Quasi-millimeter-wave-band Fixed Wireless Access (FWA) systems have higher transmission rates than 2.4-GHz or 5-GHz systems, because the available frequency bandwidth for quasi-millimeter-wave-bands is broader than the 2.4-GHz and 5-GHz bands. However, quasi-millimeter-wave-band systems are unsuitable for long-span transmission because the attenuation caused by rain is large. We propose that the symbol rate be lowered for rainfall; i.e., when it rains, a low symbol rate is used. This means narrowing the equivalent noise bandwidth so that a margin for rain attenuation is obtained. We compared a method in which the symbol rate is either high or low with one in which the symbol rate is selectable over a range of values. We verified the beneficial effect of the two-rate method through calculations and simulations. A case study in the Tokyo metropolitan area showed that the service zone radius of this method is double that of conventional systems. Changing to a low symbol rate decreases the transmission rate, but periods of heavy rainfall comprise only about 1% of the amount of time in a year, and so the average decrease in the transmission rate is approximately zero.

In this letter, iterative sequence estimation technique based on expectation-maximization (EM) algorithm is considered for quadrature amplitude modulation (QAM)-orthogonal frequency division multiplexing (OFDM) signals. For QAM-OFDM signaling, the optimal EM algorithm requires high computational complexity due to the inversion of complex matrix executed at each iteration. To avoid this problem, we propose a sub-optimal iterative sequence estimation algorithm with some approximations, which results in reduced computational complexity for QAM-OFDM signals. Moreover, we use two different approaches to obtain initial estimate for beginning iteration of proposed algorithm. One is for less time-dispersive but fast fading channel and the other is for highly time-dispersive but relatively slow fading channel. The bit error rate (BER) performances of the proposed algorithm are evaluated using computer simulations. The results show that the proposed algorithm performs nearly as well as the optimal EM algorithm.

Among the many scheduling algorithms which can guarantee delay bounds of sessions, the EDF scheduler with regulators has received wide attention since it can admit a very high number of sessions. However, due to regulators, EDF with regulators has difficulty in scalable implementation. To implement a regulator, a buffer and a timer are needed to restrict the incoming traffics. Given N number of sessions, N regulators are required. Moreover, due to regulators, the entire scheduling algorithm is not work-conserving. To enforce work-conserveness, it is known in the literature that additional buffers and a complex mechanism are required to bypass regulators. Thus, scalable implementation becomes much more difficult in the case of the work-conserving EDF with regulators. In this paper, however, we show that the buffers and timers used to implement regulators are unnecessary to guarantee delay bounds of admitted sessions in fixed-sized packet networks. Then, we can remove those unnecessary buffers and timers. By the removal, the resulting scheduling algorithm can be implemented in a scalable way and becomes work-conserving for free.

This paper reports the design and fabrication of a miniaturized superconducting microstrip line filter using YBCO film on MgO. The filter's resonators are shaped in a double spiral, and the size of the resonators is optimized from the standpoint of the unloaded Q-factor. The 15-pole bandpass filter that has the center frequency of 1.95 GHz and the bandwidth of 20 MHz is designed in the size of 9.7 44 mm. The simulated S-parameter characteristics of the filter is corresponding to the initial design parameters. We fabricated the filter on an MgO substrate with a diameter of 2 inches. The filter had very sharp cutoff and a very low insertion loss of 0.14 dB.

This study examines a slitted parallel plate waveguide (PPW) from the perspective of diffraction and equivalent circuit representation for a narrow slit and radiation, including the surface wave effect, from a wide slit. The fundamental differences between the diffraction and equivalent admittance properties of the slit discontinuities in typical microstrip and waveguide structures are considered by comparing how the waveguide heights of the PPW and dielectric constants filling the inside of the PPW correspond to those of the two structures, respectively.

This Letter presents a novel VQ-based digital image watermarking method. By modifying the conventional GLA algorithm, a codeword-labeled codebook is first generated. Each input image block is then reconstructed by the nearest codeword whose label is equal to the watermark bit. The watermark extraction can be performed blindly. Simulation results show that the proposed method is robust to JPEG compression, vector quantization (VQ) compression and some spatial-domain processing operations.

