Using a pair of matched square-root-raised-cosine (SRRC) filters in the transmitter and the receiver in a band-limited digital communication system can theoretically achieve zero inter-symbol interference (ISI). In reality, the ISI cannot be zero when both SRRC filters are approximately implemented because of some numerical precision problems in the design phase as well as in the implementation phase. In this paper, the author proposes an iterative method to design the coefficients of SRRC FIR filters. The required ISI of the system can be specified such that both ISI and frequency domain specifications are monitored in the design phase. Since the ISI can be specified beforehand, the tradeoff between performance and the filter length becomes possible in the proposed design algorithm.

We propose and demonstrate a new fabrication process of a microchannel using the Damascene process. This process aims to integrate photonic circuits with microchannels fabricated in a glass film. The microchannel is fabricated by the removal of the sacrificial layer after a sacrificial layer is formed by the Damascene process and the cover is formed by sputter deposition. A thin cover layer can be formed by the sacrificial method, because the cover layer is supported by the sacrificial layer during film formation. The cover layer is hermetically sealed, since it is formed by radio frequency (RF) sputtering deposition. The thickness is 1 µm and the width ranges from 3.5 to 8 µm. Using the proposed microchannel fabrication method, we prepared a microelectromechanical system (MEMS) optical switch using microfluidics, and we confirmed its functional operation. This optical switch actuates a minute droplet of liquid injected into the microchannel using Maxwell's stresses. Light propagates straight through the waveguide so that the light passes through the microchannel when the droplet is in the microchannel, but the light rays are completely reflected into a crossed waveguide when the droplet is not in the microchannel. Since this fabrication method uses techniques common to those in the formation of copper wiring in an IC chip, it can be used in the microchannel process.

In CDMA cellular systems, the frequency reuse factor equals one. Therefore, the soft-handoff technology with combining macroscopic diversity was introduced to enhance the link performance. In this work, a novel macroscopic diversity combining scheme is proposed to enhance the link performance of the forward-link. The basic concept of this scheme is to integrate error correction coding into the soft-handoff technology. According to the number of soft-handoff channels, the source information is encoded by a convolutional code with a lower code rate. The coded symbols are then equally distributed to all channels from different BSs to the MS, and each channel carries a disjointed set of coded symbols. For this proposed scheme, no extra transmission power or bandwidth is required. The only cost is a slight increase of the encoding and decoding complexity of the convolutional codes. Numerical and simulation results show that a performance gain of 1 dB in bit energy-to-total noise power density ratio can be obtained as compared with the conventional scheme in the same conditions.

To make the best use of the resources in a shared grid environment, an application scheduler must make a prediction of available performance on each resource. In this paper, we examine the problem of predicting available CPU performance in time-shared grid system. We present and evaluate a new and innovative method to predict the one-step-ahead CPU load in a grid. Our prediction strategy forecasts the future CPU load based on the variety tendency in several past steps and in previous similar patterns, and uses a polynomial fitting method. Our experimental results on large load traces collected from four different kinds of machines demonstrate that this new prediction strategy achieves average prediction errors which are between 22% and 86% less than those incurred by four previous methods.

The relationship between the topology and collective function of a nonlinear oscillator network was investigated using nonlinear electrochemical oscillators. The constitutive experiments showed that the physiological robustness in the living system is due to their topological redundancy and asymmetry in the nonlinear network.

A typical watermarking scheme consists of an embedding scheme and a detection scheme. In detecting a watermark, there are two kinds of detection errors, a false positive error (FPE) and a false negative error (FNE). A detection scheme is said to be optimum if the FNE probability is minimized for a given FPE probability. In this paper, we present an optimum watermark detection scheme for an additive embedding scheme with a spatial domain. The key idea of the proposed scheme is to use the differences between two brightnesses for detecting a watermark. We prove that under the same FPE probability the FNE probability of the proposed optimum detection scheme is no more than that of the previous optimum detection scheme for the additive embedding scheme with the spatial domain. Then, it is confirmed that for an actual image, the FNE probability of the proposed optimum detection scheme is much lower than that of the previous optimum detection scheme. Moreover, it is confirmed experimentally that the proposed optimum detection scheme can control the FPE probability strictly so that the FPE probability is close to a given probability.

