IEEE 802.11 standard and the enhanced amendments have defined several transmission rates for mobile stations to transmit and receive data frames. With the characteristic of modulation schemes, a higher network throughput can be expected by using higher level modulation scheme, but frame error probability will also become higher. Doubtlessly, it is an open issue of selecting a proper modulation scheme for a pair of mobile stations in time-varying indoor environment. This paper proposes a safe multiple access-rates transmission (SMART) scheme to enhance the reliability of data transmission in IEEE 802.11 multi-rate infrastructure wireless networks. SMART scheme provides reliable transmission by reserving a retransmission period which immediately follows the transmitted frame and is estimated by a lower transmission rate according to the transmitted frame. The performance of SMART scheme is evaluated by analytical model and simulation experiment, which show that the proposed scheme is significantly better than the IEEE 802.11 standard under the real environment with asymmetric traffic load. An enhanced SMART (ESMART) scheme is also proposed especially to improve bandwidth waste for long packet length at access point (AP). The performance measurements, such as goodput, throughput, average access delay, and service rate, are obtained and compared for the different schemes.

The present paper introduces a new construction of a class of binary sequence set having a zero-correlation zone (hereafter binary zcz sequence set). The cross-correlation function and the side-lobe of the auto-correlation function of the proposed sequence set is zero for the phase shifts within the zero-correlation zone. This paper shows that such a construction generates a binary zcz sequence set from an arbitrary pair of Hadamard matrices of common size. Since the proposed sequence construction generates a sequence set from an arbitrary pair of Hadamard matrices, many more types of sequence sets can be generated by the proposed sequence construction than is possible by a sequence construction that generates sequence sets from a single arbitrary Hadamard matrix.

In face recognition, simple classifiers are frequently used. For a robust system, it is common to construct a multi-class classifier by combining the outputs of several binary classifiers; this is called output coding method. The two basic output coding methods for this purpose are known as OnePerClass (OPC) and PairWise Coupling (PWC). The performance of output coding methods depends on accuracy of base dichotomizers. Support Vector Machine (SVM) is suitable for this purpose. In this paper, we review output coding methods and introduce a new sequential fusion method using SVM as a base classifier based on OPC and PWC according to their properties. In the experiments, we compare our proposed method with others. The experimental results show that our proposed method can improve the performance significantly on the real dataset.

We propose a new method for Depth from Defocus (DFD) using wavelet transform. Most of the existing DFD methods use inverse filtering in a transform domain to determine the measure of defocus. These methods suffer from inaccuracies in finding the frequency domain representation due to windowing and border effects. The proposed method uses wavelets that allow performing both the local analysis and windowing with variable-sized regions for images with varying textural properties. Experimental results show that the proposed method gives more accurate depth maps than the previous methods.

It is inevitable for driver assist and warning systems to consider the drivers' state of consciousness. Drowsiness is one of the important factors in estimating the drivers' state of consciousness. A Method to extract the driver's initial stage of drowsiness was developed by means of the eyelid's opening relevant to each various characteristic of objects with motion pictures processing in the actual driving environment. The result was that an increase of the long eyelid closure time was the key factor in estimating the initial stage of drivers' drowsiness while driving. And the state of drowsiness could be presumed by checking the frequencies of long eyelid closure time per unit period.

The side channel attack (SCA) is a serious attack on wearable devices that have scarce computational resources. Cryptographic algorithms on them should be efficient using small memory--we have to make efforts to optimize the trade-off between efficiency and memory. In this paper we present efficient SCA-resistant scalar multiplications based on window method. Moller proposed an SPA-resistant window method based on 2w-ary window method, which replaces w-consecutive zeros to 1 plus w-consecutive and it requires 2w points of table (or 2w-1 + 1 points if the signed 2w-ary is used). The most efficient window method with small memory is the width-w NAF, which requires 2w-2 points of table. In this paper we convert the width-w NAF to an SPA-resistant addition chain. Indeed we generate a scalar sequence with the fixed pattern, e.g. |00x|00x||00x|, where x is positive odd points < 2w. Thus the size of the table is 2w-1, which is optimal in the construction of the SPA-resistant chain based on width-w NAF. The table sizes of the proposed scheme are 6% to 50% smaller than those of Moller's scheme for w = 2,3,4,5, which are relevant choices in the sense of efficiency for 160-bit ECC.

