This letter analyzes the outage probability of limited feedback beamforming systems with receive antenna selection. Tight analytical closed-form expressions of outage performance are derived for both cases, with and without spatial fading correlation, which allow for evaluation of the performance as a function of the codebook size, the level of fading correlation, and the number of transmit and receive antennas. Simulation results are also provided to verify the analysis.

To evaluate frequency-domain interference between orthogonally intersecting stripline geometries, a lumped mutual capacitance was incorporated into a circuit model, and then a simplified circuit was proposed in the previous paper. The circuit model was approximated from an investigation of the distribution of mutual capacitance but it has remained how the capacitance is approximated. In this paper, a technique using an error function is proposed for the problem. Then, the time-domain response in an analytical expression is studied using the simplified circuit model in a Laplace transformation to make the mechanism clear. Comparing the experimental and the computed results verifies the proposed models.

Organic static induction transistor (OSIT) is a promising driving device for the displays, since it shows high-speed, high-power and low-voltage operation. In this study, the OSIT with fine gate electrode patterned by electron beam exposure were fabricated. We investigated the basic electrical characteristics of copper phthalocyanine OSIT and compared with the calculation results obtained by two-dimensional (2D) device simulator. The experimental results show that the gate modulation improved by reducing the electrode gap and on/off current ratio depends on the gate gap.

Recently, a data-selective method has been proposed to achieve low misalignment in affine projection algorithm (APA) by keeping the condition number of an input data matrix small. We present an improved method, and a complexity reduction algorithm for the APA with the data-selective method. Experimental results show that the proposed algorithm has lower misalignment and a lower condition number for an input data matrix than both the conventional APA and the APA with the previous data-selective method.

We have developed an amperometric sensor employing a photoconductive organic thin film that enables the measurement of the two-dimensional distribution of redox current on a sensor surface. The sensor simply consists of photoconductive film and transparent electrode. A focused light beam through the transparent electrode excites the photoconductive film that leads to detect local redox current at the beam position. Intensity of the redox current depends on local concentration of redox species of solution on the sensor. We investigated several materials for the photoconductive film and found a suitable structure is Cu-phthalocyanine doped polyvinylcarbazole film/indium tin oxide/glass substrate. Compared with a conventional two-dimensional chemical sensor, our newly developed sensor can be prepared by lower cost fabrication methods without complex semiconductor processes. The sensor showed a good signal dependence on the concentration of K3Fe(CN)6/K4Fe(CN)6 in an aqueous solution at 15.4 nA/dec at a constant bias voltage of 0.8 V. We measured the two-dimensional distribution of ions in an agarose gel of 2 mm thickness. The result showed a photograph of the diffusion process of redox species. We also discuss the discrimination of redox species like voltammetry.

A function F:F2n F2n is almost perfect nonlinear (APN) if, for every a 0, b in F2n, the equation F(x)+F(x+a)=b has at most two solutions in F2n. When used as an S-box in a block cipher, it contributes optimally to the resistance to differential cryptanalysis. The function F is almost bent (AB) if the minimum Hamming distance between all its component functions v F, v∈F2n {0} (where "" denotes any inner product in F2n ) and all affine Boolean functions on F2n takes the maximal value 2n-1-2. AB functions exist for n odd only and contribute optimally to the resistance to the linear cryptanalysis. Every AB function is APN, and in the n odd case, any quadratic APN function is AB. The APN and AB properties are preserved by affine equivalence: F F' if F'=A1 F A2, where A1,A2 are affine permutations. More generally, they are preserved by CCZ-equivalence, that is, affine equivalence of the graphs of F: {(x,F(xv)) | x∈ F2n} and of F'. Until recently, the only known constructions of APN and AB functions were CCZ-equivalent to power functions F(x)=xd over finite fields (F2n being identified with F2n and an inner product being x y=tr(xy) where tr is the trace function). Several recent infinite classes of APN functions have been proved CCZ-inequivalent to power functions. In this paper, we describe the state of the art in the domain and we also present original results. We indicate what are the most important open problems and make some new observations about them. Many results presented are from joint works with Lilya Budaghyan, Gregor Leander and Alexander Pott.

This paper proposes a novel algorithm for image feature extraction-the dual two-dimensional fuzzy class preserving projections ((2D)2FCPP). The main advantages of (2D)2FCPP over two-dimensional locality preserving projections (2DLPP) are: (1) utilizing the fuzzy assignation mechanisms to construct the weight matrix, which can improve the classification results; (2) incorporating 2DLPP and alternative 2DLPP to get a more efficient dimensionality reduction method-(2D)2LPP.

