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[Keyword] IT(16991hit)

461-480hit(16991hit)

  • Construction of Odd-Variable Strictly Almost Optimal Resilient Boolean Functions with Higher Resiliency Order via Modifying High-Meets-Low Technique

    Hui GE  Zepeng ZHUO  Xiaoni DU  

     
    LETTER-Cryptography and Information Security

      Pubricized:
    2022/07/12
      Vol:
    E106-A No:1
      Page(s):
    73-77

    Construction of resilient Boolean functions in odd variables having strictly almost optimal (SAO) nonlinearity appears to be a rather difficult task in stream cipher and coding theory. In this paper, based on the modified High-Meets-Low technique, a general construction to obtain odd-variable SAO resilient Boolean functions without directly using PW functions or KY functions is presented. It is shown that the new class of functions possess higher resiliency order than the known functions while keeping higher SAO nonlinearity, and in addition the resiliency order increases rapidly with the variable number n.

  • Global Asymptotic Stabilization of Feedforward Systems with an Uncertain Delay in the Input by Event-Triggered Control

    Ho-Lim CHOI  

     
    LETTER-Systems and Control

      Pubricized:
    2022/06/28
      Vol:
    E106-A No:1
      Page(s):
    69-72

    In this letter, we consider a global stabilization problem for a class of feedforward systems by an event-triggered control. This is an extended work of [10] in a way that there are uncertain feedforward nonlinearity and time-varying input delay in the system. First, we show that the considered system is globally asymptotically stabilized by a proposed event-triggered controller with a gain-scaling factor. Then, we also show that the interexecution times can be enlarged by adjusting a gain-scaling factor. A simulation example is given for illustration.

  • Constructions of Optimal Single-Parity Locally Repairable Codes with Multiple Repair Sets

    Yang DING  Qingye LI  Yuting QIU  

     
    LETTER-Coding Theory

      Pubricized:
    2022/08/03
      Vol:
    E106-A No:1
      Page(s):
    78-82

    Locally repairable codes have attracted lots of interest in Distributed Storage Systems. If a symbol of a code can be repaired respectively by t disjoint groups of other symbols, each groups has size at most r, we say that the code symbol has (r, t)-locality. In this paper, we employ parity-check matrix to construct information single-parity (r, t)-locality LRCs. All our codes attain the Singleton-like bound of LRCs where each repair group contains a single parity symbol and thus are optimal.

  • A Hybrid Routing Algorithm for V2V Communication in VANETs Based on Blocked Q-Learning

    Xiang BI  Huang HUANG  Benhong ZHANG  Xing WEI  

     
    PAPER-Network

      Pubricized:
    2022/05/31
      Vol:
    E106-B No:1
      Page(s):
    1-17

    It is of great significance to design a stable and reliable routing protocol for Vehicular Ad Hoc Networks (VANETs) that adopt Vehicle to Vehicle (V2V) communications in the face of frequent network topology changes. In this paper, we propose a hybrid routing algorithm, RCRIQ, based on improved Q-learning. For an established cluster structure, the cluster head is used to select the gateway vehicle according to the gateway utility function to expand the communication range of the cluster further. During the link construction stage, an improved Q-learning algorithm is adopted. The corresponding neighbor vehicle is chosen according to the maximum Q value in the neighbor list. The heuristic algorithm selects the next-hop by the maximum heuristic function value when selecting the next-hop neighbor node. The above two strategies are comprehensively evaluated to determine the next hop. This way ensures the optimal selection of the next hop in terms of reachability and other communication parameters. Simulation experiments show that the algorithm proposed in this article has better performance in terms of routing stability, throughput, and communication delay in the urban traffic scene.

  • Entropy Regularized Unsupervised Clustering Based on Maximum Correntropy Criterion and Adaptive Neighbors

    Xinyu LI  Hui FAN  Jinglei LIU  

     
    LETTER-Artificial Intelligence, Data Mining

      Pubricized:
    2022/10/06
      Vol:
    E106-D No:1
      Page(s):
    82-85

    Constructing accurate similarity graph is an important process in graph-based clustering. However, traditional methods have three drawbacks, such as the inaccuracy of the similarity graph, the vulnerability to noise and outliers, and the need for additional discretization process. In order to eliminate these limitations, an entropy regularized unsupervised clustering based on maximum correntropy criterion and adaptive neighbors (ERMCC) is proposed. 1) Combining information entropy and adaptive neighbors to solve the trivial similarity distributions. And we introduce l0-norm and spectral embedding to construct similarity graph with sparsity and strong segmentation ability. 2) Reducing the negative impact of non-Gaussian noise by reconstructing the error using correntropy. 3) The prediction label vector is directly obtained by calculating the sparse strongly connected components of the similarity graph Z, which avoids additional discretization process. Experiments are conducted on six typical datasets and the results showed the effectiveness of the method.

