We demonstrate that the frequency modulated video signals in the subcarrier multiple access optical network can be satisfactorily transmitted using our proposed method, that broadens an optical spectrum by multiplying the subcarrier signals by an additional signal and that reduces optical beat interference, even if the wavelengths of four Fabry-Perot laser diodes are very close each other.

The increasing activity at millimeter wave frequency band and the growing demand for waveguide components to be applied for integrated circuit purpose have promoted the need for applying the field-theory-based approaches to the design procedure. In this paper, genetic algorithms (GA's) are applied to accurately design the iris-coupled waveguide filters based on network-boundary element method (NBEM). GA's model the natural selection and evolve towards the global optimum, thus avoid being trapped in local minima. Network-boundary element method, which combines boundary element method with network analysis method, derives the network parameters of the guided wave structures with less storage location and central processing unit time. Therefore, NBEM is a feasible and efficient field-theory-based approach for the GA optimization of waveguide filters. With NBEM performing the task of evaluating the performance of the filter designs optimized by the GA, rigorous and optimal designs of the waveguide filters are realized. The obtained analysis and optimization results are compared to a number of reference solutions to demonstrate the validity and accuracy of the proposed approach.

Error performance as well as ATM cell transfer characteristics in a new category of wireless access systems is discussed. Relocatable wireless access with neutral feature between the fixed and mobile systems can convey Mbit/s-order capacity with fairly high quality under line-of-sight propagation. It is an important question for such wireless access systems whether they are able to form a part of wired networks satisfying performance objectives specified in ITU-T Recommendations. This paper analyzes the characteristics of relocatable systems under Gamma-distribution fading environments, and clarifies quantitative relations between Bit Error Rate (BER), Severely Errored Second (SES), Errored Second (ES) and Cell Loss Ratio (CLR) in a calculation model employing QPSK and typical HEC (Header Error Control). Thus it is demonstrated for the first time that in most cases the dominant parameter is the SES objective. Also it will be possible for a relocatable system with appropriate fade margin to meet the ITU-T performance specifications.

This paper proposes a novel bidirectional rod antenna (BIRA) comprising a collinear antenna and parasitic wires as a base station antenna for a street microcell. The spacing between the collinear antenna and the parasitic wire, and the length of the parasitic wires, which are the design parameters obtaining a bidirectional pattern, are investigated using the moment method. The results show that wide spacing enlarges the bandwidth obtaining the bidirectional pattern, however it decreases the gain. Furthermore, to enlarge the bandwidth, a BIRA with arc parasitic plates whose radius is the same as that of the radome is also proposed. The configuration can be constructed using the same exterior as the BIRA with parasitic wires. It is also shown that the arc parasitic plates enlarge the bandwidth in proportion to the area projected onto the tangential plane at the center of the arc. Finally, a prototype of the proposed antenna is shown.

Theoretical calculations of the pulsing operation and the intensity noise under the optical feedback are demonstrated for operation of the self-sustained pulsation lasers. Two alternative models for the optical feedback effect, namely the time delayed injection model and the external cavity model, are applied in a combined manner to analyze the phenomena. The calculation starts by supposing the geometrical structure of the laser and the material parameters, and are ended by evaluating the noise. Characteristics of the feedback induced noise for variations of the operating parameters, such as the injection current, the feedback distance and the feedback ratio, are examined. A comparison to experimental data is also given to ensure accuracy of the calculation.

Almost all broadcasting systems and their equipment would be digitalized in the near future. In Japan, investigation of digital broadcasting has been going on for a long time, aiming at a realization of improvement of picture quality, new services, system flexibility, etc. Japanese digital broadcasting systems under development have a lot of technical merits, for example, a high transmission capacity and a hierarchical transmission scheme for satellite, and mobile reception for terrestrial digital broadcasting systems, compared to conventional digital systems.

