This paper proposes wavelet packets for use in ultra wideband communications. The pulse shapes that are generated are quasi orthogonal and have almost identical time duration. After normalization, an M-ary signaling set can be constructed allowing higher data rate. Finally, the performance of such a system when multipath propagation occurs is investigated by computer simulations. In order to combat multipath fading, a Rake receiver using coherent channel estimation is designed. This channel estimation is carried out using adaptive algorithms such as least-mean square (LMS), normalized least-mean square (NLMS), or recursive least square (RLS) algorithms which adapt the received signal given a reference signal.

We propose a new two-stage blind separation and deconvolution strategy for multiple-input multiple-output (MIMO)-FIR systems driven by colored sound sources, in which single-input multiple-output (SIMO)-model-based ICA (SIMO-ICA) and blind multichannel inverse filtering are combined. SIMO-ICA can separate the mixed signals, not into monaural source signals but into SIMO-model-based signals from independent sources as they are at the microphones. After the separation by the SIMO-ICA, a blind deconvolution technique for the SIMO model can be applied even when each source signal is temporally correlated and the mixing system has a nonminimum phase property. The simulation results reveal that the proposed algorithm can successfully achieve separation and deconvolution of a convolutive mixture of speech, and outperforms a number of conventional ICA-based BSD methods.

We propose a method for the recovery of projective structure and motion by the factorization of the rank 1 matrix containing the images of all points in all views. In our method, the unknowns are the 3D motion and relative depths of the set of points, not their 3D positions. The coordinates of the points along the camera plane are given by their image positions in the first frame. The knowledge of the coordinates along the camera plane enables us to solve the SFM problem by iteratively factorizing the rank 1 matrix. This simplifies the decomposition compared with the SVD (Singular Value Decomposition). Experiments with both simulated and real data show that the method is efficient for the recovery of projective structure and motion.

In this paper, a refined analytic model is presented for the IEEE 802.11 distributed coordination function (DCF) in a time-varying channel environment. In the proposed model, the channel is modelled using a finite-state Markov (FSM) chain. The saturation throughput and average packet delay are analyzed from the proposed model. It is shown using OPNETTM and UltraSANTM simulations that the proposed model accurately predicts the performance of the IEEE 802.11 DCF.

In this paper, we evaluate the computational complexity and the performance of the RAKE receivers for the Direct Sequence--Ultra Wideband (DS-UWB) with considering the accuracy of channel estimation in a multipath channel. As RAKE receivers for DS-UWB, we consider the maximal-ratio combining (MRC)-RAKE, the minimum mean square error (MMSE)-RAKE, and the MRC-RAKE-Equalizer that is the MRC-RAKE followed by a liner equalizer. Generally, if the channel estimation is perfect, as the number of fingers or taps increases, the performance of each receiver is improved, however the computational complexity of each receiver increases. In practice, the channel estimation is not perfect. The channel estimation error makes their performances degraded. Therefore, the performances of the RAKE receivers depend on the accuracy of channel estimation. Consequently, we evaluate the computational complexities and the Bit Error Rates (BERs) of MRC-RAKE, MMSE-RAKE, and MRC-RAKE-Equalizer with considering the accuracy of channel estimation for DS-UWB. We show that the accuracy of channel estimation affects the BER of each receiver significantly. We also show that when the accuracy of channel estimation is high, MRC-RAKE-Equalizer can achieve the better BER than MMSE-RAKE with less computational complexity, while MMSE-RAKE can achieve the better BER than MRC-RAKE-Equalizer when the accuracy of channel estimation is low.

In our former paper, we formalized a Logic of Multiple-valued Argumentation (LMA) on an expressive knowledge representation language, Extended Annotated Logic Programming (EALP), in order to make it possible to construct arguments under uncertain information. In this paper, We confirm expressivity and applicability by applying LMA to arguments reflecting Easterners' preference over argumentation as well as Eastern thought and philosophy. In doing so, we exploit a wide variety of complete lattices as truth-values, showing the flexibility and adaptability of LMA to various multiple-valuedness required in argumentation under uncertain information. In particular, we consider a significant specialization of LMA to Tetralemma with an Eastern mind. Through various argument examples, it is shown that LMA allows for a kind of pluralistic argumentation, or a fusion of Eastern and Western argumentation.

