Inter-cell asynchronous DS-CDMA cellular mobile radio allows continuous system deployment from outdoors to indoors since no outer timing source is required. All the forward link channels(control and traffic channels)of each cell site are first spread by orthogonal short spreading codes and then randomized by a long random code uniquely assigned to each cell site. However, inter-cell asynchronous systems generally require much longer cell search time than inter-cell synchronous systems. This paper proposes a fast cell search algorithm based on the periodic masking of the long random code when transmitting the control channel(CCH)signal. The same short spreading code is used for the CCHs of all cell sites. The same short spreading code periodically appears in the signals transmitted from all cell sites so the mobile station can detect the long random code timing(or more precisely the masking timing)by using a matched filter. By grouping the long random codes used in the system and transmitting a group identification(GI)code from each cell site during the masking period, we can avoid searching all long random codes. This significantly reduces the cell search time. Simulation results demonstrate that cell search can be accomplished in less than 500 ms at 90% of the locations when the number of long random codes(having a repetition period of 10 ms)is 512 and the number of those per group is 32.

In this paper, CDMA slotted ALOHA system with finite size of buffers is proposed. To analyze the system performance, we use the linear approximate solution based on restricted occupancy urn models. We evaluate the system performance in terms of throughput, average delay, and rejection probability and clarify the effect of buffer capacity.

Electrochemomechanical deformation (ECMD) of poly(o-methoxyaniline) (PoMAn) film has been studied in various acid solutions, such as Cl-, HSO4-, BF4-, and p-toluene sulfate. The magnitude of ECMD of the film depends linearly on the degree of oxidation of the film similarly to the case of polyaniline (PAn). 2. 53% of deformation ratios along the stretched direction are obtained for 30% of reduction. In contrast to that of PAn, however, the ECMDs of PoMAn do not markedly depend on the kind of anions. Transient responses of current and deformation are investigated by the potential application stepwise and the diffusion coefficient of ions in films. The results are discussed in terms of the effect of substituted methoxy group.

The Rician factor is an important parameter in evaluating the outage probability and reuse distance of cellular systems. From the measurement of 1. 8 GHz radio propagation in outdoor urban microcells, it is found that the measured pdf of the Rician factor for low tier systems follows a lognormal distribution and the factor is independent on the propagation distance.

For a real Schur polynomial, estimates are derived for a Schur stability margin in terms of matrix entries or tableau entries in some stability test methods. An average size of the zeros of the polynomial is also estimated. These estimates enable us to obtain more information than stability once a polynomial is tested to be stable via the established Schur stability criterion for real polynomials.

In this paper, we propose a new cooperative search algorithm based on pheromone communication for solving the Vehicle Routing Problems. In this algorithm, multi-agents can partition the problem cooperatively and search partial solutions independently using pheromone communication, which mimics the communication method of real ants. Through some computer experiments the cooperative search of multi-agents is confirmed.

Two approaches to the design of resonant-type switches with low distortion characteristics operating at a 2-V power supply voltage have been proposed for use in the 1. 9-GHz-band personal handy phone system (PHS). One approach is to use three stacked FETs at the receiver side. They are composed of a dual-gate FET and a single-gate FET. An insertion loss of 0. 41 dB and an isolation of 44. 0 dB were obtained at 1. 9 GHz. A third-order distortion value of -52 dBc was achieved at 19 dBm output power. Another approach is to insert a capacitor in the resonator. A third-order distortion of -49 dBc at 19-dBm output power when two stacked FETs were used at the receiver side. The layout area of the resonator is drastically reduced as compared with the above-mentioned case.

This paper describes new IC design concepts using flip-chip bonding technologies for microwave and millimeter-wave circuit integration. Two types of bonding technologies, stud bump bonding (SBB) and micro bump bonding (MBB) are introduced, and their applications to microwave and millimeter-wave ICs are presented. Receiver front-end hybrid IC (HIC) for cellular and PHS handsets using SBB and new millimeter-wave ICs on Si substrate called millimeter flip-chip IC (MFIC) using MBB have been designed and fabricated to prove their advantages. These flip-chip bonding technologies are experimentally proven to provide excellent solutions for high performance and compact-sized ICs with low-cost. The HIC concept is applicable consistently over a wide range of devices from RF/microwave to millimeter-wave region.

