range sidelobes in multiple-input multiple-output (MIMO) radar, we propose a new method to construct Doppler resilient complementary waveforms from complete complementary code (CCC). By jointly designing the transmit pulse train and the receive pulse weights, the range sidelobes can vanish within a specified Doppler interval. In addition, the output signal-to-noise ratio (SNR) is maximized subject to the Doppler resilience constraint. Numerical results show that the designed waveforms have better Doppler resilience than the previous works.

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  • Yujin ZHENG, Junwei ZHANG, Yan LIN, Qinglin ZHANG, Qiaoqiao XIA
    Article type: LETTER
    Article ID: 2021EAL2114
    Published: 2022
    Advance online publication: May 20, 2022
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    The Euclidean projection operation is the most complex and time-consuming of the alternating direction method of multipliers (ADMM) decoding algorithms, resulting in a large number of resources when deployed on hardware platforms. We propose a simplified line segment projection algorithm (SLSA) and present the hardware design and the quantization scheme of the SLSA. In simulation results, the proposed SLSA module has a better performance than the original algorithm with the same fixed bitwidths due to the centrosymmetric structure of SLSA. Furthermore, the proposed SLSA module with a simpler structure without hypercube projection can reduce time consuming by up to 72.2% and reduce hardware resource usage by more than 87% compared to other Euclidean projection modules in the experiments.

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  • Yao Zhou, Hairui Yu, Wenjie Xu, Siyi Yao, Li Wang, Hongshu Liao, Wanch ...
    Article type: PAPER
    Article ID: 2021EAP1141
    Published: 2022
    Advance online publication: May 18, 2022
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    In this paper, a passive multiple-input multiple-output (MIMO) radar system with widely separated antennas that estimates the positions and velocities of multiple moving targets by utilizing time delay (TD) and doppler shift (DS) measurements is proposed. Passive radar systems can detect targets by using multiple uncoordinated and unsynchronized illuminators and we assume that all the measurements including TD and DS have been known by a preprocessing method. In this study, the algorithm can be divided into three stages. First, based on location information within a certain range and utilizing the DBSCAN cluster algorithm we can obtain the initial position of each target. In the second stage according to the correlation between the TD measurements of each target in a specific receiver and the DSs, we can find the set of DS measurements for each target. Therefore, the initial speed estimated values can be obtained employing the least squares (LS) method. Finally, maximum likelihood (ML) estimation of a first-order Taylor expansion joint TD and DS is applied for a better solution. Extensive simulations show that the proposed algorithm has a good estimation performance and can achieve the Cramér-Rao lower bound (CRLB) under the condition of moderate measurement errors.

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  • Zhangti YAN, Zhi GU, Wei GUO, Jianpeng WANG
    Article type: LETTER
    Article ID: 2021EAL2109
    Published: 2022
    Advance online publication: May 16, 2022
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    Codebooks with small maximal cross-correlation amplitudes have important applications in code division multiple access (CDMA) communication, coding theory and compressed sensing. In this letter, we design a new codebook based on a construction of Ramanujan graphs over finite abelian groups. We prove that the new codebook with length K = q + 1 and size N = q2 + 2q + 2 is asymptotically optimal with nearly achieving the Levenshtein bound when n = 3, where q is a prime power. The parameters of the new codebook are new.

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  • Taiki HAYASHI, Kazuyoshi ISHIMURA, Isao T. TOKUDA
    Article type: PAPER
    Article ID: 2022EAP1028
    Published: 2022
    Advance online publication: May 16, 2022
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    Towards the realization of a noise-induced synchronization in a natural environment, an experimental study is carried out using the Van der Pol oscillator circuit. We focus on acoustic sounds as a potential source of noise that may exist in nature. To mimic such a natural environment, white noise sounds were generated from a loud speaker and recorded into microphone signals. These signals were then injected into the oscillator circuits. We show that the oscillator circuits spontaneously give rise to synchronized dynamics when the microphone signals are highly correlated with each other. As the correlation among the input microphone signals is decreased, the level of synchrony is lowered monotonously, implying that the input correlation is the key determinant for noise-induced synchronization. Our study provides an experimental basis for synchronizing clocks in distributed sensor networks and other engineering devices in natural environment.

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  • Jingke ZHANG, Huina SONG, Mengyuan WANG, Zhaoyang QIU, Xuyang TENG, Qi ...
    Article type: LETTER
    Article ID: 2021EAL2092
    Published: 2022
    Advance online publication: May 13, 2022
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    Adaptive multilooking is a critical processing step in multitemporal interferometric synthetic aperture radar (InSAR) measurement, especially in small temporal baseline subsets. Various amplitude-based adaptive multilook approaches have been proposed for the improvement of interferometric processing. However, the phase signal, which is fundamental in interferometric systems, is typically ignored in these methods. To fully exploit the information in complex SAR images, a nonlocal adaptive multilooking is proposed based on complex covariance matrix in this work. The complex signal is here exploited for the similiarity measurement between two pixels. Given the complexity of objects in SAR images, structure feature detection is introduced to adaptively estimate covariance matrix. The effectiveness and reliability of the proposed approach are demonstrated with experiments both on simulated and real data.

