This paper proposes a superposed SSMA (Spread Spectrum Multiple Access)-QPSK (Quadrature Phase Shift Keying) signal transmission scheme over high speed QPSK signals to achieve higher frequency utilization efficiency and to facilitate lower power transmitters for SSMA-QPSK signal transmission. Experimental results show that the proposed scheme which employs the coding-rate of one-half FEC (Forward Error Correction) and a newly proposed co-channel interference cancellation scheme for SSMA-QPSK signals can transmit twenty SSMA-QPSK channels simultaneously over a nonlinearly amplified high speed QPSK signal transmission channel and achieve as ten times SSMA channels transmission as that without co-channel interference cancellation when the SSMA-QPSK signal power to the high speed QPSK signal power ratio equals -30dB. Moreover, cancellation feasibility generation of the interference signals replica through practical hardware implementation is clarified.

This paper presents an optimization method for pseudo-Kronecker expressions of p-valued input two-valued output functions by using multi-place decision diagrams for p2 and p4. A conventional method using extended truth tables requires memory of O (3n) to simplify an n-variable expression, and is only practical for functions of up to n14 variables when p2. The method presented here utilizes multi-place decision diagrams, and can optimize considerably larger problems. Experimental results for up to n39 variables are shown.

This paper describes a monolithic 10-b A/D converter that realized a maximum conversion frequency of 300 MHz. Through the development of the interpolated-parallel scheme, the severe requirement for the transistor Vbe matching can be alleviated drastically, which improves differential nonlinearity (DNL) significantly to within 0.4 LSB. Furthermore, an extremely small input capacitance of 8 pF can be attained, which translates into better dynamic performance such as SNR of 56 dB and THD of 59 dB for an input frequency of 10 MHz. Additionally, the folded differential logic circuit has been developed to reduce the number of elements, power dissipation, and die area drastically. Consequently, the A/D converter has been implemented as a 9.0 4.2-mm2 chip integrating 36K elements, which consumes 4.0 W using a 1.0-µm-rule, 25-GHz ft, double-polysilicon self-aligned bipolar technology.

This paper proposes a feedback-loop type transmission power control (TPC) scheme coupled with first and second order prediction methods and analyzes the optimum control period and residual control error. In order to minimize residual control error, the three main factors contributing to residual control error are analyzed. First, to detect accurately up-link rain attenuation, a channel quality detection method is proposed and analyzed experimentally for puseudo-error detection. Second, rain attenuation rates in Ka band are measured and analyzed statistically. Finally, the optimum control period of the proposed TPC scheme is analyzed. The simulation results on the prototype TPC system show a maximum of 4.5 dB residual control error is achievable with an optimum control period of about 1 second to 1.5 seconds.

With the arrival of B-ISDN, point-to-point routing alone is no longer adequate. A new class of computer and video related services, such as mass mailing, TV broadcasting, teleconferencing, and video 900 service, requires the network to handle multiple destination routing (MDR). Multiple destination routing enables widespread usage of multipoint services at a lower cost than networks using point-to-point routing. With this in mind, network providers are researching more into MDR algorithms. However, the MDR problem itself is very complex. Furthermore, its optimal solution, the Steiner tree problem, is NP-complete and thus not suitable for real-time applications. Recently, various algorithms which approximate the Steiner tree problem have been proposed and, in this invited paper, we will summarize the simulation results of these algorithms. But first, we will define the MDR problem, the issues involved, and the benchmark used to compare MDR algorithms. Then, we will categorize the existing MDR algorithms into a five-level classification tree. Lastly, we will present various published results of static algorithms and our own simulation results of quasi-static algorithms.

A group-based random access communication system which consists of two groups of many users is considered. The two different groups share a common random multiple access channel. Users from a group are allocated a high transmitting power level and have a high probability of correct reception among overlapping packets. We set a threshold, θ, which is such that the group with the high power level will occupy the channel if less than or equal to θ packets are transmitted from the group with the low power level. We obtain a two-dimensional Markovian model by tracing the number of backlogged users in the two groups. The two-dimensional Markov chain is shown to be not ergodic and thus the system is not stable. A two-dimensional retransmission algorithm is developed to stabilize the system and the retransmission control parameters are chosen so as to maximize the channel throughput. An equilibrium point analysis is performed by studying the drift functions of the system backlog and it is shown that there is a unique global equilibrium point. The channel capacity for the system is found to be in the range from 0.47 up to 0.53, which is a remarkable increase compared to the conventional slotted ALOHA system.

This paper describes new methematical tools, taken from quantum field theory (QFT), which may make it possible to characterize localized excitations (including solitons, but also including chaotic modes) generated by PDE systems. The significance to computer hardware and neurocomputing is also discussed. This mathematics--IF further developed--may also have the potential to reorganize and simplify our understanding of QFT itself--a topic of very great intellectual and practical importance. The paper concludes by describing three new possibilities for research, which will be very important to achieving these goals.

