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Akihisa TOMITA
2010 Volume E93.A Issue 5 Pages
871
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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Yasuyuki SAKAI, Hidema TANAKA
Article type: INVITED PAPER
2010 Volume E93.A Issue 5 Pages
872-879
Published: May 01, 2010
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Quantum cryptography has become a subject of widespread interest. In particular, quantum key distribution, which provides a secure key agreement by using quantum systems, is believed to be the most important application of quantum cryptography. Quantum key distribution has the potential to achieve the “unconditionally” secure infrastructure. We also have many cryptographic tools that are based on “modern cryptography” at the present time. They are being used in an effort to guarantee secure communication over open networks such as the Internet. Unfortunately, their ultimate efficacy is in doubt. Quantum key distribution systems are believed to be close to practical and commercial use. In this paper, we discuss what we should do to apply quantum cryptography to our communications. We also discuss how quantum key distribution can be combined with or used to replace cryptographic tools based on modern cryptography.
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Kiyoshi TAMAKI, Toyohiro TSURUMARU
Article type: INVITED PAPER
2010 Volume E93.A Issue 5 Pages
880-888
Published: May 01, 2010
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Quantum key distribution (QKD) is a way to securely expand the secret key to be used in One-time pad, and it is attracting great interest from not only theorists but also experimentalists or engineers who are aiming for the actual implementations. In this paper, we review the theoretical aspect of QKD, especially we focus on its security proof, and we briefly mention the possible problems and future directions.
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Akio TAJIMA, Akihiro TANAKA, Seigo TAKAHASHI, Ken-ichiro YOSHINO, Yosh ...
Article type: INVITED PAPER
2010 Volume E93.A Issue 5 Pages
889-896
Published: May 01, 2010
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Quantum key distribution (QKD) systems can generate unconditionally secure common keys between remote users. Improvements of QKD performance, particularly in key generation rate, have been required to meet current network traffic. A high-speed QKD system should be equipped with low-loss receivers with high visibility, highly efficient photon detectors with small dark count probability. A solution to these issues is to employ planar lightwave circuit (PLC) interferometers, single photon detection circuits and modules, together with multi-wavelength channels transmission using wavelength division multiplexing (WDM) technique.
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Kyo INOUE
Article type: INVITED PAPER
2010 Volume E93.A Issue 5 Pages
897-902
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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Differential-phase-shift (DPS) quantum key distribution (QKD) is one scheme of quantum key distribution whose security is based on the quantum nature of lightwave. This protocol features simplicity, a high key creation rate, and robustness against photon-number-splitting attacks. We describe DPS-QKD in this paper, including its setup and operation, eavesdropping against DPS-QKD, system performance, and modified systems to improve the system performance.
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Hiroki TAKESUE, Toshimori HONJO, Kenichi HARADA, Benjamin MIQUEL
Article type: INVITED PAPER
2010 Volume E93.A Issue 5 Pages
903-909
Published: May 01, 2010
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Entanglement is expected to play a crucial role in the next-generation quantum communication systems. This paper reviews recent quantum communication experiments over optical fiber using 1.5-µm telecom-band entangled photon pairs. After describing the telecom-band entanglement sources based on spontaneous parametric processes, we review three quantum communication experiments using entangled photons: a long-distance entanglement distribution, an entanglement-based quantum key distribution, and an entanglement swapping.
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Masahide SASAKI
Article type: INVITED PAPER
2010 Volume E93.A Issue 5 Pages
910-913
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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Quantum cryptography reaches a decisive phase to innovate secure communications technology beyond a subject reserved for scientists. Every core technology of quantum cryptography should be unified with photonic network technology and contemporary cryptography to realize secure photonic network. As another important avenue, new quantum crypto-schemes taking every merit of known schemes and quantum node technology for fully quantum networking must be pursued for new generation quantum cryptography.
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Sha LI, Brian L.F. DAKU
Article type: PAPER
Subject area: Engineering Acoustics
2010 Volume E93.A Issue 5 Pages
914-925
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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This paper focuses on the development of Cramér-Rao Bound (CRB) expressions for passive source location estimation in various Gaussian noise environments. The scenarios considered involve an unknown deterministic source signal with a short time duration, and additive general Gaussian noise. The mathematical derivation procedure presented is applicable to non-stationary Gaussian noise problems. Specifically, explicit closed-form CRB expressions are presented using the spectrum representation of the signal and noise for stationary Gaussian noise cases.