A multimedia coding standard, MPEG4 has frozen its Committee Draft (CD) as the MPEG4 version 1 CD, last October. It defines Audio-Visual (AV) coding Algorithms and their System Multiplex/Composition formats. Founding on Object-base concept, Video part adopts Shape Coding technology in addition to conventional Texture Coding skills. Audio part consists of voice coding tools (HVXC and CELP core) and audio coding tools (HILN and MPEG2 AAC or Twin VQ). Error resilience technologies and Synthetic and Natural Hybrid Coding (SNHC) technologies are the MPEG4 specific features. System part defines flexible Multiplexing of audio-visual bitstreams and Scene Composition for user-interactive re-construction of the scenes at decoder side. The version 1 standardization will be finalized in 1998, with some possible minute changes. The expected application areas are real-time communication, mobile multimedia, internet/intranet accessing, broadcasting, storage media, surveillance, and so on.

We have developed and fabricated an LSI called the FMPP-VQ64. The LSI is a memory-based shared-bus SIMD parallel processor containing 64 PEs, intended for low bit-rate image compression using vector quantization. It accelerates the nearest neighbor search (NNS) during vector quantization. The computation time does not depend on the number of code vectors. The FMPP-VQ64 performs 53,000 NNSs per second, while its power dissipation is 20 mW. It can be applied to the mobile telecommunication system.

This paper describes the design concept and characteristics of a power supply for optical network units in Fiber To The Home (FTTH) systems. Powering architectures of local powering, network powering and power hub powering are compared in terms of cost and maintainability. A local powering architecture is selected for an ONU power supply because it is the most cost-effective overall compared with the others. The local power supply is mainly composed of a rectifier, DC-DC converters, a ringer, and batteries. A battery deterioration test function is important for the local power supply because battery lifetime varies depending on ambient temperature, discharge history, and charging conditions, and it is shorter than other electrical components used in ONU. Supplying power using alternative batteries is also necessary because the capacity of batteries installed in the power supply is limited. These functions and electrical characteristics are checked using an experimental power supply with Ni-Cd batteries.

Many image-processing techniques are based on texture features or gradation features of the image. However, Landsat images are complex; they also include physical features of reflection radiation and heat radiation from land cover. In this paper, we describe a method of constructing a super-resolution image of Band 6 of the Landsat TM sensor, oriented to analysis of an agricultural area, by combining information (texture features, gradation features, physical features) from other bands. In this method, a knowledge-based hierarchical classifier is first used to identify land cover in each pixel and then the least-squares approach is applied to estimate the mean temperature of each type of land cover. By reassigning the mean temperature to each pixel, a finer spatial resolution is obtained in Band 6. Computational results show the efficiency of this method.

In this letter, a design method of linear-phase paraunitary filter banks is proposed for an odd number of channels. In the proposed method, a non-linear unconstrained optimization process is assumed to be applied to a lattice structure which makes the starting guess of design parameters simple. In order to avoid insignificant local minimum solutions, a recursive initialization procedure is proposed. The significance of our proposed method is verified by some design examples.

In this paper, we propose a new lemma facility, called the strong contraction rule, for model elimination calculus, and we study some implementation issues of strong contraction in a PTTP-based theorem prover. Strong contraction has the ability to shorten possible proofs and prevent some irrelevant computation to a target goal. Strong contraction never broadens the search space, in principle, and thus, has a stable effect on the acceleration of top-down proof search. However, it is difficult to embed the strong contraction into a PTTP-based theorem prover, because strong contraction imposes a truncation operation of center chains in model elimination calculus. We show a self-truncation-style Prolog code, which makes it possible to retain the high performance of a PTTP-based prover with strong contraction. Finally, we evaluate the performance and effect of strong contraction by performing some experiments.

This paper proposes polling-based real-time software for MPEG2 System protocol LSIs, which is a typical embedded and real-time system on a chip, and demonstrates its performance and usefulness. The polling-based real-time software is designed and optimized by analyzing application specific function requirements and deciding scheduling intervals and the execution cycles of each task. It requires neither hardware for multiple interrupt handling nor software for heavy context switching. The polling-based approach provides sufficient performance without any hardware and software overhead for a real-time application like the MPEG2 System protocol.

