Large-scale integration (LSI) microchips are widely used in many types of modern electronic products including electric appliances, cellular phones, toys, electronic games, and automobiles. The electromagnetic interference (EMI) noise produced by these micro devices can cause significant operational problems in other devices in the system. Some methods that have been proposed for such analysis estimates the EMI noise characteristic through transistor-level power simulation. However, in these methods, transistor-level circuit simulation is performed by combining the power-supply impedance model and the power-supply source model. In general, transistor-level simulators are too slow for practical application-specific integrated circuit (ASIC) design. In this paper, a total solution for reducing EMI noise in LSI microchips was presented. The proposed design methodology integrates fast and accurate estimation, reduction, and verification. The method was successfully applied to the design of a 32-bit microprocessor, achieving a 2-dB noise reduction in the FM frequency band and 10-dB reduction at 1 GHz. The proposed design methodology is a powerful solution for LSI designers as a tool for minimizing EMI noise and achieve higher levels of reliability for the microelectronic products.

A simple depth-key-based image composition is proposed, which uses two still images with depth information, background and foreground object. The proposed method can place the object at various locations in the background considering the depth in the 3D world coordinate system. The main feature is that a simple algorithm is provided, which enables us to achieve the depthward movement within the camera plane, without being aware of the 3D world coordinate system. Two algorithms are proposed (P-OMDD and O-OMDD), which are based on the pin-hole camera model. As an advantage, camera calibration is not required before applying the algorithm in these methods. Since a single image is used for the object representation, each of the proposed methods has its limitations in terms of fidelity of the composite image. P-OMDD faithfully reproduces the angle at which the object is seen, but the pixels of the hidden surface are missing. On the contrary, O-OMDD can avoid the hidden surface problem, but the angle of the object is fixed, wherever it moves. It is verified through several experiments that, when using O-OMDD, subjectively natural composite images can be obtained under any object movement, in terms of size and position in the camera plane. Future tasks include improving the change in illumination due to positional changes and the partial loss of objects due to noise in depth images.

In a variety of communication systems, the multipath propagation due to various reflections is often encountered. In this paper, the directions-of-arrival (DOA) estimation of the cyclostationary coherent signals is investigated. A new approach is proposed for estimating the DOA of the coherent signals impinging on a uniform linear array (ULA) by utilizing the spatial smoothing (SS) technique. In order to improve the robustness of the DOA estimation by exploiting the cyclic statistical information sufficiently and handling the coherence effectively, we give a cyclic algorithm with multiple lag parameters and the optimal subarray size. The performance of the presented method is verified and compared with the conventional methods through numerical examples.

Satellite communications (SATCOM) systems play important roles in wireless communication systems. In the future, they will be required to accommodate rapidly increasing communication requests from various types of users. Therefore, we propose a framework for efficient resource management in large-scale SATCOM systems that integrate multiple satellites. Such systems contain hundreds of thousands of communication satellites, user terminals, and gateway stations; thus, our proposed framework enables simpler and more reliable communication between users and satellites. To manage and control this system efficiently, we formulate an optimization problem that designs the network structure and allocates communication resources for a large-scale SATCOM system. In this mixed integer programming problem, we allow the cost function to be a combination of various factors so that SATCOM operators can design the network according to their individual management strategies. These factors include the total allocated bandwidth to users, the number of satellites and gateway stations to be used, and the number of total satellite handovers. Our numerical simulations show that the proposed management strategy outperforms a conventional strategy in which a user can connect to only one specific satellite determined in advance. Furthermore, we determine the effect of the number of satellites in the system on overall system performance.

In this paper, a method of the signal subspace interpolation to constructing a continuous fingerprint database for radio localization is proposed. When using the fingerprint technique, enhancing the accuracy of location estimation requires very fine spatial resolution of the database, which entails much time in collecting the data to build up the database. Interpolated signal subspace is presented to achieve a fine spatial resolution of the fingerprint database. The angle of arrival (AOA) and the measured signal subspace at known locations are needed to obtain the interpolated signal subspaces. The effectiveness of this method is verified by an outdoor experiment and the estimated location using this method was compared with those using the geometrically calculated fingerprint and the measured signal subspace fingerprint techniques.

