This paper proposes a new approach to fuzzy inference system for modeling nonlinear systems based on measured input and output data. In the suggested fuzzy inference system, the number of fuzzy rules and parameter values of membership functions are automatically decided by using the extended kernel method. The extended kernel method individually performs linear transformation and kernel mapping. Linear transformation projects input space into linearly transformed input space. Kernel mapping projects linearly transformed input space into high dimensional feature space. Especially, the process of linear transformation is needed in order to solve difficulty determining the type of kernel function which presents the nonlinear mapping in according to nonlinear system. The structure of the proposed fuzzy inference system is equal to a Takagi-Sugeno fuzzy model whose input variables are weighted linear combinations of input variables. In addition, the number of fuzzy rules can be reduced under the condition of optimizing a given criterion by adjusting linear transformation matrix and parameter values of kernel functions using the gradient descent method. Once a structure is selected, coefficients in consequent part are determined by the least square method. Simulated results of the proposed technique are illustrated by examples involving benchmark nonlinear systems.

A shared-TDD scheme has been proposed for accommodation of asymmetric communications between uplink and downlink traffic. The application of shared-TDD scheme to CDMA cellular systems causes inter-link interference because CDMA cellular systems use the same frequency band for all cells. This paper proposes a transmission control scheme for uplink packets to relieve the effect of inter-link interference in CDMA/shared-TDD cellular packet systems. In the proposed scheme, mobile stations select transmission slots based on their location and the status of slot allocations in own and the adjacent cells. Computer simulations show that the proposed scheme relieves the effect of inter-link interference, and thus improves the downlink transmission efficiency.

Complete complementary codes have the property that the sum of correlation functions of several sequences satisfies both ideal autocorrelation and cross-correlation values. Modulatable complete complementary codes (MCC codes), which is a type of periodic complete complementary codes, are suitable for spreading sequences of M-ary CDMA systems. In the present paper, we propose a new method for constructing MCC codes. Using this method, we can easily generate various MCC codes.

We consider the problem of constructing nonlinear dynamical systems that realize an arbitrary prescribed tree sources. We give a construction of dynamical systems by using piecewise-linear maps. Furthermore, we examine the obtained dynamical system to show that the structure of the memory of tree sources is characterized with some geometrical property of the constructed dynamical systems. Using a similar method, we also construct a dynamical system generating an arbitrary prescribed reverse tree source and show that the obtained dynamical system has some interesting geometrical property explicitly reflecting the tree structure of the memory of the reverse tree source.

In this paper, we present an output feedback controller using a fuzzy controller and observer for nonlinear systems with unknown time-delay. Recently, Cao et al. proposed a stabilization method for the nonlinear time-delay systems using a fuzzy controller when the time-delay is known. In general, however, it is impossible to know or measure this time-varying delay. The proposed method requires only the upper bound of the derivative of the time-delay. We represent the nonlinear system with the unknown time-delay by Takagi-Sugeno (T-S) fuzzy model and design the fuzzy controller and observer for the systems using the parallel distributed compensation (PDC) scheme. In addition, we derive the sufficient condition for the asymptotic stability of the equilibrium point by applying Lyapunov-Krasovskii theorem to the closed-loop system and solve the condition in the formulation of LMI. Finally, computer simulations are included to demonstrate the effectiveness of the suggested method.

Let us introduce n ( 2) nonlinear mappings fi (i = 1,2,,n) defined on complete linear metric spaces (Xi-1,ρ) (i = 1,2,,n), respectively, and let fi: Xi-1 Xi be completely continuous on bounded convex closed subsets Xi-1,(i = 1,2,,n 0), such that fi() . Moreover, let us introduce n fuzzy-set-valued nonlinear mappings Fi: Xi-1 Xi {a family of all non-empty closed compact fuzzy subsets of Xi}. Here, we have a fixed point theorem on the recurrent system of β-level fuzzy-set-valued mapping equations: xi Fiβ(xi-1,fi(xi-1)), (i = 1,2,,n 0), where the fuzzy set Fi is characterized by a membership function µFi(xi): Xi [0,1], and the β-level set Fiβ of the fuzzy set Fi is defined as Fiβ {ξi Xi | µFi(ξi) β}, for any constant β (0,1]. This theorem can be applied immediately to discussion for characteristics of ring nonlinear network systems disturbed by undesirable uncertain fluctuations and to fine estimation of available behaviors of those disturbed systems. In this paper, its mathematical situation and proof are discussed, in detail.

