We propose a new band selective stop filter construction to decrease the out of band intermodulation distortion (IMD) noise generated in the transmitting power amplifier. Suppression of IMD noise directly improves the adjacent channel leakage power ratio (ACLR). A high-temperature superconducting (HTS) device with extremely high-Q performance with very small hybrid IC pattern would make it possible to implement the proposed filter construction as a practical device. To confirm the effectiveness of the HTS reaction-type filter (HTS-RTF) in improving ACLR, investigations based on both experiments and numerical analyses are carried out. The structure of a 5-GHz split open-ring resonator is investigated; its targets include high-unload Q-factor, low current densities, and low radiation. A designed 5-GHz HTS-RTF with 4 MHz suppression bandwidth and more than 40 dB MHz-1 sharp skirt is fabricated and experimentally investigated. The measured ACLR values are improved by a maximum of 12.8 dB and are constant up to the passband signal power of 40 dBm. In addition, to examine the power efficiency improvement offered by noise suppression of the HTS-RTF, numerical analyses based on measured results of gallium nitride HEMT power amplifier characteristics are conducted. The analyzed results shows the drain efficiency of the amplifier can be improved to 44.2% of the amplifier with the filter from the 15.7% of the without filter.

The superconducting band-pass filter has small insertion loss and excellent out-of-band rejection properties. It has been put to practical use in a number of applications. However, in order to expand its range of application, a tuning technique that can restore the filter characteristics is needed. We propose an automatic tuning system using a trimming library and checked the feasibility of the system by tuning a forward-coupled filter with three resonators. The results show that the trimming library method is an effective way of automatically improving the filter characteristics.

An impedance-isolation technique is proposed for on-chip ESD protection design for radio-frequency (RF) integrated circuits (ICs), which has been successfully verified in a 0.25-µm CMOS process with thick top-layer metal. With the resonance of LC-tank at the operating frequency of the RF circuit, the impedance (especially, the parasitic capacitance) of the ESD protection devices can be isolated from the RF input node of low-noise amplifier (LNA). Therefore, the LNA can be co-designed with the proposed impedance-isolation technique to simultaneously achieve excellent RF performance and high ESD robustness. The power gain (S21-parameter) and noise figure of the ESD protection circuits with the proposed impedance-isolation technique have been experimentally measured and compared to those with the conventional double-diodes ESD protection scheme. The proposed impedance-isolation technique had been demonstrated to be suitable for on-chip ESD protection design for RF ICs.

A method is proposed for estimating code and carrier phase parameters of GNSS reflected signals in low SNR (signal-to-noise ratio) environments. Simulation results show that the multipath impact on code and carrier with 0.022 C/A chips delay can be estimated in 0 dB SNR in the condition of 46 MHz sampling rate.

A desired property of large distributed systems is self adaptability against the faults that occur more frequently as the size of the distributed system grows. Self-stabilizing protocols provide autonomous recovery from finite number of transient faults. Fault-containing self-stabilizing protocols promise not only self-stabilization but also containment of faults (quick recovery and small effect) against small number of faults. However, existing composition techniques for self-stabilizing protocols (e.g. fair composition) cannot preserve the fault-containment property when composing fault-containing self-stabilizing protocols. In this paper, we present Recovery Waiting Fault-containing Composition (RWFC) framework that provides a composition of multiple fault-containing self-stabilizing protocols while preserving the fault-containment property of the source protocols.

This paper proposes a pilot-based channel state information (CSI) feedback from a terminal to a base station (BS), considering the terminal's co-channel interference in a time-division duplex/multi-input multi-output system. In the proposed method, the terminal determines a precoding matrix according to the terminal's co-channel interference characteristics and transmits the precoded pilot signals on uplink. Using the responses of the precoded pilot signals, the BS determines appropriate weight vectors for downlink transmit beams considering the terminal's interference characteristics. Furthermore, the BS can predict the terminal's output signal-to-interference-plus-noise power ratio (SINR) for the downlink data stream. Numerical results show that the BS can achieve efficient transmission and accurate SINR prediction using the proposed CSI feedback.

By use of the shadow theory developed recently, this paper deals with the transverse electric (TE) wave diffraction by a perfectly conductive periodic array of rectangular grooves. A set of equations for scattering factors and mode factors are derived and solved numerically. In terms of the scattering factors, diffraction amplitudes and diffraction efficiencies are calculated and shown in figures. It is demonstrated that diffraction efficiencies become discontinuous at an incident wave number where the incident wave is switched from a propagating wave to an evanescent one, whereas scattering factors and diffraction amplitudes are continuous even at such an incident wave number.

