This paper proposes a new method to design an optimal pipelined instructions set processor for ASIP development using a formal HW/SW codesign methodology. First, a HW/SW partioning algorithm for selecting an optimal pipelined architecture is outlined. Then, an adaptive detabase approach is presented that enables to enhance the optimality of the design through very accurate estimation of the performance of a pipelined ASIP in the HW/SW partitioning process. The experimental results show that the proposed method is effective and efficient.

Recently applications of Hilbert curves are studied in the area of image processing, image compression, computer hologram, etc. We have proposed a fast Hilbert scanning algorithm using lookup tables in N dimensional space. However, this scan is different from the one of previously proposed scanning algorithms. Making the lookup tables is a problem for the generation of several Hilbert scans. In this note, we describe a method of making lookup tables from a given Hilbert scan which is obtained by other scanning methods.

A single chip MPEG2 MP@HL Video decoder has been developed, which consists mainly of specific functional units and macroblock level pipeline buffers. A new organization is also devised for a set of off-chip frame memories and the interfaces associated with it. Owing to sophisticated I/O interfaces among functional units, the macroblock level pipeline in conjunction with different decording facilities attains a high throughput to such an extent as to decode HDTV images in real time. Moreover, a set of these functional units, pipeline buffers, and frame memory interfaces, together with a sequence controller, is integrated for the first time in a single chip, which has the total area of 8.8 9.2mm2 with a 0.6µm triple-mental CMOS technology, and dissipates 1.2 W from a single 3.3 V supply.

We have developed a complete chromium oxide (Cr2O3) passivated gas tubing system by introducing ferritic stainless steel instead of conventional austenitic stainless steel (SUS316L). 100% Cr2O3 passivation film can be formed on electropolished ferritic stainless steel surface because the diffusion coefficient of Cr in ferritic stainless steel is 104 times larger than in austenitic stainless steel. In ferritic stainless steel, moreover, welded bead surface is covered by 100% Cr2O3 pas-sivated film by an introduction of advanced welding technology.

Circuit simulators are used to verify circuit functionality and to obtain detailed timing information before the expensive fabrication process takes place. They have become an essential CAD tool in an era of sub-micron technology. We have developed a new event-driven MOS circuit simulator to replace a direct method circuit simulator. In our simulator, partitioned subcircuits are analyzed by a direct method matrix solver, and these are controlled by an event-driven scheme to maintain accuracy. The key of this approach is how to manage events for circuit simulation. We introduced two types of events: self-control events for a subcircuit and prediction correcting events between subcircuits. They control simulation accuracy, and bring simulation efficiency through multi-rate behavior of a large scale circuit. The event-driven scheme also brings some useful functions which are not available from a direct method circuit simulator, such as a selected block simulation function and a batch simulation function for load variation. We simulated logic modules (buffer, adder, and counter) with about 1000 MOSFETs with our event-driven MOS circuit simulator. Our simulator was 5-7 times faster than a SPICE-like circuit simulator, while maintaining the less than 1% error accuracy. The selected block simulation function enables to shorten simulation time without losing any accuracy by selecting valid blocks in a circuit to simulate specified node waveforms. Using this function, the logic modules were simulated 13-28 times faster than the SPICE-like circuit simulator while maintaining the same accuracy.

In this paper, we show a collusion attack on the novel and sophisticated ID-based non-interactive key sharing scheme proposed by Tanaka [2], [3]. It is based on a linear algebraic approach [4]. We discuss its complexity and provide numerical simulation results of the success probability in forging the shared keys.

In order to reduce the ever increasing cost for ULSI manufacturing due to the complexity of integrated circuits, dramatic simplification in the logic LSI architecture as well as the very flexible circuit configuration have been achieved using a highfunctionality device neuron-MOSFET (γMOS).In γMOS logic circuits, however, computations based on the multiple-valued logic is the key for enhancing the functionality. Therefore, much higher accuracy of processing is required. After brief description of the operational principle of γMOS logic, the relationship between the number of multiple logic levels and the functionality enhancement is discussed for further enhancing the functionality of γMOS logic circuits by increasing the number of multiple logic levels, and the accuracy requirements for the manufacturing processes are studied. The order of a few percent accuracy is required for all principal device structural parameters when it is aimed to handle 50-level multiple-valued variable in the γMOS logic circuit.

