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  • The PRF Security of Compression-Function-Based MAC Functions in the Multi-User Setting Open Access

    Shoichi HIROSE  

     
    PAPER-Cryptography and Information Security

      Vol:
    E102-A No:1
      Page(s):
    270-277

    A compression-function-based MAC function called FMAC was presented as well as a vector-input PRF called vFMAC in 2016. They were proven to be secure PRFs on the assumption that their compression function is a secure PRF against related-key attacks with respect to their non-cryptographic permutations in the single user setting. In this paper, it is shown that both FMAC and vFMAC are also secure PRFs in the multi-user setting on the same assumption as in the single user setting. These results imply that their security in the multi-user setting does not degrade with the number of the users and is as good as in the single user setting.

  • Center Clamp for Wide Input Voltage Range Applications

    Alagu DHEERAJ  Rajini VEERARAGHAVALU  

     
    PAPER-Electronic Circuits

      Vol:
    E102-C No:1
      Page(s):
    77-82

    Forward converter is most suitable for low voltage and high current applications such as LEDs, battery chargers, EHV etc. The active clamp transformer reset technique offers many advantages over conventional single-ended reset techniques, including lower voltage stress on the main switch, the ability to switch at zero voltage and duty cycle operation above 50 percent. Several papers have compared the functional merits of the active clamp over the more extensively used RCD clamp, third winding and resonant reset techniques. This paper discusses about a center clamp technique with one common core reset circuit making it suitable for wide input voltage applications with extended duty cycle.

  • Unrestricted-Rate Parallel Random Input-Output Codes for Multilevel Flash Memory

    Shan LU  Hiroshi KAMABE  Jun CHENG  Akira YAMAWAKI  

     
    PAPER-Coding theory for storage

      Vol:
    E101-A No:12
      Page(s):
    2135-2140

    Recent years have seen increasing efforts to improve the input/output performance of multilevel flash memory. In this regard, we propose a coding scheme for two-page unrestricted-rate parallel random input-output (P-RIO) code, which enables different code rates to be used for each page of multilevel memory. On the second page, the set of cell-state vectors for each message consists of two complementary vectors with length n. There are a total of 2n-1 sets that are disjoint to guarantee that they are uniquely decodable for 2n-1 messages. On the first page, the set of cell-state vectors for each message consists of all weight-u vectors with their non-zero elements restricted to the same (2u-1) positions, where the non-negative integer u is less than or equal to half of the code length. Finding cell-state vector sets such that they are disjoint on the first page is equivalent to the construction of constant-weight codes, and the number of disjoint sets is the best-known number of code words in the constant-weight codes. Our coding scheme is constructive, and the code length is arbitrary. The sum rates of our proposed codes are higher than those of previous work.

  • More General QAM Complementary Sequences

    Fanxin ZENG  Xiping HE  Guojun LI  Guixin XUAN  Zhenyu ZHANG  Yanni PENG  Sheng LU  Li YAN  

     
    LETTER-Information Theory

      Vol:
    E101-A No:12
      Page(s):
    2409-2414

    This paper improves the family size of quadrature amplitude modulation (QAM) complementary sequences with binary inputs. By employing new mathematical description: B-type-2 of 4q-QAM constellation (integer q ≥ 2), a new construction yielding 4q-QAM complementary sequences (CSs) with length 2m (integer m ≥ 2) is developed. The resultant sequences include the known QAM CSs with binary inputs as special cases, and the family sizes of new sequences are approximately 22·2q-4q-1(22·2q-3-1) times as many as the known. Also, both new sequences and the known have the same the peak envelope power (PEP) upper bounds, when they are used in an orthogonal frequency-division multiplexing communication system.

  • Parallel Precomputation with Input Value Prediction for Model Predictive Control Systems

    Satoshi KAWAKAMI  Takatsugu ONO  Toshiyuki OHTSUKA  Koji INOUE  

     
    PAPER-Real-time Systems

      Pubricized:
    2018/09/18
      Vol:
    E101-D No:12
      Page(s):
    2864-2877

    We propose a parallel precomputation method for real-time model predictive control. The key idea is to use predicted input values produced by model predictive control to solve an optimal control problem in advance. It is well known that control systems are not suitable for multi- or many-core processors because feedback-loop control systems are inherently based on sequential operations. However, since the proposed method does not rely on conventional thread-/data-level parallelism, it can be easily applied to such control systems without changing the algorithm in applications. A practical evaluation using three real-world model predictive control system simulation programs demonstrates drastic performance improvement without degrading control quality offered by the proposed method.

