Digital watermarking schemes have been discussed to solve the problem associated with copyright enforcement. Previously, we proposed a method using inter-block correlation of DCT coefficients. It has the features that the embedded watermark can be extracted without the original image nor the parameters used in embedding process and that the amount of modification, the strength of embedded watermark, depends on the local feature of an image. This feature makes it difficult for pirate to predict the position in which the watermark signal is embedded. In this paper, we propose a method which can embed/extract watermark with high speed by utilizing this watermarking method for JPEG file format.

This paper is concerned with fuzzy modeling in some reduction methods of inference rules with gradient descent. Reduction methods are presented, which have a reduction mechanism of the rule unit that is applicable in three parameters--the central value and the width of the membership function in the antecedent part, and the real number in the consequent part--which constitute the standard fuzzy system. In the present techniques, the necessary number of rules is set beforehand and the rules are sequentially deleted to the prespecified number. These methods indicate that techniques other than the reduction approach introduced previously exist. Experimental results are presented in order to show that the effectiveness differs between the proposed techniques according to the average inference error and the number of learning iterations.

The hardware-software codesign of distributed embedded systems is a more challenging task, because each phase of codesign, such as copartitioning, cosynthesis, cosimulation, and coverification must consider the physical restrictions imposed by the distributed characteristics of such systems. Distributed systems often contain several similar parts for which design reuse techniques can be applied. Object-oriented (OO) codesign approach, which allows physical restriction and object design reuse, is adopted in our newly proposed Distributed Embedded System Codesign (DESC) methodology. DESC methodology uses three types of models: Object Modeling Technique (OMT) models for system description and input, Linear Hybrid Automata (LHA) models for internal modeling and verification, and SES/workbench simulation models for performance evaluation. A two-level partitioning algorithm is proposed specifically for distributed systems. Software is synthesized by task scheduling and hardware is synthesized by system-level and object-oriented techniques. Design alternatives for synthesized hardware-software systems are then checked for design feasibility through rapid prototyping using hardware-software emulators. Through a case study on a Vehicle Parking Management System (VPMS), we depict each design phase of the DESC methodology to show benefits of OO codesign and the necessity of a two-level partitioning algorithm.

With the advancement of technologies in wireless communication and computer down-sizing, it becomes possible to access a global network using handy terminals which are equipped with wireless communication facilities. In such a mobile computing environment, data management is one of the primary objectives of effective computer uses. However, since conventional distributed data management technologies assume that servers and clients are fixed at certain locations in a network, they do not provide any tools to construct advanced applications which make full use of dynamically changing information in such an environment. In this paper, in order to incorporate data distributed over mobile computing environment, we propose a dynamic data integration mechanism called MobiView which is an enhanced view mechanism of a conventional database system. In MobiView, we introduce four methods for database indication without using conventional host name or its local name: host-specified, cell-specified, location-dependent, and MobiView-oriented, through which we discuss how to handle both mobile database servers and mobile database clients.

Many experimentally and theoretically based models have been proposed to predict, quantitatively evaluate, and combat the fading phenomenon in mobile communication systems. However, to the best of the authors' knowledge, up to now there is no objective method to determine which is the most suitable distribution to model the fading phenomenon based on experimental data. In this work, the Minimum Description Length (MDL) criterion for model selection is proposed for that purpose. Furthermore, the MDL analysis is performed for some of the most widely used fading models based on measurements taken in a sub-urban environment.

In software-based wireless multimedia communications systems, each mobile terminal will be able to select its best-suited transmission format according to its quality of service (QoS) and channel condition. In this paper, we focus attention on "access scheme selectability" in such a software-based system, and discuss the traffic performance improvement due to adaptive access scheme selection. Assuming a software-based TDMA/CDMA system where time division multiple access (TDMA) and direct sequence code division multiple access (DS-CDMA) schemes are flexibly selectable, we evaluate the traffic performance in terms of average delay with a typical multimedia service model to be supported in future wireless communications systems. In the TDMA/CDMA system, how to determine an appropriate access scheme for a user is a key issue. Therefore, we discuss the selection algorithm for efficiently supporting heterogeneous multimedia services. Our computer simulation results show that the software-based system with a simple access scheme selection algorithm can significantly improve the traffic performance as compared with conventional hardware-based systems.

In this letter, we present a method to generate sets of sequences suitable for multicode transmission in quasi-synchronous (QS) CDMA systems. We focus on Gold code but extension to orthogonal Gold code is straightforward. We show that by appropriate classification of sequences, it is possible to have sets whose cross correlation is small in QS situations.

Most natural images are well modeled as smoothed areas segmented by edges. The smooth areas can be well represented by a wavelet transform with high regularity and with fewer coefficients which requires highpass filters with some vanishing moments. However for the regions around edges, short highpass filters are preferable. In one recently proposed approach, this problem was solved by switching filter banks using longer filters for smoothed areas of the images and shorter filters for areas with edges. This approach was applied to lossy image coding resulting in a reduction of ringing artifacts. As edges were predicted using neighboring pixels, the nonlinear transforms made the decorrelation more flexible. In this paper we propose a time-varying filterbank and apply it to lossless image coding. In this scheme, we estimate the standard deviation of the neighboring pixels of the current pixel by solving the maximum likelihood problem. The filterbank is switched between three filter banks, depending on the estimated standard deviation.