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  • Li Ding, Jing Jin, Jianjun Zhou
    Article type: PAPER
    Article ID: 2021KEP0006
    Published: 2022
    Advance online publication: May 13, 2022
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    This brief presents A 16/32 Gb/s dual-mode transmitter including a linearity calibration loop to maintain amplitude linearity of the SST driver. Linearity detection and corresponding master-slave power supply circuits are designed to implement the proposed architecture. The proposed transmitter is manufactured in a 22nm FD-SOI process. The linearity calibration loop reduces the peak INL errors of the transmitter by 50%, and the RLM rises from 92.4% to 98.5% when the transmitter is in PAM4 mode. The chip area of the transmitter is 0.067 mm2, while the proposed linearity enhanced part is 0.05 × 0.02 mm2 and the total power consumption is 64.6mW with a 1.1V power supply. The linearity calibration loop can be detached from the circuit without consuming extra power.

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  • Takehiro KITAMURA, Mahfuzul ISLAM, Takashi HISAKADO, Osami WADA
    Article type: PAPER
    Article ID: 2021KEP0007
    Published: 2022
    Advance online publication: May 13, 2022
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    High-speed flash ADCs are useful in high-speed applications such as communication receivers. Due to offset voltage variation in the sub-micron processes, the power consumption and the area increase significantly to suppress variation. As an alternative to suppressing the variation, we have developed a flash ADC architecture that selects the comparators based on offset voltage ranking for reference generation. Specifically, with the order statistics as a basis, our method selects the minimum number of comparators to obtain equally spaced reference values. Because the proposed ADC utilizes offset voltages as references, no resistor ladder is required. We also developed a time-domain sorting mechanism for the offset voltages to achieve on-chip comparator selection. We first perform a detailed analysis of the order statistics based selection method and then design a 4-bit ADC in a commercial 65-nm process and perform transistor-level simulation. When using 127 comparators, INLs of 20 virtual chips are in the range of -0.34 LSB/+0.29 LSB to -0.83 LSB/+0.74 LSB, and DNLs are in the range of -0.33 LSB/+0.24 LSB to -0.77 LSB/+1.18 LSB at 1-GS/s operation. Our ADC achieves the SNDR of 20.9 dB at Nyquist-frequency input and the power consumption of 0.84 mW.

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  • Daiki OGAWA, Koichi KOBAYASHI, Yuh YAMASHITA
    Article type: PAPER
    Article ID: 2021EAP1162
    Published: 2022
    Advance online publication: May 12, 2022
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    Design of distributed energy management systems composed of several agents such as factories and buildings is important for realizing smart cities. In addition, demand response for saving the power consumption is also important. In this paper, we propose a design method of distributed energy management systems with real-time demand response, in which both electrical energy and thermal energy are considered. Here, we use ADMM (Alternating Direction Method of Multipliers), which is well known as one of the powerful methods in distributed optimization. In the proposed method, demand response is performed in real-time, based on the difference between the planned demand and the actual value. Furthermore, utilizing a blockchain is also discussed. The effectiveness of the proposed method is presented by a numerical example. The importance of introducing a blockchain is pointed out by presenting the adverse effect of tampering the actual value.

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  • Satoshi Tanaka
    Article type: PAPER
    Article ID: 2021KEP0004
    Published: 2022
    Advance online publication: May 11, 2022
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    When confirming the ACLR (adjacent channel leakage power ratio), which are representative indicators of distortion in the design of PA (power amplifier), it is well known how to calculate the AM-AM/PM characteristics of PA, input time series data of modulated signals, and analyze the output by Fourier analysis. In 5G (5th generation) mobile phones, not only QPSK (quadrature phase shift keying) modulation but also 16QAM (quadrature modulation), 64QAM, and 256QAM are becoming more multivalued as modulation signals. In addition, the modulation band may exceed 100 MHz, and the amount of time series data increases, and the increase in calculation time becomes a problem. In order to shorten the calculation time, calculating the total amount of distortion generated by PA from the probability density of the modulation signal and the AM (amplitude modulation)-AM/PM (phase modulation) characteristics of PA is considered. For the AM-AM characteristics of PA, in this paper, IMD3 (inter modulation distortion 3) obtained from probability density and IMD3 by Fourier analysis, which are often used so long, are compared. As a result, it was confirmed that the result of probability density analysis is similar to that of Fourier analysis, when the nonlinearity is somewhat small. In addition, the agreement between the proposed method and the conventional method was confirmed with an error of about 2.0 dB of ACLR using the modulation waves with bandwidth of 5MHz, RB (resource block) being 25, and QPSK modulation.

