IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Online ISSN : 1745-1337
Print ISSN : 0916-8508
Volume E91.A , Issue 10
Showing 1-50 articles out of 55 articles from the selected issue
Special Section on Information Theory and Its Applications
  • Kin-ichiroh TOKIWA
    2008 Volume E91.A Issue 10 Pages 2695
    Published: October 01, 2008
    Released: July 01, 2018
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  • Brian M. KURKOSKI
    Type: SURVEY PAPER
    Subject area: Communication Theory
    2008 Volume E91.A Issue 10 Pages 2696-2703
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper gives a survey and comparison of algorithms for the detection of binary data in the presence of two-dimensional (2-D) intersymbol interference. This is a general problem of communication theory, because it can be applied to various practical problems in data storage and transmission. Major results on trellis-based detection algorithms, previously disparate are drawn together, and placed into a common framework. All algorithms have better complexity than optimal detection, and complexity is compared. On the one hand, many algorithms perform within 1.0dB or better of optimal performance. On the other hand, none of these proposed algorithms can find the optimal solution at high SNR, which is surprising. Extensive discussion outlines further open problems.
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  • Te-Sun HAN
    Type: PAPER
    Subject area: Information Theory
    2008 Volume E91.A Issue 10 Pages 2704-2719
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper we show some new look at large deviation theorems from the viewpoint of the information-spectrum (IS) methods, which has been first exploited in information theory, and also demonstrate a new basic formula for the large deviation rate function in general, which is expressed as a pair of the lower and upper IS rate functions. In particular, we are interested in establishing the general large deviation rate functions that are derivable as the Fenchel-Legendre transform of the cumulant generating function. The final goal is to show, under some mild condition, a necessary and sufficient condition for the IS rate function to be derivable as the Fenchel-Legendre transform of the cumulant generating function, i. e., to be a rate function of Gärtner-Ellis type.
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  • Kunihiko HARADA, Hirosuke YAMAMOTO
    Type: PAPER
    Subject area: Information Theory
    2008 Volume E91.A Issue 10 Pages 2720-2728
    Published: October 01, 2008
    Released: March 01, 2010
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    In a network with capacity h for multicast, information Xh=(X1, X2, …, Xh) can be transmitted from a source node to sink nodes without error by a linear network code. Furthermore, secret information Sr=(S1, S2, …, Sr) can be transmitted securely against wiretappers by k-secure network coding for kh-r. In this case, no information of the secret leaks out even if an adversary wiretaps k edges, i. e. channels. However, if an adversary wiretaps k+1 edges, some Si may leak out explicitly. In this paper, we propose strongly k-secure network coding based on strongly secure ramp secret sharing schemes. In this coding, no information leaks out for every (Si1, Si2, …,Sir-j) even if an adversary wiretaps k+j channels. We also give an algorithm to construct a strongly k-secure network code directly and a transform to convert a nonsecure network code to a strongly k-secure network code. Furthermore, some sufficient conditions of alphabet size to realize the strongly k-secure network coding are derived for the case of k<h-r.
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  • Haruo OGIWARA, Kyouhei SHIMAMURA, Toshiyuki SHOHON
    Type: PAPER
    Subject area: Coding Theory
    2008 Volume E91.A Issue 10 Pages 2729-2736
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper proposes methods to improve soft-input and soft-output decoding performance of BCH codes by sum-product algorithm (SPA). A method to remove cycles of length four (RmFC) in the Tanner graph has been proposed. However, the RmFC can not realize good decoding performance for BCH codes which have more than one error correcting capability. To overcome this problem, this paper proposes two methods. One is to use a parity check matrix of the echelon canonical form as the starting check matrix of RmFC. The other is to use a parity check matrix that is concatenation (ConC) of multiple parity check matrices. For BCH(31,11,11) code, SPA with ConC realizes Eb/No 3.7dB better at bit error rate 10-5 than the original SPA, and 3.1dB better than the SPA with only RmFC.
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  • Takayuki NOZAKI, Kenta KASAI, Tomoharu SHIBUYA, Kohichi SAKANIWA
    Type: PAPER
    Subject area: Coding Theory
    2008 Volume E91.A Issue 10 Pages 2737-2744
    Published: October 01, 2008
    Released: March 01, 2010
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    Luby et al. derived evolution of degree distributions in residual graphs for irregular LDPC code ensembles. Evolution of degree distributions in residual graphs is important characteristic which is used for finite-length analysis of the expected block and bit error probability over the binary erasure channel. In this paper, we derive detailed evolution of degree distributions in residual graphs for irregular LDPC code ensembles with joint degree distributions.
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  • Yoshiyuki SATO, Gou HOSOYA, Hideki YAGI, Shigeichi HIRASAWA
    Type: PAPER
    Subject area: Coding Theory
    2008 Volume E91.A Issue 10 Pages 2745-2753
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper, we propose a method for enhancing performance of a sequential version of the belief-propagation (BP) decoding algorithm, the group shuffled BP decoding algorithm for low-density parity-check (LDPC) codes. An improved BP decoding algorithm, called the shuffled BP decoding algorithm, decodes each symbol node in serial at each iteration. To reduce the decoding delay of the shuffled BP decoding algorithm, the group shuffled BP decoding algorithm divides all symbol nodes into several groups. In contrast to the original group shuffled BP, which automatically generates groups according to symbol positions, in this paper we propose a method for grouping symbol nodes which generates groups according to the structure of a Tanner graph of the codes. The proposed method can accelerate the convergence of the group shuffled BP algorithm and obtain a lower error rate in a small number of iterations. We show by simulation results that the decoding performance of the proposed method is improved compared with those of the shuffled BP decoding algorithm and the group shuffled BP decoding algorithm.
