A complementary cross-coupled differential Colpitts voltage controlled oscillator (VCO) is reported. The combination of gm-boosting and the complementary transistors allows record low power integrated VCO implementation. The proposed VCO and the corresponding parallel quadrature VCO (P-QVCO) are implemented using 0.25-µm CMOS technology for 1.8 GHz operation. Measurements for the VCO and P-QVCO show phase noise of -116.8 and -117.7 dBc/Hz at 1 MHz offset, while dissipating only 0.4 and 1.1 mA from a 0.9-V supply, respectively.

A compact OTA suitable for low-voltage active-RC and MOSFET-C filters is presented. The input stage of the OTA utilises the NMOS pseudo-differential amplifier with PMOS active load. The output stage relies upon the dual-mode feed-forward class-AB technique (based on an inverter-type transconductor) with common-mode rejection capability that incurs no penalty on transconductance/bias-current efficiency. Simulation results of a 0.5-V 100-kHz 5th-order Chebyshev filter based on the proposed OTA in a 0.18 µm CMOS process indicate SNR and SFDR of 68 dB and 63 dB (at 50 kHz+55 kHz) respectively. The filter consumes total power consumption of 60 µW.

Owing to simple structure, low cost and high performance, NRD-guide millimeter wave circuits have attracted much attention in recent years. In this paper, a variety of NRD-guide passive components are reviewed with emphasis on design techniques and performance estimation in the 60 GHz frequency band where the license-free advantage is available. The passive components to be discussed here include compact bends, wideband hybrid couplers, practical three-port junctions, versatile E-plane filters, and effective feeding structures for lens antennas. Some of them are employed to construct millimeter wave transceivers. Eye patterns observed at 1.5 Gbps confirm the potential ability of the fabricated NRD-guide transceivers for high bit-rate, wireless applications.

Comb capacitors suitable for use in advanced complementary metal-oxide semiconductor (CMOS) technology nodes are frequently constructed from low metal layers located closely above the conductive silicon substrate. This results in high parasitic capacitances across the thin dielectric between the two layers. Therefore, a shield for reducing this parasitic capacitance is proposed in order to use the comb capacitor at high frequency. From electromagnetic (EM) simulation results using a 3D EM simulator, the quality factor (Q-factor) of the proposed shielded comb capacitor for the differential signal improved by 20% at 30-110 GHz compared to the unshielded capacitor. Consequently, a scalable model is proposed, which operates up to millimeter-wave frequencies. The results are verified by experimental data using fabricated comb capacitors from a 90 nm 1P9M CMOS process. Compared with the experimental results, the simulated common-mode and differential-mode S parameters of the model has a root-mean-square (r.m.s.) error of under 2.1%.

This letter describes a millimeter wave slot array antenna using a rectangular waveguide and a ferrite. The radiation direction of the leaky wave from the slot array can be scanned by applying a dc bias magnetic field parallel to the ferrite. The radiation pattern of a prototype antenna has been measured at 40 GHz. The main beam direction changes from 10 to 3 degree by the bias magnetic field of 0.73 T.

This letter concerns the Schur stability of convex combinations of complex polynomials. For given two Schur stable complex polynomials, a sufficient condition is given such that the convex combination of polynomials is also Schur stable.

IEEE 802.11e Medium Access Control (MAC) is a supplement to the IEEE 802.11 Wireless Network (WLAN) standard to support Quality of Service (QoS). The 802.11e MAC defines a new coordination function, namely Hybrid Coordination Function (HCF), which takes the QoS requirements of flows into account and allocates Transmission Opportunity (TXOP) to stations. On the basis of mean sending rate, delay of Variable Bit Rate (VBR) traffic cannot be bounded with the reference HCF scheduling algorithm proposed in this supplement. In this paper, we propose a new Connection Admission Control (CAC) and a scheduling algorithm that utilize the token bucket and a modified Latency-Rate (LR) scheduling algorithm to guarantee a bounded delay for HCF Controlled Channel Access (HCCA). The new Service Interval (SI) is calculated to optimize the number of stations accommodated and takes into account delay bound and token bucket parameters. We show that it is possible to obtain worst-case performance guarantees on delay. First, we analyze the behavior of the new scheduler with a loss free wireless channel model and after this, with a burst loss model and we explain how it is possible to extend this scheduler for a multi-rate scheme. Properties of the proposal are investigated both theoretically and using ns-2 simulations. We present a set of simulations with both Constant Bit Rate (CBR) and VBR flows and performance comparisons with HCF scheduling algorithm. The results show that the delay upper bound can be achieved for a large range of networks load with bandwidth optimization.

This letter proposes a new weighted fair queueing algorithm, which adjusts dynamically each flow's service probability according to its weight and average packet length and then uses the service probability parameters to implement fair queueing. This solves the main drawback of traditional weighted fair queueing algorithms--the packet-based tracing of weight parameters. In addition, this letter proposes a novel service probability calculation method which solves the unfairness problem induced by the variable packet length.