  • Robust Optimization Model for Primary and Backup Capacity Allocations against Multiple Physical Machine Failures under Uncertain Demands in Cloud

    Mitsuki ITO  Fujun HE  Kento YOKOUCHI  Eiji OKI  

     
    PAPER-Network

      Pubricized:
    2022/07/05
      Vol:
    E106-B No:1
      Page(s):
    18-34

    This paper proposes a robust optimization model for probabilistic protection under uncertain capacity demands to minimize the total required capacity against multiple simultaneous failures of physical machines. The proposed model determines both primary and backup virtual machine allocations simultaneously under the probabilistic protection guarantee. To express the uncertainty of capacity demands, we introduce an uncertainty set that considers the upper bound of the total demand and the upper and lower bounds of each demand. The robust optimization technique is applied to the optimization model to deal with two uncertainties: failure event and capacity demand. With this technique, the model is formulated as a mixed integer linear programming (MILP) problem. To solve larger sized problems, a simulated annealing (SA) heuristic is introduced. In SA, we obtain the capacity demands by solving maximum flow problems. Numerical results show that our proposed model reduces the total required capacity compared with the conventional model by determining both primary and backup virtual machine allocations simultaneously. We also compare the results of MILP, SA, and a baseline greedy algorithm. For a larger sized problem, we obtain approximate solutions in a practical time by using SA and the greedy algorithm.

  • A Low Insertion Loss Wideband Bonding-Wire Based Interconnection for 400 Gbps PAM4 Transceivers

    Xiangyu MENG  Yecong LI  Zhiyi YU  

     
    PAPER-Electronic Components

      Pubricized:
    2022/06/23
      Vol:
    E106-C No:1
      Page(s):
    14-19

    This paper proposes a design of high-speed interconnection between optical modules and electrical modules via bonding-wires and coplanar waveguide transmission lines on printed circuit boards for 400 Gbps 4-channel optical communication systems. In order to broaden the interconnection bandwidth, interdigitated capacitors were integrated with GSG pads on chip for the first time. Simulation results indicate the reflection coefficient is below -10 dB from DC to 53 GHz and the insertion loss is below 1 dB from DC to 45 GHz. Both indicators show that the proposed interconnection structure can effectively satisfy the communication bandwidth requirements of 100-Gbps or even higher data-rate PAM4 signals.

  • A Novel e-Cash Payment System with Divisibility Based on Proxy Blind Signature in Web of Things

    Iuon-Chang LIN  Chin-Chen CHANG  Hsiao-Chi CHIANG  

     
    PAPER-Information Network

      Pubricized:
    2022/09/02
      Vol:
    E105-D No:12
      Page(s):
    2092-2103

    The prosperous Internet communication technologies have led to e-commerce in mobile computing and made Web of Things become popular. Electronic payment is the most important part of e-commerce, so many electronic payment schemes have been proposed. However, most of proposed schemes cannot give change. Based on proxy blind signatures, an e-cash payment system is proposed in this paper to solve this problem. This system can not only provide change divisibility through Web of Things, but also provide anonymity, verifiability, unforgeability and double-spending owner track.

  • Ground Test of Radio Frequency Compatibility for Cn-Band Satellite Navigation and Microwave Landing System Open Access

    Ruihua LIU  Yin LI  Ling ZOU  Yude NI  

     
    PAPER-Satellite Communications

      Pubricized:
    2022/05/19
      Vol:
    E105-B No:12
      Page(s):
    1580-1588

    Testing the radio frequency compatibility between Cn-band Satellite Navigation and Microwave Landing System (MLS) has included establishing a specific interference model and reporting the effect of such interference. This paper considers two interference scenarios according to the interfered system. By calculating the Power Flux Density (PFD) values, the interference for Cn-band satellite navigation downlink signal from several visible space stations on MLS service is evaluated. Simulation analysis of the interference for MLS DPSK-data word signal and scanning signal on Cn-band satellite navigation signal is based on the Spectral Separation Coefficient (SSC) and equivalent Carrier-to-Noise Ratio methodologies. Ground tests at a particular military airfield equipped with MLS ground stations were successfully carried out, and some measured data verified the theoretical and numerical results. This study will certainly benefit the design of Cn-band satellite navigation signals and guide the interoperability and compatibility research of Cn-band satellite navigation and MLS.

