This paper reviews analog LSI design issues for optical transmission applications; covering ultra-high-speed transmission over 10 Gb/s, multi-Gb/s systems, optical interconnection systems, and optical access. In the future system development, further advancements in not only optical device technology but also LSI technology are eagerly required. More and more sophisticated circuit design techniques are needed to lower power and operation voltage, increase integration, eliminate external elements and adjustments.

In this paper, a new method capable of effectively coding arbitrarity-shaped image regions is presented. The image region is spanned into the 8 8 rectangular block and its intermediate luminances are interpolated. After all liminances in the 8 8 block are obtained from pixels in the region, they are transformed by 8 8 DCT. The proposed extension/interpolation (EL) method is compared with conventional ones, such as SA-DCT, mean stuffing, etc., under three aspects: peak signal-to-noise ratio (PSNR), hardware complexity, and the flexibility for improvement of performance. Simulation results show that the performance of the proposed method is superior to that of the conventional ones. In addition, we introduce an improved version by repetitively performing the EL method.

We propose an improved orthogonal frequency division multiplexing (OFDM) signal detector which uses the minimum mean-square error (MMSE) noise feedback equalization (NFE). The input bit stream is trellis-coded to form OFDM signal blocks and the maximal ratio combining (MRC) is adopted at the receiver in order to improve the performance of the detector. As a result, we obtain significantly improved detection performance compared with the conventional OFDM receivers as follows. Using the proposed MMSE-NFE in the receiver, we can obtain the performance gain of about 1.5 dB to 2 dB in symbol energy to noise power spectral density (Es/No) for Doppler frequencies of fd=20 and 100 Hz, respectively, over the receiver with the MMSE linear equalization (LE) alone at symbol error rate (SER) of about 10-3. With MRC and trellis coding, the performance gain of about 11 dB in Es/No for fd=20 and 100 Hz at SER of about 10-3 is obtained.

Signal Transition Graphs (STG's) are Petri nets, which were introduced to represent a behavior of asynchronous circuits. To derive logic functions from an STG, the reachability graph should be constructed. In the verification of STG's some method based on an Occurrence net (OCN) and its prefix, called an unfolding, has been proposed. OCN's can represent both causality and concurrency between two nodes by net structure. In this paper, we propose a method to derive a logic function by generating sub state space of a given STG using the structural properties of OCN.

We developed a 1200 dots-per-inch light emitting diode array (1200 dpi LED array) chip using a GaAs0.8 P0.2 epitaxial substrate for the first time. One LED array chip consists of 256 LEDs. In general, LED arrays are fabricated by vapor-phase zinc diffusion. From the viewpoint that shallow junctions should be formed to fabricate a very high-density LED array, solid-phase diffusion seems to be more suitable. We fabricated the LED array using selectively-masked solid-phase zinc diffusion, and the diffusion depth was controlled at 1 µm. The diffusion depth was uniform under the diffusion window. The ratio of the length of lateral diffusion to the diffusion depth was about 1.7. These features imply that Zn diffusion was well controlled. In the Zn diffusion, the carrier concentration in the Zn diffusion region was high enough and the sheet resistance of the diffusion region with a diffusion depth of 1 µm was low enough to obtain a sufficient level of emitted light power. The results of performance tests showed that the characteristics of the LED array chip are satisfactory for application in optical printer print heads, because of the array's highly-resolved near-field pattern characteristic, ample emitted light power, low emitted-light-power deviation, and long life.

In this paper, algorithms for resource allocation in an ATM node that serves heterogeneous traffic sources subject to varying Quality of Service (QoS) requirements are proposed. The node can be either a switch port or a multiplexer. Each connection is first individually treated as logical queue. Quick and efficient algorithms allocating service rate and buffer space to each connection based on traffic characteristics and QoS requirement are developed. In order to improve link and buffer utilization, the aggregate traffic is next replaced by an appropriately parameterized new traffic source that still preserves the key characteristics of the aggregate traffic. The most stringest QoS requirement among all connections is selected to be the QoS target of the new traffic source to assure that QoS of each individual connection is satisfied. Resource allocation for the aggregate traffic is determined based on the traffic parameters and QoS target of the new source. Each individually determined service rate and buffer space can be used in cell transmission scheduling and selective cell discarding. In other words, resource allocation together with two related side problems: cell transmission and cell discarding, are treated in this paper in an integrated and efficient manner. The resource allocation algorithms proposed in this paper can also be used to support Call Admission Control (CAC) in ATM networks.