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  • Jinjie LIANG, Zhenyu LIU, Zhiheng ZHOU, Yan XU
    Article type: PAPER
    Article ID: 2022EAP1004
    Published: 2022
    Advance online publication: May 11, 2022
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    Federated learning is a promising strategy for indoor localization that can reduce the labor cost of constructing a fingerprint dataset in a distributed training manner without privacy disclosure. However, the traffic generated during the whole training process of federated learning is a burden on the up-and-down link, which leads to huge energy consumption for mobile devices. Moreover, the non-independent and identically distributed (Non-IID) problem impairs the global localization performance during the federated learning. This paper proposes a communication-efficient FedAvg method for federated indoor localization which is improved by the layerwise asynchronous aggregation strategy and layerwise swapping training strategy. Energy efficiency can be improved by performing asynchronous aggregation between the model layers to reduce the traffic cost in the training process. Moreover, the impact of the Non-IID problem on the localization performance can be mitigated by performing swapping training on the deep layers. Extensive experimental results show that the proposed methods reduce communication traffic and improve energy efficiency significantly while mitigating the impact of the Non-IID problem on the precision of localization.

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  • Daisuke SATOH, Takemi MOCHIDA
    Article type: PAPER
    Article ID: 2021EAP1094
    Published: 2022
    Advance online publication: May 10, 2022
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    The road space rationing (RSR) method regulates a period in which a user group can make telephone calls in order to decrease the call attempt rate and induce calling parties to shorten their calls during disaster congestion. This paper investigates what settings of this indirect control induce more self-restraint and how the settings change calling parties' behavior using experimental psychology. Our experiments revealed that the length of the regulated period differently affected calling parties' behavior (call duration and call attempt rate) and indicated that the 60-min RSR method (i.e., 10 six-min periods) is the most effective setting against disaster congestion.

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  • Wei HE, Yu ZHANG, Yin LI
    Article type: LETTER
    Article ID: 2022EAL2002
    Published: 2022
    Advance online publication: April 26, 2022
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    We introduce a new type of exponentiation algorithm in GF(2m) using Euclidean inversion. Our approach is based on the fact that Euclidean inversion cost much less logic gates than ordinary multiplication in GF(2m). By applying signed binary form of the exponent instead of classic binary form, the proposed algorithm can reduce the number of operations further compared with the classic algorithms.

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  • Yuki OKABE, Daisuke KANEMOTO, Osamu MAIDA, Tetsuya HIROSE
    Article type: LETTER
    Article ID: 2021EAL2099
    Published: 2022
    Advance online publication: April 22, 2022
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    We propose a sampling method that incorporates a normally distributed sampling series for EEG measurements using compressed sensing. We confirmed that the ADC sampling count and amount of wirelessly transmitted data can be reduced by 11% while maintaining a reconstruction accuracy similar to that of the conventional method.

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  • Nobuyuki SUGIO, Yasutaka IGARASHI, Sadayuki HONGO
    Article type: PAPER
    Article ID: 2021EAP1124
    Published: 2022
    Advance online publication: April 22, 2022
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    Integral cryptanalysis is one of the most powerful attacks on symmetric key block ciphers. Attackers preliminarily search integral characteristics of a target cipher and use them for an attack. Todo proposed a novel technique named the bit-based division property to find integral characteristics. Xiang et al. extended Mixed Integer Linear Programming (MILP) method to search integral characteristics of lightweight block ciphers based on the bit-based division property. In this paper, we apply these techniques to the symmetric key block cipher KASUMI which was developed by modifying MISTY1. As a result, we found new 4.5-round characteristics of KASUMI for the first time. We show that 7-round KASUMI is attackable with 263 data and 2120 encryptions.

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  • Linyan YU, Pinhui KE, Zuling CHANG
    Article type: LETTER
    Article ID: 2021EAL2111
    Published: 2022
    Advance online publication: April 20, 2022
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    In this letter, we give a new construction of a family of sequences of period pk -1 with low correlation value by using additive and multiplicative characters over Galois rings. The new constructed sequence family has family size (M-1)(pk-1)r pkr(e-1) and alphabet size Mpe. Based on the characters sum over Galois rings, an upper bound on the correlation of this sequence family is presented.

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  • Jian BAI, Lin LIU, Xiaoyang ZHANG
    Article type: LETTER
    Article ID: 2022EAL2009
    Published: 2022
    Advance online publication: April 20, 2022
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    The characteristics of antenna array, like sensor location, gain and phase response are rarely perfectly known in realistic situations. Location errors usually have a serious impact on the DOA (direction of arrival) estimation. In this paper, a novel array location calibration method of MUSIC (multiple signal classification) algorithm based on the virtual interpolated array is proposed. First, the paper introduces the antenna array positioning scheme. Then, the self-calibration algorithm of FIR-Winner filter based on virtual interpolation array is derived, and its application restriction are also analyzed. Finally, by simulating the different location errors of antenna array, the effectiveness of the proposed method is validated.

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  • Takanori MAEHARA, Kazutoshi ANDO
    Article type: PAPER
    Article ID: 2021DMP0014
    Published: 2022
    Advance online publication: April 19, 2022
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    In this paper, we address the problem of finding a representation of a subtree distance, which is an extension of a tree metric. We show that a minimal representation is uniquely determined by a given subtree distance, and give an O(n2) time algorithm that finds such a representation, where n is the size of the ground set. Since a lower bound of the problem is Ω(n2), our algorithm achieves the optimal time complexity.