In this paper we present a network layer based admission control and simple class based service differentiation model to support QoS in mobile ad hoc network. Our distributed admission control procedure works along with the route finding phase of reactive routing protocols for mobile ad hoc network (AODV, DSR etc). We also propose a simple class based distributed service differentiation system to support QoS once a traffic is admitted by our admission control mechanism. The proposed service differentiation is based on DiffServ model and includes modifications like configuration of each node with edge and core functionality, dynamic selection of edge/core functionality, use of minimal and simple classes. Simulation results show that our system allows seven times more real time traffic in the network than the proposed QoS for AODV model while satisfying the demanded end-to-end delay and providing low jitter.

Short-range propagation measurements were carried out using ultra wideband (UWB) and continuous wave (CW) signals on a rectangular aluminum conductive plate, simulating typical office desks, with and without a low vertical metal partition panels. The frequency of the UWB signal spanned from 3.1 to 10.6 GHz and that of the CW signal was 6.85 GHz. A vector network analyzer and two omnidirectional UWB antennas were used to obtain the frequency-domain response of the propagation paths. With the partition panel, the CW reception level showed approximately a 20-dB spatial variation, induced by the interference between the direct and the reflected waves, but the UWB reception level had no particular plunges. The additional losses were also measured when the 500-mm propagation path was blocked with a human arm, a coffee cup, and a copy paper pile and when the receiving antenna was covered with a human palm on the plate without the partition panel. The maximum additional propagation losses were found as follows: 10-12 dB by a human arm, 10 dB with a coffee cup, and 2 dB with a paper pile. Further additional loss caused by a palm covering the antenna was found to be 10 to 12 dB, mainly due to palm absorption.

To increase the number of the embedded secrets and to improve the quality of the stego-image in the vector quantization (VQ)-based information hiding scheme, in this paper, we present a novel information-hiding scheme to embed secrets into the side match vector quantization (SMVQ) compressed code. First, a host image is partitioned into non-overlapping blocks. For these seed blocks of the image, VQ is adopted without hiding secrets. Then, for each of the residual blocks, SMVQ or VQ is employed according to the smoothness of the block such that the proper codeword is chosen from the state codebook or the original codebook to compress it. Finally, these compressed codes represent not only the host image but also the secret data. Experimental results show that the performance of the proposed scheme is better than other VQ-based information hiding scheme in terms of the embedding capacity and the image quality. Moreover, in the proposed scheme, the compression rate is better than the compared scheme.

To use the voluntary electromyogram (EMG) as a control signal of the EMG controlled functional electrical stimulator (FES), it is required to reduce the stimulation artifact and non-voluntary contribution (M-wave). In this study, a Gram-Schmidt (GS) prediction error filter (PEF) that can effectively eliminates the M-wave from voluntary EMG is presented. Also, the presented GS PEF is implemented on the field the programmable gate array (FPGA) for real-time processing and the performance is tested with simulated and real signals. Experimental results showed that GS-PEF was effective in reducing M-wave and preserving voluntary EMG.

This investigation proposed a novel dual-mode circular patch bandpass filter (BPF) with enhanced stopband performance. The novelty of the proposed structure is to use a pair of square etched areas acting as a perturbation element on the circular patch resonator such that two split modes are coupled and the filter structure can be reduced. The coupling coefficients of two split modes are obtained. To improve the stopband performance, a pairs of H-shaped defected ground structure (DGS) cells are used below the input/output port to suppress the spurious response of the proposed BPF. The equivalent circuit of the DGS cell is discussed and the relations between bandstop characteristic and the suitable DGS dimensions are also investigated. The proposed BPF is demonstrated with a central frequency fo = 2.2 GHz, a 3-dB fractional bandwidth of 8% and a wider stopband of -35 dB from 2.5 to 6 GHz. Measured results of experimental filter have good agreement with the theoretical simulated results.

Over the past few years, a considerable number of studies have been conducted on modeling the bargaining game using artificial agents on within-model interaction. However, very few attempts have been made at study on the interaction and co-evolutionary process among heterogeneous artificial agents. Therefore, we present two kinds of artificial agents, based on genetic algorithm (GA) and reinforcement learning (RL), which play a game on between-model interaction. We investigate their co-evolutionary processes and analyze their parameters using the analysis of variance.

We demonstrate a novel fiber device exhibiting magnetic circular dichroism (MCD) and Faraday rotation in sharpened optical fibers coated with Fe. The degree of MCD was 0.68 in a magnetic field of 0.35 T and the Faraday rotation angle was as great as 110 degrees. Such great magneto-optical effect is due to optical near-field interactions in the sub-wavelength region, i.e., in the tip of the near-field fiber probe. These effects can be attributed to the large magnitude of the magneto optical coefficient of Fe.