For L 2, M 8, and transmission rate R = (log2M-1) bit/sym, a method for constructing GU trellis codes with L MPSK constellations is proposed and it is shown that the maximally achievable free distance is twice larger than it was previously reported for GU codes. Basides being geometrically uniform, these codes perform as good as Pietrobon's non-GU trellis codes with multidimensional MPSK constellations.

The present paper clarifies that the variance of the maximum likelihood estimator (MLE) of a parameter does not reach the Cramer-Rao lower bound (CRLB) when fitting a straight-line to observed two-dimensional data. In addition, the variance of the MLE can be shown to be equal to the CRLB only if observed noise reduces to a one-dimensional Gaussian variable. For most practical applications, it can be assumed that noise is added only to the range direction. In this case, the MLE is clearly an asymptotically effective estimator. However, even if we assume such a noise model, ML line-fitting to the data from many points of view has a high computational cost. The present paper proposes an alternative fitting method in order to provide a cost-effective unbiased estimator. The reliability of this new method is analyzed statistically and by computer simulation.

Petri net is a graphical and mathematical tool for modelling, analysis, verification, and evaluation of discrete event systems. Liveness is one of the most important problems of Petri net analysis. This is concerned with a capability for firing of transitions and can be interpreted as a problem to decide whether the system under consideration is always able to reach a stationary behavior, or to decide whether the system is free from any redundant elements. An asymmetric choice (AC) net is a superclass of useful subclasses such as EFCs, FCs, SMs, and MGs, where SMs admit no synchronization, MGs admit no conflicts, FCs as well as EFCs admit no confusion, and ACs allow asymmetric confusion but disallow symmetric confusion. It is known that an AC net N is live iff it is place-live, but this is not the "initial-marking-based" condition and place-liveness is in general hard to test. For the initial-marking-based liveness for AC nets, it is only known that an AC net N is live if (but not only if) every deadlock in N contains a marked structural trap.

The quality of ELTRAN wafers has been improved by pre-injection in epitaxial growth, surface treatment just before bonding, high temperature annealing at bonding, high selective etching and hydrogen annealing. The pre-injection reduces defects. The surface treatment eliminates edge-voids. The high temperature bonding dramatically reduces voids all over the wafer. Hydrogen annealing is very effective for surface flattening and boron out-diffusion. In particular, the edge-void elimination by the surface treatment just before bonding is greatly effective for enlarging the SOI area and reduces the edge exclusion down to only two mm. The gate oxide integrity is well evaluated. This process promises high yield and through-put, because each of the steps can be independently optimized.

The parasitic bipolar effect in a 200-V-class thin-film SOI power MOSFET fabricated using the silicon wafer direct bonding wafer was investigated by electrical measurement, two-dimensional process simulation, emission microscopy, and 2-dimensional thermal analysis. It degraded the breakdown voltage of the thin-film SOI power MOSFET and was caused by the increase in the sheet resistance of the body contact region. Photo emission analysis indicated that excess holes recombined in the n+-source region.

This paper deals with minimization of ESOPs (exclusive-or sum-of-products) which represent symmetric functions. Se propose an efficient simplification algorithm for symmetric functions, which guarantees the minimality for some subclass of symmetric functions, and present the minimum ESOPs for all 6-variable symmetric functions.

This paper presents an analog 2-dimensional discrete cosine transform (2-D DCT) processor for focal-plane image compression. The on-chip analog 2-D DCT processor can process directly the analog signal of the CMOS image sensor. The analog-to-digital conversion (ADC) is preformed after the 2-D DCT, and this leads to efficient AD conversion of video signals. Most of the 2-D DCT coefficients can be digitized by a relatively low-resolution ADC or a zero detector. The quantization process after the 2-D DCT can be realized by the ADC at the same time. The 88-point analog 2-D DCT processor is designed by switched-capacitor (SC) coefficient multipliers and an SC analog memory based on 0.35µm CMOS technology. The 2-D DCT processor has sufficient precision, high processing speed, low power dissipation, and small silicon area. The resulting smart image sensor chips with data compression and digital transmission functions are useful for the high-speed image acquisition devices and portable digital video camera systems.

In this paper, an efficient one-way point-to-multipoint communication protocol (PTMP) is proposed. The PTM protocol is helpful to distribute information to many workstations simultaneously and correctly. The PTM protocol is designed for network channels with low error possibility. The PTM protocol utilizes broadcast for data distributing. Re-transmission request for lost packet is returned to the server, and acknowledgment for correctly received packets is not returned to the server. We have applied the protocol to the network presentation system. The network presentation system is intended to display same graphical images to multiple workstations simultaneously on an X window system. This presentation system is able to provide services for at least forty X servers simultaneously, the capacity is limited to X server performance, except for pixmap drawing. For the case of pixmap drawing, the system capacity is limited to the network bandwidth. To solve network bandwidth problem, we combined PTM protocol with the network presentation system. With PTM protocol, system performance is improved and the use of network bandwidth is lowered.

