Some results are presented of a one-year measurement period on an INTELSAT down link at Ku band with elevation of 14 for concurrent measurements of beacon attenuation, sky noise and point rainfall rate. Also some results are presented of line-of-sight (LOS) link fading characteristics at the same place. The projection of the down link trajectory on earth has nearly the same direction as the LOS path trajectory. The measurement results are compared with the theoretical values according to the CCIR recommended procedures of rain attenuation predictions for tropical regions, especially Surabaya, Indonesia. A record rain attenuation value of 80dB was observed.

The relation between the radiation pattern and the dimension of the conducting box for a portable telephone is illustrated both theoretically and experimentally. The Galerkin-moment method using the Fourier series expansion for the surface current of the conducting box, which has a great advantage of having a high accuracy, is employed to obtain the radiation pattern. As an example of antennas, a quarter-wavelength monopole antenna having a sinusoidal current distribution is used. As a result, it is pointed out that the radiation pattern of a monopole antenna mounted on the box tends to tilt in a lower direction both in theory and in experiment as well. The relation between the radiation pattern and the location of the monopole antenna is also described. An asymmetrical, or distorted pattern is observed when the monopole antenna moves away from the center of the top plane.

By using measured attenuation time-series data over 2 years at 19.5GHz with an integration time of 1 sec, effects of the integration time on attenuation statistics are presented. It is observed that the effect on cumulative distribution of attenuation and the relation between annual and the worst-month cumulative time percentages are not significant for the practical prediction purposes. The effect is significant in attenuation duration statistics.

Two types of circuit architecture for GaAs LSI are described. The first circuit is named Stacked DCFL which has supply voltage compatibility with Si CMOS/BiCMOS and ECL operating on 3 V or 3.3 V. A divide by 128/129 prescaler IC has been developed to confirm the Stacked DCFL circuit operation. The second circuit is named SVFL which operates on single supply voltage by using Schottky FET characteristics in spite of normally-on FET logic. Both circuit architectures are based on the virtual ground concept. The transition time of 45 psec was obtained by the SVFL ring oscillator circuit fabricated with 1 µm gate length FET process, and the transition time of DCFL using the same process was from 80 psec to 100 psec. Stacked DCFL and SVFL are candidates for an internal gate and an input/output interface circuit for GaAs ASIC, respectively.

Electronics and automobiles were bound together by the introduction of emission regulations in the 1970's. The rapid progress of control technology and semiconductors that typify microcomputers has brought still closer relations between them. Without electronics, it would be impossible to realize features such as pursuit of comfort and environmental and safety measures which should be added to the automobile's fundamental features. In looking ahead to the future, the role of electronics in achieving electric automobiles and the ultimate goal of "automatic driving" is ever-increasing. Everyone knows that automobiles have become indispensable in our lives. In the future, the role of electronics will become increasingly important in order to evolve automobiles even further to allow harmonization with society.

This paper describes our recent developments of ASICs for automotive multiplexing and data communications to implement in-vehicle networks. With the advancement of automotive electronics, there are ever growing needs for in-vehicle networks. One need is associated with solving the problem of an increasing number of electrical signal wires that inevitably accompany the increasing applications of automotive electronics. Another kind of need is concerned with sharing vehicle control data among several electronic control units such as engine, brake, suspension, and steering electronic control units to achieve an integrated vehicle control system for the purpose of obtaining higher performances in vehicle dynamics. In order to reduce the number of signal wires and share the control data, in-vehicle networks based on multiplexing and data communications are required. In this paper, two original communication protocols are presented to respectively cover low- and highi-speed multiplexing and data communications that are two most needed communication speed areas in our present and future automobiles. ASICs for the presented communication protoclos were designed and fabricated, using 2 µm COMS process. They have the chip size of 3.2 mm2.7 mm with 5,000 transistors and 6.9 mm4.9 mm with 18,000 transistors respectively for low- and high-speed multiplexing and data communications. An elaborate bus driver/receiver ASIC required for high-speed multiplexing and data communications was also designed and fabricated, using 35 V DC bipolar process. As one of its distinctive features, it can greatly suppress radio frequency noise radiated from a communication bus. It has the chip size of 4.8 mm3.8 mm that contains 570 device elements. The features of the protocols are given in detail with the descriptions of the developed ASICs.