Gaussian integer has a potential to enhance the safety of elliptic curve cryptography (ECC) on system under the condition fixing bit length of integral and floating point types, in viewpoint of the order of a finite field. However, there seems to have been no algorithm which makes Gaussian integer ECC safer under the condition. We present the algorithm to enhance the safety of ECC under the condition. Then, we confirm our Gaussian integer ECC is safer in viewpoint of the order of finite field than rational integer ECC or Gaussian integer ECC of naive methods under the condition.

We propose an approach to allocate bandwidth for a satellite communications (SATCOM) system that includes the recent high-throughput satellite (HTS) with frequency flexibility. To efficiently operate the system, we manage the limited bandwidth resources available for SATCOM by employing a control method that allows the allocated bandwidths to exceed the communication demand of user terminals per HTS beam. To this end, we consider bandwidth allocation for SATCOM as an optimal control problem. Then, assuming that the model of communication requests is available, we propose an optimal control method by combining model predictive control and sparse optimization. The resulting control method enables the efficient use of the limited bandwidth and reduces the bandwidth loss and number of control actions for the HTS compared to a setup with conventional frequency allocation and no frequency flexibility. Furthermore, the proposed method allows to allocate bandwidth depending on various control objectives and beam priorities by tuning the corresponding weighting matrices. These findings were verified through numerical simulations by using a simple time variation model of the communication requests and predicted aircraft communication demand obtained from the analysis of actual flight tracking data.

Although subspace-based methods for estimating the Angle of Arrival (AOA) require a precise array response to achieve highly accurate results, it is difficult to obtain this response in practice even though the antennas are calibrated. Therefore, a method of compensating for errors in calibration is required. This paper proposes a procedure to enable precise AOA estimates to be obtained in a real system by applying array calibration and spatial smoothing preprocessing (SSP). Measured data were collected from experiments using two scenarios, i.e., in an anechoic chamber and at an open site, where a single source signal arrived at the array antenna. All measured data were then calibrated by using data obtained at 0 deg in an anechoic chamber before the AOAs were estimated. Nevertheless, errors in the array response remained after calibration because errors in the AOA estimates could still be observed. SSP was then applied to the calibrated data to obtain more accurate AOA estimates. We found that SSP can reduce the random error in an array response obtained in a real system, leading to reduced errors in AOA estimates in the observed data. To generalize the problem that SSP can reduce random perturbation in the array response, simple expressions are illustrated and verified by Monte-Carlo simulation. Random gain and phase errors in the array response are only considered in this paper and ESPRIT was used to estimate the AOAs.

Dynamic power supply noise measurements with resolutions of 100 ps and 100 µV for 100 ns and 1 V ranges are performed at various operating frequencies up to 400 MHz on multiple points in a low power register file and SRAM for product chips by using on-chip noise detectors. The measurements show that the noises are clearly emphasized in frequency domains by the interaction of circuit operations and bias network's AC transfers. A proposed design methodology that covers a fast SPICE simulator and parasitic extractors can predict dynamic noises from power supplies, ground, well, and substrate interactions to provide robustness to the design of low power body bias control circuitry.

We propose a semi-dynamic timing analysis flow applicable to large-scale circuits that takes into account dynamic power-supply drop. Logic delay is accurately estimated in the presence of power-supply noise through timing correction as a function of power-supply voltage during operation, where a time-dependent power-supply noise waveform is derived by way of a vectorless technique. Measurements and analysis of dynamic supply-noise waveforms and associated delay changes were performed on a sub-100-nm CMOS test circuit with embedded on-chip noise detectors and delay monitors. The proposed analysis technique was extended and applied to a test digital circuit with more than 10 million gates and validated toward a multi-10-million-gate CMOS SoC design.