In this paper, we analyze existing vulnerabilities in handover for mobile WiMAX networks. To overcome these vulnerabilities, we propose a secure handover protocol that guarantees mutual authentication and forward/backward secrecy in handover. We present a formal analysis of our protocol using a logic-based formal method.

The multi-log2N network architecture is attractive for constructing optical switches, and the related routing algorithms are critical for the operation and efficiency of such switches. Although several routing algorithms have been proposed for multi-log2N networks, a full performance comparison among them has not been published up to now. Thus, we rectify this omission by providing such a comparison in terms of blocking probability, time complexity, hardware cost and load balancing capability. Notice that the load balance is important for reducing the peak power requirement of a switch, so we also propose in this paper a new routing algorithm for optical multi-log2N networks to achieve a better load balance.

In this paper, we propose an extension to GridFTP that optimizes its performance by dynamically adjusting the number of parallel TCP connections. GridFTP has been used as a data transfer protocol to effectively transfer a large volume of data in Grid computing. GridFTP supports a feature called parallel data transfer that improves throughput by establishing multiple TCP connections in parallel. However, for achieving high GridFTP throughput, the number of TCP connections should be optimized based on the network status. In this paper, we propose an automatic parallelism tuning mechanism called GridFTP-APT (GridFTP with Automatic Parallelism Tuning) that adjusts the number of parallel TCP connections according to information available to the Grid middleware. Through simulations, we demonstrate that GridFTP-APT significantly improves the performance of GridFTP in various network environments.

It is essential to ensure a satisfactory QoS (Quality of Service) when offering a speech communication system with a noise reduction algorithm. In this paper, we propose a new obejective test methodology for noise-reduced speech that estimates word intelligibility by using a distortion measure. Experimental results confirmed that the proposed methodology gives an accurate estimate with independence of noise reduction algorithms and noise types.

A modified successive interference cancellation (SIC) algorithm for orthogonal frequency division multiplexing (OFDM) system is presented. The presented modified SIC algorithm makes use of an index sequence to avoid the subcarriers re-ordering calculation. Furthermore, by combining the SIC with the conventional zero-forcing (ZF) detection, computation complexity of the presented algorithm can be significantly reduced and meanwhile excellent performance can be maintained.

A new online, unsupervised voice activity detection (VAD) method is proposed. The method is based on a feature derived from high-order statistics (HOS), enhanced by a second metric based on normalized autocorrelation peaks to improve its robustness to non-Gaussian noises. This feature is also oriented for discriminating between close-talk and far-field speech, thus providing a VAD method in the context of human-to-human interaction independent of the energy level. The classification is done by an online variation of the Expectation-Maximization (EM) algorithm, to track and adapt to noise variations in the speech signal. Performance of the proposed method is evaluated on an in-house data and on CENSREC-1-C, a publicly available database used for VAD in the context of automatic speech recognition (ASR). On both test sets, the proposed method outperforms a simple energy-based algorithm and is shown to be more robust against the change in speech sparsity, SNR variability and the noise type.

A detector for space-time block coding is proposed to combat time-selective fading. To suppress both noise and interference, a minimum mean square error (MMSE) based detector is introduced for space-time block coding. It is shown by simulations that the proposed detector outperforms the conventional detectors when the channel is time-selective fading.

In this paper, we design and manufacture a flanged double ridged waveguide with a tapered section as a sample holder for measuring the electromagnetic shielding effectiveness (SE) of planar material in broadband frequency ranges up to 10 GHz. The proposed technique overcomes the limitations of the conventional ASTM D4935 test method at high frequencies. The simulation results for the designed sample holders agree well with the fabricated ones in consideration of the design specification of S11 < -20 dB within the frequency range of 1-10 GHz. To verify the proposed measurement apparatus, the measured SE data of the commercial shielding materials from 1 to 10 GHz were indirectly compared with those obtained from the ASTM D4935 from 30 MHz to 1 GHz. We observed that the SE data obtained by using both experimental techniques agree with each other.