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  • Yifang BAO, Shigeru YAMASHITA, Bing LI, Tsung-Yi HO
    Article type: PAPER
    Article ID: 2021EAP1114
    Published: 2022
    Advance online publication: April 18, 2022
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    When we use a Programmable Microfluidic Device (PMD), we need to wash some contaminated area to use the chip for further experiments. Recently, a novel washing technique called Block-Flushing has been proposed. Block-Flushing washes contaminated area in PMDs by using buffer flows. In Block-Flushing, we need to keep a buffer flow from an input port to an output port of a PMD for a long period to dissolve residual contaminants. Thus, we may need a lot of buffer fluids and washing time even if the contaminated area is small. Another disadvantage of the washing method by Block-Flushing is such that we may not able to clean residual contaminants at valves completely by only buffer flows.

    To address the above-mentioned issues, this paper proposes a totally new idea to wash PMDs; our method does not use buffer flows, but washes contaminated area by using mixers. By using a mixer, we can dissolve residual contaminants at valves in the area of the mixer very efficiently. In this paper, we propose two methods to wash PMDs by using mixers. The first method can wash the whole chip area by using only four times of a single 2x2-mixer time. We also propose the second method which is a heuristic to reduce the number of moving valves because valves may wear down if they are used many times. We also show some experimental results to confirm that the second method can indeed decrease the number of used valves.

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  • Ryosuke ADACHI, Yuji WAKASA
    Article type: PAPER
    Article ID: 2021KEP0008
    Published: 2022
    Advance online publication: April 12, 2022
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    This paper addresses a distributed filter over wireless sensor networks for optimal estimation. A distributed filter over the networks allows all local estimators to calculate optimal estimates with a scalable communication cost. Outputs of the distributed filter for the optimal estimation can be denoted as a solution of a consensus optimization problem. Thus, the distributed filter is designed based on distributed alternating direction method of multipliers (ADMM). The remarkable points of the distributed filter based on the ADMM are that: the distributed filter has a faster convergence rate than distributed subgradient projection algorithm; the weight, which is optimized by a semidefinite programming problem, accelerates the convergence rate of the proposed method.

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  • Ryosuke MISHIMA, Kunihiko HIRAISHI
    Article type: PAPER
    Article ID: 2021EAP1147
    Published: 2022
    Advance online publication: April 11, 2022
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    In 2015, the Ministry of Land, Infrastructure and Transportation started to provide information on aircraft flying over Japan, called CARATS Open Data, and to promote research on aviation systems actively. The airspace is divided into sectors, which are used for limiting air traffic to control safely and efficiently. Since the demand for air transportation is increasing, new optimization techniques and efficient control have been required to predict and resolve demand-capacity imbalances in the airspace. In this paper, we aim to construct mathematical models of the inter-sector air traffic flow from CARATS Open Data. In addition, we develop methods to predict future sector demand. Accuracy of the prediction is evaluated by comparison between predicted sector demand and the actual data.

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  • Yuanwei HOU, Yu GU, Weiping LI, Zhi LIU
    Article type: PAPER
    Article ID: 2021EAP1119
    Published: 2022
    Advance online publication: April 01, 2022
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    The fast evolving credential attacks have been a great security challenge to current password-based information systems. Recently, biometrics factors like facial, iris, or fingerprint that are difficult to forge rise as key elements for designing passwordless authentication. However, capturing and analyzing such factors usually require special devices, hindering their feasibility and practicality. To this end, we present WiASK, a device-free WiFi sensing enabled Authentication System exploring Keystroke dynamics. More specifically, WiASK captures keystrokes of a user typing a pre-defined easy-to-remember string leveraging the existing WiFi infrastructure. But instead of focusing on the string itself which are vulnerable to password attacks, WiASK interprets the way it is typed, i.e., keystroke dynamics, into user identity, based on the biologically validated correlation between them. We prototype WiASK on the low-cost off-the-shelf WiFi devices and verify its performance in three real environments. Empirical results show that WiASK achieves on average 93.7% authentication accuracy, 2.5% false accept rate, and 5.1% false reject rate.

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  • Kento SAKA, Toshimichi SAITO
    Article type: LETTER
    Article ID: 2021EAL2113
    Published: 2022
    Advance online publication: March 29, 2022
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    This letter studies a biobjective optimization problem in binary associative memories characterized by ternary connection parameters. First, we introduce a condition of parameters that guarantees storage of any desired memories and suppression of oscillatory behavior. Second, we define a biobjective problem based on two objectives that evaluate uniform stability of desired memories and sparsity of connection parameters. Performing precise numerical analysis for typical examples, we have clarified existence of a trade-off between the two objectives.