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  • Manabu KOBAYASHI, Hideki YAGI, Toshiyasu MATSUSHIMA, Shigeichi HIRASAW ...
    Type: PAPER
    Subject area: Coding Theory
    2008 Volume E91.A Issue 10 Pages 2754-2764
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper, we analyze the robustness for low-density parity-check (LDPC) codes over the Gilbert-Elliott (GE) channel. For this purpose we propose a density evolution method for the case where LDPC decoder uses the mismatched parameters for the GE channel. Using this method, we derive the region of tuples of true parameters and mismatched decoding parameters for the GE channel, where the decoding error probability approaches asymptotically to zero.
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  • Gou HOSOYA, Toshiyasu MATSUSHIMA, Shigeichi HIRASAWA
    Type: PAPER
    Subject area: Coding Theory
    2008 Volume E91.A Issue 10 Pages 2765-2778
    Published: October 01, 2008
    Released: March 01, 2010
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    A new ensemble of low-density parity-check (LDPC) codes for correcting a solid burst erasure is proposed. This ensemble is an instance of a combined matrix ensemble obtained by concatenating some LDPC matrices. We derive a new bound on the critical minimum span ratio of stopping sets for the proposed code ensemble by modifying the bound for ordinary code ensemble. By calculating this bound, we show that the critical minimum span ratio of stopping sets for the proposed code ensemble is better than that of the conventional one with keeping the same critical exponent of stopping ratio for both ensemble. Furthermore from experimental results, we show that the average minimum span of stopping sets for a solid burst erasure of the proposed codes is larger than that of the conventional ones.
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  • Nobuyoshi KOMURO, Hiromasa HABUCHI, Toshinori TSUBOI
    Type: PAPER
    Subject area: Communication Theory
    2008 Volume E91.A Issue 10 Pages 2779-2786
    Published: October 01, 2008
    Released: March 01, 2010
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    The measurements for Multiple Access Interference (MAI) problems and the improvement of the data rate are key issues on the advanced wireless networks. In this paper, the nonorthogonal Code Shift Keying Code Division Multiple Access (CSK/CDMA) with received-power adaptive access control scheme is proposed. In our system, a user who is ready to send measures the received power from other users, and then the user decides whether to transmit or refrain from transmission according to the received power and a pre-decided threshold. Not only overcoming the MAI problems, but our system also improve the throughput performance. The throughput performance of the proposed system is evaluated by theoretical analysis. Consequently, the nonorthogonal CSK/CDMA system improves by applying received-power adaptive access control. It was also found that the throughput performance of the nonorthogonal CSK/CDMA system is better than that of the orthogonal CSK/CDMA system at any Eb/N0. We conclude that the nonorthogonal CSK/CDMA system with received-power adaptive access control scheme is expected to be effective in advanced wireless networks.
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  • Masatsugu HIGASHINAKA, Hiroshi KUBO, Akihiro OKAZAKI, Yasutaka OGAWA, ...
    Type: PAPER
    Subject area: Communication Theory
    2008 Volume E91.A Issue 10 Pages 2787-2797
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper proposes a novel channel estimation method for iterative equalization in MIMO systems. The proposed method incorporates co-channel interference (CCI) cancellation in the channel estimator and the channel estimation is successively performed with respect to each stream. Accuracy of channel estimation holds the key to be successfully converged the iterative equalization and decoding process. Although the channel estimates can be re-estimated by means of LS (Least Square) channel estimation using tentative decisions obtained in the iterative process, its performance is severely limited in a MIMO system because of erroneous decisions and ill-conditioned channel estimation matrix. The proposed method can suppress the above effects by means of CCI cancellation and successive channel estimation. Computer simulation confirms that the proposed channel estimation method can accurately estimate the channel, and the receiver with iterative equalization and the proposed method achieves excellent decoding performance in a MIMO-SM system.
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  • Yutaka MURAKAMI, Takashi MATSUOKA, Masayuki ORIHASHI
    Type: PAPER
    Subject area: Communication Theory
    2008 Volume E91.A Issue 10 Pages 2798-2807
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper, BER (Bit Error Rate) performance in 2×2 MIMO (Multiple-Input Multiple-Output) spatial multiplexing systems under Rician fading channels is evaluated. We examine BER performances employing inverse channel detection (ICD) under Rician fading channels, adding the phase of the direct path and Rician factor as a parameter. The results clearly indicate that the phase of the direct path and Rician factor have a great influence on BER performances employing ICD under Rician fading channels.
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  • Tetsuki TANIGUCHI, Shen SHA, Yoshio KARASAWA
    Type: PAPER
    Subject area: Communication Theory
    2008 Volume E91.A Issue 10 Pages 2808-2817
    Published: October 01, 2008
    Released: March 01, 2010
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    In multiple input multiple output (MIMO) communication systems, eigenvalues of channel correlation matrices play an essential role for the performance analysis, and particularly the investigation about their behavior under time-variant environment ruled by a certain statistics is an important problem. This paper first gives the theoretical expressions for the marginal distributions of all the ordered eigenvalues of MIMO correlation matrices under i. i. d. (independent and identically distributed) Rayleigh fading environment. Then, an approximation method of those marginal distributions is presented: We show that the theory of SIMO space diversity using maximal ratio combining (MRC) is applicable to the approximation of statistical distributions of all eigenvalues in MIMO systems with the same number of diversity branches. The derived approximation has a monomial form suitable for the calculation of various performance measures utilized in MIMO systems. Through computer simulations, the effectiveness of the proposed method is demonstrated.
