This paper deals with a set of differential operators for calculating the differentials of an observed signal by the Daubechies wavelet and its application for the estimation of the transfer function of a linear system by using non-stationary step-like signals. The differential operators are constructed by iterative projections of the differential of the scaling function for a multiresolution analysis into a dilation subspace. By the proposed differential operators we can extract the arbitrary order differentials of a signal. We propose a set of identifiable filters constructed by the sum of multiple filters with the first order lag characteristics. Using the above differentials and the identifiable filters we propose an identification method for the transfer function of a linear system. In order to ensure the appropriateness and effectiveness of the proposed method some numerical simulations are presented.

The matrix decomposition of transformation associated with the Kronecker product not only provides a thoughtful structure in hardware realization but also bestows a skillful tool for complexity evaluation. Hence, there are several fast algorithms developed to achieve efficient computation of two-dimensional (2-D) discrete cosine transform (DCT) with matrix decomposition techniques. However, we found that their derivations associated with their computation structures were not shown formally. In this paper, we propose formal derivations to remedy their deficiencies to achieve more structural 2-D DCT and inverse DCT (IDCT) algorithms. Furthermore, we also show that the remedied algorithms are with less computational complexity and more regular structure for realization.

We present a realization of the transparent wave absorber effective for the use at V-band frequency. First, we propose a structure of the transparent wave absorber consisting of spacer (polycarbonate) and two transparent resistive sheet (polyethylene terephtalate deposited with Indium Tin Oxide) used as a reflection film and an absorption film. Second, a design chart for this type of wave absorber is shown. Third, a design method and manufacturing process of the transparent wave absorber are described particularly for V-band frequency. As a result, the measurement of reflection loss of the absorber indicate that a peak absorption of 32-38 dB is attained at a target frequency of 60 GHz.

The increasing activity at millimeter wave frequency band and the growing demand for waveguide components to be applied for integrated circuit purpose have promoted the need for applying the field-theory-based approaches to the design procedure. In this paper, genetic algorithms (GA's) are applied to accurately design the iris-coupled waveguide filters based on network-boundary element method (NBEM). GA's model the natural selection and evolve towards the global optimum, thus avoid being trapped in local minima. Network-boundary element method, which combines boundary element method with network analysis method, derives the network parameters of the guided wave structures with less storage location and central processing unit time. Therefore, NBEM is a feasible and efficient field-theory-based approach for the GA optimization of waveguide filters. With NBEM performing the task of evaluating the performance of the filter designs optimized by the GA, rigorous and optimal designs of the waveguide filters are realized. The obtained analysis and optimization results are compared to a number of reference solutions to demonstrate the validity and accuracy of the proposed approach.

A mobility management scheme that reduces signaling traffic load and connection setup time is a pivotal issue in designing future personal communication service (PCS) networks to satisfy Quality of Services requirements and use network resources efficiently. Particularly, required is scalable mobility management, to meet the explosive growth in number of users for the current second-generation wireless communication systems, and to materialize PCS concepts such as terminal, personal, and service mobility. Many mobility management schemes have been proposed for the reduction of signaling traffic. However, these schemes have not been sufficiently compared using a unified performance measure that is free of assumptions as to mobility model or database architecture. In this paper, we categorize the various mobility management schemes for advanced PCSs in distributed environments into four types and clarify the appropriate domain for each type. To do this, we settled on the number of signals at connection setup and location registration as a unified performance measure, since this value closely relates to connection setup time and network efficiency. We found two kinds of schemes with replicating and caching functions of user information that are extremely effective for reducing signaling load and hence connection setup time. These schemes are appropriate when the probability that a user is in his/her home area is relatively small or the connection setup rate is relatively high compared to the location registration rate. These are the most likely situations in the advanced PCS for global environments.

This paper describes a new high resolution algorithm for the two-dimensional (2-D) frequency estimation problem, which, in particular, is noise insensitive in view of the fact that in many practical applications the contaminated noise may not be white noise. For this purpose, the approach is set in the context of higher-order statistics (HOS), which has demonstrated to be an effective approach under a colored noise environment. The algorithm begins with the consideration of the fourth-order moments of the available 2-D data. Two auxiliary matrices, constituted by a novel stacking of the diagonal slice of the computed fourth-order moments, are then introduced and through which the two frequency components can be precisely determined, respectively, via matrix factorizations along with the subspace rotational invariance (SRI) technique. Simulation results are also provided to verify the proposed algorithm.

This paper proposes polling-based real-time software for MPEG2 System protocol LSIs, which is a typical embedded and real-time system on a chip, and demonstrates its performance and usefulness. The polling-based real-time software is designed and optimized by analyzing application specific function requirements and deciding scheduling intervals and the execution cycles of each task. It requires neither hardware for multiple interrupt handling nor software for heavy context switching. The polling-based approach provides sufficient performance without any hardware and software overhead for a real-time application like the MPEG2 System protocol.

