A self-similar behavior characterizes the traffic in many real-world communication networks. This traffic is traditionally modeled as an ON/OFF discrete-time second-order self-similar random process. The self-similar processes are identified by means of a polynomially decaying trend of the autocovariance function. In this work we concentrate on two criteria to build a chaotic system able to generate self-similar trajectories. The first criterion relates self-similarity with the polynomially decaying trend of the autocovariance function. The second one relates self-similarity with the heavy-tailedness of the distributions of the sojourn times in the ON and/or OFF states. A family of discrete-time chaotic systems is then devised among the countable piecewise affine Pseudo-Markov maps. These maps can be constructed so that the quantization of their trajectories emulates traffic processes with different Hurst parameters and average load. Some simulations are reported showing how, according to the theory, the map design is able to fit those specifications.

We study a class of nonlinear dynamical systems to develop efficient algorithms. As an efficient algorithm, interior point method based on Newton's method is well-known for solving convex programming problems which include linear, quadratic, semidefinite and lp-programming problems. On the other hand, the geodesic of information geometry is represented by a continuous Newton's method for minimizing a convex function called divergence. Thus, we discuss a relation between information geometry and convex programming in a related family of continuous Newton's method. In particular, we consider the α-projection problem from a given data onto an information geometric submanifold spanned with power-functions. In general, an information geometric structure can be induced from a standard convex programming problem. In contrast, the correspondence from information geometry to convex programming is slightly complicated. We first present there exists a same structure between the α-projection and semidefinite programming problems. The structure is based on the linearities or autoparallelisms in the function space and the space of matrices, respectively. However, the α-projection problem is not a form of convex programming. Thus, we reformulate it to a lp-programming and the related ones. For the reformulated problems, we derive self-concordant barrier functions according to the values of α. The existence of a polynomial time algorithm is theoretically confirmed for the problem. Furthermore, we present the coincidence with the gradient vectors for the divergence and a modified barrier function. These results connect a part of nonlinear and algorithm theories by the discreteness of variables.

Detection of nonlinearly distorted signals is an essential problem in telecommunications. Recently, neural network combined conventional equalizer has been used to improve the performance especially in compensating for nonlinear distortions. In this paper, the self-organizing map (SOM) combined with the conventional symbol-by-symbol detector is used as an adaptive detector after the output of the decision feedback equalizer (DFE), which updates the decision levels to follow up the nonlinear distortions. In the proposed scheme, we use the box distance to define the neighborhood of the winning neuron of the SOM algorithm. The error performance has been investigated in both 16 QAM and 64 QAM systems with nonlinear distortions. Simulation results have shown that the system performance is remarkably improved by using SOM detector compared with the conventional DFE scheme.

It has been reported that IP packet traffic exhibits the self-similar nature and causes the degradation of network performance. Therefore it is crucial for the appropriate buffer design of routers and switches to predict the queueing behavior with self-similar input. It is well known that the fitting methods based on the second-order statistics of counts for the arrival process are not sufficient for predicting the performance of the queueing system with self-similar input. However recent studies have revealed that the loss probability of finite queuing system can be well approximated by the Markovian input models. This paper studies the time-scale impact on the loss probability of MMPP/D/1/K system where the MMPP is generated so as to match the variance of the self-similar process over specified time-scales. We investigate the loss probability in terms of system size, Hurst parameters and time-scales. We also compare the loss probability of resulting MMPP/D/1/K with simulation. Numerical results show that the loss probability of MMPP/D/1/K are not significantly affected by time-scale and that the loss probability is well approximated with resulting MMPP/D/1/K.

PID control schemes based on the classical control theory, have been widely used for various real control systems. However, in practice, since it is considerably difficult to determine the PID parameters suitably, lots of researches have been reported with respect to tuning schemes of PID parameters. Furthermore, several self-tuning and auto-tuning techniques in the PID control have been reported for systems with unknown or slowly time-varying parameters. On the other hand, so-called a generalized predictive control (GPC) scheme has been reported as a useful self-tuning control technique for unknown and/or time variant delay systems. In this paper, a new self-tuning predictive PID control algorithm based on a GPC criterion is proposed.

