Hogg and Huberman have proposed a strategy for stabilizing chaotic multi-agent systems. This paper applies their strategy to a resource allocation problem in a manufacturing system consisting of two machines and two types of parts. These part-types conflict each other over resource allocation. We introduce a discrete-time model of the system by using game theory, and examine stability and bifurcation phenomena of its fixed point. We show by computer simulation that chaotic behaviors are observed after successive occurrence of period-doubling bifurcations. It is also shown that the optimal state of the system is stabilized by a reward mechanism.

A simple digital circuit based on the probabilistic cellular automata is proposed whose temporal evolution generates 1/f noise over many frequency decades. The N cells with internal states form a one-dimensional network and probabilistically interact with nearest-neighbor ones. The internal state of the cell is either the stable state or the unstable state. Each cell obeys simple rules as follows. When the excitatory signal is applied to the cell in the stable state, the state changes to the unstable state. On the other hand, when the state is unstable, the state changes to the stable state, and then the cell generates the excitatory signal. The excitatory signal is applied to the cell which is randomly chosen between the right side cell and the left side cell. The edge condition of the network is open, so that the excitatory signal can leave both the first edge and the last edge. The excitatory signal is randomly added to the first edge of the network at intervals of T time. Then the sequential interactions may occur like avalanche breakdown. After the interactions, the network goes to the equilibrium state. Considering that the breakdown happen simultaneously and assigning the stable state and the unstable state to 0 and 1, respectively, one can get the random pulse stream on the internal state of each cell. The power spectra of pulse streams are Lorentzian with various pole frequencies. The probability distribution of the pole frequency is inversely proportional to the frequency, i. e. , obeys Zipf law. Then the total sum of the internal states of all cells fluctuates following 1/f power law. The frequency range following 1/f power law can be easily varied by changing the number of the cells for the summation. A prototype generator using 15 cells generates 1/f noise over 3 frequency decades. This simple circuit is composed of only full adders and needs not complex components such as multipliers. Fine-tuning of any parameters and precise components also are not needed. Therefore integration into one chip using standard CMOS process is easy.

In multilevel block modulation codes for QPSK and 8-PSK modulation, a construction of binary component codes is given. These codes have a good minimum Euclidean distance by using different forms of the dependency properties of the binary component codes. Interdependency among component codes is formed by using the binary component subcodes which are derived by the coset decomposition of the binary component codes. The algebraic structures of the codes are investigated to find out how interdependency among component codes gives a good minimum Euclidean distance. First, it is shown that cyclic codes over ZM for M-PSK (M=4,8), where the coding scheme is given by Piret, can be constructed by forming specific interdependency among binary component codes for proposed multilevel coding method. Furthermore, it is shown that better minimum Euclidean distance than above can be obtained by modifying the composition of interdependency among binary component codes. These proposed multilevel codes have algebraic structure of additive group and cyclic property over GF(M). Finally, error performances are compared with those of some code's reference modulation scheme for transmitting the same number of information bits.

This paper presents a design of CMOS Chua-type analog chaos circuit by using a signal-flow-graph (SFG) method. In this circuit, the transmittance of a nonlinear element is realized by an OTA with a feedback resistor, and other linear elements are realized by op-amp based circuits. The proposed circuit is insensitive to the finite admittance of OTA's and to the parasitics of resistors except a feedback resistor in the nonlinear element. The performance and chaotic behavior of the proposed circuit are confirmed by SPICE simulations.

Fuzzy value is a Fuzzy set the α-cuts of which are closed intervals. Let [0,1] be the set of Fuzzy values on [0,1]. We introduce two kinds of metric D and D1 in it, and investigate some topological properties.