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  • Ha Duyen TRUNG, Watit BENJAPOLAKUL, Kiyomichi ARAKI
    Type: PAPER
    Subject area: Communication Theory
    2008 Volume E91.A Issue 10 Pages 2818-2826
    Published: October 01, 2008
    Released: March 01, 2010
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    MIMO (Multiple Input Multiple Output) communications systems equipped with array antennas at both the transmitter and receiver sides are a promising scheme to realize higher rate and/or reliable data transmission. In this paper, capacity analysis of MIMO Rayleigh channel with spatial correlation at the receiver of multipath taken into account is presented. In general, a model configuration of local scattering around a mobile station in MIMO environment is carried out by simulation to examine spatial correlation coefficients. Based on statistical properties of the eigenvalues of correlated complex random Wishart matrices, the exact closed-form expressions of distribution of the eigenvalues are investigated. Then, the general closed-form evaluation of integral form is proposed based on Meijer's G-function. The results demonstrate that the ergodic capacities are improved by increasing the number of the antennas and the SNR's. Compared with i. i. d. (independent identically distributed) Rayleigh channel, the incremental improvement of correlated Rayleigh channel is reduced by spatial fading correlation. The analytical results validated by Monte-Carlo simulations show a good agreement.
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  • Won-Joo HWANG, Cong-Loi LE
    Type: PAPER
    Subject area: Communication Theory
    2008 Volume E91.A Issue 10 Pages 2827-2832
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper considers a proportional fairness of end-to-end session rates in a multihop wireless network through the rate control framework. In multihop wireless networks, there are two classes of rate control problem. One focuses in optimizing the transmission attempt probabilities at the lower layers, but not the transmit powers while other problem is closely related to jointly optimal congestion control and power control. Proportional fairness is a fundamental concept in flow control problems. In this paper, we give in-depth analysis and show that the optimal solutions of these problems are proportionally fair provided that the objective functions are suitably chosen.
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  • Atsuko MIYAJI
    Type: PAPER
    Subject area: Cryptography and Information Security
    2008 Volume E91.A Issue 10 Pages 2833-2842
    Published: October 01, 2008
    Released: March 01, 2010
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    In the execution on a smart card, elliptic curve cryptosystems have to be secure against side channel attacks such as the simple power analysis (SPA), the differential power analysis (DPA), and the refined power analysis (RPA), and so on. MMM-algorithm proposed by Mamiya, Miyaji, and Morimoto is a scalar multiplication algorithm secure against SPA, DPA, and RPA, which can decrease the computational complexity by increasing the size of a pre-computed table. However, it provides only 4 different cases of pre-computed tables. From the practical point of view, a wider range of time-memory tradeoffs is usually desired. This paper generalizes MMM-algorithm to improve the flexibility of tables as well as the computational complexity. Our improved algorithm is secure, efficient and flexible for the storage size.
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  • Masaaki SHIRASE, Dong-Guk HAN, Yasushi HIBINO, Howon KIM, Tsuyoshi TAK ...
    Type: PAPER
    Subject area: Cryptography and Information Security
    2008 Volume E91.A Issue 10 Pages 2843-2850
    Published: October 01, 2008
    Released: March 01, 2010
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    XTR is one of the most efficient public-key cryptosystems that allow us to compress the communication bandwidth of their ciphertext. The compact representation can be achieved by deploying a subgroup Fq2 of extension field Fq6, so that the compression ratio of XTR cryptosystem is 1/3. On the other hand, Dijk et al. proposed an efficient public-key cryptosystem using a torus over Fq30 whose compression ratio is 4/15. It is an open problem to construct an efficient public-key cryptosystem whose compression ratio is smaller than 4/15. In this paper we propose a new variant of XTR cryptosystem over finite fields with characteristic three whose compression ratio is 1/6. The key observation is that there exists a trace map from Fq6 to Fq in the case of characteristic three. Moreover, the cost of compression and decompression algorithm requires only about 1% overhead compared with the original XTR cryptosystem. Therefore, the proposed variant of XTR cryptosystem is one of the fastest public-key cryptosystems with the smallest compression ratio.
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  • Hidenori KUWAKADO, Masakatu MORII
    Type: PAPER
    Subject area: Cryptography and Information Security
    2008 Volume E91.A Issue 10 Pages 2851-2859
    Published: October 01, 2008
    Released: March 01, 2010
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    Since Bellare and Ristenpart showed a multi-property preserving domain extension transform, the problem of the construction for multi-property hash functions has been reduced to that of the construction for multi-property compression functions. However, the Davies-Meyer compression function that is commonly used for standard hash functions is not a multi-property compression function. That is, in the ideal cipher model, the Davies-Meyer compression function is collision resistant, but it is not indifferentiable from a random oracle. In this paper, we show that the compression function proposed by Lai and Massey is a multi-property compression function. In addition, we show that the simplified version of the Lai-Massey compression function is also a multi-property compression function. The use of these compression functions enables us to construct multi-property hash functions by the multi-property preserving domain extension transform.
