The applicability of Dynamic Channel Assignment methods to a Reuse Partitioning system in cellular radio systems is investigated in this paper. The investigations indicate that such a system has a tendency to increase the difference between blocking probability for the partitioning two coverage areas in comparison with the conventional Reuse Partitioning system employing Fixed Channel Assignment method. Two schemes using new Channel Rearrangement algorithms are also proposed in order to alleviate the difference as a disadvantage which gives unequal service to the system. The simulation results show that the proposed schemes are able to reduce the difference significantly while increasing the carried traffic by 10% as compared with the conventional system.

Packet Reservation Multiple Access (PRMA) is emerging as a possible multiple access scheme for the forth-coming Personal Communication systems, due to its inherent flexibility and to its capability to exploit silence periods to perform a statistical multiplexing of traffic sources, often characterised by a high burstiness. On the other hand, the current trend in reducing cell sizes and the more complex traffic scenarios pose major planning problems, which are best coped with by adaptive allocation schemes. The identification of adaptive schemes suitable to operate on a shorter time scale, which is typical of packetised information, disclose a number of problems which are addressed in this paper. A viable solution is provided by a well-known self-adaptive assignment method (Channel Segregation), originally developed for FDMA systems, provided it is conveniently adapted for PRMA operation. Simulations show good performance, provided that values of some system variables are correctly chosen. These results encourage further studies in order to refine adaptive methods suitable for cellular, packet switched personal communications systems.

This paper presents a new structure for noise and echo cancelers based on a combined fast abaptive algorithm. The main purpose of the new structure is to detect both the double-talk and the unknown path change. This goal is accomplished by using two adaptive filters. A main adaptive filter Fn, adjusted only in the non-double-talk period by the normalized LMS algorithm, is used for providing the canceler output. An auxiliary adaptive filter Ff, adjusted by the fast RLS algorithm, is used for detecting the double-talk and obtaining a near optimum tap-weight vector for Fn in the initialization period and whenever the unknown path has a sudden or fast change. The proposed structure is examined through computer simulation on a noise cancellation problem. Good cancellation performance and stable operation are obtained when signal is a speech corrupted by a white noise, a colored noise and another speech signal. Simulation results also show that the proposed structure is capable of distinguishing the near-end signal from the noise path change and quickly tracking this change.

New multimedia applications have emerged on top of information infrastructures, such as on-demand services, digital libraries and museums, online shopping, information Q & A, concurrent engineering, document management, and desktop program production, which require new databases. That is, next-generation database systems must enable users to efficiently and flexibly develop and execute such advanced multimedia applications. Moreover, in some applications, there is no existent data; in others, there are databases or files to be integrated. This requires both top-down and bottom-up database development. To this end, we focus on development of a database system which enables flexible and efficient acquisition, storage, access and retrieval, and distribution and presentation of large amounts of heterogeneous media data. In particular, we propose a multimedia data model as an integration of structural, temporal, spatial, and control functionality. That is, we take an approach based on an object-oriented database, which is more suitable for description of media structures and operations than a traditional relational database. And we extend the object-oriented approach by providing temporal and spatial operators, and control of distributing computing and QOS (quality of service). In this paper, we describe a multimedia data model and its efficient implementation.

The goal of this paper is to propose a new symbolic model checking approach named time-space modal model checking, which could be applicable to verification of bit-slice microprocessor of infinite bit width and one dimensional systolic array of infinite length. A simple benchmark result shows the effectiveness of the proposed approach.

Current testing has been proposed as an alternative technique for testing fully CMOS digital LSIs. Current testing has higher fault coverage than conventional stuck-at fault (SAF) testing and is more economical because it detects a wide range of faults and requires fewer test vectors than does SAF testing. We have proposed a current testing that measures the integral of the power supply current (IDD) during one clock period including the switching current. Since this method cannot be affected by the switching current, it can be used to test an LSI operating at a relatively high clock freuqnecy. This paper presents an improved current testing method for CMOS digital and analog LSIs. The method uses two current values (i.e., an upper limit and a lower limit) and judges the circuit under test to be faulty if the measured IDD is outside these limits. The proposed current testing is evaluated here for some kinds of faults (e.g., the bridging fault and the breaking fault) in digital and mixed-signal LSIs, and its efficiency of the current testing using SPICE3.

A single bridging fault location technique for CMOS combinational circuits is proposed. In this technique, the cause of an error observed at the primary outputs in deduced using a diagnosis table constructed from the circuit under test and the given tests. The size of a diagnosis table is [the number of gates][the number of tests]2 bits, which is much smaller than that of the fault dictionary. The experimental results show that the number of possible bridging faults is reduced to less than 5 in several seconds, when using the tests to detect single stuck-at faults and considering only the bridging faults between physically adjacent nets.