  • Accurate Parallel Flow Monitoring for Loss Measurements

    Kohei WATABE  Norinosuke MURAI  Shintaro HIRAKAWA  Kenji NAKAGAWA  

     
    PAPER-Network Management/Operation

      Pubricized:
    2022/06/29
      Vol:
    E105-B No:12
      Page(s):
    1530-1539

    End-to-end loss and delay are both fundamental metrics in network performance evaluation, and accurate measurements for these end-to-end metrics are one of the keys to keeping delay/loss-sensitive applications (e.g., audio/video conferencing, IP telephony, or telesurgery) comfortable on networks. In our previous work [1], we proposed a parallel flow monitoring method that can provide accurate active measurements of end-to-end delay. In this method, delay samples of a target flow increase by utilizing the observation results of other flows sharing the source/destination with the target flow. In this paper, to improve accuracy of loss measurements, we propose a loss measurement method by extending our delay measurement method. Additionally, we improve the loss measurement method so that it enables to fully utilize information of all flows including flows with different source and destination. We evaluate the proposed method through theoretical and simulation analyses. The evaluations show that the accuracy of the proposed method is bounded by theoretical upper/lower bounds, and it is confirmed that it reduces the error of loss rate estimations by 57.5% on average.

  • The Implementation of a Hybrid Router and Dynamic Switching Algorithm on a Multi-FPGA System

    Tomoki SHIMIZU  Kohei ITO  Kensuke IIZUKA  Kazuei HIRONAKA  Hideharu AMANO  

     
    PAPER

      Pubricized:
    2022/06/30
      Vol:
    E105-D No:12
      Page(s):
    2008-2018

    The multi-FPGA system known as, the Flow-in-Cloud (FiC) system, is composed of mid-range FPGAs that are directly interconnected by high-speed serial links. FiC is currently being developed as a server for multi-access edge computing (MEC), which is one of the core technologies of 5G. Because the applications of MEC are sometimes timing-critical, a static time division multiplexing (STDM) network has been used on FiC. However, the STDM network exhibits the disadvantage of decreasing link utilization, especially under light traffic. To solve this problem, we propose a hybrid router that combines packet switching for low-priority communication and STDM for high-priority communication. In our hybrid network, the packet switching uses slots that are unused by the STDM; therefore, best-effort communication by packet switching and QoS guarantee communication by the STDM can be used simultaneously. Furthermore, to improve each link utilization under a low network traffic load, we propose a dynamic communication switching algorithm. In our algorithm, each router monitors the network load metrics, and according to the metrics, timing-critical tasks select the STDM according to the metrics only when congestion occurs. This can achieve both QoS guarantee and efficient utilization of each link with a small resource overhead. In our evaluation, the dynamic algorithm was up to 24.6% faster on the execution time with a high network load compared to the packet switching on a real multi-FPGA system with 24 boards.

  • Emitter Tracking via Direct Target Motion Analysis

    Yiqi CHEN  Ping WEI  Gaiyou LI  Huaguo ZHANG  Hongshu LIAO  

     
    PAPER-Digital Signal Processing

      Pubricized:
    2022/06/08
      Vol:
    E105-A No:12
      Page(s):
    1522-1536

    This paper considers tracking of a non-cooperative emitter based on a single sensor. To this end, the direct target motion analysis (DTMA) approach, where the target state is straightforwardly achieved from the received signal, is exploited. In order to achieve observability, the sensor has to perform a maneuver relative to the emitter. By suitably building an approximated likelihood function, the unscented Kalman filter (UKF), which is able to work under high nonlinearity of the measurement model, is adopted to recursively estimate the target state. Besides, the posterior Cramér-Rao bound (PCRB) of DTMA, which can be used as performance benchmark, is also achieved. The effectiveness of proposed method is verified via simulation experiments.

  • Random Access Identifier-Linked Receiver Beamforming with Transmitter Filtering in TDD-Based Random Access Open Access

    Yuto MUROKI  Yotaro MURAKAMI  Yoshihisa KISHIYAMA  Kenichi HIGUCHI  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2022/05/25
      Vol:
    E105-B No:12
      Page(s):
    1548-1558