In a secure partially blind signature scheme, the signer assures that the blind signatures issued by him contains the information he desires. The techniques make it possible to minimize the unlimited growth of the bank's database which storing all spent electronic cash in an anonymous electronic cash system. In this paper we propose an efficient partially blind signature scheme for electronic cash. In our scheme, only several modular additions and modular multiplications are required for a signature requester to obtain and verify a signature. It turns out that the proposed scheme is suitable for mobile clients and smart-card applications because no time-consuming computations are required, such as modular exponentiation and inverse computations. Comparing with the existing blind signature schemes proposed in the literatures, our method reduces the amount of computations for signature requesters by almost 98%.

This paper describes a chip set architecture and its implementation for programmable MPEG2 MP@ML (main profile at main level) video encoder. The chip set features a functional partitioning architecture based on the MPEG2 layer structure. Using this partitioning scheme, an optimized system configuration with double bus structure is proposed. In addition, a hybrid architecture with dual video-oriented on-chip RISC processors and dedicated hardware and a hierarchical pipeline scheme covering all layers are newly introduced to realize flexibility. Also, effective motion estimation is achieved by a scalable solution for high picture quality. Adopting these features, three kinds of VLSI have been developed using 0. 5 micron double metal CMOS technology. The chip set consists of a controller-LSI (C-LSI), a macroblock level pixel processor-LSI (P-LSI) and a motion estimation-LSI (ME-LSI). The chip set combined with synchronous DRAMs (SDRAM) supports all the layer processing including rate-control and realizes real-time encoding for ITU-R-601 resolution video (720480 pixels at 30 frames/s) with glue less logic. The exhaustive motion estimation capability is scalable up to 63. 5 and 15. 5 in the horizontal and vertical directions respectively. This chip set solution realizes a low cost MPEG2 video encoder system with excellent video quality on a single PC extension board. The evaluation system and application development environment is also introduced.

This paper proposes a top-down co-verification approach in the design of embedded systems composed of both hardware and software, for multimedia applications. In order to realize the optimized embedded system in cost, performance, power consumption and flexibility, hardware/software co-design becomes to be essential. In this top-down co-design flow, a target design is verified at three different levels: (1) algorithmic, (2) implementation, and (3) experimental. We have developed a methodology of top-down co-verification, which consists of the system level simulation at the algorithmic level, two type of co-simulations at the implementation level and the co-emulation at the experimental level. We have realized an environment optimized for verification performance by employing verification models appropriate to each verification stage and an efficient top-down environment by introducing the component logical bus architecture as the interface between hardware and software. Through actual application to a image compression and expansion system, the possibility of efficient co-verification was demonstrated.

We have developed a low bit-rate video coding using a video digital signal processor (DSP) called VDSP1χ, which performs real-time encoding and decoding for discrete cosine transform-(DCT-) based algorithms, such as ITU-T H. 261, H. 263 and wavelet-based subband encoding algorithms. This LSI features a processing unit which implements wavelet filters at high speeds, a compact DCT circuit, and a fast, flexible DRAM interface for low-cost systems. This system is capable of processing quarter common intermediate format (QCIF)(176144 pixels) size pictures at a rate greater than 15 frames/s.

Multi-recast techniques make it possible for a voter to participate in a sequence of different designated votings by using only one ticket. In a multi-recastable ticket scheme for electronic voting, every voter of a group can obtain an m-castable ticket (m-ticket), and through the m-ticket, the voter can participate in a sequence of m different designated votings held in this group. The m-ticket contains all possible intentions of the voter in the sequence of votings, and in each of the m votings, a voter casts his vote by just making appropriate modifications to his m-ticket. The authority cannot produce both the opposite version of a vote cast by a voter in one voting and the succeeding uncast votes of the voter. Only one round of registration action is required for a voter to request an m-ticket from the authority. Moreover, the size of such an m-ticket is not larger than that of an ordinary vote. It turns out that the proposed scheme greatly reduces the network traffic between the voters and the authority during the registration stages in a sequence of different votings, for example, the proposed method reduces the communication traffic by almost 80% for a sequence of 5 votings and by nearly 90% for a sequence of 10 votings.

A novel channel assignment scheme in DS-CDMA cellular systems is proposed, which overcomes the handoff interruptions of delay sensitive services by increasing the probability that soft handoff occurs in handoff for them. For that purpose, the priority of using the frequency channels served by all of cells is given to delay sensitive services over delay insensitive ones.

This paper describes two attacks against blind decryption (decode) based on the commutative random-self reducibility and RSA systems utilizing the transformability of digital signatures proposed in [2]. The transformable digital signature was introduced in [2],[8] for defeating an oracle attack, where the decrypter could be abused as an oracle to release useful information for an attacker acting as a requester of blind decryption. It was believed in [2],[8] that the correctness of a query to an oracle was ensured by the transformable signature derived from an original signature issued by the decrypter in advance, and a malicious query to an oracle could be detected before the blind decryption by the decrypter or would lead to release no useful information to an attacker. The first attack can decrypt all encrypted data with one access to an oracle. The second one generates a valid signature for an arbitrary message selected by an attacker abusing the validation check procedure.