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  • Kouya TOCHIKUBO
    Type: PAPER
    Subject area: Cryptography and Information Security
    2008 Volume E91.A Issue 10 Pages 2860-2867
    Published: October 01, 2008
    Released: March 01, 2010
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    We propose two multiple assignment secret sharing schemes realizing general access structures. One is always more efficient than the secret sharing scheme proposed by Ito, Saito and Nishizeki [5] from the viewpoint of the number of shares distributed to each participant. The other is also always more efficient than the scheme I of [7].
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  • Shigeaki KUZUOKA
    Type: LETTER
    Subject area: Information Theory
    2008 Volume E91.A Issue 10 Pages 2868-2869
    Published: October 01, 2008
    Released: March 01, 2010
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    This letter reveals that linear lossy codes cannot attain the rate-distortion function in general, even if the source is binary i. i. d. and the distortion is measured by the Hamming distortion measure.
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  • Ryutaroh MATSUMOTO, Shun WATANABE
    Type: LETTER
    Subject area: Information Theory
    2008 Volume E91.A Issue 10 Pages 2870-2873
    Published: October 01, 2008
    Released: March 01, 2010
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    We consider the mismatched measurements in the BB84 quantum key distribution protocol, in which measuring bases are different from transmitting bases. We give a lower bound on the amount of a secret key that can be extracted from the mismatched measurements. Our lower bound shows that we can extract a secret key from the mismatched measurements with certain quantum channels, such as the channel over which the Hadamard matrix is applied to each qubit with high probability. Moreover, the entropic uncertainty principle implies that one cannot extract the secret key from both matched measurements and mismatched ones simultaneously, when we use the standard information reconciliation and privacy amplification procedure.
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  • Cheon Ho LEE, Young Chai KO, Jun HEO
    Type: LETTER
    Subject area: Coding Theory
    2008 Volume E91.A Issue 10 Pages 2874-2876
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper presents an improved min-sum iterative decoding scheme for regular and irregular LDPC codes. The proposed decoding scheme scales the extrinsic soft information from variable nodes to check. Different scaling factors are applied for iterations and the scaling factors are obtained by a simplified vector optimization method.
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  • Hideki YOSHIKAWA
    Type: LETTER
    Subject area: Coding Theory
    2008 Volume E91.A Issue 10 Pages 2877-2880
    Published: October 01, 2008
    Released: March 01, 2010
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    In this letter, a theoretical analysis of bit error probability for 4-state convolutional code with Max-Log-maximum a posteriori probability (MAP) decoding is presented. This technique employs an iterative calculation of probability density function of the state metric per one transition, and gives the exact bit error probability for all signal-to-noise power ratio.
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  • Tetsuya KOJIMA, Masahiro AONO
    Type: LETTER
    Subject area: Spectrum Technologies
    2008 Volume E91.A Issue 10 Pages 2881-2884
    Published: October 01, 2008
    Released: March 01, 2010
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    A convoluted-time and code division multiple access (CT-CDMA) communication system based on complete complementary codes has been proposed. In this letter, the properties of this communication system are discussed and compared with those of the conventional CDMA systems using complete complementary codes.
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  • Yuji KIMURA, Koji SHIBATA, Takakazu SAKAI
    Type: LETTER
    Subject area: Spectrum Technologies
    2008 Volume E91.A Issue 10 Pages 2885-2888
    Published: October 01, 2008
    Released: March 01, 2010
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    We study the performances of a synchronous chip-interleaved, block spread (CIBS) code division multiple access (CDMA) with space-time block-coding (STBC) in the presence of frequency-selective fading. For providing the space diversity gain due to STBC, we introduce the optimum precoding for the STBC. Zero-forcing and minimum mean square error equalizers for CIBS-CDMA are derived. Simulation results confirm that the proposed precoder is valid under the frequency selective fading.
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  • Takeshi NASAKO, Yasuyuki MURAKAMI, Masao KASAHARA
    Type: LETTER
    Subject area: Cryptography and Information Security
    2008 Volume E91.A Issue 10 Pages 2889-2892
    Published: October 01, 2008
    Released: March 01, 2010
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    In 2003, Kobayashi et al. proposed a new class of knapsack public-key cryptosystems over Gaussian integer ring. This scheme using two-sequences as the public key. In 2005, Sakamoto and Hayashi proposed an improved version of Kobayashi's scheme. In this paper, we propose the knapsack PKC using l-sequences as the public key and present the low-density attack on it. We have described Schemes R and G for l=2, in which the public keys are constructed over rational integer ring and over Gaussian integer ring, respectively. We discusses on the difference of the security against the low-density attack. We show that the security levels of Schemes R and G differ only slightly.
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  • Li-ming HAO, Song-nian LU, Shu-tang YANG, Ning LIU, Qi-shan HUANG
    Type: LETTER
    Subject area: Cryptography and Information Security
    2008 Volume E91.A Issue 10 Pages 2893-2895
    Published: October 01, 2008
    Released: March 01, 2010
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    In 2006, Miranda et al. proposed an anonymity scheme to achieve peers' anonymity in Peer-to-Peer. (P2P) reputation systems. In this paper, we show that this scheme can not achieve peers' anonymity in two cases. We also propose an improvement which solves the problem and improves the degree of anonymity.