One conventional technique for source localization is to utilize the time-difference-of-arrival (TDOA) measurements of a signal received at spatially separated sensors. A simple TDOA-based location algorithm that combines the advantages of two efficient positioning methods is developed. It is demonstrated that the proposed approach can give optimum performance in geolocation via satellites at different noise conditions.

Data compression is popularly applied to computer systems and communication systems. Especially, lossless compression is applied to text compression. Since compressed data are very sensitive to errors, several error control methods for data compression using probability model, such as for arithmetic coding, have been proposed. This paper proposes to apply an unequal error protection, or a UEP, scheme to LZ77 coding and LZW coding. This investigates a structure of the compressed data and clarifies a part which is more sensitive to errors than the other by using theoretical analysis and computer simulation. The UEP scheme protects the error-sensitive part from errors more strongly than the others. Computer simulation says that the proposed scheme can recover from errors in the compressed data more effectively than the conventional methods.

The fuzzy set framework can be utilized in several different approaches to modeling the diagnostic process. In this paper, we introduce two main relations between symptoms and diseases where the relations are described by intuitionistic fuzzy set data. Also, we suggest four measures for medical diagnosis. We are dealing with the preliminary diagnosis from the information of interview chart. We quantify the qualitative information based on the interview chart by dual scaling. Prototype of fuzzy diagnostic sets and the linear regression methods are established with these quantified data. These methods can be used to classify new patient's tone of diseases with certain degrees of belief and its concerned symptoms.

We have developed a planarization method applicable to large-scale superconductive Nb device fabrication. A planarized multi-layer wiring structure is obtained independently of the wiring size (width, length, and density) by combining three steps for fabricating an SiO2 insulator layer: bias-sputtering, chemical mechanical polishing, and etching with a reversal mask. Fabricated three-level wiring structures, consisting of 200- or 300-nm-thick Nb and SiO2 layers, had excellent layer flatness, and the leakage current (< 0.1 µA/cm2) between the Nb layers was sufficiently low. Two hundred chains of stepwise and stacked contacts yielded a sufficiently large critical current, typically more than 10 mA at 4.2 K.

This paper focuses on the realization of low spurious responses by various bandpass filters (BPFs) using open-ended λ/2 resonators. The first part of this paper gives the resonance characteristics of the open-ended λ/2 resonators when the excitation methods are chosen. Secondly, various BPFs obtained with our methodology are provided. For constructing the BPF, (1) point-coupled resonators, (2) comb-line resonators, (3) quasi comb-line resonators and (4) parallel-coupled resonators are used. It is verified that the presented BPFs can be used to obtain low spurious responses both theoretically and experimentally.

Recently, wireless networks have become a major sector in the telecommunication industry. More and more applications seek to become wireless. However, a major obstacle in adapting wired applications to wireless is the quality of service problem. Although the wireless bandwidth is improving at a fast pace, it still is not enough for modern multimedia applications. Even if we solve the bandwidth problem, the mobility of users also poses challenges for QoS provision. If the user moves randomly, how and where can resources be reserved in advance for roaming users to move smoothly and seamlessly? In this paper, we propose a method for predictive resource reservation in wireless networks. Resources reserved but not used will seriously affect the system performance. Therefore, we also have mechanisms to release the reserved resources when it is not used within a time limit and allow resources to be used temporarily by another mobile user. We compare the performance of our method with those of fixed allocation scheme and shadow cluster scheme. The results indicate its effectiveness and feasibility.

A novel double-image Green's function approach is proposed to compute the frequency- dependent capacitance and conductance for the general CMOS oriented transmission lines with one protective layer. The ε-algorithm of Pade approximation is adopted to reduce the time for establishing coefficient matrix in this letter. The parameters gained from this new approach are shown to be in good agreement with the data obtained by the full-wave method and the total charge Green's function method.

