Ultra-wideband pulse radars are promising candidates for 3-dimensional environment measurements by autonomous robots. Estimating 3-dimensional target shapes by scanning with an omni-directional antenna is an ill-posed inverse problem. Conventional algorithms such as the synthetic aperture method or parametric algorithms have a problem in terms of their calculation times. We have clarified the existence of a reversible transform between received data and target shapes for 3-dimensional systems. Calculation times are remarkably reduced by applying this transform because it directly estimates target shapes without iterations. We propose a new algorithm based on the transform and present an application example using numerical simulations. We confirm that the proposed algorithm has sufficient accuracy and a short calculation time.

In this paper, theoretical properties of deinterlacer banks are analyzed. Deinterlacer banks are novel filter banks in the sense that a progressive video sequence is separated into two progressive video sequences of a half frame rate and, furthermore, interlaced sequences are produced as intermediate data. Unlike the conventional filter banks, our deinterlacer banks are constructed in a way unique to multidimensional systems by using invertible deinterlacers, which the authors have proposed before. The system is a kind of shift-varying filter banks and it was impossible to derive the optimal bit-allocation control without any equivalent parallel filter banks. This paper derives an equivalent polyphase matrix representation of the whole system and its equivalent parallel structure, and then shows the optimal rate allocation for the deinterlacer banks. Some experimental results justify the effectiveness of the optimal rate allocation through our theoretical analysis.

An optimization model with maximum ratio combining (MRC) diversity soft handover is proposed for WCDMA base station location planning with heuristic algorithm, which can calculate the influence of MRC diversity soft handover directly in the process of base station location planning. Experimental results show that the proposed model can get better capacity and coverage performance in the planning results than the traditional optimization model without MRC diversity.

In this research, a sub-array preconditioner is applied to improve the convergence of conjugate gradient (CG) iterative solver in the fast multipole method and fast Fourier transform (FMM-FFT) implementation on a large-scale finite periodic array antenna with arbitrary geometry elements. The performance of the sub-array preconditioner is compared with the near-group preconditioner in the array antenna analysis. It is found that the near-group preconditioner achieves a little better convergence, while the sub-array preconditioner can be easily constructed and programmed with less CPU-time. The efficiency of the CG-FMM-FFT with high efficient preconditioner has been demonstrated in numerical analysis of a finite periodic array antenna.

In this paper, Integration of Fractional Gaussian Window transform (IFRGWT) is proposed for the parameter estimation of linear FM (LFM) signal; the proposal is based on the integration of the Fractional Fourier transform modified by Gaussian Window. The peak values can be detected by adjusting the standard deviation of Gaussian function and locating the optimal rotated angles. And also the parameters of the signal can be estimated well. As an application, detection and parameter estimation of multiple LFM signals are investigated in low signal-to-noise ratios (SNRs). The analytic results and simulations clearly demonstrate that the method is effective.

Decoding performance of LDPC (Low-Density Parity-Check) codes is highly dependent on the degree distributions of the Tanner graphs which define the LDPC codes. We compare two LDPC code ensembles, one has a uniform degree distribution and the other a non-uniform one over a BEC (Binary Erasure Channel) and a BSC (Binary Symmetric Channel) thorough DE (Density Evolution). We then derive sufficient conditions on the erasure probability of a BEC and the error probability of a BSC, under which the LDPC code ensembles with uniform degree distributions outperform those with non-uniform degree distributions.

We report the generation of time- and wavelength-interleaved optical pulses using the principle of sub-harmonic pulse gating in a dispersion-managed fiber cavity. The pulsed source has been applied to the processing of electrical and optical signals including analog-to-digital conversion, wavelength multicast, and serial-to-parallel optical data conversion.