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Special Section on Smart Multimedia & Communication Systems
  • Akira TAGUCHI, Takao ONOYE
    2008 Volume E91.A Issue 10 Pages 2896
    Published: October 01, 2008
    Released: July 01, 2018
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  • KokSheik WONG, Kiyoshi TANAKA
    Type: PAPER
    Subject area: Image Security
    2008 Volume E91.A Issue 10 Pages 2897-2908
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper proposes a DCT-based steganographic method named StegErmelc in the JPEG domain. Three strategies are proposed, namely (i) edge-like block selection, (ii) recursive matrix encoding, and (iii) largest coefficient serving, to form a novel steganographic method for achieving scalable carrier capacity, low detectability by universal blind steganalyzer, and high image quality, simultaneously. For a given message length, StegErmelc flexibly scales its carrier capacity to accommodate the message while trading off with stego detectability. At full capacity, StegErmelc has comparable carrier capacity relative to the existing methods. When embedding the same amount of information, StegErmelc remarkably reduces the stego detection rate to about 0.3-0.5 lower than that of the existing methods considered, and consequently StegErmelc can withstand blind steganalyzer when embedding up to 0.10bpc. Under the same condition, StegErmelc produces stego image with quality higher than that of the existing methods considered. Graphical comparison with three additional evaluation metrics is also presented to show the relative performance of StegErmelc with respect to the existing methods considered.
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  • Ryoji HASHIMOTO, Tomoya MATSUMURA, Yoshihiro NOZATO, Kenji WATANABE, T ...
    Type: PAPER
    Subject area: Video Processing Systems
    2008 Volume E91.A Issue 10 Pages 2909-2917
    Published: October 01, 2008
    Released: March 01, 2010
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    A multi-agent object attention system is proposed, which is based on biologically inspired attractor selection model. Object attention is facilitated by using a video sequence and a depth map obtained through a compound-eye image sensor TOMBO. Robustness of the multi-agent system over environmental changes is enhanced by utilizing the biological model of adaptive response by attractor selection. To implement the proposed system, an efficient VLSI architecture is employed with reducing enormous computational costs and memory accesses required for depth map processing and multi-agent attractor selection process. According to the FPGA implementation result of the proposed object attention system, which is accomplished by using 7,063 slices, 640×512 pixel input images can be processed in real-time with three agents at a rate of 9fps in 48MHz operation.
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  • Hanieh AMIRSHAHI, Satoshi KONDO, Koichi ITO, Takafumi AOKI
    Type: PAPER
    Subject area: Image Processing
    2008 Volume E91.A Issue 10 Pages 2918-2927
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper, we propose an image completion algorithm which takes advantage of the countless number of images available on Internet photo sharing sites to replace occlusions in an input image. The algorithm 1) automatically selects the most suitable images from a database of downloaded images and 2) seamlessly completes the input image using the selected images with minimal user intervention. Experimental results on input images captured at various locations and scene conditions demonstrate the effectiveness of the proposed technique in seamlessly reconstructing user-defined occlusions.
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  • Masahiro OKUDA, Nicola ADAMI
    Type: PAPER
    Subject area: Image Coding
    2008 Volume E91.A Issue 10 Pages 2928-2933
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper, we propose a coding method for camera raw images with high dynamic ranges. Our encoder has two layers. In the first layer, 24bit low dynamic range image is encoded by a conventional codec, and then the residual image that represents the difference between the raw image and its approximation is encoded in the second layer. The approximation is derived by a polynomial fitting. The main advantage of this approach is that applying the polynomial model reduces the correlation between the raw and 24bit images, which increases coding efficiency. Experiments shows compression efficiency is significantly improved by taking an inverse tone mapping into account.
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  • Yiqing HUANG, Qin LIU, Takeshi IKENAGA
    Type: PAPER
    Subject area: Video Coding
    2008 Volume E91.A Issue 10 Pages 2934-2944
    Published: October 01, 2008
    Released: March 01, 2010
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    In H.264/AVC standard, many new techniques such as variable block size (VBS) and multiple reference frame (MRF) are used in motion estimation (ME) part to achieve superior coding performance. However, the use of new techniques will also cause great burden on computation complexity, which leads to problems in low power hardware implementation. Many software based fast ME algorithms are proposed to reduce complexity. For real-time hardwired encoder, the huge throughput of fractional motion estimation (FME) and integer motion estimation (IME) makes pipeline stage a must. In this case, IME is arranged in a single stage, which deteriorates the efficiency of many software based algorithms. Based on the hardware data flow, this paper provides a complexity reduction algorithm which speeds up ME procedure through three schemes. Firstly, the proposed algorithm executes similarity analysis to detect big mode MB and apply early termination in IME stage. Secondly, for normal MB, motion feature is extracted after IME of each frame and a 6-ring based search range adjustment scheme is introduced to remove redundant search positions. Thirdly, for MBs which have large motion feature, the pixel difference is very small due to the blur effect on video sensor. So, we use subsampling technique to reduce computation complexity for such MBs. Experimental results show that, compared with hardware friendly full search algorithm, the proposed fast ME algorithm can reduce 52.63% to 83.21% ME time with negligible video quality degradation. Furthermore, since the proposed algorithm works in a hardware friendly way, it can be embedded into 3-stage real-time hardwired video encoder to achieve low power design.