This paper proposes a λ-ring system that is a wavelength-based self-healing-ring application unlike ordinary fiber-based ones. To design survivable networks of interconnected such self-healing ring systems, a virtual mesh network scheme is used, in which wavelength assignment in virtual links can be considered according to the λ-ring-system or fiber-ring-system applications of the bidirectional wavelength-path switched architecture. Integer-programming-based design problems are then formulated that minimize the total fiber length in these self-healing-ring applications. Numerical examples show that the λ-ring-system application is always superior to 4-fiber and 2-fiber-ring-system applications and 1+1 end-to-end path protection.

This paper is concerned with a comparative study of the accepting powers of deterministic, Las Vegas, self-verifying nondeterminisic, and nondeterministic (simple) multihead finite automata. We show that (1) for each k 2, one-way deterministic k-head (resp., simple k-head) finite automata are less powerful than one-way Las Vegas k-head (resp., simple k-head) finite automata, (2) there is a language accepted by a one-way self-verifying nondeterministic simple 2-head finite automaton, but not accepted by any one-way deterministic simple multihead finite automaton, (3) there is a language accepted by a one-way nondeterministic 2-head (resp., simple 2-head) finite automaton, but not accepted by any one-way self-verifying nondeterministic multihead (resp., simple multihead) finite automaton, (4) for each k 1, two-way Las Vegas k-head (resp., simple k-head) finite automata have the same accepting powers as two-way self-verifying nondeterministic k-head (resp., simple k-head) finite automata, and (5) two-way Las Vegas simple 2-head finite automata are more powerful than two-way deterministic simple 2-head finite automata.

Recent studies on traffic measurement analysis in the various networks (LAN, MAN, WAN) have shown that packet traffic exhibits Self-Similarity. The packet traffic represents some behavior quite different from what it has been assumed. Some papers reported that Self-Similarity degrades the network performance, such as buffer overflow and network congestion. Thus, we need new network control scheme considering Self-Similar properties. The control scheme requires high-speed calculation method of Hurst Parameter. In this paper, we propose high-speed calculation method of Hurst Parameter based on the Variance-Time Plot method, and show its performance. Furthermore, we try to apply this method to the simple network control, in order to show effectiveness of the network control with Self-Similarity.

We propose middleware which works on widely-used commercial off-the-shelf platforms (UDP/IP, FastEthernet, and Windows NT or commercial real-time kernels) to realize real-time distributed services for plant monitoring and control systems. It is not suitable to use TCP/IP for the systems because of its unpredictable re-transmission, while, as well known, UDP/IP does not guarantee certain arrivals of packets and it is also not acceptable for the systems. With UDP/IP, packets are lost mainly because of collisions in a network and buffer overflows. To avoid these packet losses, the middleware controls scheduling of all the packets transmitted between the nodes in a distributed system and prevents excessive collisions and buffer overflows. The middleware provides a necessary set of functions for plant monitoring and control applications. The middleware on each node in a distributed system consists of library functions and run-time modules. An application program on the node is required to use these library functions according to the rules the middleware provides. In this way the middleware can manage all the traffic among the nodes in the system. Receiving requests from the application via library functions, the run-time module of the middleware schedules transmission of messages to other nodes, avoiding unexpected delivery delays or buffer overflows. The module also guarantees application-to-application quality of service (QoS), such as transmission period and delivery deadline, required by the applications. This is achieved by assigning the resources not shared by other services to each distributed service and scheduling these resources so as not to violate the assignment. Here, resources include maximum numbers of packets which a node can receive or send in a specific period (20 msec, for example). We show implementation of the middleware to make it clear how to guarantee application-to-application QoS with some application examples.

