A dielectric resonator antenna (DRA) is located below a radiating patch of an planar inverted F antenna (PIFA) to achieve a compact hybrid antenna and a multiple band operation. Loop-type structures with PIFA shorting pins are used as feeds for both the DRA and the PIFA. The proposed antenna operates well in two frequency bands without perturbing the fundamental radiation characteristics of each operating radiation mode of the DRA and the PIFA. Its electromagnetic performance and the desirable practical size of the proposed hybrid antenna are attractive for small mobile communication devices.

In this paper, joint water filling and maximal ratio transmission (joint WF-MRT) downlink transmit diversity for a single-carrier distributed antenna network (SC DAN) is proposed. The joint WF-MRT transmit weight allocates the transmit power in both transmit antenna dimension and frequency dimension, i.e., the power allocation is done both across frequencies based on WF theorem and across transmit antennas based on MRT strategy. The cumulative distribution function (CDF) of the channel capacity achievable by joint WF-MRT transmit diversity is evaluated by Monte-Carlo numerical computation method. The channel capacities achievable with joint WF-MRT, MRT, and WF transmit weight (WF transmit weight is done across transmit antennas and frequencies based on WF theorem) are compared. It is shown that the joint WF-MRT transmit weight provides the highest channel capacity among three transmit weights.

We proposed a novel representation of the thermal noise for scaled MOSFETs by applying an extended van der Ziel's model. A comparison between the proposed representation and Pospieszalski's model is also performed. We confirmed that the representation of drain noise temperature, Td corresponds to the electron temperature in a gradual channel region.

In this paper, we propose a genetic algorithm (GA) based equalization approach for direct sequence ultra-wideband (DS-UWB) wireless communication systems, where the GA is combined with a RAKE receiver to combat the inter-symbol interference (ISI) due to the frequency selective nature of UWB channels for high data rate transmission. The proposed GA based equalizer outperforms significantly the RAKE and the RAKE-minimum mean square error (MMSE) receivers according to results obtained from intensive simulation work. The RAKE-GA receiver also provides bit-error-rate (BER) performance very close to that of the optimal RAKE-maximum likelihood detection (MLD) approach, while offering a much lower computational complexity.

A new scheme to avoid null zone for HF-band RFID without expanding antenna size is proposed. At first, we demonstrate by FDTD simulation that the null zone occurs because of cancellation of magnetic fields over the loop surface. To prevent cancellation of magnetic fields, the loop antenna is split into four parts, which work as a planar array antenna. The outputs of antennas are gathered by using combining circuit. We have validated by FDTD simulation that the proposed scheme enlarges the worst received power by 13.1 dB.

Kernel logistic regression (KLR) is a powerful and flexible classification algorithm, which possesses an ability to provide the confidence of class prediction. However, its training--typically carried out by (quasi-)Newton methods--is rather time-consuming. In this paper, we propose an alternative probabilistic classification algorithm called Least-Squares Probabilistic Classifier (LSPC). KLR models the class-posterior probability by the log-linear combination of kernel functions and its parameters are learned by (regularized) maximum likelihood. In contrast, LSPC employs the linear combination of kernel functions and its parameters are learned by regularized least-squares fitting of the true class-posterior probability. Thanks to this linear regularized least-squares formulation, the solution of LSPC can be computed analytically just by solving a regularized system of linear equations in a class-wise manner. Thus LSPC is computationally very efficient and numerically stable. Through experiments, we show that the computation time of LSPC is faster than that of KLR by two orders of magnitude, with comparable classification accuracy.

A characteristic-based constrained interpolation profile (CIP) method for solving three-dimensional, time-dependent Maxwell's equations is successfully developed. It is utilized to solve one-dimensional wave equations in the formulation of the Maxwell's equations. Calculation procedure of the CIP method for three-dimensional scattering analysis is described in details. Update equations for boundary conditions of a perfectly conducting (PEC) interface and a dielectric interface are formulated and obtained in explicit forms. Numerical analyses of electromagnetic scatterings of PEC sphere, dielectric sphere and PEC cube are performed and the scattering coefficient is calculated and compared with the Mie's analytic results. As a result, the scattering coefficients show good agreement with the Mie's results, which demonstrates the validity of the CIP method and the formulated update equations. It is also shown that the phase of the scattering coefficients determined by the CIP method are slightly more accurate than that of the FDTD method.

Platforms of hosting services are expected to provide a virtual private computing infrastructure with guaranteed levels of performance to support each reservation request sent by a client. To enhance the performance of the computing infrastructure in responding to reservation requests, the platforms are required to reserve, coordinate, and control globally distributed computing and network resources across multiple domains. This paper proposes Grid Network Service -- Web Services Interface version 2 (GNS-WSI2). GNS-WSI2 is a resource-reservation messaging protocol that establishes a client-server relationship. A server is a kind of management system in the management plane, and it allocates available network resources within its own domain in response to each reservation request from a client. GNS-WSI2 has the ability to reserve network resources rapidly and reliably over multiple network domains. This paper also presents the results of feasibility tests on a transpacific testbed that validate GNS-WSI2 in terms of the scalable reservation of network resources over multiple network domains. In the tests, two computing infrastructures over multiple network domains are dynamically provided for scientific computing and remote-visualization applications. The applications are successfully executed on the provided infrastructures.