A system which employs a stylus as an input device is suitable for creative activities like writing and painting. However, such a system does not always provide the user with a GUI that is easy to operate using the stylus. In addition, system usability is diminished because the stylus is not always integrated into the system in a way that takes into consideration the features of a pen. The purpose of our research is to improve the usability of a system which uses a stylus as an input device. We propose shortcut actions, which are interaction techniques for operation with a stylus that are controlled through a user's hand motions made in the air. We developed the Context Sensitive Stylus as a device to implement the shortcut actions. The Context Sensitive Stylus consists of an accelerometer and a conventional stylus. We also developed application programs to which we applied the shortcut actions; e.g., a drawing tool, a scroll supporting tool, and so on. Results from our evaluation of the shortcut actions indicate that users can concentrate better on their work when using the shortcut actions than when using conventional menu operations.

In this paper, we propose a new algorithm to detect the presence of narrow band interference signals on the band of an Ultra Wide-Band (UWB) system when the UWB spectrum overlaps the bands of other narrow band wireless services. In our proposed algorithm for an UWB Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) system, an appropriate model is selected from the assumed interference models based on the Akaike Information Criterion (AIC) which is an explicit theoretic criterion and a measure of fit of the model. The proposed algorithm does not need a priori information on the interference signals except that we can reduce a computational complexity to implement the algorithm if we have knowledge of the bands of the interference signals. Furthermore, we introduce the Expectation Maximization (EM) algorithm to our algorithm in order to estimate the transmitted signals and the interference signals simultaneously. The proposed algorithm may not require the pilot symbols in the assumed UWB system to detect the presence of other systems. By computer simulations, we show that the proposed algorithm validly detects the presence of interference signals on the UWB band.

This paper presents a novel interference cancellation (IC) scheme for both synchronous and asynchronous direct-sequence code-division multiple-access (DS-CDMA) wireless channels. In the DS-CDMA system, the multiple access interference (MAI) and the near-far problem (NFP) are the two factors which reduce the capacity of the system. In this paper, we propose a new algorithm that is able to detect all interference signals as an individual MAI signal by maximum correlation detection. It is based on the discovery of all the unknowing spreading codes of the interference signals. Then, all possible MAI patterns so called replicas are generated as a summation of interference signals. And the true MAI pattern is found by taking correlation between the received signal and the replicas. Moreover, the receiver executes MAI cancellation in a successive manner, removing all interference signals by single-stage. Numerical results will show that the proposed IC strategy, which alleviates the detrimental effect of the MAI and the near-far problem, can significantly improve the system performance. Especially, we can obtain almost the same receiving characteristics as in the absense of interference for asynchrnous system when received powers are equal. Also, the same performances can be seen under any received power state for synchronous system.

In order to timely response to a user query at run-time, next generation Semantic Web applications demand a robust mechanism to dynamically select one or more existing ontologies available on the Web and combine them automatically if needed. Although existing ontology retrieval systems return a lengthy list of resultant ontologies, they cannot identify which ones can completely meet the query requirements nor determine a minimum set of resultant ontologies that can jointly satisfy the requirements if no single ontology is available to satisfy them. Therefore, this paper presents an ontology retrieval system, namely combiSQORE, which can return single or combinative ontologies that completely satisfy a submitted query when the available ontology database is adequate to answer such query. In addition, the proposed system ranks the returned results based on their semantic similarities to the given query and their modification (integration) costs. The experimental results show that combiSQORE system yields practical combinative ontologies and useful rankings.

This paper introduces a theory for fast optimization of the circuit topology and parameters in sinusoidal oscillators. The theory starts from a system model composed of standard active and passive elements. We then include even the output load in the circuit, so that there is no longer any interaction with the outside of the system through the port. This model is thus called no-input-no-output (NINO) oscillator. The circuit is cut at an arbitrary branch, and is characterized in terms of the scalar impedance from the cut point. This is called active impedance because it is a function of not only the stimulating frequency but also the active device gain. The oscillation frequency and necessary device gain are estimated by solving impedance-domain Barkhausen equilibrium equations. This estimation works for the adjustment of circuit elements to meet the specified oscillation frequency. The estimation of necessary device gain enables us to maximize the oscillation amplitude, thanks to the inherent negative-slope nonlinearity of active devices. The active impedance is also used to derive the oscillation Q (quality) factor, which serves as a key criterion for sideband noise minimization i.e. frequency spectrum purification. As an alternative measure to active impedance, we also introduce branch admittance matrix determinant. This has the same numerical effect as the scalar impedance but can be used to formulate oscillator characteristics in a more elegant fashion, and provides a lucent picture of the physical behavior of each element in the circuit. Based on the proposed theory, we provide the tabled formulas of oscillation frequency, necessary device gain, active Q factor for a variety of typical Colpitts, Hartley, and cross-coupled twin-FET (field-effect transistor) oscillators.