We have developed a signal processing method that is appropriate for detecting electromagnetic radiation due to earthquake activities. The radiation is usually accompanied by a background noise that is mainly caused by atmospheric discharges in the tropical regions. Data representing the seismic radiation is presented as sound via the concept of sonification. This is useful for immediately finding out anomalous seismic radiations, which are often followed by a disastrous earthquake, from the massive data collected from over forty observation stations. It is illustrated that the auditory display is valuable for future earthquake prediction systems.

A feasibility study has been made of the detection possibility of radio wave noises, i.e., Martian atmospherics, emitted from discharges in the Martian atmosphere during large dust storms. The spacecraft NOZOMI, which was launched in 1998, is to be placed on an elliptic orbit around Mars with perigee of 150-200 km. An onboard-equipment LFA (Low Frequency Plasma wave Analyzer) has capability to measure the low frequency plasma waves in the frequency range from 10 Hz to 32 kHz. In order to know if the LFA can detect the atmospheric radio noises, the propagation characteristics of electromagnetic waves through the Martian ionosphere are studied theoretically by using a full-wave method. The ionosphere is modeled as a magneto-ionic medium based on the recent observations of magnetic anomaly by Mars Global Surveyor spacecraft, and the atmospheric constituent and electron density by Viking observations. Our calculation shows that the waves at frequencies less than a hundred hertz can propagate with low attenuation and reach to altitudes above 200 km in the whistler-mode in the regions of magnetic anomalies in the dayside ionosphere. It is shown that the radio noises emitted from electric discharge in an intense dust storm, with the intensity over -30 dBV/m/Hz at the ionospheric entry point, can be sensed by the LFA. The observational identification of Martian atmospherics will contribute to the physical study of charge/discharge process in the Martian atmosphere.

The cellular-communication systems of the future will be required to provide multimedia services to users moving about in a variety of ways (on foot, in automobiles etc.). Different forms of motion have different characteristics. The characterization of the different forms of motion and their effects on telecommunications traffic is important in the planning, design and operation of mobile communication networks. The characterization of the motion of various platform types (inter-city buses, recreational vehicles, freight trucks, and taxis) based on measurements using Global Positioning System is presented in this paper. The measured characteristics of motion are then used to evaluate teletraffic statistics such as cell cross-over rate and cell dwell time by overlaying hypothetical cell systems on the measured loci of vehicles. Self-similarity was discovered in the cell dwell time characteristic of the taxis.

The authors propose and experimentally demonstrate an all-optical exclusive OR (XOR) logic gate based on self-phase modulation (SPM) of a semiconductor optical amplifier (SOA). The scheme is insensitive to the polarization of the input signal and requires no additional synchronized clock. The output of the XOR gate showed the contrast ratio of more than 17 dB for the input signal at 2.5 GHz.

NOR self-decimated sequences are attractive for stream ciphers because they have a good statistical property and the hardware construction is very simple. This paper presents an analysis of NOR self-decimation system for any parameter. We first determine the period. Then we show the exact distribution of consecutive two bits and three bits, which are shown to be almost uniform distribution.

A 3.3 V CMOS PLL (Phase Locked loop) with a self-feedback VCO (Voltage Controlled Oscillator) is designed for a high frequency, low voltage, and low power applications. This paper proposes a new PLL architecture to improve voltage-to-frequency linearity of VCO with a new delay cell. The proposed VCO with a self-feedback path operates at a wide frequency range of 30 MHz-1 GHz with a good linearity. The DC-DC Voltage Up/Down Converter is newly designed to regulate the control voltage of the two-stage VCO. The designed PLL architecture is implemented on a 0.6 µm n-well CMOS process. The simulation results illustrate a locking time of 2.6 µsec at 1 GHz, lock in range of 100 MHz-1 GHz, and a power dissipation of 112 mW.