This paper proposes a channel capacity maximization method for Multiple-Input Multiple-Output (MIMO) antennas with parasitic elements. Reactive terminations are connected to the parasitic elements, and the reactance values are determined to achieve stochastically high channel capacity for the environment targeted. This method treats the S-parameter and propagation channel of the antenna, including the parasitic elements, as a combined circuit. The idea of the 'parasitic channel,' which is observed at the parasitic antenna, is introduced to simplify the optimization procedure. This method can significantly reduce the number of necessary measurements of the channel for designing the antenna. As a design example, a bidirectional Yagi-Uda array, which has two driven antennas at both ends of the linear array, is measured in an indoor environment. The resulting design offers enhanced channel capacity mainly due to its improved signal-to-noise ratio compared to the antenna without the parasitic antennas.

This paper attempts to analyze theoretically the propagation characteristics in the transverse section of upper body to support on-body wireless communications. The analytical estimation assumes that the human body is structured as a lossy-dielectric circular cylinder with infinite length that consists of the 2/3-muscle equivalent uniform tissue. Each scattering electric field formulation inside and outside of the cylinder is derived for scattering characteristics in the propagation environment including the human body when the source current has the vertical direction to the cylinder surface or the horizontal direction to the cylinder axis. In order to confirm the reliability of the formulation, total electric field distributions at 2.45 GHz are compared with the results by the finite-difference time-domain (FDTD) method. In each current direction, general scattering characteristics and the influence on the total propagation are estimated. Furthermore, from scattering and total electric field intensities evaluated with the variations of operating frequency, radius of the human body, and distance between a source and the human body, propagation characteristics are investigated to assist in the design of a device for on-body propagation channel with the upper body.

We developed a slotted waveguide planer array antenna with partially parallel feeding in millimeter-wave band. Travelling-wave excitation is more effective for low loss feeding of array antennas than parallel feeding systems. However, array antenna with travelling-wave excitation essentially possesses a significant problem of long line effect which degrades gain due to beam shift by frequency change when the array antenna is fed from the edge of the radiating waveguide. We propose the way to reduce the gain degradation due to frequency change, thus, partially parallel feeding system is developed. Measured performance of the developed antenna is evaluated in this paper.

Broadband antennas have various applications in digital terrestrial television (DTV) services. Compact broadband antennas are required for arranging in long and narrow space along the rim of a laptop display. A leaky-wave antenna using the composite right/left-handed transmission line (CRLH-TL) is one of the candidates for achieving the broadband antenna. However, there are not enough to design guideline of small leaky wave antennas using the CRLH-TL for UHF band. In this paper, a CRLH-TL comprising a ladder network is proposed for broadband and simple structure. The paper also discusses the design of a leaky-wave antenna with the CRLH-TL operating in the DTV band. The relation between the operating bandwidth and attenuation constant of the CRLH-TL is discussed. An antenna that can be accommodated in the limited and narrow space available in mobile terminals has to be designed. Hence, the effects of the number of cells and a finite ground plane are discussed with the purpose of achieving the miniaturization of the antenna. In this study, the transmission and radiation characteristics of the fabricated antennas are measured. The gain of the fabricated antenna is confirmed to remain almost constant even when the operating frequency is varied. The maximum gain and operating band achieved in this study are approximately -0.6 dBi and about 54%, respectively.

This paper presents a newly developed small-sized shaped beam base station antenna in order to reduce inter-sector interference for next generation high speed wireless data communication systems. The developed antenna realizes polarization diversity as a single small-sized antenna without decreasing the 3 dB main beamwidth compared with the conventional antenna by applying a newly designed beam shaping method. Furthermore, side sub-reflectors are newly installed in the radome to reduce the antenna beam gain in the direction toward the edge region neighboring the other sectors of the horizontal antenna pattern. By adopting this type of reflector, the diameter of the radome can be minimized at 0.65 λ, which is slightly longer than that of the conventional antenna. Both a computer simulation and a field measurement test based on an actual cellular network were conducted for the purpose of clarifying the validity of the shaped beam antenna. In the results, the CINR at the service area by the shaped beam antenna was 1 dB and 3.5 dB better than that of the conventional antenna at the median and 10% of CDF, respectively. The developed antenna will be expected to contribute to the enhancement of the quality of cellular radio systems in the future.