As microprocessor units have become faster, DRAMs have also been required to become faster. One of the fast DRAMs is the synchronous DRAM, which transfers data at a high rate. We have developed a 100-MHz Synchronous DRAM using pipeline architecture and new high speed I/O lines method. This paper describes some features of the DRAM and its new pipeline architecture.

Mobile communications have been developing rapidly in recent years. In Japan, a new digital cellular system and digital trunked radio system were introduced. Soon a new personal communication system and road information system will be introduced. Other than those systems, many new mobile communication systems are being developed. These are new pager systems, future public land mobile communication systems, wireless card system and anti-collision radar system etc.

This paper describes the new α-particle induced soft error mechanism, the Minority Carrier Outflow (MCO) effect, which may seriously affect the reliability of the scaled DRAMs with three dimensional capacitors. The MCO chargge increases as the device size miniaturizes because of the three dimensional capacitor effect as below. As the device scales down, the storage node volume decreases which results in the higher minority carrier density in the storage node and larger outflow charge. Also as the device plan view miniaturizes, the stack capacitor height or trench depth does not scales down or even increases to keep the storage node capacitance, therefore the initially generated minority carrier becomes larger. A simple analytical MCO model is introduced to evaluate the MCO effect quantitatively. The model agrees well with the three dimensional device simulation. The MCO model predicts that the life time of the minority carrier in the storage node strongly affects the MCO charge, however, even when the life time is as small as the order of 100 ps, the MCO effect can be the major soft error mechanism.

A fiber optic temperature sensor using a conventional graded index multimode optical fiber is proposed. The multimode fiber is excited by two selected modes using a computer-generated holographic filter. A clear periodic signal created by interference between two modes is observed in the experiment.

This paper gives several explicit formulas for the waiting times in each stage in an alternating-service, two-stage tandem queue (M/G/1 type queue) with a gate in the first stage and server vacations (or setup time). These formula are obtained by using simple conversion relationships between the performance measures. This study has been motivated by the performance evaluation of call (packet or message) processing in telecommunication switching systems.

Multimedia communication services are being made available with the advent of broadband optical fiber networks. As many different services will be accommodated in such networks, network survivability has been recognized to be a crucial concern. In this paper, we propose a new restoration algorithm for ATM networks providing multimedia services. Our proposed restoration algorithm adopts the message bundling scheme of the Multi-Destination Flooding (MDF) algorithm which was previously proposed for STM-based networks to handle catastrophic failures such as multiple link and node failures. Virtual Paths (VP) with the same communication speed are bundled and Operation Administration and Maintenance (OAM) cells are used for communication of restoration messages. In addition, the following modifications are made on the original MDF to improve restoration performance. The pre-cancellation scheme is adopted to arbitrate reservation contention to realize high restoration ratio. The dual queue scheme is applied to avoid congestion of restoration messages. Moreover, the connection control scheme for VPI connections is proposed to prevent alternative routes from being misconnected. This paper describes the design concept of our restoration algorithm, processes in each restoration phase, and the performance evaluation by computer simulation.

This paper describes an 8:1 multiplexer and a 1:8 demultiplexer for fiber optic transmission systems. These chips incorporate new architectures having a smaller hardware and enabling the use of a lower supply voltage. The multiplexer and the demultiplexer are fabricated using 0.8 µm silicon-bipolar process with a double polysilicon self-aligned structure. The multiplexer operates at a bit rate of up to 3.0 Gb/s, while the demultiplexer operates at a bit rate of up to 4.1 Gb/s. The multiplexer consumes 272 mW and the demultiplexer consumes 388 mW under the power supplies of VEE=-4.0 V and VTT=-2.0 V. These values are the smallest so far above 2.5 Gb/s which is the standard of the Level-16 of the synchronous transfer mode (STM-16).

Retiming is a technique to resynthesize a synchronous sequential circuit by rearranging flip-flops. In view of logic optimization, retiming can potentially derive a circuit which is more simplified and testable because retiming can convert several sequential redundancies into combinational redundancies. Retiming methods proposed before have no guarantee to generate the same output sequences when the circuit start from a specified initial state such as the reset state. If the circuit with a specified initial state must have the same output sequences after retiming, rearrangement of flip-flops should be restricted. This paper presents a retiming method for circuits with a specified initial state so that retimed circuits give the same output sequences of the original circuits for any input sequences. In the proposed method, during the procedure of retiming each flip-flop keeps a value corresponding to the initial state and unification of flip-flops with different value is avoided. Our procedures uses 5-valued logic on gate level implementation to describe and calculate the values of flip-flops. Therefore after optimization using our method, the circuit has completely the same behavior as that of the original. Experimental results for ISCAS'89 benchmark circuits show the method can be used to optimize the circuits as well as a method without considering the initial state. And testability of the retimed circuit is more enhanced than that of the original circuit.