    This paper proposes a novel random access identifier (RAID)-linked receiver beamforming method for time division duplex (TDD)-based random access. When the number of receiver antennas at the base station is large in a massive multiple-input multiple-output (MIMO) scenario, the channel estimation accuracy per receiver antenna at the base station receiver is degraded due to the limited received signal power per antenna from the user terminal. This results in degradation in the receiver beamforming (BF) or antenna diversity combining and active RAID detection. The purpose of the proposed method is to achieve accurate active RAID detection and channel estimation with a reasonable level of computational complexity at the base station receiver. In the proposed method, a unique receiver BF vector applied at the base station is linked to each of the M RAIDs prepared by the system. The user terminal selects an appropriate pair comprising a receiver BF vector and a RAID in advance based on the channel estimation results in the downlink assuming channel reciprocity in a TDD system. Therefore, per-receiver antenna channel estimation for receiver BF is not necessary in the proposed method. Furthermore, in order to utilize fully the knowledge of the channel at the user transmitter, we propose applying transmitter filtering (TF) to the proposed method for effective channel shortening in order to increase the orthogonal preambles for active RAID detection and channel estimation prepared for each RAID. Computer simulation results show that the proposed method greatly improves the accuracy of active RAID detection and channel estimation. This results in lower error rates than that for the conventional method performing channel estimation at each antenna in a massive MIMO environment.

  • A Novel Fixed-Point Conversion Methodology For Digital Signal Processing Systems

    Phuong T.K. DINH  Linh T.T. DINH  Tung T. TRAN  Lam S. PHAM  Han Le DUC  Chi P. HOANG  Minh D. NGUYEN  

     
    PAPER-Digital Signal Processing

      Pubricized:
    2022/06/17
      Vol:
    E105-A No:12
      Page(s):
    1537-1550

    Recently, most signal processing algorithms have been developed with floating-point arithmetic, while the fixed-point arithmetic is more popular with most commercial devices and low-power real-time applications which are implemented on embedded/ASIC/FPGA systems. Therefore, the optimal Floating-point to Fixed-point Conversion (FFC) methodology is a promising solution. In this paper, we propose the FFC consisting of signal grouping technique and simulation-based word length optimization. In order to evaluate the performance of the proposed technique, simulations are carried out and hardware co-simulation on Field Programmable Gate Arrays (FPGAs) platform have been applied to complex Digital Signal Processing (DSP) algorithms: Linear Time Invariant (LTI) systems, multi-mode Fast Fourier Transform (FFT) circuit for IEEE 802.11 ax WLAN Devices and the calibration algorithm of gain and clock skew in Time-Interleaved ADC (TI-ADC) using Adaptive Noise Canceller (ANC). The results show that the proposed technique can reduce the hardware cost about 30% while being able to maintain its speed and reliability.

  • Functional Connectivity Estimation by Phase Synchronization and Information Flow Approaches in Coupled Chaotic Dynamical Systems

    Mayuna TOBE  Sou NOBUKAWA  

     
    PAPER-Neural Networks and Bioengineering

      Pubricized:
    2022/06/03
      Vol:
    E105-A No:12
      Page(s):
    1604-1611

    Various types of indices for estimating functional connectivity have been developed over the years that have introduced effective approaches to discovering complex neural networks in the brain. Two significant examples are the phase lag index (PLI) and transfer entropy (TE). Both indices have specific benefits; PLI, defined using instantaneous phase dynamics, achieves high spatiotemporal resolution, whereas transfer entropy (TE), defined using information flow, reveals directed network characteristics. However, the relationship between these indices remains unclear. In this study, we hypothesize that there exists a complementary relationship between PLI and TE to discover new aspects of functional connectivity that cannot be detected using either PLI or TE. To validate this hypothesis, we evaluated the synchronization in a coupled Rössler model using PLI and TE. Consequently, we proved the existence of non-linear relationships between PLI and TE. Both indexes exhibit a specific trend that demonstrates a linear relationship in the region of small TE values. However, above a specific TE value, PLI converges to a constant irrespective of the TE value. In addition to this relational difference in synchronization, there is another characteristic difference between these indices. Moreover, by virtue of its finer temporal resolution, PLI can capture the temporal variability of the degree of synchronization, which is called dynamical functional connectivity. TE lacks this temporal characteristic because it requires a longer evaluation period in this estimation process. Therefore, combining the advantages of both indices might contribute to revealing complex spatiotemporal functional connectivity in brain activity.

  • Vehicle Re-Identification Based on Quadratic Split Architecture and Auxiliary Information Embedding

    Tongwei LU  Hao ZHANG  Feng MIN  Shihai JIA  

     
    LETTER-Image

      Pubricized:
    2022/05/24
      Vol:
    E105-A No:12
      Page(s):
    1621-1625

    Convolutional neural network (CNN) based vehicle re-identificatioin (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.