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Tetsuji OGAWA, Shintaro TAKADA, Kenzo AKAGIRI, Tetsunori KOBAYASHI
Article type: PAPER
Subject area: Speech and Hearing
2010 Volume E93.A Issue 5 Pages
926-935
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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We propose a new speech enhancement method suitable for mobile devices used in the presence of various types of noise. In order to achieve high-performance speech recognition and auditory perception in mobile devices, various types of noise have to be removed under the constraints of a space-saving microphone arrangement and few computational resources. The proposed method can reduce both the directional noise and the diffuse noise under the abovementioned constraints for mobile devices by employing a square microphone array and conducting low-computational-cost processing that consists of multiple null beamforming, minimum power channel selection, and Wiener filtering. The effectiveness of the proposed method is experimentally verified in terms of speech recognition accuracy and speech quality when both the directional noise and the diffuse noise are observed simultaneously; this method reduces the number of word errors and improves the log-spectral distances as compared to conventional methods.
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Hisashi TANAKA, Koichi TANNO, Ryota MIWA, Hiroki TAMURA, Kenji MURAO
Article type: PAPER
Subject area: Analog Signal Processing
2010 Volume E93.A Issue 5 Pages
936-941
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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In this paper, a low-voltage, wide-common-mode-range and high-CMRR OTA is presented. The proposed OTA consists of two circuit blocks; one is the input stage and operates as a differential level shifter, and the other is a highly linear output stage. Furthermore, the OTA can be operated in both weak and strong inversion regions. The proposed OTA is evaluated through Star-HSPICE with 0.18µm CMOS device parameters (LEVEL53). Simulation results demonstrate a CMRR of 158dB, a common-mode-input-range of 65mV to 720mV and a current consumption of 1.2µA when
VDD=0.8V.
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Xuan ZHANG, Qiaoyan WEN, Jie ZHANG
Article type: PAPER
Subject area: Communication Theory and Signals
2010 Volume E93.A Issue 5 Pages
942-949
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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In this paper, we propose four new general constructions of LCZ/ZCZ sequence sets based on interleaving technique and affine transformations. A larger family of LCZ/ZCZ sequence sets with longer period are generated by these constructions, which are more flexible among the selection of the alphabet size, the period of the sequences and the length of LCZ/ZCZ, compared with those generated by the known constructions. Especially, two families of the newly constructed sequences can achieve or almost achieve the theoretic bound.
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Akihiko SUGIURA, Ryoichi BABA, Hideyuki KOBAYASHI
Article type: PAPER
Subject area: Mobile Information Network and Personal Communications
2010 Volume E93.A Issue 5 Pages
950-957
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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With the increasing number of crimes and accidents in which children are becoming involved, there is a growing demand for devices to safeguard children's security by detecting their locations on their way to and from school. This paper proposes a system that uses an IEEE802.15.4-standard network to detect children's locations. To overcome the susceptibility of radio interference from nearby wireless LANs, frequency division multiplexing is applied to this IEEE802.15.4-based network, toward improving data acquisition from terminal units. The effectiveness of the system was field-tested with elementary school students who used about 400 IEEE 802.15.4-compliant terminal units. An experiment verified that the use of frequency division multiplexing in an environment where radio interference by wireless LANs is strong allowed the network to double the success rate of information communication from terminal units relative to that without frequency division multiplexing. In the experiment for detecting elementary schoolers' arrival at and departure from school, the terminal detection rate was 99% and the terminal detection rate on the designated school routes was 90%. These results prove the effectiveness of the system in detecting locations.
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Takeshi OKUNO, Takao NISHITANI
Article type: PAPER
Subject area: Image
2010 Volume E93.A Issue 5 Pages
958-965
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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This paper describes an efficient image enhancement method based on the Multi-Scale Retinex (MSR) approach for pre-processing of video applications. The processing amount is drastically reduced to 4 orders less than that of the original MSR, and 1 order less than the latest fast MSR method. For the efficient processing, our proposed method employs multi-stage and multi-rate filter processing which is constructed by a
x-
y separable and polyphase structure. In addition, the MSR association is effectively implemented during the above multi-stage processing. The method also modifies a weighting function for enhancement to improve color rendition of bright areas in an image. A variety of evaluation results show that the performance of our simplified method is similar to those of the original MSR, in terms of visual perception, contrast enhancement effects, and hue changes. Moreover, experimental results show that pre-processing of the proposed method contributes to clear foreground object separation.