This paper proposes an indoor event detection system for homes and offices that is based on electric wave reception such as intrusion into home or office. The proposed system places antenna array on the receiver side and detects events such as intrusion using the eigenvector spanning signal subspace obtained by the antenna array. The eigenvector is based on not received signal strengths (RSS) but direction of arrival (DOA) of incident signals on the antenna array. Therefore, in a static state, the variance of the eigenvector over time is smaller than that of RSS. The eigenvector changes only when the indoor environment of interest changes intermittently and statically, or dynamically. The installation cost is low, because the detection range is wide owing to indoor reflections and diffraction of electric wave and only a pair of transmitter and receiver are used. Experimental results reveal that the proposed method can distinguish the state when no event occurs and that when an event occurs clearly. Since the proposed method has a low false detection rate, it offers higher detection rates than the systems based on RSS.

To improve the resolution capability of the directions-of-arrival (DOA) estimation, some subspace-based methods have recently been developed by exploiting the specific signal properties (e.g. non-Gaussian property and cyclostationarity) of communication signals. However, these methods perform poorly as the ordinary subspace-based methods in multipath propagation situations, which are often encountered in mobile communication systems because of various reflections. In this paper, we investigate the direction estimation of coherent signals by jointly utilizing the merits of higher-order statistics and cyclostationarity to enhance the performance of DOA estimation and to effectively reject interference and noise. For estimating the DOA of narrow-band coherent signals impinging on a uniform linear array, a new higher-order cyclostationarity based approach is proposed by incorporating a subarray scheme into a linear prediction technique. This method can improve the resolution capability and alleviate the difficulty of choosing the optimal lag parameter. It is shown numerically that the proposed method is superior to the conventional ones.

In satellite/terrestrial integrated mobile communication systems (STICSs), a user terminal directly connects both terrestrial and satellite base stations. STICS enables expansion of service areas and provides a robust communication service for large disasters. However, the cell radius of the satellite system is large (approximately 100km), and thus a capacity enhancement of the satellite subsystem for accommodating many users is needed. Therefore, in this paper, we propose an application of two methods — multiple-input multiple-output (MIMO) transmission using multi-satellites and non-orthogonal multiple access (NOMA) for STICS — to realize the performance improvement in terms of system capacity and user fairness. Through numerical simulations, we show that system capacity and user fairness are increased by the proposed scheme that applies the two methods.

We describe a new system for high-speed wireless access systems between base stations and mobile terminals. In the proposed system, the base station has an array antenna and tracks mobile terminals by using a new tracking algorithm. A radio-on-fiber technique is used to simplify and miniaturize the components of the base station. Estimating the direction-of-arrival of the signals from a mobile terminal is important in implementing the proposed system. We propose a new tracking algorithm that uses directions-of-arrival, angular velocities of mobile terminals, and scatter modeling in multipath communications channels to improve the tracking performance. We also developed experimental equipment to demonstrate the feasibility of the proposed millimeter-wave broadband wireless access system and the efficiency of the tracking algorithm using an array antenna system. In this paper, we describe our system and present a new approach for tracking mobile terminals, which is the key feature of the system. We also discuss our simulation and experimental results.

In this paper, we propose a digital image enlargement method based on a fuzzy technique that improves half-pixel generation, especially for convex and concave signals. The proposed method is a modified version of the image enlargement scheme previously proposed by the authors, which achieves accurate half-pixel interpolation and enlarges the original image by convolution with the Lanczos function. However, the method causes impulse-like artifacts in the enlarged image. In this paper, therefore, we introduce a fuzzy set and fuzzy rule for generating half-pixels to improve the interpolation of convex and concave signals. Experimental results demonstrate that, in terms of image quality, the proposed method shows superior performance compared to bicubic interpolation and our previous method.

In the move toward higher clock rates and advanced process technologies, designers of the latest electronic products are finding increasing silicon failure with respect to noise. On the other hand, the minimum dimension of patterns on LSIs is much smaller than the wavelength of exposure, making it difficult for LSI manufacturers to obtain high yield. In this paper, we present a solution to reduce power-supply noise in LSI microchips. The proposed design methodology also considers design for manufacturability (DFM) at the same time as power integrity. The method was successfully applied to the design of a system-on-chip (SOC), achieving a 13.1-13.2% noise reduction in power-supply voltage and uniformity of pattern density for chemical mechanical polishing (CMP).