  • A New Semi-Blind Method for Spatial Equalization in MIMO Systems

    Liu YANG  Hang ZHANG  Yang CAI  Qiao SU  

     
    LETTER-Digital Signal Processing

      Vol:
    E101-A No:10
      Page(s):
    1693-1697

    In this letter, a new semi-blind approach incorporating the bounded nature of communication sources with the distance between the equalizer outputs and the training sequence is proposed. By utilizing the sparsity property of l1-norm cost function, the proposed algorithm can outperform the semi-blind method based on higher-order statistics (HOS) criterion especially for transmitting sources with non-constant modulus. Experimental results demonstrate that the proposed method shows superior performance over the HOS based semi-blind method and the classical training-based method for QPSK and 16QAM sources equalization. While for 64QAM signal inputs, the proposed algorithm exhibits its superiority in low signal-to-noise-ratio (SNR) conditions compared with the training-based method.

  • Full-Duplex Cooperative Cognitive Radio Networks with Simultaneous Transmit and Receive Antennas in MIMO Channels

    Sangwoo PARK  Iickho SONG  Seungwon LEE  Seokho YOON  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2018/01/31
      Vol:
    E101-B No:8
      Page(s):
    1903-1915

    We propose a cooperative cognitive radio network (CCRN) with secondary users (SUs) employing two simultaneous transmit and receive (STAR) antennas. In the proposed framework of full-duplex (FD) multiple-input-multiple-output (MIMO) CCRN, the region of achievable rate is expanded via FD communication among SUs enabled by the STAR antennas adopted for the SUs. The link capacity of the proposed framework is analyzed theoretically. It is shown through numerical analysis that the proposed FD MIMO-CCRN framework can provide a considerable performance gain over the conventional frameworks of CCRN and MIMO-CCRN.

  • A Unified Analysis of the Signal Transfer Characteristics of a Single-Path FET-R-C Circuit Open Access

    Tetsuya IIZUKA  Asad A. ABIDI  

     
    INVITED PAPER

      Vol:
    E101-C No:7
      Page(s):
    432-443

    A frequently occurring subcircuit consists of a loop of a resistor (R), a field-effect transistor (FET), and a capacitor (C). The FET acts as a switch, controlled at its gate terminal by a clock voltage. This subcircuit may be acting as a sample-and-hold (S/H), as a passive mixer (P-M), or as a bandpass filter or bandpass impedance. In this work, we will present a useful analysis that leads to a simple signal flow graph (SFG), which captures the FET-R-C circuit's action completely across a wide range of design parameters. The SFG dissects the circuit into three filtering functions and ideal sampling. This greatly simplifies analysis of frequency response, noise, input impedance, and conversion gain, and leads to guidelines for optimum design. This paper focuses on the analysis of a single-path FET-R-C circuit's signal transfer characteristics including the reconstruction of the complete waveform from the discrete-time sampled voltage.

  • Dynamic Group-Based Antenna Selection for Uplink Multi-User MIMO in Distributed Antenna System

    Sho YOSHIDA  Kentaro NISHIMORI  Soichi ITO  Tomoki MURAKAMI  Koichi ISHIHARA  Yasushi TAKATORI  

     
    PAPER

      Pubricized:
    2018/01/22
      Vol:
    E101-B No:7
      Page(s):
    1552-1560

    This paper proposes a hardware configuration for uplink multi-user multiple-input multiple-output (MU-MIMO) transmissions in a distributed antenna system (DAS). The demand for high-speed transmission in the uplink has increased recently, because of which standardizations in LTE-advanced and IEEE 802.11ax networks is currently underway. User terminal (UT) scheduling on the downlink MU-MIMO transmission is easy even in unlicensed band such as those in wireless local area network (WLAN) systems. However, the detailed management of the UTs is difficult on the uplink MU-MIMO transmissions because of the decentralized wireless access control. The proposed configuration allows an antenna to be selected from an external device on the access point (AP). All AP antennas are divided into groups, and the received signal in each group is input to the amplitude detector via a directional coupler. Subsequently, the selected antenna is fed by a multiple-to-one switch instead of a matrix switch. To clarify the effectiveness of the proposed configuration, we conduct computer simulations based on the ray-tracing method for propagation channels in an indoor environment.