In this article, we shall propose an efficient anonymous channel protocol for wireless communications. The most important feature of our proposed protocol has the property of untraceability. In our scheme, the mobile stations (MSs) and the home network (HN) must authenticate each other. Moreover, the HN is untraceable in such a way that supports location anonymity and MSs identity anonymity for MSs roaming, dynamic channel assignment and broadcasting. Compare our protocol with Juang et al.'s protocol, our mobile agent communication cost is 3m which is more efficient than the Juang et al.'s protocol 5m. At the same time, our mobile agent computation cost is 2Th which is also more efficient than the Juang et al.'s protocol 1Tpublic+1Th. We can avoid employing public key cryptography in the anonymous channel ticket authentication phase since to keep the computation cost down.

Processes in image recognition include target detection and shape extraction. Active Net has been proposed as one of the methods for such processing. It treats the target detection in an image as an energy optimization problem. In this paper, a problem of the conventional Active Net is presented and the new Active Net is proposed. The new net is improved the ability for detecting a target. Finally, the validity of the proposed net is confirmed by experimental results.

This paper describes a method for classification of hematoxylin and eosin (HE)-stained breast tumor images into benign or malignant using the adaptive searching ability of artificial organisms. Each artificial organism has some attributes, such as, age, internal energy and coordinates. In addition, the artificial organism has a differentiation function for evaluating "malignant" or "benign" tumors and the adaptive behaviors of each artificial organism are evaluated using five kinds of texture features. The texture feature of nuclei regions in normal mammary glands and that of carcinoma regions in malignant tumors are treated as "self" and "non-self," respectively. This model consists of two stages of operations for detecting tumor regions, the learning and searching stages. At the learning stage, the nuclei regions are roughly detected and classified into benign or malignant tumors. At the searching stage, the similarity of each organism's environment is investigated before and after the movement for detecting breast tumor regions precisely. The method developed was applied to 21 cases of test images and the distinction between malignant and benign tumors by the artificial organisms was successful in all cases. The proposed method has the following advantages: the texture feature values for the evaluation of tumor regions at the searching stage are decided automatically during the learning stage in every input image. Evaluation of the environment, whether the target pixel is a malignant tumor or not, is performed based on the angular difference in each texture feature. Therefore, this model can successfully detect tumor regions and classify the type of tumors correctly without affecting a wide variety of breast tumor images, which depends on the tissue condition and the degree of malignancy in each breast tumor case.

As noncoherent direct sequence code-division multiple-access (DS-CDMA) mobile satellite communications, two typical transmission schemes are compared; one is a quasi-synchronous differential BPSK (QS-DBPSK) where orthogonal signals are used for reducing the multiple access interference and the other is M-ary orthogonal signaling (MOS) scheme where orthogonal signals are used for exploiting more efficient modulation. The performances are evaluated in additive white Gaussian noise (AWGN) and shadowed Rician fading (SRF) channels and the effects of timing misalignments in the QS-DBPSK system and the amount of Doppler shifts of a SRF channel are investigated. The results show that MOS much outperforms QS-DBPSK in the region of low system loading up to about 50% and a precise chip synchronization is required for QS-DBPSK. In a SRF channel, it is also shown that QS-DBPSK much outperforms MOS in a slow fading channel but MOS has a performance gain against the large Doppler shift.

In cellular networks, the system performance can be degraded because of the inefficient use of channels with the two types of traffic, that is, the new call traffic and handover call traffic. This problem can be alleviated if the channels are used efficiently for new call traffic and handover call traffic. In this paper, we consider the proper ratio of the number of channels for new calls to the number of total channels denoted as α. We introduce the new call channel limiting technique incorporating velocity of mobile user. We model one-dimensional cellular networks and evaluate the performance in terms of the blocking probabilities, the probability of call dropping and the probability of incomplete call. We show with numerical examples that the system performance can be improved by selecting the appropriate α for various velocities of mobile users.

This paper proposes an autonomous relay access algorithm that provides an intelligent wireless network structure for inter-vehicle communication systems. The proposed algorithm introduces a special classification among mobile terminals and assigns terminals to one of several terminal groups, which are adaptively and autonomously constructed according to traffic conditions. The proposed algorithm uses the terminal groups to conduct relay access transmission among terminals, and achieves a high rate of successful inter-terminal transmission. Computer simulation confirms that the proposed algorithm can achieve a lower blocking probability than that without a relay access scheme.