In this paper, we propose an efficient and powerful crossover operator in the genetic algorithm for solving the traveling salesman problem (TSP). Our proposed crossover is called the complete subtour exchange crossover (CSEX), and inherits as many good subtours as possible because they are worth preserving for descendants. Before generating the descendants, a prerequisite for the CSEX is that it enumerates all common subtours, which consist of the same set in a pair of subtours on the given two tours of n cities. An algorithm to enumerate all common subtours in the CSEX consumes only O(n) time. In a fundamental experiment, we show the experimental number and length of the common subtours for two randomly generated tours with 5 to 500 thousand elements. In addition, we give the practical behavior of the CSEX and compare the CSEX with a hopeful crossover operator using the benchmark instances for the TSP. Moreover, in another experiment of parallel computing, in order to analyze the performance of the CSEX, we compare the CSEX with hopeful crossovers for 25 benchmarks (48 - 2392 city) using a parallel supercomputer, Paragon. From these results, the CSEX shows an extremely bright performance.

Quality of service requirements are satisfied conjointly by the service model, which determines how resources are shared and by network engineering, which determines how much capacity is provided. In this paper we consider the impact of the adopted charging scheme on the feasibility of fulfilling QoS requirements. We identify three categories of charging scheme based respectively on flat rate pricing, congestion pricing and transaction pricing.

Physics principles of a new type of microwave input amplifiers are described. Cyclotron wave electrostatic amplifier (CWESA) has a low noise level, broad band, switchable gain, super high self-protection against microwave overloads, rapid recovery and small DC consumption. CWESAs are widely used in Russian pulse Doppler radars and other systems.

We have developed a low bit-rate video coding using a video digital signal processor (DSP) called VDSP1χ, which performs real-time encoding and decoding for discrete cosine transform-(DCT-) based algorithms, such as ITU-T H. 261, H. 263 and wavelet-based subband encoding algorithms. This LSI features a processing unit which implements wavelet filters at high speeds, a compact DCT circuit, and a fast, flexible DRAM interface for low-cost systems. This system is capable of processing quarter common intermediate format (QCIF)(176144 pixels) size pictures at a rate greater than 15 frames/s.

This paper investigates the relations between the computational complexity and the restrictions for several problems that determine whether a given graph with edge costs and edge lengths has a spanning subgraph with such restrictions as the diameter, the connectivity, and the NA-distance and the NA-(edge)-connectivity proposed and investigated in [1]-[5]. The NA-distance and the NA-(edge)-connectivity are the measures for the distance and the connectivity between a vertex and a vertex subset (area). In this paper we prove that the minimum diameter spanning subgraph problem considering the restrictions of the diameter and the sum of edge costs is NP-complete even if the following restrictions are satisfied: all edge costs and all edge lengths are equal to one, and the upper bound of the diameter is restricted to four. Next, we prove that the minimum NA-distance spanning subgraph problem considering the restrictions of the NA-distances and the sum of edge costs is NP-complete even if the following conditions are satisfied: all edge costs and all edge lengths are equal to one, the upper bound of the NA-distance is restricted to four, each area is composed of a vertex, and the number of areas is restricted to two. Finally, we investigate the preserving NA-distance and NA-edge-connectivity spanning subgraph problem considering the preservations of the NA-distances and the NA-edge-connectivity and the restrictions of the sum of edge costs, and prove that a sparse spanning subgraph can be constructed in polynomial time if all edge costs are equal to one.

The exact expected test lengths of pseudo-random patterns that are generated by LFSRs are theoretically analyzed for a CUT containing hard random-pattern-resistant faults. The exact expected test lengths are also analyzed when more than one primitive polynomials are selected.

In live multimedia applications with multiple videos, it is necessary to develop an efficient mechanism of multiplexing several MPEG video streams into a single stream and transmitting it over network without wasting excessive bandwidth. In this paper, we present an efficient multiplexing and traffic smoothing scheme for multiple variable bit rate (VBR) MPEG video streams in live video applications with finite buffer sizes. First, we describe the constraints imposed by the allowable delay bound for each elementary stream and by the multiplexer/receiver buffer sizes. Based on these constraints, a new multiplexing and traffic smoothing scheme is designed in such a way as to smooth maximally the multiplexed transmission rate by exploiting temporal and spatial averaging effects, while avoiding the buffer overflow and underflow. Through computer experiments based on an MPEG-coded video trace of Star-wars, it is shown that the proposed scheme significantly reduces the peak rate, coefficient of variation, and effective bandwidth of the multiplexed transmission rate.