A new linearly tapered slot antenna (LTSA) with defected sides is proposed in this letter. Both sides are defected with half-dumbbell shape slots that may alter the surface current intensities on both sides. As the half-dumbbell size is increased, the 3-dB beamwidth of the proposed antenna is 4° and 6° lower in the E/H-plane, respectively, than these of the LTSA without defects. Accordingly, the measured gain is improved by up to 3.75 dB and the first side lobe level is lowered by about -10.8 dB and -5.8 dB in the E/H-planes, respectively.

Boolean matching is a fundamental problem in FPGA synthesis, but existing Boolean matchers are not scalable to complex PLBs (programmable logic blocks) and large circuits. This paper proposes a filter-based Boolean matching method, F-BM, which accelerates Boolean matching using lookup tables implemented by Bloom filters storing pre-calculated matching results. To show the effectiveness of the proposed F-BM, a post-mapping re-synthesis minimizing area which employs Boolean matching as the kernel has been implemented. Tested on a broad selection of benchmarks, the re-synthesizer using F-BM is 80X faster with 0.5% more area, compared with the one using a SAT-based Boolean matcher.

The hybrid antenna consisted of cylindrical dielectric resonator and rectangular slot was implemented. The hybrid antenna resonated at two different frequencies. The lower resonant frequency was associated with the rectangular slot while the higher resonant frequency was associated with the cylindrical dielectric resonator. Parametric investigation was carried out using simulation software. The proposed hybrid antenna had good agreement between the simulation and measurement results. A 24% bandwidth (return loss < 10 dB) of 2.30 GHz, and a 18% bandwidth (return loss < 10 dB) of 5.46 GHz was implemented successfully for application in ISM and UNII band.

Bandwidth and gain enhancement of microstrip patch antennas (MPAs) is proposed using reflective metasurface (RMS) as a superstrate. Two different types of the RMS, namely- the double split-ring resonator (DSR) and double closed-ring resonator (DCR) are separately investigated. The two antenna prototypes were manufactured, measured and compared. The experimental results confirm that the RMS loaded MPAs achieve high-gain as well as bandwidth improvement. The desinged antenna using the RMS as a superstrate has a high-gain of over 9.0 dBi and a wide impedance bandwidth of over 13%. The RMS is also utilized to achieve a thin antenna with a cavity height of 6 mm, which is equivalent to λ/21 at the center frequency of 2.45 GHz. At the same time, the cross polarization level and front-to-back ratio of these antennas are also examined.

Multi-source broadcasting is one of the information dissemination problems on interconnection networks such that some (but not all) units disseminate distinct information to all other units. In this paper, we discuss multi-source broadcasting on the Kautz digraph which is one of the models of interconnection networks. We decompose the Kautz digraph K(d,n) into isomorphic cycle-rooted trees whose root-cycle has length 2, then we present an algorithm for multi-source broadcasting using these cycle-rooted trees. This algorithm is able to treat d(d+1) messages simultaneously and takes the same order for required times as lower bound.

Design of high gain and high efficiency antennas is one of the key challenges in antenna engineering and especially in millimeter wave communication systems. Various types of planar waveguide arrays with series-fed traveling wave operation have been developed in Tokyo Tech with the special focus upon efficiency enhancement as well as reduction of fabrication cost. In this review, four kinds of single layer waveguide arrays characterized with the series fed travelling wave operation are surveyed first. To cope with the bandwidth narrowing effects due to long line effects associated with the series fed operation, authors have introduced partially corporate feed embedded in the single layer waveguide. They further extended the study to cover fully corporate feed arrays with multiple layer waveguide as well; a new fabrication technique of diffusion bonding of laminated thin plates has the potential to realize the low cost mass production of multi-layer structures for the millimeter wave application. Secondly, the novel methods for loss evaluation of copper plate substrate are established for the design of post-wall waveguide arrays where dielectric loss and conductor loss is determined in wide range of millimeter wave band, by using the Whispering gallery mode resonator. This enables us to design the planar arrays with the loss taken into account. Finally, the planar arrays are now applied to two kinds of systems in the Tokyo Tech millimeter wave project; the indoor short range file-transfer systems and the outdoor communication systems for the medium range backhaul links. The latter has been field-tested in the model network built in Tokyo Tech Ookayama campus. Early stage progress of the project including unique propagation data is also reported.

Narrow-wall-connected microstrip-to-waveguide transition using V-shaped patch element in millimeter-wave band is proposed. Since the microstrip line on the narrow-wall is perpendicular to the E-plane of the waveguide, waveguide field does not couple directly to the microstrip line. The current on the V-shaped patch element flows along inclined edges, then current on the V-shaped patch element couples to the microstrip line efficiently. Three types of transitions are investigated. A numerical investigation of these transitions show some relations between bandwidth and insertion loss. It is confirmed that the improved transition exhibits an insertion loss of 0.6 dB from 76 to 77 GHz, and a bandwidth of 4.1% (3.15 GHz) for the reflection coefficient below -15 dB.