Let T be a text of length n and P be a pattern of length m, both strings over a fixed finite alphabet. The Pattern Matching with Swaps problem is to find all occurrences of P in T if adjacent pattern characters can be swapped. In the Approximate Pattern Matching problem with Swaps, one seeks for every text location with a swapped match of P, the number of swaps necessary to obtain a match at the location. In this paper we provide the first off-line solution for the swap matching problem and the approximate pattern matching problem with swaps. We present a new data-structure called a Swap-transforming Tree. And we give a precise upper-bond of the number of the swapped versions of a pattern. By using the swap-transforming tree, we can solve both problems in time O(λmlog2 n) on an O(nHk) bits indexing data structure. Here λ is a constant. Our solution is more effective when the pattern is short.

In this paper, a simple type of printed dipole is proposed for Multi-Input Multi-Output (MIMO) applications in cognitive radio. The antenna is composed of a transmission line and a dipole. Some examinations of key factors and optimized parameters of the antenna are presented. The measured results illustrate that the proposed antenna offers a bandwidth of over 50% for Voltage Standing Wave Ratio (VSWR) less than 2, extending from 2.4 GHz to 4.0 GHz. The antenna peak gain in E-plane and radiation patterns at different frequencies are also explored. In addition, based on the proposed antenna, we introduce two simple broadband arrays for MIMO applications in cognitive radio. One has two ports and the other has four ports. Measurement results indicate that the arrays also work in a broad bandwidth. Mutual couplings between ports in each array are kept under -10 dB at the low frequencies and under -20 dB at the high frequencies of bandwidth of the arrays. Furthermore, we utilized the antenna arrays for some MIMO experiments to estimate the channel capacity in a wide frequency range.

A broadband microstrip comb-line antenna using a corporate feeding system was developed. The antenna was composed of four colinearly-arranged comb-line antennas with traveling-wave excitation fed by a parallel-feeding circuit of tournament configuration. The total phase deviation due to frequency change became one fourth of the ordinary series feeding from the end of the antenna. Furthermore, the terminations of the inner two comb-lines were connected at the overall center of the developed antenna. Therefore, the narrowband matching elements are not necessary and the amplitude deviation of the aperture distribution for input from one side due to frequency change is compensated by deviation for input from the other side. Broad bandwidth can be expected by using the proposed configuration. The proposed antenna was designed at 76.5 GHz. The effect of the proposed feeding-circuit for broadband operation was confirmed by comparing the measured performances of the antennas fed by other feeding circuits; the end feeding, the center feeding and the ordinary corporate feeding. The bandwidth of the proposed corporate feeding antenna with the center connecting was approximately 14% and 7% wider than the antennas of the center feeding and of the ordinary corporate feeding, respectively.

This paper presents a 65-nm CMOS 8-antenna array transmitter operating in 117–130-GHz range for short range and portable millimeter-wave (mm-wave) active imaging applications. Each antenna element is a new on-chip antenna located on the top metal. By using on-chip transformer, pulse output of each resistor-less mm-wave pulse generators (PG) are sent to each integrated antenna. To adjust pulse delays for the purpose of pulse beam-forming, a 7-bit digitally programmable delay circuit (DPDC) is added to each of PGs. Moreover, in order to dynamically adjust pulse delays among eight SW's outputs, we implemented on-chip jitter and relative skew measuring circuit with 20-bit digital output to achieve cumulative distribution (CDF) and probability density (PDF) functions from which DPDC's input codes are decided to align eight antenna's output pulses. Two measured radiation peaks after relative skew alignment are obtained at (θ; φ) angles of (-56; 0) and (+57; 0). Measurement results shows that beam-forming angles of the fully integrated antenna array can be adjusted by digital input codes and by the on-chip skew adjustment circuit for active imaging applications.

A readout circuit incorporating a pixel-level analog-to-digital converter (ADC) is studied for 2-dimensional microbolometer infrared focal plane arrays (IRFPAs). The integration time and signal-to-noise ratio (SNR) is improved using the current-mode bias and MSB skimming. The proposed pixel-level ADC is a two-step configuration, so its power consumption is very low. The readout circuit was designed using a 0.35 µm 2-poly 4-metal CMOS process for a 320240 microbolometer array with a pixel size of 35µm35µm. The noise equivalent temperature difference (NETD) was estimated to be 47 mK, with a power consumption of 390 nW for a pixel-level ADC.

A perfect array is an array for which the autocorrelation function is impulsive. A parameterization of perfect arrays of real numbers is presented. Perfect arrays are represented by trigonometric functions. Three formulae are obtained according to the parities of the size of the array. Examples corresponding to each formula are shown. In the case of 66 arrays, the existence of a set of perfect arrays having integer components is shown.