The discrete nature of data in a functional domain can generally be replaced by the global nature of data in the spectrum domain. In this paper we propose a fast procedure to detect autosymmetric function as an application of the spectrum technique. The autosymmetric function differs from the usual symmetric function and strongly relates with EXOR-based representations. It is known that many practical logical networks are autosymmetric, and this nature allows a useful functional class to realize a compact network with EXOR gates. Our procedure is able to detect autosymmetric functions quickly by using spectral coefficients. In experiments, our technique can detect the autosymmetry of most networks with a small number of checks of the spectrum.

In this paper, as an important technology for the software-defined radio, a novel scheme of adaptive array antenna utilizing bandpass sampling technique is proposed. For adaptive signal processing, it is necessary to convert the radio frequency signal received by the antenna that is given by real number into baseband region, i.e., complex number region. Then, the method for dividing the bandpass sampled signal to in-phase and quadrature components is analyzed. The sampling scheme is called the IQ-division bandpass sampling. An adaptive array antenna based on the IQ-division bandpass sampling is characterized by the signal processing at the bandpass sampled signal stage, namely, intermediate frequency stage, not baseband. Finally, we will confirm the validity of the proposed scheme through an experiment in a radio anechoic chamber.

This paper proposes a fast multi-cycle path detection method for large sequential circuits. The proposed method is based on ATPG techniques, especially on implication techniques, to use circuit structures and multi-cycle path conditions directly. The method also checks whether or not a multi-cycle path may be invalidated by static hazards at the inputs of flip-flops. Then we explain how to apply the proposed algorithm to real industrial designs. Experimental results show that our method is much faster than conventional ones and that it is efficient enough to handle large industrial designs.

This paper discusses the frequency to extract RLC values from interconnects. In circuit design, frequency-independent equivalent circuit is widely used, and many design and analysis techniques based on this equivalent circuit are proposed so far. However in reality, characteristics of interconnects are frequency-dependent. Also pulse waveforms in digital circuits contain multiple frequency components. The frequency used for RLC extraction affects the accuracy of interconnect characterization, and hence careful determination of extraction frequency is critical. We propose a representative frequency for RLC extraction. Conventionally, representative frequencies are determined by input pulse. The proposed method decides the representative frequency based on the interconnect length, whereas conventional representative frequencies are determined by input pulse shape, period and patterns. We verify that the extraction at the proposed frequency provides the most accurate transition waveform against various input signals and interconnect structures in digital circuits.

A test generation method with time-expansion model can achieve high fault efficiency for acyclic sequential circuits, which can be obtained by partial scan design. This method, however, requires combinational test pattern generation algorithm that can deal with multiple stuck-at faults, even if the target faults are single stuck-at faults. In this paper, we propose a test generation method for acyclic sequential circuits with a circuit model, called MS-model, which can express multiple stuck-at faults in time-expansion model as single stuck-at faults. Our procedure can generate test sequences for acyclic sequential circuits with just combinational test pattern generation algorithm for single stuck-at faults. Experimental results show that test sequences for acyclic sequential circuits with high fault efficiency are generated in small computational effort.

In this paper, for convex rectilinear block packing problem, we propose 1) a novel algorithm to obtain a packing based on a given sequence-pair in O(n2) time (conventional method needs O(n3) time), where n is the number of rectangle sub-blocks made from convex blocks, 2) a move operation for Simulated Annealing which is symmetric and can guarantee reachability for the first time, and 3) a method to generate a random adjacent sequence-pair in O(n2) time. By using 1), 2) and 3) together, the time complexity of the inner loop in Simulated Annealing becomes surely O(n2) time. Experimental results show that the proposed algorithm is faster than the conventional ones in practical and the wire length as well as packing area is taken into consideration in the proposed method.

We propose a stochastic model for signals generated through the electron multiplying effect of detectors in charged particle beam equipments. This model is based on a stochastic variable characterized by a log-normal type distribution. The model is simple and can be used to represent a wide dynamic range of signals from pulse-like signals when the primary beam current is small to continuous signals when the primary beam current is large. For the model base reference a normalization of actual signal detectors is presented. This base reference yields the unique stochastic parameter used in our model. The proposed model better approximates the actual signals in the power spectrum distribution as compared to the filtered Poisson method presented elsewhere.