System LSI is a new principal product of semiconductor industry and also a key component of Information Technology (IT). Design of a system LSI contains two different characteristics, system design and LSI design. It is keen issue to establish a design methodology of system LSIs in which designers have much freedom on their design from system level to device level and also can control various design parameters to optimize their design. In this paper, considerations on markets of system LSIs and requirements from each application are summarized. Some proposals on new directions of design methodology are also surveyed.

This paper surveys the research topics and results on nonlinear theory and its applications which have been achieved in Japan or by Japanese researchers during the last decade. The paticular emphasis is placed on chaos, neural networks, nonlinear circuit analysis, nonlinear system theory, and numerical methods for solving nonlinear systems.

Nowadays, when people colloquially use the word "wireless," they almost always mean a portable telephone. Over the last 10 years, there has been tremendous growth in the mobile communications markets not only in Japan but also worldwide. For these 10 years, the most popular service has been dominated by voice communication. However, modern mobile communications systems are shifting their focus from solely voice communication to electronic mailing and Internet access. From now, we will evolve into a wireless multimedia society, where a combination of mobile communications and the Internet will play an important role. Wireless technology is the core of mobile communications systems. This article, which focuses on wireless technology, looks at how mobile communications systems have evolved over the last 10 years and looks to the future of advanced wireless technologies that will be necessary to realize a true wireless multimedia society in the coming decade.

In this paper, first, we propose two of the high rate methods based on Morii-Kasahara cryptosystem. Method A-I is based on Schalkwijk algorithm. Method A-II is based on the extended Schalkwijk algorithm, which is proposed in this paper. We then show that these proposed methods can yield a higher rate compared with ElGamal cryptosystem. Next, we also propose two methods for a fast encryption by dividing the message vector into several pieces. Regarding each of the divided vectors as an index, we can realize a fast transformation of the index into a limited weight vector. In Method B-I, Schalkwijk algorithm is used for the fast transformation. In Method B-II, the fast transformation is realized with the method of table-lookup. These methods can realize a faster encryption than Method A-I, Method A-II and Morii-Kasahara cryptosystem. The security of these proposed methods are based on the security of Morii-Kasahara cryptosystem.

NOR self-decimated sequences are attractive for stream ciphers because they have a good statistical property and the hardware construction is very simple. This paper presents an analysis of NOR self-decimation system for any parameter. We first determine the period. Then we show the exact distribution of consecutive two bits and three bits, which are shown to be almost uniform distribution.

System capacity of a system consisting of N classes of users is characterized by N-vectors representing the number of users that can be accommodated under a specified BER (bit error rate) constraint in each class. In this paper, system capacity of the reverse link of a wireless multimedia CDMA system with processing gain control is analyzed in the asymptotic regime, when the processing gain G, for receivers with and without CCI cancellers. A new scheme for processing gain control with an optimized power allocation is proposed and its system capacity is compared with the conventional processing gain control scheme as well as the previously discussed power control scheme. It is shown that the proposed scheme has a certain advantage over other schemes.

This paper, for the first time, presents a provably secure signature scheme with message recovery based on the elliptic-curve discrete logarithm. The proposed scheme is proven to be secure in the strongest sense (i.e., existentially unforgeable against adaptively chosen message attacks) in the random oracle model under the discrete logarithm assumption. We give a concrete analysis of the security reduction. When practical hash functions are used in place of truly random functions, the proposed scheme is almost as efficient as the elliptic-curve version of the Schnorr signature scheme and existing schemes with message recovery such as the elliptic-curve version of the Nyberg-Rueppel and Miyaji schemes.

A broadcast distribution system (BDS) is a system for the distribution of digital contents over broadcast channel where the data supplier broadcasts the contents in encrypted form and gives each subscriber a decoder containing a secret decryption key. A traitor is a subscriber who offers the information which allows to decrypt the broadcast. When a pirate decoder is captured, if at least one traitor can be identified from it, a BDS is said to be traitor-tracing. If the data supplier can prevent subscribers from obtaining the contents without recalling their decoders, a BDS is said to be subscriber-excluding. In this paper, we propose an efficient BDS which is both subscriber-excluding and traitor-tracing. We use similar mathematics to a threshold cryptosystem. In the proposed BDS, the maximum number of excluded subscribers reaches the maximum number of traitors in a coalition for which at least one traitor can be identified. We prove that the proposed BDS is secure against ciphertext-only attack if and only if ElGamal cryptosystem is secure against the attack and the discrete logarithm problem is hard. The proposed BDS is the first one which satisfies all the following features: Both subscriber-excluding and traitor-tracing, identifying all the traitors, black box tracing and public key system.