  • Joint Wireless Information and Energy Transfer in Two-Way Relay Channels

    Xiaofeng LING  Rui WANG  Ping WANG  Yu ZHU  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2017/12/06
      Vol:
    E101-B No:6
      Page(s):
    1476-1484

    In this paper, we study simultaneous wireless information and power transfer (SWIPT) in two-way relay channels where two users exchange information with each other via a multi-antenna relay node. The signals forwarded by the relay node are also used to supply the power to two users. We formulate a max-min optimization problem aiming to maximize the minimum harvested energy between two users to achieve fairness. We jointly optimize the relay beamforming matrix and allocating powers at the two users subject to the quality of service (QoS) constraints. To be specific, we consider the amplify-and-forward (AF) relay strategy and the time splitting SWIPT strategy. To this end, we propose two different time splitting protocols to enable relay to supply power to two users. To solve the non-convex joint optimization problem, we propose to split the original optimization problem into two subproblems and solving them iteratively to obtain the final solution. It is shown that the first subproblem dealing with the beamforming matrix can be optimally solved by using the technique of relaxed semidefinite programming (SDR), and the second subproblem, which deals with the power allocation, can be solved via linear programming. The performance comparison of two schemes as well as the one-way relaying scheme are provided and the effectiveness of the proposed schemes is verified.

  • BackAssist: Augmenting Mobile Touch Manipulation with Back-of-Device Assistance

    Liang CHEN  Dongyi CHEN  Xiao CHEN  

     
    LETTER-Computer System

      Pubricized:
    2018/03/16
      Vol:
    E101-D No:6
      Page(s):
    1682-1685

    Operations, such as text entry and zooming, are simple and frequently used on mobile touch devices. However, these operations are far from being perfectly supported. In this paper, we present our prototype, BackAssist, which takes advantage of back-of-device input to augment front-of-device touch interaction. Furthermore, we present the results of a user study to evaluate whether users can master the back-of-device control of BackAssist or not. The results show that the back-of-device control can be easily grasped and used by ordinary smart phone users. Finally, we present two BackAssist supported applications - a virtual keyboard application and a map application. Users who tried out the two applications give positive feedback to the BackAssist supported augmentation.

  • Two-Input Functional Encryption for Inner Products from Bilinear Maps

    Kwangsu LEE  Dong Hoon LEE  

     
    PAPER-Cryptography and Information Security

      Vol:
    E101-A No:6
      Page(s):
    915-928

    Functional encryption is a new paradigm of public-key encryption that allows a user to compute f(x) on encrypted data CT(x) with a private key SKf to finely control the revealed information. Multi-input functional encryption is an important extension of (single-input) functional encryption that allows the computation f(x1,...,xn) on multiple ciphertexts CT(x1),...,CT(xn) with a private key SKf. Although multi-input functional encryption has many interesting applications like running SQL queries on encrypted database and computation on encrypted stream, current candidates are not yet practical since many of them are built on indistinguishability obfuscation. To solve this unsatisfactory situation, we show that practical two-input functional encryption schemes for inner products can be built based on bilinear maps. In this paper, we first propose a two-input functional encryption scheme for inner products in composite-order bilinear groups and prove its selective IND-security under simple assumptions. Next, we propose a two-client functional encryption scheme for inner products where each ciphertext can be associated with a time period and prove its selective IND-security. Furthermore, we show that our two-input functional encryption schemes in composite-order bilinear groups can be converted into schemes in prime-order asymmetric bilinear groups by using the asymmetric property of asymmetric bilinear groups.

  • Cooperative Jamming for Secure Transmission with Finite Alphabet Input under Individual Power Constraint

    Kuo CAO  Yueming CAI  Yongpeng WU  Weiwei YANG  

     
    LETTER-Digital Signal Processing

      Vol:
    E101-A No:6
      Page(s):
    961-966

    This letter studies secure transmission design with finite alphabet input for cooperative jamming network under individual power constraint. By adopting the zero-force scheme, where the jamming signal is fully laid in the null space of the relay-destination channel, the problem of enhancing the achievable secrecy rate is decomposed into two independent subproblems: relay weights design and power control. We reveal that the problem of relay weights design is identical to the problem of minimizing the maximal equivalent source-eavesdropper channel gain, which can be transformed into a semi-definite programming (SDP) problem and thus is tackled using interior point method. Besides, the problem of power control is solved with the fundamental relation between mutual information and minimum mean square error (MMSE). Numerical results show that the proposed scheme achieves significant performance gains compared to the conventional Gaussian design.