In this paper, we propose a new scheme to represent three-dimensional (3-D) dynamic scenes using a hierarchical decomposition of depth maps. In the hierarchical decomposition, we split a depth map into four types of images: regular mesh, boundary, feature point and number-of-layer (NOL) images. A regular mesh image is obtained by down-sampling a depth map. A boundary image is generated by gathering pixels of the depth map on the region of edges. For generating feature point images, we select pixels of the depth map on the region of no edges according to their influence on the shape of a 3-D surface, and convert the selected pixels into images. A NOL image includes structural information to manage the other three images. In order to render a frame of 3-D dynamic scenes, we first generate an initial surface utilizing the information of regular mesh, boundary and NOL images. Then, we enhance the initial surface by adding the depth information of feature point images. With the proposed scheme, we can represent consecutive 3-D scenes successfully within the framework of a multi-layer structure. Furthermore, we can compress the data of 3-D dynamic scenes represented by a mesh structure by a 2-D video coder.

In this letter, we show that Jung's ID-based scheme, which is the improved version of the Chikazawa-Yamagishi scheme, satisfies only the weak forward secrecy. But the weak forward secrecy is not quite realistic, since it is not sufficient for modeling the real attacks. To address this problem, the strong forward secrecy has been pursued, which is modeling the more realistic attacks. We then suggest a modification of Jung's ID-based scheme to provide the strong forward secrecy.

In this paper, we present a new fast Fourier transform (FFT) algorithm to reduce the table size of twiddle factors required in pipelined FFT processing. The table size is large enough to occupy significant area and power consumption in long-point FFT processing. The proposed algorithm can reduce the table size to half, compared to the radix-22 algorithm, while retaining the simple structure. To verify the proposed algorithm, a 2048-point pipelined FFT processor is designed using a 0.18 µm CMOS process. By combining the proposed algorithm and the radix-22 algorithm, the table size is reduced to 34% and 51% compared to the radix-2 and radix-22 algorithms, respectively. The FFT processor occupies 1.28 mm2 and achieves a signal-to-quantization-noise ratio (SQNR) of more than 50 dB.

We have been developing a secure and reliable distributed storage system, which uses a secret sharing scheme. In order to efficiently store data in the system, this paper introduces an optimal share transfer problem, and proves it to be, generally, NP-hard. It is also shown that the problem can be resolved into a Steiner tree problem. Finally, through computational experiments we perform the comparison of heuristic algorithms for the Steiner tree problem.

In this paper, an efficient cyclic prefix reconstruction (CPR) technique with turbo equalization is developed for multi-antenna single-carrier frequency-domain equalization (SC-FDE) systems, which are for multi-input multi-output (MIMO), space-time block code (STBC), and space-frequency block code (SFBC) applications. The proposed method includes pre-processing estimation (PPE), weighted interblock interference cancellation (WIBIC), or residual intercarrier interference suppression (RICIS). PPE is employed to compute initial values of MIMO turbo equalization and the WIBIC is developed to cancel interblock interference (IBI) at the initial iteration of the CPR for STBC SC-FDE. RICIS is used to mitigate residual intercarrier interference (ICI) after each iteration of the CPR. By applying the proposed method to the multi-antenna SC-FDE system with insufficient cyclic prefix (CP), we can significantly improve its error performance, obtaining the benefits of spectral efficiency gain and multiplexing/diversity gain in MIMO/STBC/SFBC.

Scene changes occur frequently in film broadcasting, and tend to destabilize the performance with blurred, jagged, and artifacts effects when de-interlacing methods are utilized. This paper presents an efficient VLSI architecture of video de-interlacing with considering scene change to improve the quality of video results. This de-interlacing architecture contains three main parts. The first is scene change detection, which is designed based on examining the absolute pixel difference value of two adjacent even or odd fields. The second is background index mechanism for classifying motion and non-motion pixels of input field. The third component, spatial-temporal edge-based median filter, is used to deal with the interpolation for those motion pixels. Comparing with the existed de-interlacing approaches, our architecture design can significantly ameliorate the PSNRs of the video sequences with various scene changes; for other situations, it also maintains better performances. The proposed architecture has been implemented as a VLSI chip based on UMC 0.18-µm CMOS technology process. The total gate count is 30114 and its layout area is about 710 710-µm. The power consumption is 39.78 mW at working frequency 128.2 MHz, which is able to process de-interlacing for HDTV in real-time.

For simulating i.i.d. time-varying MIMO channels using multiple Jakes' rings, it is desirable to generate channels having stable statistics with fewer scatterers. The statistical property of the conventional Jakes' model may depend on the initial phase set assigned to scattering points. In this letter, we present simple and effective conditions on arrangement of scattering points to achieve stable fading properties. The results show that the proposed arrangement provides higher statistical stability in generating time-varying channels.