In the information engineering learning environment, there may be more than one solution to any given problem. We have developed CAMELOT using the Nominal Group Technique for group problem solving. This paper describes the collaborative learning system on the Internet using discussion model, the effectiveness of collaborative learning in modeling the entity-relationship diagram within the field of information engineering, and how to apply AI technologies such as rule-based reasoning and case-based reasoning to the pedagogical strategy. By using CAMELOT, each learner learns how to analyze through case studies and how to collaborate with his or her group in problem solving. As a result. We have found evidence for the effectiveness of collaborative learning, such as getting a deeper understanding by using CAMELOT than by individual learning, because they can reach better solutions through discussion, tips from other learners, examination of one another's individual solutions, and understanding alternative solutions using case-based reasoning.

This study proposes an amplitude limiting type spread spectrum communication to be applied to extremely low power radio wave communicaion and evaluates capability of the code division multiplex. First, changes in output from the correlation device, maximum power, and in allowable noise power are compared by computer simulation for the case where the number of multiplex channels is increased. Second, possible relationship between noise intensity and error rate is measured by actual loading experiments using a device developed for trial purpose. Third, majority decision logic is proposed for the said device to realize amplitude limiting type code division multiplex easily. When the amplitude is limited, the maximum power can be controlled at about 2 dB, and channels with more than half of the number of spread sign can be used. It is revealed that, in the spread spectrum, alteration of the number of multiplex channels is made easy by application of this method.

We propose an nn optical switch that is suitable for flexible and reliable optical access networks and for reconfigurable optical inter-module connections in large-scale processing systems. The switch consists of an intersecting waveguide matrix, matching oil, and microactuators. Switching is based on the movement of oil due to capillary pressure, which is controlled by the microactuator. The necessary switching conditions were calculated and the results showed that both the oil volume and the microactuator position must be controlled. A trial optical switch was fabricated to test the switching principle, and switching and self-holding were both confirmed. These results show the feasibility of a very small self-holding nn optical switch that uses a waveguide matrix and microactuators made by using microfabrication technologies.

Force curves obtained from an elastic contact theory are shown and compared with experimental results. In the elastic contact theory, a pin-on-disk contact is assumed and the following interaction are taken into consideration; (i) elastic deformation, (ii) the specific energy of adhesion in the area of the contact, which is expressed as the difference between the surface energies and the interface energy, (iii) the long-range interaction outside the area of contact, assuming the additivity of the Lennard-Jones type potential, and (iv) another elastic term for the measurement system such as the cantilever stiffness of an atomic force microscope (AFM). In the limit when the stiffness is infinite, the theory conforms to Muller-Yushchenko-Derjaguin (MYD) theory. In the limit when the surface-surface interaction is negligible, the theory conforms to the analytical theory by Takahashi-Mizuno-Onzawa. In the limit when the stiffness is infinite and the long-range interaction outside the area of contact is negligible, the theory conforms to Johnson-Kendall-Roberts (JKR) theory. All parameters and all equations are normalized and the normalized force curve is obtained as the functional of only two parameters; (1) the normalized stiffness of the measurement system, and (2) the normalized distance which is used in the expression of the Lennard-Jones potential. The force-displacement plots are converted into force-penetration plots.

The majority of independent locomotion microrobots pack batteries as their energy source. However, because the energy that can be stored in a battery is proportional to its volume, the operating time becomes shorter as the robot becomes smaller. To solve this problem the energy must be supplied from outside by wireless transmission. We propose a microwave energy transmission system for microrobots in metal piping. Because microwave is rectified and converted in the form of electric energy in this system, we developed a receiving antenna for microrobots in piping and a microwave rectifying circuit to generate high voltage. These were loaded on a microrobot, tested to drive a locomotive mechanism, and the efficiency of the proposed system was confirmed.

Partial capture effect for multi-carrier radio packet communication network is evaluated in frequency selective fading channel. In multi-carrier modulation (MCM) network where each terminal uses several sub-carriers for transmission,the terminals have different instantaneous frequency responses because of its location, fading pattern, and other various factors. This generates the difference of received power in frequency domain, then partial capture effect can be considered at each sub-carrier. Moreover these partially captured packets are not damaged by inter symbol interference (ISI) caused by frequency selective fading, which seriously degrades single-carrier modulation (SCM) network. From this point of view we present the partial capture effect for the MCM network in the frequency selective fading environment. The results show that the MCM network with partial capture has more advantages than the MCM network without partial capture in terms of the throughput and the average number of transmissions.