The subject is the horizontal coil's temperature rise in DY for high frequency by being unavoidable for the tendency of more information on display monitor equipments. Writers made the temperature-balance model from a point of view that this temperature rise is coming from the heat rise and the conductivity, and we expressed the temperature rise of DY by using amount of the heat rise and conductivity characteristics of each element. Also, we indicated the method to decide about the selection of the wire size of coils, the section area and deflection sensitivity, with regard to reducing the temperature rise. We confirmed the effect of the temperature rise reduction by about 9 on products, under the condition of 64 kHz horizontal frequency.

Some undetectable stuck-at faults called the redundant faults are included in practical combinational circuits. The redundant fault does not affect the functional behavior of the circuit even if it exists. The redundant fault, however, causes undesirable effects to the circuit such as increase of delay time and decrease of testability of the circuit. It is considered that some redundant faults may cause the logical defects in the future. In this paper, firstly, we study the testability of the redundant fault in the combinational circuit by using delay effects. Secondly, we propose a method for generating a test-pair of a redundant fault by using an extended seven-valued calculus, called TGRF (Test-pair Generation for Redundant Fault). TGRF generates a dynamically sensitizable path for the target line which propagates the change in the value on the target line to a primary output. Finally, we show experimental results on the benchmark circuits under the assumptions of the unit delay and the fanout weighted delay models. It shows that test-pairs for some redundant faults are generated theoretically.

The dynamics of an artificial neural network derived from a biological system, and its two applications to engineering problems are examined. The model has a multi-layer structure simulating the primary and secondary components in the olfactory system. The basic element in each layer is an oscillator which simulates the interactions between excitatory and inhibitory local neuron populations. Chaotic dynamics emerges from interactions within and between the layers, which are connected to each other by feedforward and feedback lines with distributed delays. A set of electroencephalogram (EEG) obtained from mammalian olfactory system yields aperiodic oscillation with 1/f characteristics in its FFT power spectrum. The EEG also reveals abrupt state transitions between a basal and an activated state. The activated state with each inhalation consists of a burst of oscillation at a common time-varying instantaneous frequency that is spatially amplitude-modulated (AM). The spatial pattern of the activated state seems to represent the class of the input ot the system, which simulates the input from sensory receptors. The KIII model of the olfactory system yields sustained aperiodic oscillation with "1/f" spectrum by adjustment of its parameters. Input in the form of a spatially distributed step funciton induces a state transition to an activated state. This property gives the model its utility in pattern classification. Four different methods (SD, RMS, PCA and FFT) were applied to extract AM patterns of the common output wave forms of the model. The pattern classification capability of the model was evaluated, and synchronization of the output wave form was shown to be crucial in PCA and FFT methods. This synchronization has also been suggested to have an important role in biological systems related to the information extraction by spatiotemporal integration of the output of a transmitting area of cortex by a receiving area.

A new concept for a navigation and communication satellite system has been proposed. The navigation satellite system that forms the basis of the proposed system has been studied by one of the authors and extended to add a mobile communication function to the system. The satellite system consists of 15 satellites in quasi-geostationary orbit (QGEO) that have a geostationary altitude and high inclination and provide global coverage and positioning capability to the observer through only reception of the range measurement signals generated at the satellites, which are in the same configuration as the satellites in Global Positioning System (GPS), Three satellites out of the 15 satellite are designated to install a subsystem for mobile satellite communication in order to satisfy mobile communication convenience as required in a Future Air Navigation System's (FANS) concept of International Civil Aviation Organization (ICAO). The case studies of 15-satellites constellations demonstrate not only an acceptable positioning accuracy over the whole globe, but also an accuracy distribution weighted on the north pole region as an example of a weighted accuracy distribution. The addition of a mobile communication function suggests a unified system of satellite navigation and communication, which might provide convenience for the civil aviation industry, because the two functions currently depend on different systems.

A P-Fuzzy Switching Function is a meaningful class of fuzzy switching functions that is representable by a logic formula consisting of prime implicants. This paper aima at extracting knowledge represented as prime implicants from a given learning data. The main results are the necessary and sufficient conditions for the learning data to be representable with P-fuzzy switching functions, and to be determined by unique logic formula.