Communication-free Petri nets provide a net semantics for Basic Parallel Processes, which form a subclass of Milner's Calculus of Communicating Systems (CCS) a process calculus for the description and algebraic manipulation of concurrent communicating systems. It is known that the reachability problem for communication-free Petri nets is NP-complete. Lacking the synchronization mechanism, the expressive power of communication-free Petri nets is somewhat limited. It is therefore importance to see whether the power of communication-free Petri nets can be enhanced without sacrificing their analytical capabilities. As a first step towards this line of research, in this paper our main concern is to investigate, from the decidability/complexity viewpoint, the reachability problem for a number of variants of communication-free Petri nets, including communication-free Petri nets augmented with 'static priorities,' 'dynamic priorities,' 'states,' 'inhibitor arcs,' and 'timing constraints.'

Although software-attack detection via dynamic taint analysis (DTA) supports high coverage of program execution, it prohibitively degrades the performance of the monitored program. This letter explores the possibility of collaborative dynamic taint analysis among members of an application community (AC): instead of full monitoring for every request at every instance of the AC, each member uses DTA for some fraction of the incoming requests, thereby loosening the burden of heavyweight monitoring. Our experimental results using a test AC based on the Apache web server show that speedy detection of worm outbreaks is feasible with application communities of medium size (i.e., 250-500).

Image restoration based on Bayesian estimation in most previous studies has assumed that the noise accumulated in an image was independent for each pixel. However, when we take optical effects into account, it is reasonable to expect spatial correlation in the superimposed noise. In this paper, we discuss the restoration of images distorted by noise which is spatially correlated with translational symmetry in the realm of probabilistic processing. First, we assume that the original image can be produced by a Gaussian model based on only a nearest-neighbor effect and that the noise superimposed at each pixel is produced by a Gaussian model having spatial correlation characterized by translational symmetry. With this model, we can use Fourier transformation to calculate system characteristics such as the restoration error and also minimize the restoration error when the hyperparameters of the probabilistic model used in the restoration process coincides with those used in the formation process. We also discuss the characteristics of image restoration distorted by spatially correlated noise using a natural image. In addition, we estimate the hyperparameters using the maximum marginal likelihood and restore an image distorted by spatially correlated noise to evaluate this method of image restoration.

A method for measuring similarity between two variables is presented. Our approach considers the case where available observations are arbitrarily filtered versions of the variables. In order to measure the similarity between the original variables from the observations, we propose an error-minimizing filter (EMF). The EMF is designed so that an error between outputs of the EMF is minimized. In this paper, the EMF is constructed by a finite impulse response (FIR) filter, and the error between the outputs is evaluated by the mean square error (EMF). We show that minimization of the MSE results in an eigenvalue problem, and the optimal solution is given in a closed form. We also reveal that the minimal MSE by the EMF is efficient in the measurement of the similarity from the viewpoint of a correlation coefficient between the originals.

This paper shows that there is a fruitful world behind sampling theorems. For this purpose, the sampling problem is reformulated from a functional analytic standpoint, and is consequently revealed that the sampling problem is a kind of inverse problem. The sampling problem covers, for example, signal and image restoration including super resolution, image reconstruction from projections such as CT scanners in hospitals, and supervised learning such as learning in artificial neural networks. An optimal reconstruction operator is also given, providing the best approximation to an individual original signal without our knowing the original signal.

MPLS-based path technology shows promise as a means of realizing reliable IP networks. Real-time services such as VoIP and video-conference supplied through a multi-domain MPLS network must be able to guarantee end-to-end QoS of the inter-domain paths. Thus, it is important to allocate an appropriate QoS class to the inter-domain paths in each domain traversed by the inter-domain paths. Because each domain has its own policy for QoS class allocation, it is necessary to adaptively allocate the optimum QoS class based on estimation of the QoS class allocation policies in other domains. This paper proposes two kinds of adaptive QoS class allocation schemes, assuming that the arriving inter-domain path requests include the number of downstream domains traversed by the inter-domain paths and the remaining QoS value toward the destination nodes. First, a measurement-based scheme, based on measurement of the loss rates of inter-domain paths in the downstream domains, is proposed. This scheme estimates the QoS class allocation policies in the downstream domains, using the measured loss rates of path requests. Second, a state-dependent type scheme, based on measurement of the arrival rates of path requests in addition to the loss rates of paths in the downstream domains, is also proposed. This scheme allows an appropriate QoS class to be allocated according to the domain state. This paper proposes an application of the Markov decision theory to the modeling of state-dependent type scheme. The performances of the proposed schemes are evaluated and compared with those of the other less complicated non-adaptive schemes using a computer simulation. The results of the comparison reveal that the proposed schemes can adaptively increase the number of inter-domain paths accommodated in the considered domain, even when the QoS class allocation policies change in the other domains and the arrival pattern of path requests varies in the considered domain.