This paper proposes an adaptive permission probability control method for the CDMA/PRMA access protocol. The proposed method is effective to the uplink channels of the integrated voice and data wireless system. The proposed method uses the R-ALOHA protocol with end-of-use flags in order to avoid the reservation cancellations caused by excessive multiple-access interference. Also, a higher priority at packet transmission is given to voice compared with data so that the real-time transmission of voice packets can be guaranteed. Priority is controlled by suitably varying permission probabilities. Permission probabilities are adaptively calculated according to both the channel load and the channel capacities. The usefulness of this proposed method is ensured through computer simulation in an isolated cell environment. Moreover, various applications to cellular environments are investigated. The calculated results indicate that transmission efficiency has been improved compared with the conventional CDMA/PRMA protocol.

This paper proposes a bit-stream-arranged weighted modulation scheme to improve voice quality in low delay spread frequency selective fading channels. The proposed modulation scheme employs an input bit stream arrangement method that changes the bit stream order for significant bits so that they are not adjacent to each other over time; a mapping method that controls the amplitude of the modulation signals according to the importance of the bits; and modified differential encoding to prevent the error propagation from insignificant to significant bits. Computer simulations clarify that the proposed bit-stream-arranged weighted modulation scheme shows a S/N improvement of 8 dB in an 8-bit linear pulse code modulation (PCM) voice signal compared with the conventional non-weighted π/4-shift quadrature phase shift keying (QPSK) modulation scheme. The proposed scheme also shows 3. 5 dB improvement in a 4-bit adaptive differential pulse code modulation (ADPCM) voice signal. In this case, occurence of 'click noise' in recovered voice signal is halved. Although the proposed scheme increases the peak power of the modulated signals, the non-linearity of the power amplifier is not fatal.

We previously proposed a next generation cellular system for IMT-2000 based on wideband DS-CDMA with TDD scheme and have evaluated its performance by computer simulation, laboratory and field experiments. This paper presents the design concept of TDD-mode operation on wideband DS-CDMA systems. These systems employ almost the same techniques with a little difference as FDD-mode. We also present the schemes of the TDD-mode specific techniques such as fast cell search, transmission diversity and transmitter power control and show the evaluation results of them are effective. Performance can be improved by use of enhanced techniques such as interference cancellation and adaptive antenna array diversity.

The next generation mobile communications systems must support multimedia communications services as well as conventional voice service. DS-CDMA is regarded as the most promising candidate, because it is indispensable to cope with multimedia. The system capacity of DS-CDMA system is limited by the total interference level. As a result, in DS-CDMA systems many users suffer very poor communication quality if the total interference level exceeds this limit. Therefore, this paper considers smoothing interference fluctuation using the difference between voice and data in a type of QoS (quality of service). In other words, voice communication is suitable for a loss system because the quality of voice communication is delay-sensitive. On the other hand, data communication is suitable for a waiting system because the quality of data communication is non-delay-sensitive. This paper focuses on a system that applies a circuit switching method for voice traffic and a reservation type packet switching method for data traffic and proposes a data traffic control method. In this proposed data traffic control method, a base station controls data transmission from a mobile station to utilize unused voice traffic resources. As a result, the proposed method achieves highly efficient use of the radio spectra by smoothing interference fluctuation in DS-CDMA systems. This paper evaluates the performance level of the proposed method from a system capacity standpoint. It is shown that the proposed method achieves higher system capacity in voice/data integrated transmission.

The Future Public Land Mobile Telecommunication Systems (FPLMTS) standards have made it quite clear that in the near future, the capability in doing wireless data transmission will become necessary in order to make the tether-free use of multimedia applications possible. CDMA is considered the most appropriate and probable radio access method of FPLMTS for its high capacity and flexibility in accommodation of multimedia and variable rate users. In order to further increase the capacity of CDMA system, several techniques have been studied and proposed such as an interference canceller and adaptive array antenna. We propose the novel multi-user detection type interference cancellation technique named SRIC (Symbol Ranking type IC) in this paper. SRIC is very feasible for its small amount of operation compared with other multi-user detection type ICs and can be added to a base station with slight alteration according to the requirement of higher capacity. The performance of SRIC depends on the method of calculating the likelihood. We studied three methods. In order to reduce the operations, we tried to propose two more methods. We confirmed that SRIC can make the system capacity about three times greater than that of a conventional RAKE receiver. We also confirmed that SRIC can be reduce its operations very much at some sacrifice of their performance. There are nine variants of SRIC, which have a trade off between performance and amount of operation. We can choose one of them which is most fit to our requirement. The first operation of SRIC is common with that of a conventional RAKE receiver. Therefore, SRIC can be introduced to conventional systems afterwards by inserting the interference canceller block which functions replica generation, removal, and ranking between output of a RAKE receiver and FEC decoder.