The reduction of undesired electromagnetic emissions in switched power converters is a hot topic. Here, we propose a chaos based methodology to synthesize PWM-like signals for controlling the drives of induction motors. This approach reduces drastically the interference due to the drive-motor ensemble, and does not significantly alter the motor performance. The benefit is a 20 dB reduction in the peak of the emitted power density spectrum. This result is herein confirmed three times: first with an analytical approach based on approximations whose impact is progressively reduced; then by means of simulation; finally by laboratory testing of a working prototype.

A polarization switchable slot-coupled microstrip antenna using PIN diodes is proposed and studied. The microstrip feed line installed behind the ground plane is divided into two branches and each tip of the branches is connected to the ground plane through a PIN diode. One of the diodes is oriented from the tip to the ground plane and the other is oriented from the ground to the tip so that a slot in the ground can be selected to feed the patch by switching the dc bias between positive and negative. This selection contributes to switch the polarization between horizontal and vertical. In this paper, the authors investigate the polarization switching antenna theoretically and experimentally and confirmed sufficient differencce of antenna gain between horizontal and vertical polarization.

This paper presents a novel technique for reconstructing an outdoor sculpture from an uncalibrated image sequence acquired around it using a hand-held camera. The technique introduced here uses only the silhouettes of the sculpture for both motion estimation and model reconstruction, and no corner detection nor matching is necessary. This is very important as most sculptures are composed of smooth textureless surfaces, and hence their silhouettes are very often the only information available from their images. Besides, as opposed to previous works, the proposed technique does not require the camera motion to be perfectly circular (e.g., turntable sequence). It employs an image rectification step before the motion estimation step to obtain a rough estimate of the camera motion which is only approximately circular. A refinement process is then applied to obtain the true general motion of the camera. This allows the technique to handle large outdoor sculptures which cannot be rotated on a turntable, making it much more practical and flexible.

In this paper, a process is described for analysing the motion of a human target in a video stream. Moving targets are detected and their boundaries extracted. From these, a "star" skeleton is produced. Two motion cues are determined from this skeletonization: body posture, and cyclic motion of skeleton segments. These cues are used to determine human activities such as walking or running, and even potentially, the target's gait. Unlike other methods, this does not require an a priori human model, or a large number of "pixels on target". Furthermore, it is computationally inexpensive, and thus ideal for real-world video applications such as outdoor video surveillance.

In this paper, we give a theoretical analysis of χ2 attack proposed by Knudsen and Meier on the RC6 block cipher. To this end, we propose a method of security evaluation against χ2 attack precisely including key dependency by introducing a method "Transition Matrix Computing." Previously, no theoretical security evaluation against χ2 attack was known, it has been done by computer experiments. We should note that it is the first result concerning the way of security evaluation against χ2 attack is shown theoretically.

We propose a simple method for the chromatic dispersion measurement of optical fibers by using bi-directional modulation of a Mach-Zehnder electro-optical modulator embodied in a fiber loop mirror. The detected output of the bi-directionally modulated light, with time difference, creates fading in the RF domain. Dispersion is found by measuring the period of fading at different wavelengths.

A new approach for electronic sealed-bid auctions that preserve the privacy of losing bids is presented. It reduces the number of operations performed by the auctioneers to O(log ); previous protocols require O(N ) or O(N log ) where the number of bidders is N and that of available bidding prices is . Namely, the number of auctioneers' operations in our auction protocol is independent of the number of bidders. This feature offers strong advantages in massive auctions. We also propose a new scheme that checks the equality of two values without disclosing them. The scheme enhances our basic auction protocol, in terms of security and communication costs.