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  • Lei WANG, Jun WANG, Satoshi GOTO, Takeshi IKENAGA
    Type: PAPER
    Subject area: Video Coding
    2008 Volume E91.A Issue 10 Pages 2945-2953
    Published: October 01, 2008
    Released: March 01, 2010
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    With the ubiquitous application of Internet and wireless networks, H.264 video communication becomes more and more common. However, due to the high-efficiently predictive coding and the variable length entropy coding, it is more sensitive to transmission errors. The current error concealment (EC) scheme, which utilizes the spatial and temporal correlations to conceal the corrupted region, produces unsatisfied boundary artifacts. In this paper, first we propose variable block size error concealment (VBSEC) scheme inspired by variable block size motion estimation (VBSME) in H.264. This scheme provides four EC modes and four sub-block partitions. The whole corrupted macro-block (MB) will be divided into variable block size adaptively according to the actual motion. More precise motion vectors (MV) will be predicted for each sub-block. Then MV refinement (MVR) scheme is proposed to refine the MV of the heterogeneous sub-block by utilizing three step search (TSS) algorithm adaptively. Both VBSEC and MVR are based on our directional spatio-temporal boundary matching algorithm (DSTBMA). By utilizing these schemes, we can reconstruct the corrupted MB in the inter frame more accurately. The experimental results show that our proposed scheme can obtain better objective and subjective EC quality, respectively compared with the boundary matching algorithm (BMA) adopted in the JM 11.0 reference software, spatio-temporal boundary matching algorithm (STBMA) and other comparable EC methods.
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  • Jun WANG, Lei WANG, Takeshi IKENAGA, Satoshi GOTO
    Type: PAPER
    Subject area: Video Coding
    2008 Volume E91.A Issue 10 Pages 2954-2962
    Published: October 01, 2008
    Released: March 01, 2010
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    Transmission of compressed video over error prone channels may result in packet losses or errors, which can significantly degrade the image quality. Therefore an error concealment scheme is applied at the video receiver side to mask the damaged video. Considering there are 3 types of MBs (Macro Blocks) in natural video frame, i. e., Textural MB, Edged MB, and Smooth MB, this paper proposes an adaptive spatial error concealment which can choose 3 different methods for these 3 different MBs. For criteria of choosing appropriate method, 2 factors are taken into consideration. Firstly, standard deviation of our proposed edge statistical model is exploited. Secondly, some new features of latest video compression standard H.264/AVC, i. e., intra prediction mode is also considered for criterion formulation. Compared with previous works, which are only based on deterministic measurement, proposed method achieves the best image recovery. Subjective and objective image quality evaluations in experiments confirmed this.
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  • Tuchsanai PLOYSUWAN, Sawat TANTIPHANWADI, Prasit TEEKAPUT
    Type: PAPER
    Subject area: DS-CDMA
    2008 Volume E91.A Issue 10 Pages 2963-2972
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper, we develop a new iterative turbo multiuser detector for direct sequence code-division multiple access (DS-CDMA) systems over unknown frequency-selective channels by decomposing the observation signal into a number of signal components. Virtual trellis model representing the ISI channel for each separating signal user is designed to generate extrinsic probability in term of BCJR algorithm for exchange with a single channel decoder as priori information. Minimum kullback-leibler (MKL) framework is derived to calculate numerical channel estimation and extrinsic probability. In comparison with other similar receiver, simulation results demonstrate that the proposed solution achieves the desirable performance.
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  • Chusit PRADABPET, Shingo YOSHIZAWA, Yoshikazu MIYANAGA, Kobchai DEJHAN
    Type: PAPER
    Subject area: OFDM
    2008 Volume E91.A Issue 10 Pages 2973-2979
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper, we propose a new PAPR reduction by using the hybrid of a partial transmit sequences (PTS) and an adaptive peak power reduction (APPR) methods with coded side information (SI) technique. These methods are used in an Orthogonal Frequency Division Multiplexing (OFDM) system. The OFDM employs orthogonal sub-carriers for data modulation. These sub-carriers unexpectedly present a large Peak to Average Power Ratio (PAPR) in some cases. In order to reduce PAPR, the sequence of input data is rearranged by PTS. The APPR method is also used to controls the peak level of modulation signals by an adaptive algorithm. A proposed reduction method consists of these two methods and realizes both advantages at the same time. In order to make the optimum condition on PTS for PAPR reduction, a quite large calculation cost must be demanded and thus it is impossible to obtain the optimum PTS. In the proposed method, by using the pseudo-optimum condition with a coded SI technique, the total calculation cost becomes drastically reduced. In simulation results, the proposed method shows the improvement on PAPR and also reveals the high performance on bit error rate (BER) of an OFDM system.
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  • Kenji YANO, Kiyoshi TANAKA
    Type: PAPER
    Subject area: Chaotic Communication
    2008 Volume E91.A Issue 10 Pages 2980-2989
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper proposes a novel chaotic multiple-bits modulation scheme that uses the parameters in the map as data carrier for chaotic digital communication. Chaotic signals modulated with the parameters corresponding to the information to be transmitted are sent to the receiver. The information sent to the receiver can be decoded by a correlation detector. This scheme can increase the number of transmittable information bit per unit carrier signals by increasing the number of mapping parameters to be used for modulation. We verify the performance of this scheme using bit error rate (BER) through computer simulation. Also, we compare the performance of the proposed method with a conventional single-bit modulation scheme.