We have proposed a new omnidirectional image sensor COPIS (COnic Projection Image Sensor) for guiding navigation of a mobile robot. Its feature is passive sensing of the omnidirectional image of the environment in real-time (at the frame rate of a TV camera) using a conic mirror. COPIS is a suitable sensor for visual navigation in real world environment with moving objects. This paper describes a method for estimating the location and the motion of the robot by detecting the azimuth of each object in the omnidirectional image. In this method, the azimuth is matched with the given environmental map. The robot can always estimate its own location and motion precisely because COPIS observes a 360 degree view around the robot even if all edges are not extracted correctly from the omnidirectional image. We also present a method to avoid collision against unknown obstacles and estimate their locations by detecting their azimuth changes while the robot is moving in the environment. Using the COPIS system, we performed several experiments in the real world.

It is shown from a computer analysis that there exists a resonant mode of a surface wave which propagates along Goubau line, and that the attenuation of such a mode is very low. The approximate formula for obtaining the resonant frequency is also given.

Selective epitaxial growth technology has been extended to the base formation of a transistor on the basis of the SATURN (Self-Alignment Technology Utilizing Reserved Nitride) process, a high-speed bipolar LSI processing technology. The formation of a self-aligned base contact, coupled with SIC (Selective Ion-implanted Collector) fabricated by lowenergy ion implantation, has not only narrowed the transistor active regions but has drastically reduced the base width. A final base width of 800 and a maximum cut-off frequency of 31 GHz were achieved.

The authors recently proposed a design method of stable IIR digital filters based on the interpolation by rational characteristic functions of filters, for a set of values of these characteristic function and, in addition, their higher derivatives prescribed at a number of frequency. This method can be further extended so that, despite usage of a less number of interpolation points, almost the same filter characteristics as one obtained by the former method can be realized. This paper presents an improved design method for making the transfer function meet strict magnitude specifications. The method proposed in this paper is especially efficient for designing a filter whose characteristics is specified not only in the passband but also in the transition band with relatively narrow bandwidth.

Self-aligned aluminum-gate MOSFET's have been successfully fabricated by employing ultraclean ion implantation technology. The use of ultra high vacuum ion implanter and the suppression of high-energy ion-beam-induced metal sputter contamination have enabled us to form ultra-shallow low-leakage pn junctions by furnace annealing at a temperature as low as 450. The fabricated aluminum-gate MOSFET's have exhibited good electrical characteristics, thus demonstrating a large potential for application to realizing ultra-high-speed integrated circuits.

The performance of copper interconnects formed by the low-kinetic-energy ion bombardment process has been investigated. The copper films formed on SiO2 by this technology under a sufficient amount of ion energy deposition exhibit perfect orientation conversion from Cu (111) to Cu (100) upon post-metallization thermal annealing. We have discovered such crystal orientation conversion is always accompanied by a giant-grain growth as large as 100 µm. The copper film resistivity decreases due to the decrease in the grain boundary scattering, when the giant-grain growth occurs in the film. The resistivity of giant-grain copper film at a room temperature is 1.76 µΩcm which is almost equal to the bulk resistivity of copper. Furthermore, a new-accelerated electromigration life-test method has been developed to evaluate copper interconnects having large electromigration resistance within a very short period of test time. The essence of the new method is the acceleration by a large-current-stress of more than 107 A/cm2 and to utilize the self heating of test interconnect for giving temperature stress. In order to avoid uncontrollable thermal runaway and resultant interconnect melting, we adopted a very efficient cooling system that immediately removes Joule heat and keeps the interconnect temperature constant. As a result, copper interconnects formed by the low-kinetic-energy ion bombardment process exhibit three orders of magnitude longer lifetime at 300 K than Al alloy interconnects.

Two kinds of nitrided ultrathin (510 nm) SiO2 films were formed on the silicon (100) face using rapid thermal NH3-nitridation (RTN) and rapid thermal N2O-oxynitridation (RTON) technologies. The MOS capacitors with RTN SiO2 film showed that by Fowler-Nordheim (F-N) electron injection, both electron trap density and low-field leakage increase by the NH3-nitridation. In addition, the charge-to-breakdown (QBD) value decreases owing to NH3-nitridation. By contrast, RTON SiO2 films exhibited extremely low electron trap density, almost no increase of the leakage current, and large QBD value above 200C/cm2. The oxide film composition was evaluated by secondary ion mass spectroscopy (SIMS). The chemical bonding states were also examined by Fourier transform-infrared reflection attenuated total reflectance (FT-IR ATR) and X-ray photoelectron spectroscopy (XPS) measurements. These results indicate that although a large number of nitrogen (N) atoms are incorporated by the RTN and RTON, only the RTN process generates the hydrogen-related species such as NH and SiH bounds in the film, whereas the RTON film indicates only SiN bonds in bulk SiO2. From the dielectric and physical properties of the oxide films, it is considered that the oxide wearout by high-field stress is the result of the electron trapping process, in which anomalous leakage due to trap-assisted tunneling near the injected interface rapidly increases, leading to irreversible oxide failure.