Digital signatures whose security does not rely on any unproven computational assumption have recently received considerable attention. While these unconditionally secure digital signatures provide a foundation for long term integrity and non-repudiation of data, currently known schemes generally require a far greater amount of memory space for the storage of secret and public keys than a traditional digital signature. The focus of this paper is on methods for reducing memory requirements of unconditionally secure digital signatures. A major contribution of this paper is to propose two novel unconditionally secure digital signature schemes, one called a symmetric construction and other an asymmetric construction, which require a significantly smaller amount of memory. As a specific example, with a typical parameter setting the required memory size for a user is reduced to be approximately of that in a previously known scheme. Another contribution of the paper is to show an attack on a multireceiver authentication code which was proposed by Safavi-Naini and Wang. A simple method to fix the problem of the multireceiver authentication code is also proposed.

This paper addresses how to use public-keys of several different signature schemes to generate 1-out-of-n signatures. Previously known constructions are for either RSA-type keys only or DL-type keys only. We present a widely applicable method to construct a 1-out-of-n signature scheme that allows mixture use of different flavors of keys at the same time. The resulting scheme is more efficient than previous schemes even if it is used only with a single type of keys. With all DL-type keys, it yields shorter signatures than the ones of the previously known scheme based on the witness indistinguishable proofs by Cramer, et al. With all RSA-type keys, it reduces both computational and storage costs compared to that of the Ring signatures by Rivest, et al.

In this paper, a fragment-processing solution in 3D graphics rendering algorithms based on fragment lists (i.e. A-buffer) for minimizing loss of image quality is described. While all fragment information should be preserved for exact hidden surface removal, this places additional strain on hardware in terms of silicon gates and clock cycles. Therefore, we propose a fragment processing technique that can effectively merge fragments in order to decrease the depth of fragment lists. It renders scenes quite accurately even in the case when three fragments intersect each other. This algorithm improves hardware acceleration without deteriorating image quality.

The processing of noise-corrupted signals is a common problem in signal processing applications. In most of the cases, it is assumed that the additive noise is white Gaussian and that the constant noise variance is either available or can be easily measured. However, this may not be the case in practical situations. We present a new approach to additive white Gaussian noise variance estimation. The observations are assumed to be from an autoregressive process. The method presented here is iterative, and uses low-order Yule-Walker equations (LOYWEs). The noise variance is obtained by minimizing the difference in the second norms of the noisy Yule-Walker solution and the estimated noise-free Yule-Walker solution. The noise-free solution is constrained to match the observed autocorrelation sequence. In the iterative noise variance estimation method, a variable step-size update scheme for the noise variance parameter is utilized. Simulation results are given to confirm the effectiveness of the proposed method.

The Single Instruction, Multiple Data (SIMD) architecture enables computation in parallel on a single processor. The SIMD operations are implemented on some processors such as Pentium 3/4, Athlon, SPARC, or even on smart cards. This paper proposes efficient algorithms for assembling an elliptic curve addition (ECADD), doubling (ECDBL), and k-iterated ECDBL (k-ECDBL) with SIMD operations. We optimize the number of auxiliary variables and the order of basic field operations used for these addition formulas. If an addition chain has k-bit zero run, we can replace k-time ECDBLs to the proposed faster k-ECDBL and the total efficiency of the scalar multiplication can be improved. Using the singed binary chain, we can compute a scalar multiplication about 10% faster than the previously fastest algorithm proposed by Aoki et al. Combined with the sliding window method or the width-w NAF window method, we also achieve about 10% faster parallelized scalar multiplication algorithms with SIMD operations. For the implementation on smart cards, we establish two fast parallelized scalar multiplication algorithms with SIMD resistant against side channel attacks.

Faces of a person performing freely in front of the camera can be captured in a sufficient resolution for facial parts recognition by the proposed camera system enhanced with a special PTZ camera. Head region, facial parts regions such as eyes and mouth and the borders of facial parts are extracted hierarchically by being guided by the irises and nostrils preliminarily extracted from the images of PTZ camera. In order to show the effectivity of this system, we proposed a possibility to generate the borders of facial parts of the face for the facial caricaturing and to introduce eye-contacting facial images which can eye-contact bilaterally with each other on the TV conference environment.

Davidson's scheme utilizes the order of basic blocks to embed a digital signature in a computer program. To preserve the function of the original program, additional jump instructions are inserted. This involves some overhead in both size and performance. In our implementation, the increase in size was between 9% and 24%. The performance of benchmark programs was 86-102% of the original.