  • 920MHz Path Loss Prediction Formula Based on FDTD Method for IoT Wireless System close to Ceiling with Concrete Beam

    Naotake YAMAMOTO  Taichi SASAKI  Atsushi YAMAMOTO  Tetsuya HISHIKAWA  Kentaro SAITO  Jun-ichi TAKADA  Toshiyuki MAEYAMA  

     
    PAPER-Antennas and Propagation

      Pubricized:
    2022/06/22
      Vol:
    E105-B No:12
      Page(s):
    1540-1547

    A path loss prediction formula for IoT (Internet of Things) wireless communication close to ceiling beams in the 920MHz band is presented. In first step of our investigation, we conduct simulations using the FDTD (Finite Difference Time Domain) method and propagation tests close to a beam on the ceiling of a concrete building. In the second step, we derive a path loss prediction formula from the simulation results by using the FDTD method, by dividing into three regions of LoS (line-of-sight) situation, situation in the vicinity of the beam, and NLoS (non-line-of-sight) situation, depending on the positional relationship between the beam and transmitter (Tx) and receiver (Rx) antennas. For each condition, the prediction formula is expressed by a relatively simple form as a function of height of the antennas with respect to the beam bottom. Thus, the prediction formula is very useful for the wireless site planning for the IoT wireless devices set close to concrete beam ceiling.

  • Accurate Doppler Velocity Estimation by Iterative WKD Algorithm for Pulse-Doppler Radar

    Takumi HAYASHI  Takeru ANDO  Shouhei KIDERA  

     
    PAPER-Sensing

      Pubricized:
    2022/06/29
      Vol:
    E105-B No:12
      Page(s):
    1600-1613

    In this study, we propose an accurate range-Doppler analysis algorithm for moving multiple objects in a short range using microwave (including millimeter wave) radars. As a promising Doppler analysis for the above model, we previously proposed a weighted kernel density (WKD) estimator algorithm, which overcomes several disadvantages in coherent integration based methods, such as a trade-off between temporal and frequency resolutions. However, in handling multiple objects like human body, it is difficult to maintain the accuracy of the Doppler velocity estimation, because there are multiple responses from multiple parts of object, like human body, incurring inaccuracies in range or Doppler velocity estimation. To address this issue, we propose an iterative algorithm by exploiting an output of the WKD algorithm. Three-dimensional numerical analysis, assuming a human body model in motion, and experimental tests demonstrate that the proposed algorithm provides more accurate, high-resolution range-Doppler velocity profiles than the original WKD algorithm, without increasing computational complexity. Particularly, the simulation results show that the cumulative probabilities of range errors within 10mm, and Doppler velocity error within 0.1m/s are enhanced from 34% (by the former method) to 63% (by the proposed method).

  • Design for Operation in Two Frequency Bands by Division of the Coupled Region in a Waveguide 2-Plane Coupler

    Shihao CHEN  Takashi TOMURA  Jiro HIROKAWA  Kota ITO  Mizuki SUGA  Yushi SHIRATO  Daisei UCHIDA  Naoki KITA  

     
    PAPER-Electromagnetic Theory

      Pubricized:
    2022/05/23
      Vol:
    E105-C No:12
      Page(s):
    729-739

    A waveguide 2-plane hybrid coupler with two operating bands is proposed. The cross-sectional shape of the coupled region inside the proposed coupler is designed with a two-dimensional arbitrary geometry sorting method. Simulations of the proposed hybrid coupler has a fractional bandwidth (FBW) of 2.17% at the center of 24.99GHz, and at the center of 28.28GHz an FBW of 6.13%. The proposed coupler is analyzed by the mode-matching finite-element hybrid method, and the final result is obtained using a genetic algorithm. The analyzed result of the coupling for the main modes in the coupled region is presented. The design result is confirmed by measurements.

  • Model-Agnostic Multi-Domain Learning with Domain-Specific Adapters for Action Recognition

    Kazuki OMI  Jun KIMATA  Toru TAMAKI  

     
    PAPER-Image Recognition, Computer Vision

      Pubricized:
    2022/09/15
      Vol:
    E105-D No:12
      Page(s):
    2119-2126

    In this paper, we propose a multi-domain learning model for action recognition. The proposed method inserts domain-specific adapters between layers of domain-independent layers of a backbone network. Unlike a multi-head network that switches classification heads only, our model switches not only the heads, but also the adapters for facilitating to learn feature representations universal to multiple domains. Unlike prior works, the proposed method is model-agnostic and doesn't assume model structures unlike prior works. Experimental results on three popular action recognition datasets (HMDB51, UCF101, and Kinetics-400) demonstrate that the proposed method is more effective than a multi-head architecture and more efficient than separately training models for each domain.

461-480hit(16991hit)