High-performance ULSI devices require ultraclean silicon surfaces, the complete removal of native oxides, and atomic level flatness and stabilization of the cleaned surfaces against molecular contaminants. Dry cleaning techniques are an attractive alternative to conventional wet processing for future ULSI production using cluster chambers or multi-process cham-bers. Organic contaminants, including photoresist polymers, are effectively removed by photo-excited ozone cleaning. We have found photo-excited halogen radicals to be useful for removing trace metals and native oxides from silicon surfaces without damaging on silicon and silicon-dioxide surfaces. We success-fully terminated hydrogen on (100) silicon surfaces by annealing in pure hydrogen ambient. A dry cleaning system with these sequential processes will be useful in constructing fully-integrated mass-production lines of high-performance ULSI devices.

Multiple TDMA bursts assignment between a base station and a personal terminal will be required for multimedia communications that offers high speed signal transmission such as voice and data simultaneous transmission. This paper proposes a reliable packet transmission method for TDMA based wireless multimedia communications. The proposed method employs an adaptive transmission rate control according to the packet length and a burst diversity technique is applied to improve the frame error rate of a packet. The frame error rate performance has been approximated theoretically by using fade- and infade-duration statistics of a Rayleigh fading channel and a computer simulation has been carried out for two control channels, FACCH/SACCH (Fast/Slow Associated Control CHannel) in the PHS as well as GSM. Both results indicate that the frame error rate is dramatically improved, about one order, when two bursts have different frequency and improved by about 25% when the two bursts have the same frequency.

In order to pave the way to B-ISDN, one of the most important issues for network providers is to identify the most efficient B-ISDN introduction strategy. This paper focuses on the costs of introducing ATM transmission systems into backbone transport networks which must provide highly reliable broad band transmission capability. In this context, the main rival to ATM is Synchronous Transfer Mode (STM); recent Synchronous Digital Hierarchy (SDH) equipment supports the establishment of advanced STM-based high speed transport networks. This paper offers a cost comparison of ATM and STM based backbone transport networks. A digital path network in STM has a hierarchical structure determined by the hierarchical multiplexing scheme employed. The minimum cost STM path network can only be determined by developing a path design method that considers all hierarchical path levels and yields the optimum balance of link cost and node cost. Virtual paths have desirable features such as non-deterministic path bandwidth and non-hierarchical and direct multiplexing capability into high speed optical transmission links. These features make it possible to implement a non-hierarchical VP network with ATM cross connect systems which can handle any bandwidth VP with a universal cell switching function. This paper shows that the non-hierarchical VP routing, which strongly minimizes link cost, can be implemented without significantly increasing node cost. Network design simulations show that the virtual path scheme, possible only in an ATM network, yields the most cost effective path network configuration.

This paper proposes a novel mobile communications system of integrating microcell and macrocell for future land mobile communications which allows the user to enjoy mobile communications services by using one terminal regardless of his terminal speed. Current and developing digital land mobile communications systems are classified into two categories according to their differences in cell size, operating environments, service requirements and terminal speeds. One is a microcell system offering cordless telephone services for the user moving at low speeds and the other is a macrocell system offering vehicle telephone services for the user moving at high speeds. In order to access these two systems, the user needs to have two different terminals and to use an appropriate one according to the operating environments, service requirements and terminal speeds. In this paper, we propose a land mobile communications system in which the user can place a call without any of the inconvenienced described above. The proposed system consists of multi layered composite microcell system with no handover areas, each layer being composed of a number of microcells. This paper presents the detailed structure of this system and evaluates the performances of the channel capacity and the frequency of handovers during a call based on computer simulation results.

Several papers have been shown equalization in the reception side. However, equalization in transmission side that is partial response signaling (PRS) or precoding is also possible in a two-way interactive communication such as time or frequency division duplex (TDD of FDD). This paper proposes and investigates a system which includes a transmission equalization and reception equalization based on an array antenna. This system is the extension in spatial and temporal domains. The channel capacity can be improved in the super channel which includes the transmitter and receiver array antenna.

The scaling laws between the design rules and the smallest sizes and numbers of particles capable of causing pattern defects and scrapping dies in semiconductor device manufacturing are described. Simulation with electromagnetic waveguide model indicates the possibility that particles, the sizes of which are of comparable order or even smaller than the wavelength of the lithography irradiation sources, are capable of causing pattern defects. For example, in the future 0.25 µm-design-rule era, the critical sizes of Si, Al, and SiO2 particles are simulated as 120 nm 120 nm, 120 nm 120 nm, and 560 nm 560 nm, respectively, in the case of 0.7 µm-thick chemically-amplified positive photoresist with 47 nm-thick top anti-reflective coating films. Future giga-scale integration era is also predicted.