We designed and fabricated a prototype 0.4-µm-gate CMOS/SIMOX PLL LSI in order to verify the potential usefulness of ultrathin-film SIMOX technology for creating an extremely low-power LSI containing high-speed circuits operating at frequencies of at least 1 GHz and at low supply voltages. This PLL LSI contains both high-frequency components such a prescaler and low-frequency components such as a shift register, phase frequency comparator, and fixed divider. One application of the LSI could be for synthesizing communication band frequencies in the front-end of a battery-operated wireless handy terminal for personal communications. At a supply voltage of 2 V, this LSI operates at up to 2 GHz while dissipating only 8.4 mW. Even at only 1.2 V, 1 GHz-operation can be obtained with a power consumption of merely 1.4 mW. To explain this low-power feature, we extensively measured the electrical characteristics of individual CMOS/SIMOX basic circuits as well as transistors. Test results showed that the high performance of the LSI is mainly due to the advanced nature of the CMOS/SIMOX devices with low parasitic capacitances around source/drain regions and to the new circuit design techniques used in the dual-modulus prescalar.

In this paper, we propose an algorithm of O(|V|min{k,|V|,|A|}|A|) time complexity for finding all k-edge-connected components of a given digraph D=(V,A) and a positive integer k. When D is symmetric, incorporating a preprocessing reduces this time complexity to O(|A|+|V|2+|V|min{k,|V|}min{k|V|,|A|}), which is at most O(|A|+k2|V|2).

In this paper we propose a new application of Wu's mechanical theorem proving method to reconstruct polyhedra in 3-D space from their projection image. First we set up three groups of equations. The first group is of the geometric relations expressing that vertices are on a plane segment, on a line segment, and forming angle in 3-D space. The second is of those relations on image plane. And the rest is of the relations between the vertices in 3-D space and their correspondence on image plane. Next, we classify all the groups of equations into two sets, a set of hypotheses and a conjecture. We apply this method to seven cases of models. Then, we apply Wu's method to prove that the hypotheses follow the conjecture and obtain pseudodivided remainders of the conjectures, which represent relations of angles or lengths between 3-D space and their projected image. By this method we obtained new geometrical relations for seven cases of models. We also show that, in the region in image plane where corresponding spatial measures cannot reconstructed, leading coefficients of hypotheses polynomials approach to zero. If the vertex of an image angle is in such regions, we cannot calculate its spatial angle by direct manipulation of the hypothesis polynomials and the conjecture polynomial. But we show that by stability analysis of the pseudodivided remainder the spatial angles can be calculated even in those regions.

The Hilbert curve is one of the simplest curves which pass through all points in a space. Many researchers have worked on this curve from the engineering point of view, such as for an expression of two-dimensional patterns, for data compression in an image or in color space, for pseudo color image displays, etc. A computation algorithm of this curve is usually based on a look-up table instead of a recursive algorithm. In such algorithm, a large memory is required for the path look-up table, and the memory size becomes proportional to the image size. In this paper, we present an implementation of a fast sequential algorithm that requires little memory for two and three dimensional Hilbert curves. Our method is based on some rules of quad-tree traversal in two dimensional space, and octtree traversal in three dimensional space. The two dimensional Hilbert curve is similar to the scanning of a DF (Depth First) expression, which is a quad-tree expression of an image. The important feature is that it scans continuously from one quadrant, which is obtained by quad tree splitting, to the next adjacent one in two dimensional space. From this point, if we consider run-lengths of black and white pixels during the scan, the run-lengths of the Hilbert scan tend to be longer than those of the raster scan and the DF expression scanning. We discuss the application to data compression using binary images and three dimensional data.

This report will present an expression for the mechanical behavior of a drum-wound dual coated fiber and an analytical expression for the microbending loss in single mode dual coated fibers. These analytical expressions are then compared with experimental drumwinding microbending loss results to determine their validity.

Practical linewidth measurement accuracy better than 0.02 µm 3 sigma that meets the production requirement for devices with sub-half micron features, was achieved in a field emission scanning electron-beam metrology system (Hitachi S-7000). In order to establish high accuracy linewidth measurement, it was found in the study that reduction of electron-beam diameter and precise control of operating conditions are significantly effective. For the purpose of reducing electron-beam diameter, a novel electron optical system was adopted to minimize the chromatic aberration which defines electron-beam profile. As a result the electron beam diameter was reduced from 20 nm to 16 nm. In order to reduce measurement uncertainties associated with actual operating conditions, a field emission electron gun geometry and an objective lens current monitor were investigated. Then the measurement uncertainties due to operating conditions was reduced from 0.016 µm to 0.004 µm.