In this study, we propose a one dimensional (1D) based successive generalized sidelobe canceller (GSC) structure for the implementation of 2D adaptive beamformers using a uniform rectangular antenna array (URA). The proposed approach takes advantage of the URA feature that the 2D spatial signature of the receive signal can be decomposed into an outer product of two 1D spatial signatures. The 1D spatial signatures lie in the column and the row spaces of the receive signal matrix, respectively. It follows that the interferers can be successively eliminated by two rounds of 1D-based GSC structure. As compared to the conventional 2D-GSC structure, computer simulations show that in addition to having significantly low computational complexity, the proposed adaptive approach possesses higher convergence rate.

Dielectric rod arrays in a metallic waveguide alter the propagation modes and group velocities of electromagnetic waves. We have focused on TE30-to-TE10 mode converters and investigated how their behavior varies with frequency. A mode converter is proposed that passes the TE10 mode at frequencies lower than 2fc, and converts the TE30 mode into the TE10 mode for frequencies higher than 3fc.

A novel algorithm is presented for estimating the 3-D location (azimuth angle, elevation angle, and range) of multiple sources with a uniform circular array (UCA). Based on its centrosymmetric property, a UCA is divided into two subarrays. The steering vectors for these subarrays then yield a 2-D direction of arrival (DOA)-related rotational invariance property in the signal subspace, which enables 2-D DOA estimations using a generalized-ESPRIT algorithm. Based on the estimated 2-D DOAs, a range estimation can then be obtained for each source by defining the 1-D MUSIC spectrum. Despite its low computational complexity, the proposed algorithm can almost match the performance of the benchmark estimator 3-D MUSIC.

This paper presents a 100–120-GHz pulse transmitter chip with a 5424 on-chip loop antenna array for the purpose of beam-formability in portable millimeter-wave (mm-wave) active imaging applications. We present a new idea for silicon-based mm-wave pulse beam-forming by using voltage-varied CMOS inverter chain. This 4-mm4-mm transmitter chip is designed and fabricated in a 2.5-V 0.25-µm 4-metal-layer Si-Ge Bi-CMOS process. The 30-µm30-µm loop antenna located on the top-metal layer operates as an coil in an integrated mm-wave pulse generator. Each of on-chip pulse generators employing under-damped/over-damped conditions to produce mm-wave pulses includes an R-L-C circuit, a bipolar junction transistor (BJT) operated as a switch and a CMOS inverter chain circuit for shaping the rising edge of the input clock. Simulation results by ADS 2009 and HSPICE show that loop antenna' inductance and resistance at 80–120-GHz are 51 pH and 3 Ω, respectively. A simulation performance of an integrated 136 loop antenna array illustrates the variation of maximum radiation angles depending on different phase values between array's elements. By using an mm-wave power meter, a 90–140-GHz standard horn antenna and a Schottky diode detector, several measured radiation patterns of this loop antenna array chip are achieved. From the measurement result, we demonstrate the possibility of an integrated mm-wave pulse generator for the purpose of beam-forming by changing power supplies of inverter chains.

On the huge-scale array antenna for SSPS (space solar power systems), the problem of faulty elements and effect of mutual coupling between array elements should be considered in practice. In this paper, the effect of faulty elements as well as mutual coupling on the performance of the huge-scale array antenna are analyzed by using the proposed IEM/LAC. The result shows that effect of faulty elements and mutual coupling on the actual gain of the huge-scale array antenna are significant.

Microwave/millimeter-wave phase and amplitude characteristics of the optically controlled phased array antenna with a different SMF for each antenna feed were measured. Suitable phases for the beam steering can be realized by the adjustment of the LD wavelength independently with multiple SMFs. In addition to the phase, amplitude of each antenna feed can be controlled stably using LD current without phase variation. Furthermore, effectiveness of the calibration method of the phased array using multiple SMFs by LD wavelength adjustment is experimentally verified. Excellent microwave/millimeter-wave phase characteristics using 2- and 3-element optically controlled phased array feed were experimentally demonstrated with calibration of the phases. Phase characteristics of the array using multiple SMFs were also compared with that using a single SMF experimentally.

A circularly-polarized planar array antenna using hexagonal aperture elements is proposed. A 22-element subarray as the basic unit is excited by a corporate-feed circuit located in the lower layer of the double-layered antenna. The hexagonal aperture is designed to achieve a good axial ratio in the boresight. A 1616-element array antenna with uniform element spacing smaller than the free-space wavelength was fabricated by diffusion bonding of laminated thin metal plates for the 60 GHz-band. The high gain of 33.4 dBic is measured with 91.6% antenna efficiency, including losses.

A novel algorithm is presented for near-field source localization with a symmetric uniform linear array (ULA) consisting of an even number of sensors. Based on element reordering of a symmetric ULA, the steering vector is factorised with respect to the range-independent bearing parameters and range-relevant 2-D location parameters, which allows the range-independent bearing estimation with rank-reduction idea. With the estimated bearing, the range estimation for each source is then obtained by defining the 1-D MUSIC spectrum. Simulation results are presented to validate the performance of the proposed algorithm.