In this letter, we take advantage of both types of Interactive and Batch services by considering a hybrid multimedia-on-demand (MOD) system which provides both services. Also, we propose two serving methods with an incentive charging scheme to optimize the coexistence of both services. Numerical results show that the proposed hybrid system outperforms both individual systems. In particular, the system provider receives more revenue by serving more users concurrently, while the users have a better viewing experience due to higher availability of contents.

This paper presents an algorithm for fingerprint image restoration using Digital Reaction-Diffusion System (DRDS). The DRDS is a model of a discrete-time discrete-space nonlinear reaction-diffusion dynamical system, which is useful for generating biological textures, patterns and structures. This paper focuses on the design of a fingerprint restoration algorithm that combines (i) a ridge orientation estimation technique using an iterative coarse-to-fine processing strategy and (ii) an adaptive DRDS having a capability of enhancing low-quality fingerprint images using the estimated ridge orientation. The phase-only image matching technique is employed for evaluating the similarity between an original fingerprint image and a restored image. The proposed algorithm may be useful for person identification applications using fingerprint images.

This paper considers a transaction-based multi-server system with rejuvenation, and derive the optimal software rejuvenation policies under some system dependability measures; the steady-state availability, the probability of transaction loss and the upper bound of mean response time on transactions. We compare the system configuration based on a single-server with that based on a multi-server in terms of the software rejuvenation scheme. In numerical examples, we calculate the optimal software rejuvenation timing and its associated dependability measure, and refer to the effect of preventive maintenance in the transaction-based multi-server software systems.

This paper focuses on the investigation of RoF link noise influence in an ubiquitous antenna system, which is composed of multiple radio base stations (RBSs) deployed over the service area, central control station (CCS) and radio-on-fiber (RoF) link that connects RBSs to the CCS. The ubiquitous antenna system is capable of receiving multiple mobile terminals simultaneously operating at the same frequency channel by making effective use of joint detection. However, in the ubiquitous antenna system, since signals are transmitted from RBSs to CCS via the RoF link, the noise generated at the RoF link, such as relative intensity noise, inter modulation distortion, optical shot noise and thermal noise, may become dominant factors degrading the performance. The performance evaluations considering optical link noise is given by computer simulations. Computer simulation results show that more than 19 dB of RoF link Eb/N0 is required for achieving sufficient performance.

Passification of a non-square linear system is considered by using a parallel feedforward compensator (PFC) and a squaring gain matrix. In contrast to the previous result, a technical assumption is removed by modifying the structure of the PFC. As a result, the broader class of non-square systems can be made passive by the proposed design method. Using the static output feedback (SOF) algorithms, the input-dimensional PFC and the squaring matrix can be designed systematically. The effectiveness of the proposed method is illustrated by practical system examples in the control literature.

In this paper, we propose multiple subcarrier modulation (MSM) for infrared wireless systems using punctured convolutional codes and variable amplitude block codes to minimize the average optical power by allocating the appropriate amplitudes to the puncturing bits. The proposed system maps the coded bits corresponding to zeros in the puncturing table to the amplitudes of subcarriers, while the rate-compatible punctured convolutional (RCPC) code deletes them. We compare two proposed systems with the conventional systems: one block code maps the coded bits corresponding to zeros in the puncturing table to zeros (proposed 1), and the other maps them to the appropriate values among 0, and 1 (proposed 2) so that the required bias can be minimized. We show that the proposed 2 can achieve the minimum required SNR at the same average optical power and the same information rate among all the systems.

With the growing demand for mobile communications, multicarrier (MC) schemes are receiving an increasing amount of attention, primarily because they handle frequency selective channels better than ordinary single-carrier schemes. However, despite offering several advantages, MC systems have certain weak points. One is a high sensitivity to interchannel interference (ICI). Using a Markov chain approach, we synthesized an optimal receiver for a situation where interference affects three adjacent subchannels. Simulation results showed that the proposed 'turbo scheme' provided better BER performance than a conventional receiver, especially at higher signal-to-noise ratios. The implementation of the turbo algorithm is independent of the transmitted signal, providing complete OFDM reception compatibility.

A mathematical theory is proposed, based on the concept of functional analysis, suitable for operation of network systems extraordinarily complicated and diversified on large scales, through connected-block structures. Fundamental conditions for existence and evaluation of system behaviors of such network systems are obtained in a form of fixed point theorem for system of nonlinear mappings.