Recently, technology roadmaps have been actively constructed by various organizations such as governments, industry segments, academic societies and companies [1]. While the common basic purpose of these roadmaps is sharing common recognition of the technology among stakeholders, there exists a specific role for each organization. One of the important roles of academic societies is to show the directions in which society is moving. The IEICE technical group on Concurrent System Technology (CST) established in 1993 stands at a turning point and needs to move forward in new directions after more than a decade of activities and contributions. However, neither top-down (market-pull/requirements-pull) nor bottom-up (technology-push) roadmapping is suitable for CST because CST is a kind of systems engineering. This paper proposes a new technology roadmapping methodology (middle-up-down technology roadmapping) for systems engineering and shows three future directions of CST and one roadmap for service systems that integrate CST and services science.

In this paper, we present a new method to enhance classification performance of a multiple classifier system by combining a boosting technique called AdaBoost.M2 and Kernel Discriminant Analysis (KDA). To reduce the dependency between classifier outputs and to speed up the learning, each classifier is trained in a different feature space, which is obtained by applying KDA to a small set of hard-to-classify training samples. The training of the system is conducted based on AdaBoost.M2, and the classifiers are implemented by Radial Basis Function networks. To perform KDA at every boosting round in a realistic time scale, a new kernel selection method based on the class separability measure is proposed. Furthermore, a new criterion of the training convergence is also proposed to acquire good classification performance with fewer boosting rounds. To evaluate the proposed method, several experiments are carried out using standard evaluation datasets. The experimental results demonstrate that the proposed method can select an optimal kernel parameter more efficiently than the conventional cross-validation method, and that the training of boosting classifiers is terminated with a fairly small number of rounds to attain good classification accuracy. For multi-class classification problems, the proposed method outperforms both Boosting Linear Discriminant Analysis (BLDA) and Radial-Basis Function Network (RBFN) with regard to the classification accuracy. On the other hand, the performance evaluation for 2-class problems shows that the advantage of the proposed BKDA against BLDA and RBFN depends on the datasets.

In this paper, we describe a new ultrasonic oscillosensor and its application in a biological information measurement system. This ultrasonic sensor has a cylindrical tank of 26 mm (diameter)20 mm (height) filled with water and an ultrasonic probe. It detects the vibration of the target object by obtaining echo signals reflected from the water surface. This sensor can noninvasively detect the vibration of a patient by placing it under a bed frame. We propose a recognition system for humans in bed. Using this sensor, we could determine whether or not a patient is in the bed. Moreover, we propose a heart rate monitoring system using this sensor. When our system was tested on four volunteers, we successfully detected a heart rate comparable to that in the case of using an electrocardiograph. Fuzzy logic plays a primary role in the recognition. Consequently, this system can noninvasively determine whether a patient is in the bed as well as their heart rate using a constraint-free and compact device.

This paper discusses the behavior of the second-order modes (Hankel singular values) of linear discrete-time systems under bounded-real transformations, where the transformations are given by arbitrary transfer functions with magnitude bounded by unity. Our main result reveals that the values of the second-order modes are decreased under any of the above-mentioned transformations. This result is the generalization of the theory of Mullis and Roberts, who proved that the second-order modes are invariant under any allpass transformation, i.e. any lossless bounded-real transformation. We derive our main result by describing the controllability/observability Gramians of transformed systems with the help of the discrete-time bounded-real lemma.

This research aims to develop automatic knowledge mining of causality from texts for supporting an automatic question answering system (QA) in answering 'why' question, which is among the most crucial forms of questions. The out come of this research will assist people in diagnosing problems, such as in plant diseases, health, industrial and etc. While the previous works have extracted causality knowledge within only one or two adjacent EDUs (Elementary Discourse Units), this research focuses to mine causality knowledge existing within multiple EDUs which takes multiple causes and multiple effects in to consideration, where the adjacency between cause and effect is unnecessary. There are two main problems: how to identify the interesting causality events from documents, and how to identify the boundaries of the causative unit and the effective unit in term of the multiple EDUs. In addition, there are at least three main problems involved in boundaries identification: the implicit boundary delimiter, the nonadjacent cause-consequence, and the effect surrounded by causes. This research proposes using verb-pair rules learnt by comparing the Naïve Bayes classifier (NB) and Support Vector Machine (SVM) to identify causality EDUs in Thai agricultural and health news domains. The boundary identification problems are solved by utilizing verb-pair rules, Centering Theory and cue phrase set. The reason for emphasizing on using verbs to extract causality is that they explicitly make, in a certain way, the consequent events of cause-effect, e.g. 'Aphids suck the sap from rice leaves. Then leaves will shrink. Later, they will become yellow and dry.'. The outcome of the proposed methodology shown that the verb-pair rules extracted from NB outperform those extracted from SVM when the corpus contains high occurence of each verb, while the results from SVM is better than NB when the corpus contains less occurence of each verb. The verb-pair rules extracted from NB for causality extraction has the highest precision (0.88) with the recall of 0.75 from the plant disease corpus whereas from SVM has the highest precision (0.89) with the recall of 0.76 from bird flu news. For boundary determination, our methodology can handle very well with approximate 96% accuracy. In addition, the extracted causality results from this research can be generalized as laws in the Inductive-Statistical theory of Hempel's explanation theory, which will be useful for QA and reasoning.