This paper describes a design and application method of multiple chip module (MCM) technology into microwave applications. An X-Band transmit and receive (T/R) module that has high volume production capability is described. The MMIC chip set designed to achieve multiple functions and state of the arts performance is also described. Peak performance between 8. 5 and 10. 5 GHz includes a power output of 8 W, a noise figure of 6 dB, 23 dB of receive and transmit gains, and a 5-bit phase shifter with less than 5. 5 degree rms phase error. The MCM based module utilizes advanced packaging technique, resulting in a highly integrated and mass production capability.

Highly miniaturization technology in front-end GaAs Hybrid IC for mobile communication equipment will be presented. A combination of MBB (micro bump bonding) technology and the new GaAs IC fabrication process using high dielectric constant (εr) thin film technology has achieved a super small HIC with low cost and low power consumption. The new HIC was constructed of only a ceramic substrate in which the spiral inductors were formed on it and the GaAs IC chip that was bonded by using MBB technology. The MBB technology lead the HIC to a lower temperature process without soldering, a smaller bump diameter, at shorter intervals and the lowest parasitic in the bump. The advantage of the small bonding pad of the IC contributes to miniaturize the IC chip and reduces the chip cost. The GaAs IC process technology using high-εr thin film achieves the integration of all capacitors in the IC without increasing the chip size. Furthermore, low power consumption was achieved by 0. 5-µm LDD BP-MESFET with a high k-value. Although capacitors were integrated on the IC, all of the inductors were formed on the top of the ceramic substrate using a thin film metal process. This was used due to its large occupation area when it was integrated on the IC, and produced a low Q-factor. As a results, the chip was minimized to a size of 0. 81. 0 mm2 and achieved a low-cost chip. Two types of HICs were fabricated for 880 MHz cellular band and 1. 9 GHz PHS (Personal Handy phone System) band. The HIC at 880 MHz measures only 5. 05. 01. 0 mm3, and offered a conversion gain of 25 dB, a noise figure of 4. 2 dB and an image rejection ratio of 12 dB at 2. 7 V and at a power supply of 3. 5 mA. The HIC for 1. 9 GHz measures only 3. 54. 01. 0 mm3, and showed a conversion gain of 16. 0 dB, a II P3 of -16. 0 dBm, and an image rejection ratio of over 20 dBc at 3. 0 V and at power supply of 4. 5 mA.

An equivalent circuit for designing a coherent power combiner using a quasi-optical resonator has been developed. In the resonator, large numbers of devices (HEMT, HBT, etc. ) are arrayed two dimensionally and mounted on a surface of a metal grooved-mirror. A newly developed equivalent circuit for the resonator has been constructed using a transmission-line model. Experiments performed at Ku-band have shown that oscillation frequencies in a 33 HEMT array oscillator can be predicted with errors of less than 1% by using this equivalent circuit.

A power amplifier employing a novel linearizing technique is proposed and is applied to digital mobile communication systems. The amplifier offers both high efficiency and excellent adjacent-channel power leakage (ACP) characteristics. The power added efficiency (PAE) of the proposed amplifier is 51% with an ACP of 45 dBc, which is the PDC standard (one of the Japanese mobile communication systems standards). This amplifier can be applied to various systems merely by changing the ROM data.

This paper describes design approach and power performance of a single 1. 5 V operation two-stage power amplifier MMIC for 2. 4 GHz wireless local area network applications. The MMIC with 0. 760. 96 mm2 area includes SrTiO3 (STO) capacitors with a high capacitance density of 8. 0 fF/µm2 and double-doped AlGaAs/InGaAs/AlGaAs heterojunction FETs with a shallow threshold voltage of -0. 24 V. Utilizing a series STO capacitor and a shunt inductor as an output matching circuit, the total chip size was reduced by 40% as compared with an MMIC utilizing SiNx capacitors. Under single 1.5 V operation, the developed MMIC delivered an output power of 110 mW (20.4 dBm) and a power-added efficiency (PAE) of 36.7% with an associated gain of 20.0 dB at 2.4 GHz. Even operated at a drain bias voltage of 0.8 V, the MMIC exhibited a high PAE of 31.0%.

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.