This paper proposes an iterative maximum a posteriori probability (MAP) receiver for multiple-input-multiple-output (MIMO) and orthogonal frequency-division multiplexing (OFDM) mobile communications. For exploiting the space, time, and frequency diversity, the low-density parity-check code (LDPC) is used as a channel coding with a built-in interleaver. The receiver employs the expectation maximization (EM) algorithm so as to perform the MAP symbol detection with reasonable computational complexity. The minimum mean square error (MMSE), recursive least squares (RLS), and least mean square (LMS) algorithms are theoretically derived for the channel estimation within this framework. Furthermore, the proposed receiver performs a new scheme called backward symbol detection (BSD), in which the signal detection uses the channel impulse response that is estimated one OFDM symbol later. The advantage of BSD, which is explained from the viewpoint of the message passing algorithm, is that BSD can exploit information on the both precedent and subsequent OFDM symbols, similarly to RLS with smoothing and removing (SR-RLS) [25]. In comparison with SR-RLS, BSD reduces the complexity at the cost of packet error rate (PER) performance. Computer simulations show that the receiver employing RLS for the channel estimation outperforms the ones employing MMSE or LMS, and that BSD can improve the PER performance of the ones employing RLS or LMS.

This paper starts by describing the advantages of cascaded modulation, i.e., using multiple concatenated external modulators to modulate CW (Continuous Wave) light. Next, the paper examines computer simulations of the resulting modulated light waveform shapes and intermodulation distortion values to elucidate the basic modulation characteristics of a cascaded modulation scheme. Examples of applying cascaded modulation to a multi-channel optical signal transmission system are shown, and the characteristics are clarified by optical transmission experiments. For example, the dependency of the signal quality on the modulation depth values of each external modulator is clarified. Moreover, experiments show that cascaded modulation permits the remote insertion of local broadcast programs into wide area broadcast programs. Last, the paper shows that cascaded modulation offers better modulation properties than the conventional single modulation approach.

Substrate-coupling equivalent circuits can be derived for arbitrary isolation structures by F-matrix computation. The derived netlist represents a unified impedance network among multiple sites on a chip surface as well as internal nodes of isolation structures and can be applied with SPICE simulation to evaluate isolation strengths. Geometry dependency of isolation attributes to layout parameters such as area, width, and location distance. On the other hand, structural dependency arises from vertical impurity concentration specific to p+/n+ diffusion and deep n-well. Simulation-based prototyping of isolation structures can include all these dependences and strongly helps establish an isolation strategy against high-frequency substrate coupling in a given technology. The analysis of isolation strength provided by p+/n+ guard ring, deep n-well guard ring as well as deep n-well pocket well explains S21 measurements performed on high-frequency test structures targeting 5 GHz bandwidth, that was formed in a 0.25-µm CMOS high frequency.

JPEG2000 compression standard considers a block of wavelet coefficients, called codeblock, as the smallest coding unit that being independently entropy-coded. In this paper, we propose a codeblock-based concealment technique for JPEG2000 images to mitigate missing codeblock due to packet loss in network transmission. The proposed method creates a single JPEG2000 codestream from an image that composed of several subsampled versions of the original image and transmit the codestream over a single channel.The technique then substitutes the affected codeblock in a subsampled image with a copy of the corresponding codeblock obtained from other subsampled images. Thus, it does not require an iterative processing, which is time consuming, to construct an estimated version of the lost data. Moreover, it is applicable for a large codeblock size and can be implemented either in wavelet or codestream domain. Simulation results confirm the effectiveness of the proposed method.

A novel procedure for an efficient and rigorous solution of electromagnetic scattering problems is presented. It is based on the use of universal bases that are obtained by applying the SVD procedure to PO-derived basis functions. These bases, constructed by totally bypassing any matrix-type approach, can be used for all angles of incidence and their use leads to a matrix with relatively small dimensions. The method enables us to solve 2D scattering problems in a computationally efficient and numerically rigorous manner.

This paper presents a low cost and portable DOA (Direction Of Arrival) estimation system for surveillance using a modifed beamspace MUSIC (MUltiple Signal Classification) by a quasi-orthogonal multi-beam. This is instead of DFT processing and hardware system consisting of chip-sized phase shifters, a single ADC (Analogue to Digital Converter) and a single TR (TRanceiver) module for an antenna array. In the beamspace MUSIC, generated beampatterns have orthogonal properties. This proposed system cannot make such a beampattern due to the variable range limitation of phase shifter, then we use the quasi-orthogonal beam obtained by the calculation of correlation coefficient for beampattern. We demonstrate the proposed system using 4-element microstrip array antenna and chip-sized phase shifters. The DOA experiment in anechoic chamber confirms the proposed system performance.