In our preceding paper, I-ISMA (Idle Signal Multiple Access for Integrated services), a combination of ISMA and time reservation technique, was proposed to transmit an integrated voice and data traffic in third generation wireless communication networks. There, the channel capacity of I-ISMA was evaluated by the static analysis. To fully estimate performance of contention-based channel access protocols, however, we also need dynamic analysis to evaluate stability, delay, etc. Particularly, in systems concerning real-time voice transmission, delay is one of the most important performance measures. A six-mode model to describe an I-ISMA system is set up. With some assumptions for simplification, the dynamic behavior of the system is approximated by a Markov process so that the EPA (Equilibrium Point Analysis), a fluid approximation method, can be applied to the analysis. Then, numerical and simulation results are obtained for some examples. By means of the same analysis method and under the same conditions, the performance of PRMA is evaluated and compared briefly with that of I-ISMA.

This paper proposes a group-to-group communications algorithm that can extend the range of distributed systems where we can achieve active replication fault-tolerance to partner model distributed systems, in which all processes communicate with each other on an equal footing. Active replication approach, in which all replicated processes are active, can achieve fault-tolerance with low overhead because checkhpoint setting and rollback are not required for recovery from process failure. This algorithm guarantees that each replicated process in a process group has the same execution history and that communications between process groups keeps consistency even in the presence of process failure and message loss. The number of control messages that must be transmitted between processes for a communication between process groups is only a linear order of the number of replicated processes in each process group. Furthemore, this algorithm reduces the overhead for reconfiguration of a process group by keeping process failure and recovery information local to each process group.

A new concept for a positioning satellite system based on a new satellite constellation has been studied. The system needs a minimum of four satellites injected into quasi-geostationary orbit (QGEO) with high inclination. Due to the QGEO characteristic, the satellites are orbiting within continuous visibility range of ground control stations (GCS), from which the satellite time is controlled through the link connections of the feeder and the intersatellite communication (ISC). Consideration is made for the required high accuracy and quality checks against malfunction, wherever the satellites may be positioned. The orbit data processing function, another major function, is performed independently of the time control. The case of global coverage attained by twelve satellites has been studied in this paper. When a constellation of satellites for a global navigation satellite system (GNSS) is designed, conditions to obtain a good geometric dilution of precision (GDOP) at all places and times should be considered. Therefore, the satellites will be spread out in wide directions and are in an asymmetrical arrangement when seen by an observer are considered when setting the parameters of the ephemerides of the constellation. Under the restraints of the designed constellation, the GDOP value distribution for a third of the world map with area time parameters is computed and summarized in histograms for the system evaluation.

This paper presents a method for verifying safety property of a communication protocol modeled as two extended communicating finite-state machines with two unbounded FIFO channels connecting them. In this method, four types of atomic formulae specifying a condition on a machine and a condition on a sequence of messages in a channel are introduced. A human verifier describes a logical formula which expresses conditions expected to be satisfied by all reachable global states, and a verification system proves that the formula is indeed satisfied by such states (i.e. the formula is an invariant) by induction. If the invariant is never satisfied in any unsafe state, it can be concluded that the protocol it safe. To show the effectiveness of this method, a sample protocol extracted from the data transfer phase of the OSI session protocol was verified by using the verification system.

The performance of various ARQ protocols has recently been analyzed for multidestination environments. In all previous work, the round-trip delays between the transmitter and each of the receivers are assumed (or forced) to be equal to the maximum one, to simplify the analysis and/or the operation. This assumption obviously will sacrifice the system performance. In this paper, we evaluate the throughput efficiencies of three multidestination GBN ARQ protocols under unequal round-trip delays. In the investigated protocols, multiple copies of each data block are (re)transmitted contiguously to the receivers. Tight lower bounds are obtained for the throughput efficiencies of the schemes in which each data block is transmitted with the optimum number of copies. Results show that assuming all the round-trip delays to be equal to the maximum one may sacrifice the performance significantly. We also compare the performances of the three investigated protocols. In general, the performance becomes better as the transmitter utilizes more of the outcomes of previous transmission attempts.