This paper describes the evaluation of the Voltage Down Converter (VDC) with low ratio of consuming current to load current in DC/AC operation mode. The stability, response and power consumption are investigated. First, for the stability and response, the VDC can operate in the condition that the bounce of the down voltage (dVDL) is no more than 10% of the setting voltage and the maximum load operation frequency (fmax) is 100 MHz at the average load current 70 mA (the maximum load current 140 mA). Secondly, for the power consumption, by using this VDC technology, the value of IC/IL can be suppressed to 5.1E-4 (IC: total consuming current in VDC, IL: average load current) in the condition that dVDL is no more than 10% of the setting voltage and fmax is 10 MHz at the average load current 70 mA. Thus, it is made clear that the VDC can realize high stability, good response and low power consumption at the same time. This technology is suitable for high performance ULSIs which require large load current and low-power consumption.

This paper is concerned with Wiener-Hopf solutions to the electromagnetic wave scattering by a conducting finite thin plate when the incident wave is not a plane wave. The incident wave is approximated in terms of a piece-wise plane wave on a divided small section of the conducting plate. The final expressions are given in an analytically compact form and the results are accurate as long as the plate width is greater than the wavelength and the divided section is so small that we can expand the incident wave by a piece-wise plane wave. A criterion for the ray tracing method is also proposed.

Access control is a key technology for providing data security in database management systems (DBMSs). Recently, various authorization models for object-oriented databases (OODBs) have been proposed since authorization models for relational databases are insufficient for OODBs because of the characteristics of OODBs, such as class hierarchies, inheritance, and encapsulation. Generally, an authorization is modeled as a set of rights, where a right consists of at least three components s, o, t and means that subject s is authorized to perform operation t on object o. In specifying authorizations implicitly, inference rules are useful for deriving rights along the class hierarchies on subjects, objects, and operations. An access request req=(s,o,t) is permitted if a right corresponding to req is given explicitly or implicitly. In this paper, we define an authorization model independent of any specific database schemas and authorization policies, and also define an authorization specification language which is powerful enough to specify authorization policies proposed in the literature. Furthermore, we propose an efficient access control method for an authorization specified by the proposed language, and evaluate the proposed method by simulation.

This paper presents some fundamental properties of multiple-valued logic functions monotonic in a partial-ordering relation which is introduced in the set of truth values and does not necessarily have the greatest or least element. Two kinds of necessary and sufficient conditions for monotonic p-valued functions are given with the proofs. Their logic formulas using unary operators defined in the partial-ordering relation and a simplification method for those logic formulas are also given. These results include as their special cases our former results for p-valued functions monotonic in the ambiguity relation which is a partial-ordering relation with the greatest element.

This paper describes a complete Mandarin text-to-speech system on time domain. We take advantage of the advancement of memory technology, which achieves ever-increasing capacity and ever-lower price. We try to collect as more as possible the synthesis units in a Mandarin text-to-speech system. With such an effort, we developed simpler speech processing techniques and achieved faster processing speed by using only an ordinary personal computer. We also developed delicate methods to measure the intelligibility, comprehensibility, and naturalness of a Mandarin text-to-speech system. Our system performs very well compared with existing systems. We first develop a set of useful algorithms and methods to deal with some features of the syllables, such as duration, amplitude, fundamental frequency, pause, and so on. Based on these algorithms and methods, we then build a Mandarin text-to-speech system. Given any Chinese text in some computerized form, e. g. , in BIG-5 code representation, our system can pronounce the text in real time. Our text-to-speech system runs on an IBM 80486 compatible PC, with no special hardware for signal processing. The evaluation of our text-to-speech system is based on a proposed subjective evaluation method. An evaluation was made by 51 undergraduate students. The intelligibility of our text-to-speech system is 99. 5%, the comprehensibility of our text-to-speech system is 92. 6%, and the naturalness of our text-to-speech system is 81. 512 points in a percentile grading system (the highest score is 100 points, and the lowest score is 0 point). Other 40 Ph. D. students also did the same evaluation about naturalness. The result shows that the naturalness of our text-to-speech system is 82. 8 points in a percentile grading system.

In this paper, we propose a feature selection method to extract functional structures embedded in multidimensional data. In our approach, we do not approximate functional structures directly. Instead, we focus on the seemingly trivial property that functional structures are geometrically thin in an informative subspace. Using this property, we can exclude irrelevant features to describe functional structures. As a result, we can use conventional identification methods, which use only informative features, to accurately identify functional structures. In this paper, we define Geometrical Thickness (GT) in the Cartesian System Model (CSM), a mathematical model that can manipulate symbolic data. Additionally, we define Total Geometrical Thickness (TGT) which expresses geometrical structures in data. Using TGT, we investigate a new feature selection method and show its capabilities by applying it to two sets of artificial and one set of real data.