In the beginning of the new century, many information appliance (IA) products will replace traditional electronic appliances to help people in smart, efficient, and low-cost ways. These successful products must be capable of communicating multimedia information, which is embedded into the electronic appliances with high integration, innovation, and power-throughput tradeoff. In this paper, we develop a codesign procedure to analyze, compare, and emulate the multimedia communication applications to find the candidate implementations under different criteria. The experimental results demonstrate that in general, memory technology dominates the optimal tradeoff and ALU improvements impact greatly on particular applications. The results also show that the proposed procedure is effective and quite efficient.

Aged people who live alone are in particular need of a daily health check, medication, and of warm communication with family and friends. The authors have been developing a life-support computer system with such functions. Among them, a daily health check function with the capability of measuring blood pressure, detecting diseases from coughing, and so on would in particular be very powerful for primary care. As a first step to achieving quick services for a daily health check with a personal computer, utilization of cough information is considered. Features of cough data are analyzed aiming at developing an automatic cough data detection method. This paper proposes a novel method for extracting cough signals from other types of signals. The differential coefficient of a low-pass filtered waveform is first shown to be an effective parameter for discriminating between vowel and cough signals, and the relationship between cut-off frequency and cough detection rate is clarified. This parameter is then applied to cough signals mixed with vowel signals or white noises to evaluate robustness. The evaluation tests show that the cough feature can be perfectly detected for a 20 dB S/N ratio when the cut-off frequency is set to 24 [Hz]. The experimental results suggest that the proposed cough detection method can be a useful tool as a primary care for aged people with a bronchitis like an asthmatic bronchitis and a bronchopneumonia.

The delta-sigma modulator (DSM) is an excellent choice for high-resolution analog-to-digital converters. Recently, a band-pass DSM has been a desirable choice for direct conversion of an IF signal into a digital bit stream. This paper proposes a quadrature band-pass DSM for digitizing a narrow-band IF signal. This modulator can achieve a lower total order, higher signal-to-noise ratio (SNR), and higher bandwidth when compared with conventional band-pass modulators. An experimental prototype employing the quadrature topology has been integrated in 0.6 µm, double-poly, double-metal CMOS technology with capacitors synthesized from a stacked poly structure. This system clocked at 13 MHz and digitized a 200 kHz bandwidth signal centered at 4.875 MHz with 100 dB of dynamic range. Power consumption is 190 mW at 5 V.

This paper presents a system-level bus architecture validation technique and shows its application to a consumer product design. This technique enables the entire system to be validated with bus cycle accuracy using bus architecture level models derived from their corresponding behavioral level models. Experimental results from a digital still camera (DSC) system design show that our approach offers much faster simulation speed than register transfer level (RTL) simulators. Using this fast and accurate validation technique, bus architecture designs, validations and optimizations can be effectively carried out at system-level and total turn around time of system designs can be reduced dramatically.

This paper deals with the decentralized supervisory control problems of uncertain discrete event systems which are represented as a set of some possible models. For a given global specification, this paper provides the necessary and sufficient conditions for the existence of local supervisors to achieve the specification under model uncertainty.

A novel residue arithmetic algorithm using radix-2 signed-digit (SD) number representation is presented. By this representation, memoryless residue arithmetic circuits using SD adders can be implemented. Conventional residue arithmetic circuits have been designed using binary number arithmetic system, but the carry propagation arises which limits the speed of arithmetic operations in residue modules. In this paper, a p-digit radix-2 SD number system is introduced to simplify the residue operation. For a modulus m, 2p-1 m 2p+2p-1-1, in a residue number system (RNS), the modulo m addition is performed by using two p-digit SD adders, one for the addition and one for the residue operation. Thus, the modulo m addition time is independent of the word length of operands. When m=2p or m= 2p 1, the modulo m addition is implemented by using only one SD adder. Moreover, a modulo m multiplier is constructed using a binary modulo m SD adder tree, and the modulo m multiplication can be performed in a time proportional to log 2 p. The VHDL implementation method for the presented algorithm is also discussed. The design and simulation results of some residue arithmetic circuits show that high speed residue arithmetic circuits can be obtained by the presented algorithms.