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  • Li CUI, Xiaoyu CHEN, Yubo LI
    Article type: PAPER
    Article ID: 2021EAP1159
    Published: 2022
    Advance online publication: March 29, 2022
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    An asymmetric zero correlation zone (A-ZCZ) sequence set can be regarded as a special type of ZCZ sequence set, which consists of multiple sequence subsets. Each subset is a ZCZ sequence set, and have a common zero cross-correlation zone (ZCCZ) between sequences from different subsets. This paper supplements an existing construction of A-ZCZ sequence sets and further improves the research results. Besides, a new construction of A-ZCZ sequence sets is proposed by matrices transformation. The obtained sequence sets are optimal with respect to theoretical bound, and the parameters can be chosen more flexibly, such as the number of subsets and the lengths of ZCCZ between sequences from different subsets. Moreover, as the diversity of the orthogonal matrices and the flexibility of initial matrix, more A-ZCZ sequence sets can be obtained. The resultant sequence sets presented in this paper can be applied to multi-cell quasi-synchronous code-division multiple-access (QS-CDMA) systems, to eliminate the interference not only from the same cell but also from adjacent cells.

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  • Ren ISHIBASHI, Kazuki YONEYAMA
    Article type: PAPER
    Article ID: 2021DMP0002
    Published: 2022
    Advance online publication: March 24, 2022
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    Hierarchical ID-based authenticated key exchange (HID-AKE) is a cryptographic protocol to establish a common session key between parties with authentication based on their IDs with the hierarchical delegation of key generation functionality. All existing HID-AKE schemes are selective ID secure, and the only known standard model scheme relies on a non-standard assumption such as the q-type assumption. In this paper, we propose a generic construction of HID-AKE that is adaptive ID secure in the HID-eCK model (maximal-exposure-resilient security model) without random oracles. One of the concrete instantiations of our generic construction achieves the first adaptive ID secure HID-AKE scheme under the (standard) k-lin assumption in the standard model. Furthermore, it has the advantage that the computational complexity of pairing and exponentiation operations and the communication complexity do not depend on the depth of the hierarchy. Also, the other concrete instantiation achieves the first HID-AKE scheme based on lattices (i.e., post-quantum).

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  • Masatoshi OSUMI
    Article type: PAPER
    Article ID: 2021DMP0003
    Published: 2022
    Advance online publication: March 24, 2022
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    We initiate the study of Ramsey numbers of trails. Let k ≥ 2 be a positive integer. The Ramsey number of trails with k vertices is defined as the the smallest number n such that for every graph H with n vertices, H or the complete $\overline{H}$ contains a trail with k vertices. We prove that the Ramsey number of trails with k vertices is at most k and at least $2\sqrt{k}+\Theta(1)$. This improves the trivial upper bound of ⌊3k/2⌋ - 1.

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  • Yiyang JIA, Jun MITANI, Ryuhei UEHARA
    Article type: PAPER
    Article ID: 2021EAP1165
    Published: 2022
    Advance online publication: March 24, 2022
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    Logical matrices are binary matrices often used to represent relations. In the map folding problem, each folded state corresponds to a unique partial order on the set of squares and thus could be described with a logical matrix. The logical matrix representation is powerful than graphs or other common representations considering its association with category theory and homology theory and its generalizability to solve other computational problems. On the application level, such representations allow us to recognize map folding intuitively. For example, we can give a precise mathematical description of a folding process using logical matrices so as to solve problems like how to represent the up-and-down relations between all the layers according to their adjacency in a flat-folded state, how to check self-penetration, and how to deduce a folding process from a given order of squares that is supposed to represent a folded state of the map in a mathematical and natural manner. In this paper, we give solutions to these problems and analyze their computational complexity.

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  • Kazuho KANAHARA, Kengo KATAYAMA, Etsuji TOMITA
    Article type: PAPER
    Article ID: 2021DMP0011
    Published: 2022
    Advance online publication: March 18, 2022
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    The graph coloring problem (GCP) is a fundamental combinatorial optimization problem that has many practical applications. Degree of SATURation (DSATUR) and Recursive Largest First (RLF) are well known as typical solution construction algorithms for GCP. It is necessary to update the vertex degree in the subgraph induced by uncolored vertices when selecting vertices to be colored in both DSATUR and RLF. There is an issue that the higher the edge density of a given graph, the longer the processing time. The purposes of this paper are to propose a degree updating method called Adaptive Degree Updating (ADU for short) that improves the issue and to evaluate the effectiveness of ADU for DSATUR and RLF on DIMACS benchmark graphs as well as random graphs having a wide range of sizes and densities. Experimental results show that the construction algorithms with ADU are faster than the conventional algorithms for many graphs and the ADU method yields significant speed-ups relative to the conventional algorithms, especially in the case of large graphs with higher edge density.

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  • Ningkang CHEN, Ping WEI, Lin GAO, Huaguo ZHANG, Hongshu LIAO
    Article type: PAPER
    Article ID: 2021EAP1111
    Published: 2022
    Advance online publication: March 14, 2022
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    This paper aims to design multiple-input multiple-output (MIMO) radar receiving weights and transmitting waveforms, in order to obtain better spatial filtering performance and enhance the robustness in the case of signal-dependent interference and jointly inaccurate estimated angles of target and interference. Generally, an alternate iterative optimization algorithm is proposed for the joint design problem. Specifically, the receiving weights are designed by the generalized eigenvalue decomposition of the matrix which contains the estimated information of the target and interference. As the cost function of the transmitting waveform design is fractional, the fractional optimization problem is first converted into a secondary optimization problem. Based on the proposed algorithm, a closed-form solution of the waveform is given using the alternating projection. At the analysis stage, in the presence of estimated errors under the environment of signal-dependent interference, a robust signal-to-interference and noise ratio (SINR) performance is obtained using a small amount of calculation with an iterative procedure. Numerical examples verify the effectiveness of the performances of the designed waveform in terms of the SINR, beampattern and pulse compression.