Future electric lights will be comprised of white LEDs (Light Emitting Diodes). White LEDs with a high power output are expected to serve in the next generation of lamps. In this paper, an indoor visible data transmission system utilizing white LED lights is proposed. In the proposed system, these devices are used not only for illuminating rooms but also for an optical wireless communication system. This system is suitable for private networks such as consumer communication networks. However, it remains necessary to investigate the properties of white LEDs when they are used as optical transmitters. Based on numerical analyses and computer simulations, it was confirmed that the proposed system could be used for indoor optical transmission.

This paper studies the local Poisson property of aggregated IP traffic. First, it describes the scenario where IP traffic presents a Poisson-like characteristic within some limited range of time scales when packets from independent traffic streams are aggregated. Each of the independent traffic streams corresponds to a series of correlated IP packets such as those of a transport connection. Since the Poisson-like characteristic is observed only within some limited range of time scales, we call this characteristic the local Poisson property. The limited range of time scales of the local Poisson property can be estimated from a network configuration and characteristics of transport connections. Second, based on these observations, we seek the possibility to apply an ordinary Poisson process to evaluation of the packet loss probability in IP networks. The analytical investigation, where IP traffic is modeled by a superposition of independent branching Poisson processes that presents the local Poisson property, suggests that the packet loss probability can be estimated by a finite-buffer queue with a Poisson process when the buffer size is within a certain range. The investigation is verified by simulations. These findings expand the applicability of conventional Poisson-based approaches to IP network design issues.

A robust adaptive filtering algorithm was established recently (I. Yamada, K. Slavakis, K. Yamada 2002) based on the interactive use of statistical noise information and the ideas developed originally for efficient algorithmic solutions to the convex feasibility problems. The algorithm is computationally efficient and robust to noise because it requires only an iterative parallel projection onto a series of closed half spaces highly expected to contain the unknown system to be identified and is free from the computational load of solving a system of linear equations. In this letter, we show the potential applicability of the adaptive algorithm to the identification problem for the second order Volterra systems. The numerical examples demonstrate that a straightforward application of the algorithm to the problem soundly realizes fast and stable convergence for highly colored excited speech like input signals in possibly noisy environments.

We present a design and implementation of a QoS control mechanism in an Adaptive Multimedia Communication System (AMCS) using multiagent-based computing technology. In this paper, we first define functional requirements for AMCS. Subsequently we describe the design and implementation of AMCS with a knowledge-based multiagent framework to fulfill the functional requirements. Moreover we evaluate the adaptability of the prototype systems of AMCS with the operational situations observed in its experiments. From the result of the experiments, we conclude that the multiagent-based design and implementation is reasonable for construction of AMCS.

The explosive increase in demand for mobile communication services has created a sudden increase in the number of subscribers to these services, and in mobile communication network traffic. Mobile communication networks contain extremely large numbers of network elements (NEs). Replacing the NE software requires extremely large numbers of provisioning workers with the advance knowledge and experience. This paper describes the basic concept of the organization hierarchy agent model, devised for application to the operation support systems (OSSs) that are being used to support provisioning works. By applying this agent model to OSSs, OSS software can be rapidly and flexibly changed to meet changes and additions to provisioning works procedures. This paper also describes the characteristics of the completed systems that apply this agent model, and presents performance evaluation results for the systems.

In our previous research, we proposed a nonlinear digital filter to Estimate the Smoothed and Differential values of the sensor inputs by using Sliding mode system (ESDS). This estimator is able to eliminate impulsive noise efficiently from time series data. We applied this filter to processing outputs of robot sensors, and it became possible to perform robust environment recognition. ESDS is designed using a theory of variable structure system (VSS) with sliding mode. In short, ESDS is a nonlinear filter. Therefore, it is very difficult to clarify the behavior of the system analytically. Consequentially, we deal with the step function with impulsive noise as an example, and we attempt to eliminate this impulsive noise by keeping the sudden shift of signals. In this case, there is a trade-off between the noise elimination ability and the tracking performance for an input signal. Although ESDS is a nonlinear filter, it has the same trade-off as linear filters such as a low-pass filter. In order to satisfy these two conditions simultaneously, we use two filters whose parameters are independent of each other. Furthermore, in order to repress the adverse affect of impulsive noise in the steady-state, we introduced the boundary layer. Generally, a boundary layer is used so as to inhibit the harmful effect of chattering. Chattering is caused in the sliding mode system when the state of the system vibrates on the switching line of a sliding mode system. By introducing the boundary layer to ESDS, we can repress the adverse effect of impulsive noise in the steady-state. According to these considerations, we clarify the relationship between these characteristics of ESDS and the arbitrary parameters.