We discuss human collaborative discovery processes using a production system model as a cognitive simulator. We have developed an interactive production system architecture to construct the simulator. Two production systems interactively find targets in which the only experimental results are shared; each does not know the hypothesis the other system has. Through this kind of interaction, we verify whether or not the performance of two systems interactively finding targets exceeds that of two systems independently finding targets. If we confirm the superiority of collaborative discovery, we approve of emergence by the interaction. The results are: (1) generally speaking collaboration does not produces the emergence defined above, and (2) as the different degree of hypothesis testing strategies that the two system use gets larger, the benefits of interaction gradually increases.

This paper presents the fast cell search time performance based on laboratory and field experiments of a 2-step cell search algorithm that uses scrambling code masking for inter-cell asynchronous wideband DS-CDMA (W-CDMA) mobile radio. The scrambling code is masked at different time positions during each scrambling period on the forward-link common control channel (CCH) to detect the scrambling code timing at the mobile receiver. Experiments were conducted using the CCH-to-dedicated traffic channel (DTCH) power ratio, R of 3 dB, 10 DTCHs, and 16 scrambling codes in a single-cell and two-cell models. The field experimental results show that the cell search time of about 600 msec was achieved in vehicular environments at the detection probability of 90% and the average received Eb/N0 (N0 is the background noise without interference) of 13-15 dB for DTCH, even in the worst case scenario when the received signal power ratios of the CCH from two cell sites were 0 dB. The cell search time that was achieved with the 3-step cell search algorithm previously proposed by the authors is estimated from the experimental results; the cell search can be accomplished within about 720 msec at a probability of 96% for 512 scrambling codes and 16 scrambling code groups.

We described short time span idiotype immune network reactions by rigorous mathematical equations. For each idiotype, we described the temporal changes in concentration of (1) single bound antibody, one of its two Fab arms has bound to the complemental receptor site on the B cell. (2) double bound antibody, both of its two Fab arms have bound to the complemental receptor sites on the B cell and (3) an immune complex which is a product of reaction among the antibodies. Stimulation and secretion processes of an antibody in the idiotype network were described by non linear differential equations characterized by the magnitude of cross-linking of the complemental antibody and B cell receptor. The affinity between the mutually complemental antibody and receptor was described by an weighted affinity matrix. The activating process was expressed by an exponential function with threshold. The rate constant for the linkage of the second Fab arm of an antibody was induced from the molecular diffusion process that was modified by the Coulomb repulsive force. By using reported experimental data, we integrated 60 non linear differential equations for the idiotype immune network to obtain the temporal behavior of concentrations of the species in hour span. The concentrations of the idiotype antibody and immune complex changed synchronously. The influence of a change in one rate constant extended to all the members of the idiotype network. The concentrations of the single bound antibody, double bound antibody and immune complex oscillated as functions of the concentration of the free antibody particularly at its low concentration. By comparing to the reported experimental data, the present computational approach seems to realize biological immune network reactions.

Generating state spaces is one of important and general methods in the analysis of Petri nets. There are two reasons why state spaces of Petri nets become so large. One is concurrent occurring of transitions, and the other is periodic occurring of firing sequences. This paper focuses on the second problem, and proposes a new algorithm for exploring state spaces of finite capacity Petri nets with large capacities. In the proposed algorithm, the state space is represented in the form of a tree such that a set of markings generated by periodic occurrences of firing sequences is associated with each node, and it is much smaller than the reachability graph.

A hybrid system in which mobile terminals (MTs) themselves select whether to communicate directly or via base stations (BSs) from communication conditions, "cellularad-hoc united communication system," has been proposed by the authors. It has been confirmed to have effective channel usage and battery consumption, especially for MTs which tend to communicate with partners which are close together, such as operational mobile robots. In this paper, the hybrid system is examined with respect to handoff rate. This hybrid system uses two modes, a cellular mode and an ad-hoc mode. The former mode is for communication using BSs and the latter is for direct communication. Thus, there will be two kinds of handoffs. One is the ordinary one between BSs and the other is between the two modes. Such a system may suffer from frequent handoffs. Thus the handoff rate of the system was examined. However, by the addition of a simple hysteresis characteristic, the handoff rate was held down closer to that of a pure cellular system in a multipath environment.

A new method of sequential control has been developed in order to increase the productivity and flexibility of production systems. This advanced sequential control (ASC) method is proposed for sequential control systems based on the autonomous decentralized system (ADS) architecture. The ADS defines the system software and message formats and makes it easy to expand the number of devices and software modules. The ASC method increases productivity because it minimizes the processing and adjustment times of production lines by adjusting the starting times of production processes automatically. Experimental evaluation results of the ASC method showed that it increases the productivity of production systems. It is also applied to an actual production system and the results are reported.