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  • Luozhong GONG, Shangzhao LI
    Article type: PAPER
    Article ID: 2021EAP1146
    Published: 2022
    Advance online publication: March 10, 2022
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    The r-th nonlinearity of Boolean functions is an important cryptographic criterion associated with higher order linearity attacks on stream and block ciphers. In this paper, we tighten the lower bound of the second-order nonlinearity of a class of Boolean function over finite field F2n, fλ(x) = Trxd), where λ ∈ F*2r , d = 22r + 2r + 1 and n = 7r. This bound is much better than the lower bound of Iwata-Kurosawa.

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  • Rong CHENG, Yu ZHOU, Xinfeng DONG, Xiaoni DU
    Article type: PAPER
    Article ID: 2022EAP1010
    Published: 2022
    Advance online publication: March 10, 2022
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    S-box is one of the core components of symmetric cryptographic algorithms, but differential distribution table (DDT) is an important tool to research some properties of S-boxes to resist differential attacks. In this paper, we give a relationship between the sum-of-squares of DDT and the sum-of-squares indicator of (n,m)-functions based on the autocorrelation coefficients. We also get the upper and lower bounds on the sum-of-squares of DDT of balanced (n,m)-functions, and prove that the sum-of-squares of DDT of (n,m)-functions is affine invariant under affine affine equivalent. Furthermore, we obtain a relationship between the sum-of- squares of DDT and the signal-to-noise ratio of (n,m)-functions. In addition, we calculate the distributions of the sum-of-squares of DDT for all 3-bit S-boxes, the 4-bit optimal S-boxes and all 302 balanced S-boxes (up to affine equivalence), data experiments verify our results.

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  • Hikaru TSUCHIDA, Takashi NISHIDE
    Article type: PAPER
    Article ID: 2021DMP0016
    Published: 2022
    Advance online publication: March 09, 2022
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    Multiparty computation (MPC) is a cryptographic method that enables a set of parties to compute an arbitrary joint function of the private inputs of all parties and does not reveal any information other than the output. MPC based on a secret sharing scheme (SS-MPC) and garbled circuit (GC) is known as the most common MPC schemes. Another cryptographic method, homomorphic encryption (HE), computes an arbitrary function represented as a circuit by using ciphertexts without decrypting them. These technologies are in a trade-off relationship for the communication/round complexities, and the computation cost.

    The private decision tree evaluation (PDTE) is one of the key applications of these technologies. There exist several constant-round PDTE protocols based on GC, HE, or the hybrid schemes that are secure even if a malicious adversary who can deviate from protocol specifications corrupts some parties. There also exist other protocols based only on SS-MPC that are secure only if a semi-honest adversary who follows the protocol specification corrupts some parties. However, to the best of our knowledge, there are currently no constant-round PDTE protocols based only on SS-MPC that are secure against a malicious adversary.

    In this work, we propose a constant-round four-party PDTE protocol that achieves malicious security. Our protocol provides the PDTE securely and efficiently even when the communication environment has a large latency.

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  • Hiroshi ETO, Takehiro ITO, Zhilong LIU, Eiji MIYANO
    Article type: PAPER
    Article ID: 2021DMP0017
    Published: 2022
    Advance online publication: March 09, 2022
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    This paper studies generalized variants of the maximum independent set problem, called the Maximum Distance-d Independent Set problem (MaxDdIS for short). For an integer d ≥ 2, a distance-d independent set of an unweighted graph G = (V, E) is a subset SV of vertices such that for any pair of vertices u, vS, the number of edges in any path between u and v is at least d in G. Given an unweighted graph G, the goal of MaxDdIS is to find a maximum-cardinality distance-d independent set of G. In this paper, we analyze the (in)approximability of the problem on r-regular graphs (r ≥ 3) and planar graphs, as follows: (1) For every fixed integers d ≥ 3 and r ≥ 3, MaxDdIS on r-regular graphs is APX-hard. (2) We design polynomial-time O(rd-1)-approximation and O(rd-2/d)-approximation algorithms for MaxDdIS on r-regular graphs. (3) We sharpen the above O(rd-2/d)-approximation algorithms when restricted to d = r = 3, and give a polynomial-time 2-approximation algorithm for MaxD3IS on cubic graphs. (4) Finally, we show that MaxDdIS admits a polynomial-time approximation scheme (PTAS) for planar graphs.