To make a fast Bi-CMOS SRAM yield high without speed degradation, three defect-repair methods, the address comparison method, the fuse decoder method and the distributed fuse method, were considered in detail and their advantages and disadvantages were made clear. The distributed fuse method is demonstrated to be further improved by a built-in fuse word driver and a built-in fuse column selector, and fuse analog switches. This enhanced distributed fuse scheme was examined in a fast Bi-CMOS SRAM. A maximun access time of 14 ns and a chip size of 8.8 mm17.4 mm are expected for a 4 Mb Bi-CMOS SRAM in the future.

Until now, in a communication system which deals with multiple processes, system behavior has been described by a fixed number of processes. The state reachability problem for specified processes was generally deliberated within a pre-defined number of processes, and was analyzed by essentially searching for all possible behaviors. However, in a system whose number of processes is arbitrary, a given state which is not reachable in some situations which consists of a small number of processes might be reachable in another situation which consists of a larger number of processes. This article discusses the above problem, assuming that the behavior of a system is described by an arbitrary number of processes. After discussing the relationship between our model and the Petri net model, we clarify the properties between the set of reachable states and the number of processes involved in the system, and show an algorithm to obtain a sufficient number of processes for resolving the reachability problem.

Four circuit techniques and a layout design scheme were proposed to realize a 2 Mb VRAM used 0.8 µm technology. They are the enhanced circuit technologies for high speed operation, the functional circuit design and the effective repair schemes for a VRAM, the low power consumption techniques to active and standby mode and a careful layout design scheme realizing high noise immunity. Using these design techniques, a 2 Mb VRAM is suitable for the graphics application of a 5125128 pixels basis screen, with a clear mode of 4.6 GByte/sec and a 4-multi column write mode of 400 MByte/sec, even using the same 0.8 µm technology as the previous VRAM (1 Mb) was realized.

A stored channel simulator for digital mobile radio enviroments is proposed, which enables the field tests in the laboratory under identical conditions, since it can reproduce the actual multipath radio channels by using the channel impulse responses (CIR's) measured in the field. Linear interpolation of CIR is introduced to simplify the structure of the proposed simulator. The performance of the proposed simulator is confirmed by the laboratory tests.

A method for constructing a compact non-blocking, large matrix-size, optomechanical switch is proposed. It can be switched arbitrarily by disconnecting and reconnecting ferrules on the matrix board. A 250500, 25-mm-ferrule-pitch, 800W855D945H (mm) switch is fabricated. Although the space above the board is densely packed with many ferrule-terminated-fibers, because of the way in which they are arranged and the control of their length, there is no discernible excess loss due to fiber bending.

The synchronic distance is a fundamental concept in a Petri net. Marked graphs form a subclass of Petri nets. Given a matrix D, we are interested in the problem of finding a marked graph whose synchronic distance matrix is D. It is wellknown that the synchronic disrance matrix of a marked graph is a distance matrix. In this letter, we give a matrix D such that D is a distance matrix and there does not exist a marked graph whose synchronic distance matrix is D.

Poled polymer films doped with novel nonlinear organic materials, α-cyano unsaturated carboxylic acid (α-CUCA) derivatives, are prepared. Linear and second-order nonlinear optical properties are investigated. It is found that as the value of hyperpolarizability of the derivatives increases, the second-order nonlinear susceptibility of the film increases. Cerenkov-type second harmonic generation (SHG) of Nd: YAG laser is realized in a poled polymer waveguide doped with the α-CUCA material with a slight absorption at doubled wavelength.

A new system of measuring the thickness of thin filn or paper using 40 kHz ultrasonic wave in air is described. The thickness of samples measured is smaller by a factor of sevreal hundreds than the wavelength of sound. Experinents with polymer and metal films and paper are described to demonstrate the measurement possibilities.

Atmospheric optical communication (AOC) system using subcarrier PSK modulation is proposed and its superiority to OOK modulation in the presence of scintillation is discussed theoretically. An experimental AOC setup with a subcarrier modulated by 155.52(Mb/s) DPSK at light wave-length λ=0.83(µm) over an 1.8(km) outdoor path is employed to show the performance. Theoretical and experimental results are compared under scintillation in clear weather and a good agreement is observed. Finally, AOC systems using subcarrier M-ary PSK and multiple subcarriers are proposed and discussed.