This paper proposes a method providing efficient test compression. The proposed method is for robust testable path delay fault testing with scan design facilitating two-pattern testing. In the proposed method, test data are interleaved before test compression using statistical coding. This paper also presents test architecture for two-pattern testing using the proposed method. The proposed method is experimentally evaluated from several viewpoints such as compression rates, test application time and area overhead. For robust testable path delay fault testing on 11 out of 20 ISCAS89 benchmark circuits, the proposed method provides better compression rates than the existing methods such as Huffman coding, run-length coding, Golomb coding, frequency-directed run-length (FDR) coding and variable-length input Huffman coding (VIHC).

The block based motion estimation technique is adopted by various video coding standards to reduce the temporal redundancy in video sequences. The core of that technique is the search algorithm implemented to find the location of the best matched block. Indeed, the full search algorithm is the most straightforward and optimal but computationally demanding search algorithm. Consequently, many fast and suboptimal search algorithms have been proposed. Reduction of the number of location being searched is the approach used to decrease the computational load of full search. In this paper, hybridization between an adaptive search algorithm and the full search algorithm is proposed. The adaptive search algorithm benefits from the correlation within spatial and temporal adjacent blocks. At the same time, a feature domain based matching criteria is used to reduce the complexity resulting from applying the pixel based conventional criteria. It is shown that the proposed algorithm produces good quality performance and requires less computational time compared with popular block matching algorithms.

Jitter is the variation of latencies, when real-time Intellectual Properties (IPs) are accessing data from the data storages. It is a critical factor for such IPs from the Quality-of-Service (QoS) perspective. Jitter of a real-time IP can be measured by how frequently it experiences the underflows and overflows from its data queue in read mode and write mode, respectively. Such failures critically depend on the bus arbitration scheme which determines the bus acquisition order of IPs. The proposed idea allows IPs to inform the bus arbiter of the status of their data buffers when they assert bus requests. Such information helps the bus arbiter to determine the bus acquisition order while greatly reducing the jitter. The experimental results show that our method effectively eliminates the overflows and underflows of real-time IPs by dynamically preempting the jitter-critical bus requests.

The performance of an analog winner-take-all (WTA) circuit is affected by the corner error and the offset error. Despite the fact that the corner error can be reduced with large transconductance of the transistor, the offset error caused by device mismatch has not been completely studied. This paper presents the complete offset error analysis, and proposes low offset design guidelines and an offset cancellation scheme. The experimental results show good agreement with the theoretical analysis and the drastic improvement of the offset error.

Trust negotiation is an authorizing technique based on digital credentials, in which both a user and a server gradually establish trust in each other by repeatedly exchanging their credentials. A trust negotiation strategy is a function that answers a set of credentials to disclose to the other party, depending on policies and the set of already disclosed credentials. The disclosure tree strategy (DTS), proposed by Yu et al., is one of the strategies that satisfies preferable properties. DTS in a simple implementation requires exponential time and space; however, neither an efficient algorithm nor the lower-bound of its complexity was known. In this paper, we investigate the computational complexity of DTS. We formulate subproblems of DTS as problems on derivation trees of a context-free grammar (CFG), and analyze the computational complexity of the subproblems using the concepts of CFGs. As a result, we show that two subproblems EVL and MSET of DTS are NP-complete and NP-hard, respectively, while both are solvable in polynomial time if we modify EVL not to require non-redundancy and MSET not to answer any subset useless for leading the negotiation to success.

In this paper we present hybrid positioning schemes that combine time of arrival (TOA) and angle of arrival (AOA) measurements from only two base stations (BSs) to locate the mobile station (MS) in non-line-of-sight (NLOS) environments. The proposed methods utilize two TOA circles and two AOA lines to find all the possible intersections to locate the MS without requiring a priori information about the NLOS error. The commonly known Taylor series algorithm (TSA) and the hybrid lines of position algorithm (HLOP) have convergence problems, and the relative positioning between the MS and the BSs greatly affects the location accuracy. The resulting geometry creates a situation where small measurement errors can lead to significant errors in the estimated MS location. Simulation results show that the proposed methods always perform better than TSA and HLOP for different levels of NLOS errors, particularly when the MS/BSs have an undesirable geometric layout.

A static dependency pair method, proposed by us, can effectively prove termination of simply-typed term rewriting systems (STRSs). The theoretical basis is given by the notion of strong computability. This method analyzes a static recursive structure based on definition dependency. By solving suitable constraints generated by the analysis result, we can prove the termination. Since this method is not applicable to every system, we proposed a class, namely, plain function-passing, as a restriction. In this paper, we first propose the class of safe function-passing, which relaxes the restriction by plain function-passing. To solve constraints, we often use the notion of reduction pairs, which is designed from a reduction order by the argument filtering method. Next, we improve the argument filtering method for STRSs. Our argument filtering method does not destroy type structure unlike the existing method for STRSs. Hence, our method can effectively apply reduction orders which make use of type information. To reduce constraints, the notion of usable rules is proposed. Finally, we enhance the effectiveness of reducing constraints by incorporating argument filtering into usable rules for STRSs.