RZ signal transmission in an anomalous region with periodic dispersion compensation is examined by a straight-line experiment in terms of the compensation ratio, the signal power, and the pulse width. The optimum condition enables single-channel 20-Gbit/s RZ signal and two-WDM-channel 20-Gbit/s signals (40-Gbit/s in total) to be transmitted over 5,520 km and 2,160 km, respectively. Numerical simulations with the assistance of a basic theory enables analysis of the experimental results. It is shown that the balance between the waveform distortion and the remaining Gordon-Haus jitter determines the optimum conditions to achieve the longest transmission distance. Excess dispersion compensation results in waveform distortion, while insufficient compensation causes a greater amount of remaining jitter. Moreover, spectrum deformation during propagation is experimentally and numerically clarified to have a large effect on the transmission performance, especially for WDM transmission.

A maximal-ratio-combining (MRC) digital beamformer has been studied to attain open-loop and automatic self-beam steering towards both desired and multipath signals at the same time and diversity combining of the signals, which are made possible by spatial digital signal processing. This paper describes the performance of this beamformer under the multipath signal arrivals with various path delays using numerical simulation, aimed at application to future mobile radios with high spatial utilization efficiency. The results indicate the robustness of the MRC beamformer in a multipath environment. It features multidirectional beam steering when there is small path delay in the multipath signal and gain suppression in multipath signals when their path delay is more than about one symbol. Moreover, improvement in suppression by employing low-sidelobe amplitude distribution is discussed as a means to reduce inter-symbol interference without null-beam steering.

This paper proposes a new method to improve cooperation in concurrent systems within the framework of Multi-Agent Systems (MAS). Since subsystems work concurrently, achieving appropriate cooperation among them is important to improve the effectiveness of the overall system. When subsystems are modeled as agents, it is easy to explicitly deal with the interactions among them since they can be modeled naturally as communication among agents with intended information. Contrary to previous approaches which provided the syntax of communication protocols without semantics, we focus on the semantics of cooperation in MAS and aim at allowing agents to exploit the communicated information for cooperation. This is attempted by utilizing more coarse-grained communication based on the different perspective for the balance between formality and richness of communication contents so that each piece of communication contents can convey more meaningful information in application domains. In our approach agents cooperate each other by giving feedbacks based on the metaphor of explanation which is widely used in human interactions, in contrast to previous approaches which use direct orders given by the leader based on the pre-defined cooperation strategies. Agents show the difference between the proposal and counter-proposals for it, which are constructed with respect to the former and given as the feedbacks in the easily understandable terms for the receiver. From the comparison of proposals agents retrieve the information on which parts are agreed and disagreed by the relevant agents, and reflect the analysis in their following behavior. Furthermore, communication contents are annotated by agents to indicate the degree of importance in decision making for them, which contributes to making explanations or feedbacks more understandable. Our cooperation method was examined through experiments on the design of micro satellites and the result showed that it was effective to some extent to facilitate cooperation among agents.

In this work, a new algorithm for tracking the directions-of-arrival (DOA's) of moving targets by introducing a linear approximation is proposed. The targets are assumed to move with constant angular velocities within a short time and emitting continuously narrow-band signals that impinge on an array of sensors. Therefore the trajectories of targets can be approximated by linear functions of time, which consist of the DOA's and the angular velocities, within the short time. In the condition that the number of targets is known and the outputs vector of the sensors including the additive white complex Gaussian noises is observed continuously, a cost function which consists of the squared residual error vectors is defined. The estimation of the DOA's and the angular velocities of targets is performed by minimizing this cost function. By estimating both the DOA's and the angular velocities at the same time, the proposed algorithm is able to improve the tracking performance for rapidly moving targets. In computer simulations, the performance of the proposed algorithm is compared with the ESPRIT method, which is one of the typical subspace methods with super resolution.

One of the ways to execute a processing algorithm in high speed is parallel processing on multiple computing resources such as processors and functional units. To identify the minimum number of computing resources, the most important is the scheduling to determine when each operation in the processing algorithm is executed. Among feasible schedules satisfying all the data dependencies in the processing algorithm, an overlapped schedule can achieve the fastest execution speed for an iterative processing algorithm. In the case of processing algorithms with operations which are executed on some conditions, computing resources can be shared by those conditional operations. In this paper, we propose a scheduling method which derives an overlapped schedule where the required number of computing resources is minimized by considering the sharing by conditional operations.

Penumbral imaging is a technique which uses the facts that spatial information can be recovered from the shadow or penumbra that an unknown source casts through a simple large circular aperture. The technique is based on a linear deconvolution. In this paper, a two-step method is proposed for decoding penumbral images. First a local-statistic filter based on adaptive windowing is applied to smooth the noise; then, followed by the conventional linear deconvolution. The simulation results show that the reconstructed image is dramatically improved in comparison to that without the noise-smoothing filtering, and the proposed method is also applied to real experimental X-ray imaging.