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  • Gengxin NING, Yushen LIN, Shenjie JIANG, Jun ZHANG
    Article type: PAPER
    Article ID: 2021EAP1152
    Published: 2022
    Advance online publication: March 09, 2022
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    The performance of conventional direction of arrival (DOA) methods is susceptible to the uncertainty of acoustic velocity in the underwater environment. To solve this problem, an underwater DOA estimation method with L-shaped array for wide-band signals under unknown acoustic velocity is proposed in this paper. The proposed method refers to the idea of incoherent signal subspace method and Root-MUSIC to obtain two sets of average roots corresponding to the subarray of the L-shaped array. And the geometric relationship between two vertical linear arrays is employed to derive the expression of DOA estimation with respect to the two average roots. The acoustic velocity variable in the DOA estimation expression can be eliminated in the proposed method. The simulation results demonstrate that the proposed method is more accurate and robust than other methods in an unknown acoustic velocity environment.

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  • Tetsuya ARAKI, Hiroyuki MIYATA, Shin-ichi NAKANO
    Article type: PAPER
    Article ID: 2021DMP0004
    Published: 2022
    Advance online publication: March 08, 2022
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    Given a set of n disjoint intervals on a line and an integer k, we want to find k points in the intervals so that the minimum pairwise distance of the k points is maximized. Intuitively, given a set of n disjoint time intervals on a timeline, each of which is a time span we are allowed to check something, and an integer k, which is the number of times we will check something, we plan k checking times so that the checks occur at equal time intervals as much as possible, that is, we want to maximize the minimum time interval between the k checking times. We call the problem the k-dispersion problem on intervals. If we need to choose exactly one point in each interval, so k = n, and the disjoint intervals are given in the sorted order on the line, then two O(n) time algorithms to solve the problem are known.

    In this paper we give the first O(n) time algorithm to solve the problem for any constant k. Our algorithm works even if the disjoint intervals are given in any (not sorted) order. If the disjoint intervals are given in the sorted order on the line, then, by slightly modifying the algorithm, one can solve the problem in O(log n) time. This is the first sublinear time algorithm to solve the problem. Also we show some results on the k-dispersion problem on disks, including an FPTAS.

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  • Hiroshi FUJIWARA, Kanaho HANJI, Hiroaki YAMAMOTO
    Article type: PAPER
    Article ID: 2021DMP0013
    Published: 2022
    Advance online publication: March 08, 2022
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    In the online removable knapsack problem, a sequence of items, each labeled with its value and its size, is given one by one. At each arrival of an item, a player has to decide whether to put it into a knapsack or to discard it. The player is also allowed to discard some of the items that are already in the knapsack. The objective is to maximize the total value of the knapsack. Iwama and Taketomi gave an optimal algorithm for the case where the value of each item is equal to its size. In this paper we consider a case with an additional constraint that the capacity of the knapsack is a positive integer N and that the sizes of items are all integral. For each positive integer N, we design an algorithm and prove its optimality. It is revealed that the competitive ratio is not monotonic with respect to N.

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  • Tomu MAKITA, Atsuki NAGAO, Tatsuki OKADA, Kazuhisa SETO, Junichi TERUY ...
    Article type: PAPER
    Article ID: 2021EAP1120
    Published: 2022
    Advance online publication: March 08, 2022
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    A branching program is a well-studied model of computation and a representation for Boolean functions. It is a directed acyclic graph with a unique root node, some accepting nodes, and some rejecting nodes. Except for the accepting and rejecting nodes, each node has a label with a variable and each outgoing edge of the node has a label with a 0/1 assignment of the variable. The satisfiability problem for branching programs is, given a branching program with n variables and m nodes, to determine if there exists some assignment that activates a consistent path from the root to an accepting node. The width of a branching program is the maximum number of nodes at any level. The satisfiability problem for width-2 branching programs is known to be NP-complete. In this paper, we present a satisfiability algorithm for width-2 branching programs with n variables and cn nodes, and show that its running time is poly(n) ・ 2(1-μ(c))n, where μ(c) = 1/2O(c log c). Our algorithm consists of two phases. First, we transform a given width-2 branching program to a set of some structured formulas that consist of AND and Exclusive-OR gates. Then, we check the satisfiability of these formulas by a greedy restriction method depending on the frequency of the occurrence of variables.

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  • Asahi TAKAOKA
    Article type: PAPER
    Article ID: 2021DMP0001
    Published: 2022
    Advance online publication: March 07, 2022
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    We studied whether a statement similar to the Ghouila-Houri's theorem might hold for alternating orientations of cocomparability graphs. In this paper, we give the negative answer. We prove that it is NP-complete to decide whether a cocomparability graph has an orientation that is alternating and acyclic. Hence, cocomparability graphs with an acyclic alternating orientation form a proper subclass of alternately orientable cocomparability graphs. We also provide a separating example, that is, an alternately orientable cocomparability graph such that no alternating orientation is acyclic.