The coexistence of MPEG-2 and its powerful successor H.264/AVC has created a huge need for MPEG-2/H.264 video transcoding. However, a traditional transcoder where an MPEG-2 decoder is simply cascaded to an H.264 encoder requires huge computational power due to the adoption of a complicated rate-distortion based mode decision process in H.264. This paper proposes a 2-D Sobel filter based motion vector domain method and a DCT domain method to measure macroblock complexity and realize content-based H.264 candidate mode decision. A new local edge based fast INTRA prediction mode decision method is also adopted to boost the encoding efficiency. Simulation results confirm that with the proposed methods the computational burden of a traditional transcoder can be reduced by 20%30% with only a negligible bit-rate increase for a wide range of video sequences.

The UWB (ultra-wideband) pulse radar is a promising candidate as an environment measurement method for rescue robots. Radar imaging to locate a nearby target is known as an ill-posed inverse problem, on which various studies have been done. However, conventional algorithms require long computational time, which makes it difficult to apply them to real-time operations of robots. We have proposed a fast radar imaging algorithm, the SEABED algorithm, for UWB pulse radars. This algorithm is based on a reversible transform, BST (Boundary Scattering Transform), between the target shape and the observed data. This transform enables us to estimate target shapes quickly and accurately in a noiseless environment. However, in a noisy environment the image estimated by the SEABED algorithm is degraded because BST utilizes differential operations. We have also proposed an image stabilization method, which utilizes the upper bound of the smoothness of received data. This method can be applied only to convex objects, not to concave ones. In this paper, we propose a fractional BST, which is obtained by expanding the conventional BST, and an image stabilization method by using the fractional BST. We show that the estimated image can be stabilized regardless of the shape of target.

A remote user authentication scheme is a two-party protocol whereby an authentication server in a distributed system confirms the identity of a remote individual logging on to the server over an untrusted, open network. Recently, Lee et al. have proposed an efficient nonce-based scheme for remote user authentication using smart cards. This work reviews Lee et al.'s authentication scheme and provides a security analysis on the scheme. Our analysis shows that Lee et al.'s scheme does not achieve its basic aim of authenticating remote users and furthermore has a very hazardous method for changing passwords. In addition, we recommend some changes to the scheme so that it can attain at least its main security goal.

This paper studies the reduction among cyptographic functions. Our main result is that the prime factoring function IF does not reduce to the certified discrete logarithm function modulo a prime nor its variant with respect to some special reducibility, i.e. the range injection reducibility, under the assumption that the Heath-Brown conjecture is true and IFPF. Since there is no known direct relationship between these functions, this is the first result that could separate these functions. Our approach is based on the notion of the preimage functions.

We present generic frameworks for constructing efficient broadcast encryption schemes in the subset-cover paradigm, introduced by Naor et al., based on various key derivation techniques. Our frameworks characterize any instantiation completely to its underlying graph decompositions, which are purely combinatorial in nature. These abstract away the security of each instantiated scheme to be guaranteed by the generic one of the frameworks; thus, give flexibilities in designing schemes. Behind these, we present new techniques based on (trapdoor) RSA accumulators utilized to obtain practical performances. We then give some efficient instantiations from the frameworks, via a new structure called subset-incremental-chain. Our first construction improves the currently best schemes, including the one proposed by Goodrich et al., without any further assumptions (only pseudo-random generators are used) by some factors. The second instantiation, which is the most efficient, is instantiated based on RSA and directly improves the first scheme. Its ciphertext length is of order O(r), the key size is O(1), and its computational cost is O(n1/klog2 n) for any (arbitrary large) constant k; where r and n are the number of revoked users and all users respectively. To the best of our knowledge, this is the first explicit collusion-secure scheme in the literature that achieves both ciphertext size and key size independent of n simultaneously while keeping all other costs efficient, in particular, sub-linear in n. The third scheme improves Gentry and Ramzan's scheme, which itself is more efficient than the above schemes in the aspect of asymptotic computational cost.

In this letter, a 1.25-Gb/s 0.18-µm CMOS half-rate burst-mode clock and data recovery (CDR) circuit is presented. The CDR contains a fast-locking clock recovery circuit (CRC) using a realigned oscillation technique to recover the desired clock. To reduce the power dissipation, the CRC uses a two-stage ring structure and a current-reused concept to merge with an edge detector. The recovered clock has a peak-to-peak jitter of 34.0 ps at 625 MHz and the retimed data has a peak-to-peak jitter of 44.0 ps at 625 Mb/s. The occupied die area of the CDR is 1.41.4 mm2, and power consumption is 32 mW under a 1.8-V supply voltage.