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  • Changhyeon CHAE, Daewon CHOI, Taejin JUNG
    Type: PAPER
    Subject area: MIMO
    2008 Volume E91.A Issue 10 Pages 2990-2994
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper, a new full-rate space-time block code (STBC) possessing a quasi-orthogonal (QO) property is proposed for QAM and 8 transmit antennas. This code is designed by serially concatenating a real constellation-rotating precoder with the Alamouti scheme. The QO property enables ML decoding to be done with joint detection of only four real symbols like the conventional minimum decoding complexity QO-STBC (MDC-QO-STBC). However, the proposed code is guaranteed to achieve full spatial diversity for general QAM unlike the MDC-QO-STBC which is specifically presented for only 4-QAM. By computer simulation results, we show that the proposed code exhibits the identical and slightly degraded error performance with the MDC-QO-STBC for 4-QAM and the Sharma's QO-STBC for 4 and 16-QAM, respectively. Finally, we present a new modified scheme of the original code so that there is no any discontinuity of transmission at each transmit antenna, without any loss of error performance.
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  • Tein-Yaw CHUNG, Fong-Ching YUAN, Yung-Mu CHEN, Baw-Jhiune LIU
    Type: PAPER
    Subject area: Mobile Mulimedia Communication
    2008 Volume E91.A Issue 10 Pages 2995-3002
    Published: October 01, 2008
    Released: March 01, 2010
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    Selecting transparently a proper network connection for voice communication will be a fundamental requirement in future multimode heterogeneous wireless network. This paper presented a smart session selection (S3) scheme to meet this requirement. Instead of selecting a best access network as in conventional Always Best Connected (ABC) paradigm, S3 enables users to select a best network connection, which consists of source and destination access network pair, to satisfy quality constraint and users' preference. To support S3, we develop a user profile to specify network connection priority. Meanwhile IP multimedia subsystem (IMS) is extended to make smart decision for users. Finally, Analytic Hierarchy Process (AHP) is used to recommend a network connection with assistance of user profile and IMS signaling. An example is illustrated to show that AHP can successfully select a good network connection that fulfills the requirement of users.
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  • Jae Keun PARK, Wan Yeon LEE, Sung Je HONG, Jong KIM
    Type: LETTER
    Subject area: Mobile Information Network
    2008 Volume E91.A Issue 10 Pages 3003-3005
    Published: October 01, 2008
    Released: March 01, 2010
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    To satisfy both the bandwidth efficiency of low-speed mobile hosts (MHs) and seamless handoff of high-speed MHs in cellular networks, this paper proposes a reservation scheme which exploits a dynamic two-tier cell structure and the handoff probability. The dynamic two-tier cell structure determines the reservation and non-reservation zones according to the speed of MHs. The handoff probability is calculated using the moving speed and the direction of MHs.
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Regular Section
  • Rika NAKAO, Yoshinobu KAJIKAWA, Yasuo NOMURA
    Type: PAPER
    Subject area: Engineering Acoustics
    2008 Volume E91.A Issue 10 Pages 3006-3013
    Published: October 01, 2008
    Released: March 01, 2010
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    In this paper, we propose a method that uses Simulated Annealing (SA) to estimate the linear and nonlinear parameters of a closed-box loudspeaker system for implementing effective Mirror filters. The nonlinear parameters determined by W. Klippel's method are sometimes inaccurate and imaginary. In contrast, the proposed method can estimate the parameters with satisfactory accuracy due to its use of SA; the resulting impedance and displacement characteristics match those of an actual equivalent loudspeaker. A Mirror filter designed around these parameters can well compensate the nonlinear distortions of the loudspeaker system. Experiments demonstrate that the method can reduce the levels of nonlinear distortion by 5dB to 20dB compared to the before compensation condition.
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  • Shunsuke KOSHITA, Satoru TANAKA, Masahide ABE, Masayuki KAWAMATA
    Type: PAPER
    Subject area: Systems and Control
    2008 Volume E91.A Issue 10 Pages 3014-3021
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper proposes the Gramian-preserving frequency transformation for linear discrete-time state-space systems. In this frequency transformation, we replace each delay element of a discrete-time system with an allpass system that has a balanced realization. This approach can generate transformed systems that have the same controllability/observability Gramians as those of the original system. From this result, we show that the Gramian-preserving frequency transformation gives us transformed systems with different magnitude characteristics, but with the same structural property with respect to the Gramians as that of the original system. This paper also presents a simple method for realization of the Gramian-preserving frequency transformation. This method makes use of the cascaded normalized lattice structure of allpass systems.
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  • Muneomi SAGARA, Hiroaki MUKAIDANI, Toru YAMAMOTO
    Type: PAPER
    Subject area: Systems and Control
    2008 Volume E91.A Issue 10 Pages 3022-3029
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper discusses the infinite horizon static output feedback stochastic Nash games involving state-dependent noise in weakly coupled large-scale systems. In order to construct the strategy, the conditions for the existence of equilibria have been derived from the solutions of the sets of cross-coupled stochastic algebraic Riccati equations (CSAREs). After establishing the asymptotic structure along with the positive semidefiniteness for the solutions of CSAREs, recursive algorithm for solving CSAREs is derived. As a result, it is shown that the proposed algorithm attains the reduced-order computations and the reduction of the CPU time. As another important contribution, the uniqueness of the strategy set is proved for the sufficiently small parameter ε. Finally, in order to demonstrate the efficiency of the proposed algorithm, numerical example is given.