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Shunsuke YAMAKI, Masahide ABE, Masayuki KAWAMATA
Article type: LETTER
Subject area: Digital Signal Processing
2010 Volume E93.A Issue 5 Pages
966-971
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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This letter proposes closed form solutions to the
L2-sensitivity minimization of second-order state-space digital filters with real poles. We consider two cases of second-order digital filters: distinct real poles and multiple real poles. In case of second-order digital filters, we can express the
L2-sensitivity of second-order digital filters by a simple linear combination of exponential functions and formulate the
L2-sensitivity minimization problem by a simple polynomial equation. As a result, the minimum
L2-sensitivity realizations can be synthesized by only solving a fourth-degree polynomial equation, which can be analytically solved.
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Ligang LIU, Masahiro FUKUMOTO, Sachio SAIKI
Article type: LETTER
Subject area: Digital Signal Processing
2010 Volume E93.A Issue 5 Pages
972-975
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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The proportionate normalized least mean square algorithm (PNLMS) greatly improves the convergence of the sparse impulse response. It exploits the shape of the impulse response to decide the proportionate step gain for each coefficient. This is not always suitable. Actually, the proportionate step gain should be determined according to the difference between the current estimate of the coefficient and its optimal value. Based on this idea, an approach is proposed to determine the proportionate step gain. The proposed approach can improve the convergence of proportionate adaptive algorithms after a fast initial period. It even behaves well for the non-sparse impulse response. Simulations verify the effectiveness of the proposed approach.
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Jie JIA, Daeil YOON, Hae Kwang KIM
Article type: LETTER
Subject area: Digital Signal Processing
2010 Volume E93.A Issue 5 Pages
976-980
Published: May 01, 2010
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Video coding standard H.264/AVC employs transform coding to explore spatial correlation in inter picture prediction residue. This paper presents a block based DC offset to further explore the correlation in spatially neighboring blocks and provides H.264/AVC an enhanced coding efficiency performance. The proposed method applies DC offset to inter picture prediction residue, and encodes the offset compensated residual signal. The DC offset is derived from reconstructed residue in neighboring blocks. No additional bits are required for the DC offset representation. Simulation results report that the proposed method yields an average of 2.67% bit rate reduction for high resolution video over the H.264 baseline profile.
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Young Ik SON, In Hyuk KIM
Article type: LETTER
Subject area: Systems and Control
2010 Volume E93.A Issue 5 Pages
981-984
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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This paper proposes a robust state observer for multi-input multi-output LTI systems. Unknown inputs of polynomial form and high-frequency measurement noises are considered in the system model. The unknown inputs and the noises are not in the same form. Multiple integrations of both the observer error signal and the measurement output are used for the observer design. The existence condition of the proposed observer is shown to be the same as that of the proportional-integral (PI) observer. Computer simulations show the effectiveness of the proposed observer.
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Kei EGUCHI, Sawai PONGSWATD, Amphawan JULSEREEWONG, Kitti TIRASESTH, H ...
Article type: LETTER
Subject area: Circuit Theory
2010 Volume E93.A Issue 5 Pages
985-988
Published: May 01, 2010
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A multiple-input switched-capacitor DC-DC converter which can realize long battery runtime is proposed in this letter. Unlike conventional converters for a back-lighting application, the proposed converter drives some LEDs by converting energy from solar cells. Furthermore, the proposed converter can charge a lithium battery when an output load is light. The validity of circuit design is confirmed by theoretical analyses, simulations, and experiments.
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Myoung-Keun YOU, Gi-Yong SONG
Article type: LETTER
Subject area: VLSI Design Technology and CAD
2010 Volume E93.A Issue 5 Pages
989-992
Published: May 01, 2010
Released on J-STAGE: May 01, 2010
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In this paper, we describe a verification environment which is based on a constrained random layered testbench using SystemVerilog OOP. As SystemVerilog OOP technique does not allow multiple inheritance, we adopt SystemC to design components of a verification environment which employ multiple inheritance. Then SystemC design unit is linked to a SystemVerilog-based verification environment using SystemVerilog DPI and ModelSim macro. Employing multiple inheritance of SystemC makes the design phase of verification environment simple and easy through source code reusability without corruption due to multi-level single inheritance.
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Hiroshi SASANO, Yuuki OGAMI
Article type: LETTER
Subject area: Coding Theory
2010 Volume E93.A Issue 5 Pages
993-996
Published: May 01, 2010
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An improved bidirectional search algorithm for computing the weight spectrum of convolutional codes is presented. This algorithm does not employ the column distance function of a code which plays an important role in the original bidirectional search algorithm. We show the proposed algorithm can reduce computaion time for obtaining the weigth spectrum of convolutional codes significantly compared with that of the bidirectional search algorithm.
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