In this paper, we propose an agent architecture for a combination of speculative computation and abduction. Speculative computation is a tentative computation when complete information for performing computation is not obtained. We use a default value to complement such incomplete information. Unlike usual default reasoning, the real value for the information can be obtained during the computation and the computation can be revised on the fly. In the previous work, we applied this technique to handling distributed problem solving under incomplete communication environments in the context of multi-agent systems and proposed correct procedures in abductive logic programming in terms of perfect model semantics. In the previous work, however, we regarded assumptions as defaults and used these assumptions for speculative computation. Thus, we could not perform hypothetical reasoning, that is, the original usage of abduction. In this paper, we extend our framework so that speculative computation and abduction can be both performed. As a result, our procedure becomes an extension of the abductive procedure developed by Kakas and Mancarella augmented by dynamic belief revision mechanism about outside world.

Under dynamic and heterogenous environment, the need for adaptability and rapid response time to information service systems has become increasingly important. To cope with the continuously changing conditions of service provision and utilization, Faded Information Field (FIF) has been proposed, which is an agent-based distributed information service system architecture. In the case of a mono-service request, the system is designed to improve users' access time and preserve load balancing through the information structure. However, with interdependent requests of multi-service increasing, adaptability, reliability and timeliness have to be assured by the system. In this paper, the relationship between the timeliness and the reliability of correlated services allocation and access is clarified. Based on these factors, the autonomous network-based heterogeneous information services integration technology to provide one-stop service for users' multi-service requests is proposed. We proved the effectiveness of the proposed technology through the simulation and the results show that the integrated service can reduce the total users access time compared with the conventional systems.

Space-time array manifold model is usually used in a fast fading channel to estimate delay for the radio location. The existing additive white Gaussian noise (AWGN) estimation error model significantly overestimates the delay estimation. In this paper, we model the estimation error of the space-time array manifold channel impulse response (CIR) matrix as a correlated AWGN matrix and its performance is shown to be closer to the estimation error of practical systems than the existing model.

This letter studies a simple nonautonomous chaotic circuit constructed by adding an impulsive switch to the RCL circuit. The switch operation depends on time and on state variable through a refractory threshold. The circuit exhibits various chaotic attractors, periodic attractors and related bifurcation phenomena. The dynamics can be analyzed using 1-D return map focusing on the time-dependent switching moments. Using a simple test circuit model typical phenomena are verified in PSPICE simulations.

Ad hoc networks are becoming an interesting research area, as they inherently support unique network applications for the wireless communications in a rugged environment, which requires rapid deployment and is difficult to be provided by an infrastructure network. Many issues need to be addressed for the ad hoc networks. In this paper, we propose an efficient distributed coordination function on the media access control protocol to enhance the power conservation of mobile hosts by using a power control algorithm and the network throughput of an ad hoc network by using an algorithm for simultaneous frame transmissions. Extensive simulation is studied to evaluate the improvement of the proposed method. The results of the simulation exhibit significant improvement to the standard access control protocol. With slight improvement of network throughput, up to 85% of the consumed energy was able to be saved in compared to the standard protocol and up to 7 times of the energy efficiency was enhanced with the proposed method.

This paper introduces the concept of measuring double directional channels in ultra wideband (UWB) systems. Antenna-independent channel data were derived by doing the measurements in a wooden Japanese house. The data were useful for investigating the impact of UWB antennas and analyzing waveform distortion. Up to 100 ray paths were extracted using the SAGE algorithm and they were regarded as being dominant. The paths were then identified in a real environment, in which clusterization analyses were done using the directional information on both sides of the radio link. Propagating power was found to be concentrated around the specular directions of reflection and diffraction. This led to the observation that the spatio-temporal characteristics of extracted paths greatly reflected the structure and size of the environment. The power in the clusters indicated that the estimated 100 paths contained 73% of the total received power, while the rest existed as diffuse scattering, i.e., the accumulation of weaker paths. The practical limits of path extraction with SAGE were also discussed. Finally, we derived the scattering loss and intra-cluster properties for each reflection order, which were crucial for channel reconstrucion based on the deterministic approach.

In nanophotonic device operations, characteristic features on a nanometer scale, such as locally excited states, dependence on the excitation number, and spatial symmetry of a system, play an important role. Using these features, selective excitation energy transfer via an optical near field is shown for a quantum-dot system with discrete energy levels. This selectivity strongly depends on a dipole-inactive state of an exciton, which cannot be excited by the far-field light. Operation principles of logic gates, photon storage, and quantum information processing device, which are based on the selectivity, are proposed, and the temporal dynamics are investigated analytically and numerically by using quantum theory. Nanophotonic devices, which are constructed from quantum mechanical and classical dissipative systems, are expected to become one of a key technologies in future device architecture.