This paper presents a novel transmission diversity scheme for code division multiple access system. Conventional diversity receivers in mobile stations require space and complicated circuits, however, the proposed diversity schemes present significant diversity effect without any diversity equipment at the mobile station. It is possible to use the transmitter diversity at the base station by using the feature of time division duplex (TDD) which has strongly correlated fading patterns in both forward and reverse link. Computer simulation is performed to evaluate the performance of the proposed systems for single user environment. The performance of the system 1, which select best situated antenna, is analyzed and the BER performance for multiple access is presented.

Pilot symbol-assisted coherent delay-locked code tracking loop (PSA-CDLL) is proposed for DS-CDMA mobile radio. PSA-CDLL applies pilot symbol-assisted coherent channel estimation and uses only the in-phase component of the despread signal for controlling the received spreading code timing. The impact of the multiple access interference (MAI) and background noise can be decreased by about 3 dB compared to non-coherent DLL. The performance of the proposed PSA-CDLL is evaluated by computer simulation. Computer simulation results show that it can significantly reduce the rms tracking jitter of regenerated spreading code replica, thereby improving the bit error rate (BER) performance in fading environments.

A slow frequency-hopping/16-ary quadrature amplitude modulation (slow-FH/16QAM) system based on time-division-multiple-access (TDMA) is appropriate for third-generation land mobile cellular communications because of its high immunity to interference. The system uses 16QAM for high spectral efficiency and slow-FH and forward-error-correction (FEC) for high-quality transmission. To reduce sensitivity to interference, the system uses an improved decoding scheme based on a minimum Euclidean-distance which is effective when the interference level is dispersed by FH. The bit error rate (BER) of the system due to interference has been evaluated in a previous study, both theoretically and by computer simulation. Although computer-simulated results showed that the system improved the BER, the hardware feasibility was not considered. This paper presents a hardware implementation of the system and the results of experimental transmission using equipment we developed to verify the system and to confirm the BER performance. The laboratory experimental results indicated that the system could provide high-quality transmission over a channel that has frequency-selective fading and co-channel interference. This system provided an Eb/N0 of 9 dB with space diversity and one of 15 dB without it, when BER=10-3 and fd=120 Hz. Field experiments were also conducted in a suburban area of Tokyo to demonstrate the BER performance. The results meant that the system could lower sensitivity to vehicle velocity more than a system without FH and that the BER performance of the system was improved notably against that of a system without FH, especially at low vehicle velocity.

A communication system which attains an efficient amalgamation of base station (BS) type cellular communication and non-BS type direct communication for mobile terminals (MTs), "cellularad-hoc united communication system," is proposed. In this system, whether a cellular system or an ad-hoc communication system is chosen by distance and whether the condition is good or not between communicating MTs. In other words, when two terminals are relatively near each other and are in sufficient conditions to communicate directly, they select the ad-hoc communication, while for other cases they use the cellular system. The proposed system was confirmed to have effective channel usage and low battery consumption from the simulation results. It can be also said that this system is suited especially for MTs which tend to communicate with closer partners such as operational mobile robots and autonomous carrier vehicles.