  • Robust MIMO Radar Waveform Design to Improve the Worst-Case Detection Performance of STAP

    Hongyan WANG  Quan CHENG  Bingnan PEI  

     
    PAPER-Fundamental Theories for Communications

      Pubricized:
    2017/11/20
      Vol:
    E101-B No:5
      Page(s):
    1175-1182

    The issue of robust multi-input multi-output (MIMO) radar waveform design is investigated in the presence of imperfect clutter prior knowledge to improve the worst-case detection performance of space-time adaptive processing (STAP). Robust design is needed because waveform design is often sensitive to uncertainties in the initial parameter estimates. Following the min-max approach, a robust waveform covariance matrix (WCM) design is formulated in this work with the criterion of maximization of the worst-case output signal-interference-noise-ratio (SINR) under the constraint of the initial parameter estimation errors to ease this sensitivity systematically and thus improve the robustness of the detection performance to the uncertainties in the initial parameter estimates. To tackle the resultant complicated and nonlinear robust waveform optimization issue, a new diagonal loading (DL) based iterative approach is developed, in which the inner and outer optimization problems can be relaxed to convex problems by using DL method, and hence both of them can be solved very effectively. As compared to the non-robust method and uncorrelated waveforms, numerical simulations show that the proposed method can improve the robustness of the detection performance of STAP.

  • Robust Secure Transmit Design for SWIPT System with Many Types of Wireless Users and Passive Eavesdropper

    Pham-Viet TUAN  Insoo KOO  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2017/08/22
      Vol:
    E101-B No:2
      Page(s):
    441-450

    This paper studies a simultaneous wireless information and power transfer (SWIPT) system in which the transmitter not only sends data and energy to many types of wireless users, such as multiple information decoding users, multiple hybrid power-splitting users (i.e., users with a power-splitting structure to receive both information and energy), and multiple energy harvesting users, but also prevents information from being intercepted by a passive eavesdropper. The transmitter is equipped with multiple antennas, whereas all users and the eavesdropper are assumed to be equipped with a single antenna. Since the transmitter does not have any channel state information (CSI) about the eavesdropper, artificial noise (AN) power is maximized to mask information as well as to interfere with the eavesdropper as much as possible. The non-convex optimization problem is formulated to minimize the transmit power satisfying all signal-to-interference-plus-noise (SINR) and harvested energy requirements for all users so that the remaining power for generating AN is maximized. With perfect CSI, a semidefinite relaxation (SDR) technique is applied, and the optimal solution is proven to be tight. With imperfect CSI, SDR and a Gaussian randomization algorithm are proposed to find the suboptimal solution. Finally, numerical performance with respect to the maximum SINR at the eavesdropper is determined by a Monte-Carlo simulation to compare the proposed AN scenario with a no-AN scenario, as well as to compare perfect CSI with imperfect CSI.

  • CSI Feedback Reduction Method for Downlink Multiuser MIMO Transmission Using Dense Distributed Antenna Selection

    Tomoki MURAKAMI  Koichi ISHIHARA  Yasushi TAKATORI  Masato MIZOGUCHI  Kentaro NISHIMORI  

     
    PAPER-MIMO

      Pubricized:
    2017/08/22
      Vol:
    E101-B No:2
      Page(s):
    426-433

    This paper proposes a novel method of reducing channel state information (CSI) feedback by using transmit antenna selection for downlink multiuser multiple input multiple output (DL-MU-MIMO) transmission in dense distributed antenna systems. It is widely known that DL-MU-MIMO transmission achieves higher total bit-rate by mitigating inter-user interference based on pre-coding techniques. The pre-coding techniques require CSI between access point (AP) and multiple users. However, overhead for CSI acquisition degrades the transmission efficiency of DL-MU-MIMO transmission. In the proposed CSI feedback reduction method, AP first selects the antenna set that maximizes the received power at each user, second it skips the sequence of CSI feedback for users whose signal to interference power ratio is larger than a threshold, and finally it performs DL-MU-MIMO transmission to multiple users by using the selected antenna set. To clarify the proposed method, we evaluate it by computer simulations in an indoor scenario. The results show that the proposed method can offer higher transmission efficiency than the conventional DL-MU-MIMO transmission with the usual CSI feedback method.