This paper overviews fiber-oriented wireless communication systems, particularly in the area of microcell systems. The benefits of fiber-oriented wireless systems are discussed focusing on an application board scheme to facilitate new service deployment in light of intelligent networks. Dynamic range improvement technologies to remove interference are highlighted. Overall system performance is calculated for an economical FP-LD. Furthermore, effective modem use and a potential diversity technique are introduced. This strategy will play a role in realizing flexible fiber-optic subscriber networks.

This paper proposes an adaptive modulation system with a punctured convolutional code for land mobile communications to achieve high quality, high bit rate, and high spectral efficient data transmission in multipath fading environments. The proposed system adaptively controls the coding rate of the punctured convolutional code, symbol rate, and modulation level according to the instantaneous fading channel conditions. During good channel conditions, the modulation parameters are selected to increase the transmission rate as much as possible with satisfying a certain transmission quality. As channel conditions become worse, lower rate modulation parameters are applied or transmission is stopped. The performances in fading environments are evaluated theoretically and by computer simulations. The results show that the proposed system can realize higher quality transmission without the degradation in average bit rate compared to conventional adaptive modulation systems.

Air interfaces of the future mobile communication are widely spreading, because of the multimedia service demands, technology trends and radio propagation conditions. Radio-Highway Networks are expected to realize the universal, seamless and multi-air-interface capability for mobile access networks, and play an important role in the future multimedia radio communications. For the radio-highway networks, this paper newly proposes natural bandpass sampling - asynchronous time division multiple access (NBS-ATDMA) method, where radio signals are natural bandpass sampled at the radio base station and are asynchronously multiplexed on the optic fiber bus link and intelligently transmitted to its desired radio control station. We theoretically analyze the loss probability of the radio signal due to collision in the network and the carrier-to-noise power ratio of received radio signals at the radio control station. Moreover, in order to reduce the loss probability, two access control methods, carrier sense and pulse width control, are proposed, and it is clarified that these improve the number of base station connected to radio highway networks.

The power distribance appeared at a typical electric power system, which can be modeled by a simplified distributed circuit, is discussed. The electric power and the point where its power is injected are then estimated to suppress the power distrbance.

A novel method has been developed to improve the dry etching selectivity of aluminum alloy with respect to photoresist by implanting ions into the patterned photoresist. The selectivity becomes 7.5, which is 5 times higher than that of the unimplanted case. Accordingly, this technology is very promising for fabricating multi-level interconnections in sub-half micron LSIs.

A microphone array system with multi-stage processing for speech enhancement is presented in this paper. Two beamformers with uniform directional patterns, one aimed at the target source and the other at the interfering sources, convert the multi-channel inputs into two data sequences. A novel microphone array structure with a small aperture has been designed to obtain the dual beamformers. The outputs of the two beam-formers are then presented to a post-processing stage to further improve the quality and intelligibility of the speech signal. The post-processing stage can be selected from one of three different algorithms that are presented, which are suitable for different acoustic environments. Applications for such a system include hands-free telephony, teleconferencing and also special situations where speech signals must be picked up in an extremely noisy acoustic environment in which the microphones are hidden (e.g. in a forensic covert recording system).

A unified process flow management system (UPFMS) that combines a CIM system, process/device simulator, CAD system, and manufacturing line schedular has been developed. This new system uses a new language called PDL to describe the process flow as common information for all systems. The UPFMS consists of the flow edit section, the flow inspection section, and several types of interface programs to make it suitable for use with other systems. The process flow data described using the PDL in the UPFMS provides data for controlling lots in CIM system. If modification of the process flow data in the CIM system is required, the process flow data is returned to the UPFMS and modified with inspection using a knowledge data base. Then, the error-free process flow data is sent back to the CIM system for Processes after flow inspection. Moreover, the UPFMS, with the new language PDL, generates recipe data for the equipment using an interface program, and recipe data is input to several types of equipment. Furthermore, the PDL process flow data can also be used as input data for the manufacturing line scheduler using another interface program. Mask and layout data in a CAD system can be exchanged among process/device simulators by using the UPFMS, and thus two-dimensional device characteristics. Spice paramenters can be also to be created. The UPFMS combines with CIM system, process/device simulator, CAD system, and the manufacturing line scheduler using common information, PDL. The process flow data created in the UPFMS can be used to control all systems from the simulation to CIM system as common data.