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  • Yukihide KOHIRA, Atsushi TAKAHASHI
    Type: PAPER
    Subject area: VLSI Design Technology and CAD
    2008 Volume E91.A Issue 10 Pages 3030-3037
    Published: October 01, 2008
    Released: March 01, 2010
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    Under the assumption that the clock can be inputted to each register at an arbitrary timing, the minimum feasible clock period might be reduced by register relocation while maintaining the circuit behavior and topology. However, if the minimum feasible clock period is reduced, then the number of registers tends to be increased. In this paper, we propose a gate-level register relocation method that reduces the number of registers while keeping the target clock period. In experiments, the proposed method reduces the number of registers in the practical time in most circuits.
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  • Yuki WATANABE, Naofumi HOMMA, Takafumi AOKI, Tatsuo HIGUCHI
    Type: PAPER
    Subject area: VLSI Design Technology and CAD
    2008 Volume E91.A Issue 10 Pages 3038-3046
    Published: October 01, 2008
    Released: March 01, 2010
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    This paper presents a formal approach to verify arithmetic circuits using symbolic computer algebra. Our method describes arithmetic circuits directly with high-level mathematical objects based on weighted number systems and arithmetic formulae. Such circuit description can be effectively verified by polynomial reduction techniques using Gröbner Bases. In this paper, we describe how the symbolic computer algebra can be used to describe and verify arithmetic circuits. The advantageous effects of the proposed approach are demonstrated through experimental verification of some arithmetic circuits such as multiply-accumulator and FIR filter. The result shows that the proposed approach has a definite possibility of verifying practical arithmetic circuits.
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  • Jongsung KIM, Changhoon LEE, Jaechul SUNG, Seokhie HONG, Sangjin LEE, ...
    Type: PAPER
    Subject area: Cryptography and Information Security
    2008 Volume E91.A Issue 10 Pages 3047-3058
    Published: October 01, 2008
    Released: March 01, 2010
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    The design and analysis of block ciphers is an established field of study which has seen significant progress since the early 1990s. Nevertheless, what remains on an interesting direction to explore in this area is to design block ciphers with provable security against powerful known attacks such as differential and linear cryptanalysis. In this paper we introduce seven new block cipher structures, named Feistel-variant A, B, CLEFIA and MISTY-FO-variant A, B, C, D structures, and show that these structures are provably resistant against differential cryptanalysis. The main results of this paper are that the average differential probabilities over at least 2 rounds of Feistel-variant A structure and 1 round of Feistel-variant B structure are both upperbounded by p2, while the average differential probabilities over at least 5 rounds of CLEFIA, MISTY-FO-variant A, B, C and D structures are upperbounded by p4+2p5, p4, p4, 2p4 and 2p4, respectively, if the maximum differential probability of a round F function is p. We also give provable security for the Feistel-variant A, B and CLE-FIA structures against linear cryptanalysis. Our results are attained under the assumption that all of components in our proposed structures are bijective. We expect that our results are useful to design block ciphers with provable security against differential and linear cryptanalysis.
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  • Yoshifumi CHISAKI, Toshimichi TAKADA, Masahiro NAGANISHI, Tsuyoshi USA ...
    Type: LETTER
    Subject area: Engineering Acoustics
    2008 Volume E91.A Issue 10 Pages 3059-3062
    Published: October 01, 2008
    Released: March 01, 2010
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    The frequency domain binaural model (FDBM) has been previously proposed to localize multiple sound sources. Since the method requires only two input signals and uses interaural phase and level differences caused by the diffraction generated by the head, flexibility in application is very high when the head is considered as an object. When an object is symmetric with respect to the two microphones, the performance of sound source localization is degraded, as a human being has front-back confusion due to the symmetry in a median plane. This paper proposes to reduce the degradation of performance on sound source localization by a combination of the microphone pair outputs using the FDBM. The proposed method is evaluated by applying to a security camera system, and the results showed performance improvement in sound source localization because of reducing the number of cones of confusion.
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  • Zhenjie FENG, Taiyi ZHANG, Erlin ZENG
    Type: LETTER
    Subject area: Digital Signal Processing
    2008 Volume E91.A Issue 10 Pages 3063-3066
    Published: October 01, 2008
    Released: March 01, 2010
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    Focusing on time correlation of real communication channels, a channel quantization algorithm based on finite state vector quantization (FSVQ) is proposed. Firstly channels are partitioned into finite states, then codebooks corresponding to each state are constructed, which are used to quantize channels transferred from corresponding states. Further, the state transition function is designed to ensure the synchronization between transmitter and receiver. The proposed algorithm can achieve improved performance with the same feedback load compared with classical memoryless channel quantizer without consideration of the influence of time correlation. Simulation results verify the effectiveness of the proposed algorithm.
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  • Woon-Yong PARK, Sungsoo CHOI, Won-Cheol LEE
    Type: LETTER
    Subject area: Digital Signal Processing
    2008 Volume E91.A Issue 10 Pages 3067-3070
    Published: October 01, 2008
    Released: March 01, 2010
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    During the execution of precise ranging in the time domain, the most important fact to consider is how to achieve an accurate estimate of the time corresponding to first arrival of the transmitter. However, it is difficult to extract an estimate of the time-of-arrival (TOA) through use of a simple correlator due to degradation on correlation, and in the case where the pulse repetition interval (PRI) is less than the maximum excess delay (MED). In order to enhance the correlation capability, this paper proposes a TOA estimation method that obeys a threshold predetermined in a non-coherent system using multiple-mask operation (MMO). The performance of the proposed scheme is verified by conducting simulations under two different types of channel situations. The simulation results show that the proposed scheme performs well even in a dense indoor multipath environment and with the existence of multiple simultaneously operating piconets (SOPs).
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