One of the system greatly affecting the performance of a database server is the size-division of buffer pools. This letter proposes an adaptive control method of the buffer pool sizes. This method obtains the nearly optimal division using only observed response times in a comparatively short duration.

Menger's sponge (MS) is a kind of three-dimensional fractal structure. To analyze non-resonant electromagnetic properties of MS composed of isotropic paraelectric material, a novel, high-speed computation method employing simple recursion equations in terms of scattering amplitudes for two MS's with adjacent stage numbers, which are the parameters describing structural differences of MS's, is formulated. Within the scope of non-resonant electromagnetic phenomena, scattering patterns, forward and backward scattering amplitudes, and total cross sections of MS are investigated as a function of stage number and incident plane waves, and behaviors typical to fractal structures are extracted from the numerical results of the above equations. In addition, scattering properties at infinite stage number are discussed.

The Multiple Access Interference (MAI) and the Multipath Fading (MPF) restrict the performance of Code-Division Multiple-Access (CDMA) systems. The Multiuser Detection (MUD) based on Particle Swarm Optimization algorithm (PSO) with Rake processing is proposed in this paper to overcome these obstacles, followed by full details of how to apply the Binary PSO MUD (BPSO-MUD) on a CDMA system. Simulations show that the BPSO-MUD has significantly better performance than the Conventional Detection (CD).

A new method to approximate the receive minimum distance is presented. In the proposed approximation, the geometric mean of the singular values of the channel matrix is used instead of the conventional minimum singular value. Numerical experiments show that the proposed approximation has less mean squared error than the minimum singular value bound and outperforms the minimum singular value bound in terms of bit error rate when they are applied to the antenna subgroup selection system.

A major step in the numerical solution of electromagnetic scattering problems involves the computation of the convolution based reaction integrals. In this paper a procedure based on the analytical Fourier transform is introduced which allows us to calculate the convolution-based reaction integrals in the spectral domain without evaluating any convolution products directly. A numerical evaluation of the computational cost is presented to show the efficiency of the method when handling electrically large problems.

This paper presents the Physical Optics field calculation in terms of only line integrations by using the Modified Edge Representation technique (MER), the alternative way of the surface integration. Not only the diffracted fields as in the conventional method of equivalent edge currents (EEC) but also the scattering geometrical optics fields are expressed in terms of the MER line integrals. The far field patterns of parabolic reflector antennas with the defocused dipole feed are discussed and the satisfactory agreement with those obtained by the Physical Optics surface integration is demonstrated.

Recently, the Doherty amplifier technique has been the focus of attention not only for base stations but also for mobile terminals because of its high power-added efficiency in the large back-off region. In this paper, we present a miniaturized Doherty power amplifier (PA) module for W-CDMA mobile terminals. The developed Doherty PA module consists of a 4-mm-square ceramic substrate (4.0 mm4.0 mm1.5 mm, alumina, dielectric constant = 8.8), a 1-mm-square GaAs MMIC (1.0 mm1.0 mm0.1 mm), and 0603-size SMD passive components. To miniaturize the module size, the optimal designed quarter-wavelength transmission lines, which are used for impedance conversion for carrier amplifier output and phase compensation for peak amplifier input, are embedded in the ceramic module substrate. Two GaAs HBTs for a carrier amplifier and a peak amplifier and base bias circuits for each amplifier are integrated onto a single-chip GaAs MMIC. Measurement results at 1950 MHz in a W-CDMA uplink signal indicate that 27 dBm of the maximum output power, 45% of the power-added efficiency (PAE), 11 dB of power gain, and 43% of PAE at 6 dB back-off, i.e. 24 dBm output power, are obtained with the developed Doherty PA. In other words, the PAE is improved from the theoretical PAE of a conventional class B amplifier, namely, from 23% to 43%. This is the smallest Doherty amplifier developed in the form of a module for mobile terminals.