We review recently obtained results for CMOS (Complementary Metal Oxide Semiconductor) imaging devices used in biomedical applications. The topics include dish type image sensors, deep-brain implantation devices for small animals, and retinal prosthesis devices. Fundamental device structures and their characteristics are described, and the results of in vivo experiments are presented.

In this paper, we propose an Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) based algorithm for estimating the two-dimensional-direction-of-arrivals (2D-DOA) of signals impinging on a uniform rectangular array (URA). The basic idea of the proposed algorithm is to successively apply two rounds of one-dimensional ESPRIT (1D-ESPRIT) algorithm for 2D-DOA estimation. The first round 1D-ESPRIT is applied on columns of the URA whereas the other round 1D-ESPRIT is on the rows of the URA. In between, a grouping technique is developed to produces signal groups each containing signals with distinguishable spatial signatures. The grouping technique is performed by using the subspace projection method where the needed spatial information is provided by the first round 1D-ESPRIT algorithm. Computer simulations show that, in addition to having significantly reduced computational complexity, the proposed algorithm possesses better estimation accuracy as compared to the conventional 2D-ESPRIT algorithm.

In this paper, we present a sequentially rotated array antenna with a rectangular patch MSA fed by an L-probe. Since it's important to decrease couplings between patch elements in order to suppress the cross-polarization level, rectangular patches with aspect ratio of k are adopted. We investigate the cross-polarization level of the sequential array and discuss the relationship between the cross-polarization level and the mutual coupling. As a result, the bandwdith of the antenna element is obtained 14.6% when its VSWR is less than 1.5, and the directivity and cross-polarization level of a 4-patch sequential array are 10.8 dBic and 1.7 dBic, respectively, where k=0.6 and the patch spacing of d=0.5 wave length. These characteristics are 5.6 dB and 5.8 dB better than the corresponding values of a square patch sequential array antenna.

A semi-analytical approach for analyzing the electromagnetic radiation of a line source in cylindrical electromagnetic bandgap (EBG) structure is presented. The cylindrical structure is composed of circular rods periodically distributed along concentrically layered circular rings. The method uses the T-matrix of a circular rod in isolation, the reflection and transmission matrices of a cylindrical array expressed in terms of the cylindrical waves as the basis, and the generalized reflection and transmission matrices for a layered cylindrical structure. Using the proposed method, the radiated field from a line source placed inside a three-layered cylindrical EBG structure with defects is investigated. The defects are created by removing the particular circular rods from each circular ring. The structure is prominent from the viewpoint of flexible design of the directive antennas. Numerical examples demonstrate that the cylindrical EBG structures are very effective at forming and controlling the directed beam in the radiated fields.

In this paper, a frequency domain adaptive antenna array (FDAAA) algorithm is proposed for broadband single-carrier uplink transmissions in a cellular system. By employing AAA weight control in the frequency domain, the FDAAA receiver is able to suppress the multi-user interference (MUI) and the co-channel interference (CCI). In addition, the channel frequency selectivity can be exploited to suppress the inter-symbol interference (ISI) and to obtain frequency diversity (or the multi-path diversity). Another advantage of the FDAAA algorithm is that its performance is not affected by the spread of angles of arrival (AOA) of the received multi-path signal. In this study the structure of FDAAA receiver is discussed and the frequency domain signal-to-interference-plus-noise-ratio (SINR) after weight control is investigated. The performance of the FDAAA algorithm is confirmed by simulation results. It is shown that, the optimal FDAAA weight to obtain the best BER performance is that which fully cancels the interference when single-cell system is considered; On the other hand, when multi-cell cellular system is considered, the optimal FDAAA weight depends on both the cellular structure and the target signal to noise ratio (SNR) of transmit power control (TPC).

Two designs of wideband compact MIMO antenna using printed dipoles are proposed in this paper. One is a three-port orthogonal polarization antenna and the other is a cube-six-port antenna. Measured results for the antennas show that they resonate at 2.6 GHz and support a bandwidth of over 400 MHz. The worst mutual coupling for the three-port orthogonal polarization antenna is kept under -20 dB whereas that level of the cube-six-port antenna is -18 dB. A number of experiments are conducted on MIMO systems with these compact antennas and linear antenna arrays. Measured data are analyzed to examine channel characteristics, such as cumulative distribution functions (CDFs) of eigenvalues. Furthermore, the effect of different antenna configurations on channel capacity is highlighted and discussed. A high data rate capacity can be achieved with the compact antennas, particularly from the cube-six-port variant. These antennas might be applied in actual MIMO systems in wireless communications.