  • A Pseudorandom-Function Mode Based on Lesamnta-LW and the MDP Domain Extension and Its Applications

    Shoichi HIROSE  Hidenori KUWAKADO  Hirotaka YOSHIDA  

     
    PAPER

      Vol:
    E101-A No:1
      Page(s):
    110-118

    This paper discusses a mode for pseudorandom functions (PRFs) based on the hashing mode of Lesamnta-LW and the domain extension called Merkle-Damgård with permutation (MDP). The hashing mode of Lesamnta-LW is a plain Merkle-Damgård iteration of a block cipher with its key size half of its block size. First, a PRF mode is presented which produces multiple independent PRFs with multiple permutations and initialization vectors if the underlying block cipher is a PRP. Then, two applications of the PRF mode are presented. One is a PRF with minimum padding. Here, padding is said to be minimum if the produced message blocks do not include message blocks only with the padded sequence for any non-empty input message. The other is a vector-input PRF using the PRFs with minimum padding.

  • Efficient Sphere Decoding Based on a Regular Detection Tree for Generalized Spatial Modulation MIMO Systems

    Hye-Yeon YOON  Gwang-Ho LEE  Tae-Hwan KIM  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2017/07/10
      Vol:
    E101-B No:1
      Page(s):
    223-231

    The generalized spatial modulation (GSM) is a new transmission technique that can realize high-performance multiple-input multiple-output (MIMO) communication systems with a low RF complexity. This paper presents an efficient sphere decoding method used to perform the symbol detection for the generalized spatial modulation (GSM) multiple-input multiple-output (MIMO) systems. In the proposed method, the cost metric is modified so that it does not include the cancellation of the nonexistent interference. The modified cost metric can be computed by formulating a detection tree that has a regular structure representing the transmit antenna combinations as well as the symbol vectors, both of which are detected efficiently by finding the shortest path on the basis of an efficient tree search algorithm. As the tree search algorithm is performed for the regular detection tree to compute the modified but mathematically-equivalent cost metric, the efficiency of the sphere decoding is improved while the bit-error rate performance is not degraded. The simulation results show that the proposed method reduces the complexity significantly when compared with the previous method: for the 6×6 64QAM GSM-MIMO system with two active antennas, the average reduction rate of the complexity is as high as 45.8% in the count of the numerical operations.

  • A Paper Book Type Input Device for Page Navigation in Digital Documents Open Access

    Shohei MASUNAGA  Xingya XU  Hiroki TERABE  Kazuo SHIBUTA  Hirohito SHIBATA  

     
    INVITED PAPER

      Vol:
    E100-C No:11
      Page(s):
    984-991

    This paper aims to support quick and easy page access in digital documents. We tried to use a paper book as a device to navigate pages for digital documents. Our proposed system allows the users to perform the same interaction as a paper book such as inserting fingers among pages or folding an edge of the page as a dog-ear. Three experiments were conducted to confirm the effectiveness of the proposed system. As a result, we confirmed our proposed system was superior to conventional navigation methods especially in moving back and forth among pages.

  • Efficient Soft-Output Lattice-Reduction-Aided MIMO Detector with Low Complexity

    Hyunsub KIM  Jaeseok KIM  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2017/04/14
      Vol:
    E100-B No:10
      Page(s):
    1952-1958

    In this paper, an improved lattice reduction (LR)-aided soft-output multiple-input multiple-output (MIMO) detector is proposed. Conventional LR-aided soft-output MIMO detectors involve the empty set problem (ESP), in which an entry with a particular bit in the candidate list might not exist. To overcome the performance degradation resulting from this ESP, a post-processing algorithm that modifies the candidate list is proposed. The proposed algorithm efficiently resolves the ESP by utilizing the near-orthogonality of the lattice-reduced system model so that the bit error rate (BER) performance is enhanced. In addition, as the complexity of the candidate list generation is reduced with the aid of the post-processing algorithm, the overall complexity is also reduced. Simulation results and the complexity comparisons demonstrate that our proposed method lowers the required Eb/No by 4-5 dB at the BER of 10-5 and the complexity by 13%-55%, compared to the conventional method.

41-60hit(396hit)

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