We developed a measuring system that measures both capacitance and transmittance of a liquid crystal (LC) cell simultaneously. We then studied the dynamic orientation process of nematic LC molecules between two-photochromic command surfaces. The command surfaces consist of a polymer monolayer bearing azobenzene side chains and they are deposited on glass substrate coated with indium-tin-oxide by using the Langmuir-Blodgett technique. The capacitance of LC cells increased and decreased alternately due to orientation transition in LC molecules by irradiating ultraviolet (UV) and visible light, respectively. Similarly, with the alternating irradiation of UV and visible lights, the transmittance of the LC cell changed periodically. Mean tilt angles of LC molecules under irradiation of UV and visible lights were evaluated from the results of capacitance and transmittance. It was found that the transient transmittance response was delayed to the transient capacitance under the UV irradiation. This result corresponds to that the LC molecules in homeotropic mode tend to remain the optical alignment.

Since the development of odor sensing system is required in many fields, we have been developing the system using QCM (Quartz Crystal Microbalance, 10 MHz AT-cut) array and neural-network pattern recognition. Since it is important to obtain stable sensor responses, a sensing film of lipid blended with PVC (polyvinyl chloride) was studied here. First, we studied the stability of various sensing films e. g. , phospholipids, GC liquid stationary phase materials and others in odor sensing system. It was found that most of lipids were stable, while PEG 200, octadecane and DBP were not stable materials. Second, we studied to obtain a stable QCM sensor using a sensing film blended with PVC. 4 plasticizers blended with PVC were systematically characterized, analyzing the pattern of QCM sensor responses by multivariate analysis. It was found that the pattern of DOPP was very different from that of PVC. Thus, we adopted DOPP as plasticizer and the stable sensor response was obtained using a lipid film blended with both PVC and DOPP. Finally, we studied the influence of sensing film materials on the stability of QCM sensors. It was found that the loss of sensing film mass after many vapor exposures depended upon the molecular weight.

We have improved the optical beam induced resistance change (OBIRCH) system so as to detect (1) a current path as small as 10-50 µA from the rear side of a chip, (2) current paths in silicide lines as narrow as 0. 2 µm, (3) high-resistance Ti-depleted polysilicon regions in 0. 2 µm wide silicide lines, and (4) high-resistance amorphous thin layers as thin as a few nanometers at the bottoms of vias. All detections were possible even in observation areas as wide as 5 mm 5 mm. The physical causes of these detections were characterized by focused ion beam and transmission electron microscopy.

A series of transparent photochemical acid-generators (PAGs) has been successfully prepared and investigated to apply ArF excimer-laser lithography. These PAGs were synthesized as new alkylsulfonium salts that have cycloalkyl groups but no aromatic ones. They were almost transparent at 193. 4 nm and have high acid-generation efficiency enough to use for ArF excimer-laser resists. The photochemical reaction of these alkylsulfonium salts occurs mainly due to the S-C bond fission. A resist utilizing the PAGs was capable to resolve a 0. 2µm L/S pattern at a 50-mJ/cm2 dose with an aqueous alkaline developer. These PAGs are promising materials for use in ArF excimer-laser lithography.

The applications of adaptive arrays based on the digital beam forming technique are receiving wide attention. However, the adaptive control algorithm of the array antennas under TDMA systems is not well considered even though it requires particular consideration due to its intermittent bursts. In this paper, first, we propose a novel DOA (Direction of Arrival) estimation method which is suitable for TDMA bursts. Second, the HA (Howells-Applebaum) adaptive array based on the proposed DOA estimation method will be constructed for the terminals in the mobile communication systems using non-geostationary satellites . Then the performance of the DOA estimation method and the HA adaptive array will be examined through computer simulations and experiments.

We have studied the basic optical and physical characteristics of polymeric optical waveguide films with S-shaped waveguides and 45 mirrors applied as multimode optical interconnection components. The core and cladding of the waveguide films were made of deuterated-polymethylmethacrylate (d-PMMA) and UV-cured resin, respectively. We evaluated the insertion losses of the waveguides, the crosstalk and the 45-mirror losses in these waveguide films and demonstrated that they have low propagation loss. The shrinkage and thermal expansion of the polymeric optical waveguide films are also discussed because of the interest in improving module packaging.