The CDMA system can provide more capacity than other systems and the hierarchical layer of cells is required for system design to provide a balance between maximizing the number of users perfrequency band and minimizing the network control associated with handoff. However, the co-channel interference from microcell to macrocell and vice versa in such a two-tier structure is different from that in a homogeneous structure. In order to avoid the serious interference, different RF channels should be used in microcell and macrocell in hierarchical structure. The efficient usage of multi-channels for macrocell and microcell is of primary concern herein. In this study, we investigate the channel segregation in a two-tier cellular system. Moreover, we intentionally arrange the procedures for the MS in macrocell and microcell to choose the channel. The macrocell's (resp., microcell's ) channels to be accessed are sorted into three priority groups. In order to justify the merits of the proposed channel segregation method, we define the following three performance measures including capacity gain, response to the variation of traffic loading and system stability. Under the condition of steady-state traffic load, capacity gain is 10% on the average. If the traffic load vary, the system can respond quickly and retrieve the borrowed channels with 2tp time interval as long as appropriate system parameters are chosen.

We have developed a new traffic measuring tool and applied it to the real-time simulation of a network. It monitors IP traffic on an ATM link and continuously transfers the length and timestamp of each IP packet to a post-processing system. The post-processing system receives the data, estimates the cell's arrival epoch at the transmission queue of the ATM link, and simulates the queueing behavior on-line if conditions differ from those of the actual system. The measuring tool and real-time simulation represent a new approach to traffic engineering. A new estimation problem, the arrival sequence estimation, is shown and some algorithms are proposed and evaluated. Also, a new dimensioning algorithm called the queue decay parameter method, which is expected to be robust and applicable to real-time control, is proposed and evaluated.

This paper proposes a media synchronization scheme with causality control for distributed multimedia applications in which the temporal and causal relationships exist among media streams such as computer data, voice, and video. In the scheme, the Δ-causality control is performed for causality, and the Virtual-Time Rendering (VTR) algorithm, which the authors previously proposed, is used for media synchronization. The paper deals with a networked shooting game as an example of such applications and demonstrates the effectiveness of the scheme by experiment.

A feasibility study has been made of the detection possibility of radio wave noises, i.e., Martian atmospherics, emitted from discharges in the Martian atmosphere during large dust storms. The spacecraft NOZOMI, which was launched in 1998, is to be placed on an elliptic orbit around Mars with perigee of 150-200 km. An onboard-equipment LFA (Low Frequency Plasma wave Analyzer) has capability to measure the low frequency plasma waves in the frequency range from 10 Hz to 32 kHz. In order to know if the LFA can detect the atmospheric radio noises, the propagation characteristics of electromagnetic waves through the Martian ionosphere are studied theoretically by using a full-wave method. The ionosphere is modeled as a magneto-ionic medium based on the recent observations of magnetic anomaly by Mars Global Surveyor spacecraft, and the atmospheric constituent and electron density by Viking observations. Our calculation shows that the waves at frequencies less than a hundred hertz can propagate with low attenuation and reach to altitudes above 200 km in the whistler-mode in the regions of magnetic anomalies in the dayside ionosphere. It is shown that the radio noises emitted from electric discharge in an intense dust storm, with the intensity over -30 dBV/m/Hz at the ionospheric entry point, can be sensed by the LFA. The observational identification of Martian atmospherics will contribute to the physical study of charge/discharge process in the Martian atmosphere.

A modified version of the SAGE algorithm is presented for joint delay-azimuth-attenuation parameters' estimation in a multiuser DS-CDMA system. The introduced modification consists of using different time interval lengths when calculating the time correlations for optimizing the different channel parameters. This modification was proposed for the purpose of a further reduction in the algorithm's computational weight in case of receiving sufficiently resolvable waves. Specifically, we found that short interval windows are sufficient for estimating delays and azimuth angles, which is quite effective in reducing the computational burden in their optimization processes. As for the estimation of the attenuation parameters, a longer time window, equal to the preamble length, is considered for more accurate estimation. Also two other estimators are proposed. The first one combining the modified SAGE with a sequential estimation of the attenuation parameters, suitable for slowly varying channels. Another one, similar to the first, and primarily designed to alleviate the influence of present strong interferers. Through a numerical example, the performances of the three presented estimation schemes, in terms of their near-far resistance, are compared. And it is shown that the proposed second combined estimator outperforms the modified SAGE in environments with high MAI levels.

In order to increase the link capacity in the wideband direct sequence code division multiple access (W-CDMA) reverse link, employing a parallel-type coherent multi-stage interference canceller (COMSIC) is more practical than employing a serial (successive)-type due to its inherent advantage of a short processing delay, although its interference suppression effect is inferior to that of the serial-type. Therefore, this paper proposes a parallel-type COMSIC with iterative channel estimation (ICE) using both pilot and decision-feedback data symbols at each canceling stage in order to improve the interference suppression effect of the parallel-type COMSIC. Computer simulation results demonstrate that by applying the parallel-type COMSIC with ICE after FEC decoding, the capacity in an isolated cell can be increased by approximately 1.6 (2.5) times that of the conventional parallel-type COMSIC with channel estimation using only pilot symbols (the MF-based Rake receiver) at the required average transmit Eb/N0 of 15 dB, i.e. in the interference-limited channel. The results also show that, although the capacity in the isolated cell with the parallel-type COMSIC with ICE after FEC decoding is degraded by approximately 6% compared to that with the serial-type COMSIC with ICE after FEC decoding, the processing delay can be significantly decreased owing to the simultaneous parallel operation especially when the number of active users is large.