IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences - current issue

Identity-Based Encryptions with Tight Security Reductions to the BDH Problem

NISHIOKA, M. — 2008-05-16

We present IND-ID-CPA secure identity-based encryption (IBE) schemes with tight reductions to the bilinear Diffie-Hellman (BDH) problem. Since the methods for obtaining IND-ID-CCA secure schemes from IND-ID-CPA secure schemes with tight reductions are already known, we can consequently obtain IND-ID-CCA secure schemes with tight reductions to the BDH problem. Our constructions are based on IBE schemes with tight reductions to the list bilinear Diffie-Hellman (LBDH) problem, and the schemes are converted to those with tight reductions to the BDH problem. Interestingly, it can be shown that there exists a black box construction, in which the former IBE schemes are given as black boxes. Our constructions are very simple and reasonably efficient.

A Digital Signature Scheme Based on NP-Complete Lattice Problems

HAYASHI, S., TADA, M. — 2008-05-16

In [13], we proposed new decision problems related to lattices, and proved their NP-completeness. In this paper, we present a new public-key identification scheme and a digital signature scheme based on one of the problems in [13]. We also prove the security of our schemes under certain assumptions, and analyze the efficiency of ours.

A Simple Adaptive Algorithm for Principle Component and Independent Component Analysis

SHIN, H.-C., KIM, H.-N., SONG, W.-J. — 2008-05-16

In this letter we propose a simple adaptive algorithm which solves the unit-norm constrained optimization problem. Instead of conventional parameter norm based normalization, the proposed algorithm incorporates single parameter normalization which is computationally much simpler. The simulation results illustrate that the proposed algorithm performs as good as conventional ones while being computationally simpler.

A Closed Form Solution to L2-Sensitivity Minimization of Second-Order State-Space Digital Filters

YAMAKI, S., ABE, M., KAWAMATA, M. — 2008-05-16

This paper proposes a closed form solution to L₂-sensitivity minimization of second-order state-space digital filters. Restricting ourselves to the second-order case of state-space digital filters, we can express the L₂-sensitivity by a simple linear combination of exponential functions and formulate the L₂-sensitivity minimization problem by a simple polynomial equation. As a result, the L₂-sensitivity minimization problem can be converted into a problem to find the solution to a fourth-degree polynomial equation of constant coefficients, which can be algebraically solved in closed form without iterative calculations.

A Global Stability Analysis of a Class of Nolinear Time-Delay Systems Using Continued Fraction Property

CHOI, J.-Y. — 2008-05-16

We consider a class of nonlinear time delay systems with time-varying delays, and achieve a time delay independent sufficient condition for the global asymptotic stability. The sufficient condition is proved by constructing a continued fraction that represents the lower and upper bound variations of the system trajectory along the current of time, and showing that the continued fraction converges to the equilibrium point of the system. The simulation results show the validity of the sufficient condition, and illustrate that the sufficient condition is a close approximation to the unknown necessary and sufficient condition for the global asymptotic stability.

Efficient Calculation of the Transition Matrix in a Max-Plus Linear State-Space Representation

GOTO, H. — 2008-05-16

This research considers an efficient method for calculating the transition matrix in an MPL (Max-Plus Linear) state-space representation. This matrix can be generated by applying the Kleene star operator to an adjacency matrix. The proposed method, based on the idea of a topological sort in graph theory and block splitting, is able to calculate the transition matrix efficiently.

Extended MPEG Video Format for Efficient Dynamic Voltage Scaling

BANG, K., BANG, S.-Y., CHUNG, E.-Y. — 2008-05-16

We present an extended MPEG video format for efficient Dynamic Voltage Scaling (DVS). DVS technique has been widely researched, but the execution time variation of a periodic task (i.e. MPEG decoding) is still a challenge to be tackled. Unlike previous works, we focus on the data (video stream) rather than the execution code to overcome such limitation. The proposed video format provides the decoding costs of frames to help the precise prediction of their execution times at client machines. The experimental results show that the extended format only increases the data size less than 1% by adding about 10 bits representing the decoding cost of each frame. Also, a DVS technique adjusted for the proposed format achieves 90% of efficiency compared to the oracle case, while keeping the run time overhead of the technique negligible.

Binary Constant Weight Codes Based on Cyclic Difference Sets

LI, N., ZENG, X., HU, L. — 2008-05-16

Based on cyclic difference sets, sequences with two-valued autocorrelation can be constructed. Using these constructed sequences, two classes of binary constant weight codes are presented. Some codes proposed in this paper are proven to be optimal.

Performance of Multiband OFDM Systems with Extra Diversity

KIM, J.-H., KIM, S.-T., SONG, H.-K., YOU, Y.-H. — 2008-05-16

This letter presents the performance of ultra-wideband multi-band orthogonal frequency division multiplexing (UWB MB-OFDM) systems with an extra diversity. To fully obtain diversity gain in the current MB-OFDM system when a time-domain spreading (TDS) is adopted, two consecutive OFDM symbols are designed to be cyclic shifted against each other. Simulation results indicate that the MB-OFDM system using additional frequency diversity outperforms conventional MB-OFDM system.

Improved Fine Frequency Synchronization Method for OFDM-Based DRM

YOU, Y.-H., KIM, S.-T., LEE, K.-T., SONG, H.-K. — 2008-05-16

In this letter, a robust pilot-assisted synchronization scheme is proposed for estimation of residual frequency offset (RFO) in OFDM-based digital radio mondiale (DRM) system. The RFO estimator uses the gain reference pilots mainly reserved for the channel tracking in the DRM standard. To demonstrate the efficiency of the proposed RFO estimator, comparisons are made with the conventional RFO estimator using the frequency reference pilots in terms of mean square error (MSE) performance.