QoS restoration, a new approach to keep QoS of end-to-end ATM connections for failures is proposed. In a network with QoS restoration, each end-to-end connection's customer pre-defines the minimum QoS requirements such as minimum throughput. When a failure occurs, resources such as bandwidth of working connections are reallocated for restoration if they are dispensable to keep the minimum requirements along with the pre-assigned spare resources. This resource reallocation is done in a distributed manner and the result of the modification of a connection is notified to the customer of the connection to help him adjust the way of using it. The effect of the reallocation is mathematically evaluated. It is shown that the reallocation enables to achieve high restoration ratio with insufficient pre-assigned spare resources, such as to restore double-link failures with spare resources prepared for single-link failures, or even to restore single-link failures with no spare resources. It is also shown that pre-assigned spare resources can be reduced if the reallocation is considered in network design phase. The performance of the proposed distributed algorithm is evaluated with an event-driven simulator. The result shows that regardless of whether or not pre-assigned spare resources exist, a restoration ratio which is close to the theoretical maximum can be achieved. A proof-of-concept experimental system is developed by controlling commercial ATM switches via SNMP. The system shows it can effectively manage failures in WAN environment.

This paper proposes a new restoration concept for ATM networks. It realizes the rapid and multiple reliability/cost level restoration required to support many different network services. First, the necessity in realizing rapid and multiple-reliability-level restoration in the future network is shown. The self-healing schemes that is based on distributed restoration mechanism satisfies the rapidity in restoration, but does not satisfy multiple reliability levels. Thus a new self-healing scheme that satisfies them is presented and a Multiple Reliability Level Virtual Path network concept is proposed based on the new self-healing scheme. Next, how to realize the new self-healing scheme is explained as an extension of the existing self-healing scheme with two new simple functions. Finally, evaluations confirm the effectiveness of the proposed scheme. These results show that the proposed new scheme realizes a network that fulfills the rapidity and multiple reliability requirements that are strongly required.

A distributed system is said to be self-stabilizing if it converges to some legitimate state from an arbitrary state in a finite number of steps. The number of steps required for convergence is usually referred to as the stabilization time, and its reduction is one of the main performance issues in the design of self-stabilizing systems. In this paper, we propose an automated method for computing the stabilization time. The method uses Boolean functions to represent the state space in order to assuage the state explosion problem, and computes the stabilization time by manipulating the Boolean functions. To demonstrate the usefulness of the method, we apply it to the analysis of existing self-stabilizing algorithms. The results show that the method can perform stabilization time analysis very fast, even when an underlying state space is very huge.

The problem of self-timed implementation of Boolean functions is explained. The notions of combinational delay-insensitive code and delay-insensitive function are defined, giving precise conditions under which memoryless self-timed implementation of Boolean functions is feasible. Examples of combinational delay-insensitive code and delay-insensitive function are given. Generic design style, using standard CAD library, for constructing quasi delay-insensitive self-timed function blocks is suggested. Our design style is compared to other self-timed function block design styles.

This paper proposes an optimal design scheme for photonic transport networks that interconnect multiple wavelength division multiplexing (WDM) self-healing ring systems by using optical cross connects (OXCs). To calculate the number of OXCs required in each hub to interconnect these ring systems, a virtual mesh network is generated, on which the route of each optical path (OP) going through multiple adjacent rings ("ring" is defined as circle in network topology) is determined based on a list of hubs. An integer-programming-based design problem is then formulated that minimizes the overall cost of facilities including OXCs as well as ring systems to accommodate a given demand. By solving this problem, we can simultaneously optimize required number of ring systems in each ring, wavelength assignment within each individual bidirectional ring system, required number of OXCs in each hub, and capacity to be allocated to each OP. Numerical examples show that the ring-based network is more cost-effective than the mesh restorable network when the cost of an OADM is lower than that of an OXC, and the OXC-to-fiber cost-coefficient ratio is sufficiently large.