A novel sensing system for glucose in aqueous solution based on cataluminescence(CTL) is proposed. CTL is a kind of chemiluminescence emitted in a course of catalytic oxidation of combustible substances. A sensing system consisting of a CTL-based chemical-sensor made of the γ-Al2O3 catalyst activated with Tb and an ultrasonic nebulizer is developed. CTL is emitted by injection of air containing mist of a glucose solution prepared by the nebulizer on the catalyst. The CTL intensity measured by a photomultiplier is reproducible for the repeated injection of the mist, and the system can measure glucose concentration in a range of 1-200 mg/dl.

We prepared transparent polymer films doped with π-conjugated organic dyes around a multimode silica fiber and observed very narrow fluorescence peaks as compared with the fluorescence in solution. The peak position showed no dependence on the excitation wavelength, indicating that it could not be explained by a whispering gallery mode in a medium with broad optical gain. The peaks can be explained by amplified spontaneous emissions (ASE) because the intensity depended linearly on the excitation intensity with a threshold. When the dye-doped film was formed on the portion of a fiber with the clad etched out and was excited by the polarized laser propagating inside the fiber core, we observed ASE peaks not of the dyes but of the optical fiber itself, suggesting the possibility that the dyes were oriented with their transition moment pointing parallel to the film surface. These fiber ASE peaks shifted to longer wavelength when we varied the excitation wavelength to shorter wavelength, which clearly ruled out the possibility of silicate Raman scattering as the origin.

We demonstrate single electron counting on an alkanethiol-protected Au nanodot in a double-barrier tunneling structure by noncontact atomic-force spectroscopy (nc-AFS). The Coulomb step width dependence on the Au nanodot diameter is observed. Evaluation of fractional charge Q0 and contact potential difference by nc-AFS reveals a Vd-independent voltage shift due to Q0.

A new algorithm is proposed to reduce the number of intermediate registers of a pipelined circuit using a combination of multi-clock cycle paths and clock scheduling. The algorithm analyzes the pipelined circuit and determines the intermediate registers that can be removed. An efficient subsidiary algorithm is presented that computes the minimum feasible clock period of a circuit containing multi-clock cycle paths. Experiments with a pipelined adder and multiplier verify that the proposed algorithm can reduce the number of intermediate registers without degrading performance, even when delay variations exist.

Set Partitioning in Hierarchical Trees (SPIHT) is a highly efficient technique for compressing Discrete Wavelet Transform (DWT) decomposed images. Though its compression efficiency is a little less famous than Embedded Block Coding with Optimized Truncation (EBCOT) adopted by JPEG2000, SPIHT has a straight forward coding procedure and requires no tables. These make SPIHT a more appropriate algorithm for lower cost hardware implementation. In this paper, a modified SPIHT algorithm is presented. The modifications include a simplification of coefficient scanning process, a 1-D addressing method instead of the original 2-D arrangement of wavelet coefficients, and a fixed memory allocation for the data lists instead of a dynamic allocation approach required in the original SPIHT. Although the distortion is slightly increased, it facilitates an extremely fast throughput and easier hardware implementation. The VLSI implementation demonstrates that the proposed design can encode a CIF (352288) 4:2:0 image sequence with at least 30 frames per second at 100-MHz working frequency.

In situ observation of the adsorption process and reduction behavior of hemoglobin adsorbed on a bare glass surface was studied using slab optical waveguide (SOWG) spectroscopy. The peak position of the absorption band of hemoglobin adsorbed on the glass surface was almost the same as that of hemoglobin in solution. This result agrees with results previously reported by our group. The adsorbed hemoglobin molecules were also reduced by sodium dithionite solution. The adsorbed hemoglobin molecules still maintained their function in this experimental condition.

This paper presents a formal design of arithmetic circuits using an arithmetic description language called ARITH. The key idea in ARITH is to describe arithmetic algorithms directly with high-level mathematical objects (i.e., number representation systems and arithmetic operations/formulae). Using ARITH, we can provide formal description of arithmetic algorithms including those using unconventional number systems. In addition, the described arithmetic algorithms can be formally verified by equivalence checking with formula manipulations. The verified ARITH descriptions are easily translated into the equivalent HDL descriptions. In this paper, we also present an application of ARITH to an arithmetic module generator, which supports a variety of hardware algorithms for 2-operand adders, multi-operand adders, multipliers, constant-coefficient multipliers and multiply accumulators. The language processing system of ARITH incorporated in the generator verifies the correctness of ARITH descriptions in a formal method. As a result, we can obtain highly-reliable arithmetic modules whose functions are completely verified at the algorithm level.

RF system and circuit approaches for cognitive radios, based on software defined radio technology, are discussed. The increasing use of digital techniques, combined with wideband data converters and tunable front-end technologies, will enable these systems to become cost effective in the coming years.