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  • Binhao HE, Meiting XUE, Shubiao LIU, Feng YU, Weijie CHEN
    Article type: LETTER
    Article ID: 2021EAL2103
    Published: 2022
    Advance online publication: March 02, 2022
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    The top-K sorting is a variant of sorting used heavily in applications such as database management systems. Recently, the use of field programmable gate arrays (FPGAs) to accelerate sorting operation has attracted the interest of researchers. However, existing hardware top-K sorting algorithms are either resource-intensive or of low throughput. In this paper, we present a resource-efficient top-K sorting architecture that is composed of L cascading sorting units, and each sorting unit is composed of P sorting cells. K = PL largest elements are produced when a variable length input sequence is processed. This architecture can operate at a high frequency while consuming fewer resources. The experimental results show that our architecture achieved a maximum 1.2x throughput-to-resource improvement compared to previous studies.

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  • Chuzo IWAMOTO, Tatsuya IDE
    Article type: PAPER
    Article ID: 2021DMP0006
    Published: 2022
    Advance online publication: March 01, 2022
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    Moon-or-Sun, Nagareru, and Nurimeizu are Nikoli's pencil puzzles. We study the computational complexity of Moon-or-Sun, Nagareru, and Nurimeizu puzzles. It is shown that deciding whether a given instance of each puzzle has a solution is NP-complete.

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  • Takahiro Ogura, Haiyan Wang, Qiyao Wang, Atsuki Kiuchi, Chetan Gupta, ...
    Article type: PAPER
    Article ID: 2021EAP1110
    Published: 2022
    Advance online publication: February 25, 2022
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    We propose a penalty-based and constraint Bayesian optimization methods with an agent-based supply-chain (SC) simulator as a new Monte Carlo optimization approach for multi-echelon inventory management to improve key performance indicators such as inventory cost and sales opportunity loss. First, we formulate the multi-echelon inventory problem and introduce an agent-based SC simulator architecture for the optimization. Second, we define the optimization framework for the formulation. Finally, we discuss the evaluation of the effectiveness of the proposed methods by benchmarking it against the most commonly used genetic algorithm (GA) in simulation-based inventory optimization. Our results indicate that the constraint Bayesian optimization can minimize SC inventory cost with lower sales opportunity loss rates and converge to the optimal solution 22 times faster than GA in the best case.

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  • Norisato SUGA, Ryohei SASAKI
    Article type: LETTER
    Article ID: 2021EAL2085
    Published: 2022
    Advance online publication: February 22, 2022
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    In this letter, a ray tracing (RT) acceleration method based on rank minimization is proposed. RT is a general tool used to simulate wireless communication environments. However, the simulation is time consuming because of the large number of ray calculations. This letter focuses on radio map interpolation as an acceleration approach. In the conventional methods cannot appropriately estimate short-span variation caused by multipath fading. To overcome the shortage of the conventional methods, we adopt rank minimization based interpolation. A computational simulation using commercial RT software revealed that the interpolation accuracy of the proposed method was higher than those of other radio map interpolation methods and that RT simulation can be accelerated approximate five times faster with the missing rate of 0.8.

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  • Shi Ping CAI, Zhi HU, Chang An ZHAO
    Article type: LETTER
    Article ID: 2021EAL2086
    Published: 2022
    Advance online publication: February 22, 2022
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    The final exponentiation affects the efficiency of pairing computations especially on pairing-friendly curves with high embedding degree. We propose an efficient method for computing the hard part of the final exponentiation on the KSS18 curve at the 192-bit security level. Implementations indicate that the computation of the final exponentiation is 8.74% faster than the previously fastest result.

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  • Jaeseong JEONG, Chang HEON KIM, Namhun KOO, Soonhak KWON, Sumin LEE
    Article type: PAPER
    Article ID: 2021EAP1167
    Published: 2022
    Advance online publication: February 22, 2022
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    The differential uniformity, the boomerang uniformity, and the extended Walsh spectrum etc are important parameters to evaluate the security of S(substitution)-box. In this paper, we introduce efficient formulas to compute these cryptographic parameters of permutation polynomials of the form xrh(x(2n-1)/d) over a finite field of q = 2n elements, where r is a positive integer and d is a positive divisor of 2n -1. The computational cost of those formulas is proportional to d. We investigate differentially 4-uniform permutation polynomials of the form xrh(x(2n-1)/3) and compute the boomerang spectrum and the extended Walsh spectrum of them using the suggested formulas when 6 ≤ n ≤ 12 is even, where d = 3 is the smallest nontrivial d for even n. We also investigate the differential uniformity of some permutation polynomials introduced in some recent papers for the case d = 2n/2 + 1.

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  • Yusuke MATSUOKA, Hiroyuki KAWASAKI
    Article type: PAPER
    Article ID: 2021EAP1117
    Published: 2022
    Advance online publication: February 21, 2022
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    This paper proposes and characterizes an A/D converter (ADC) based on a spiking neuron model with a rectangular threshold signal. The neuron repeats an integrate-and-fire process and outputs a superstable spike sequence. The dynamics of this system are closely related to those of rate-encoding ADCs. We propose an ADC system based on the spiking neuron model. We derive a theoretical parameter region in a limited time interval of the digital output sequence. We analyze the conversion characteristics in this region and verify that they retain the monotonic increase and rate encoding of an ADC.

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