Performance of turbo codes over an impulsive noise channel is analyzed by extending an evaluation method over AWGN channels. Burst noise generation is considered with respect to the noise model by applying a hidden Markov model (HMM). A bound calculation method is derived by using a combined trellis which consists of code trellis and HMM trellis. In the simulation, an iterative decoder using the combined trellis into each component decoder is proposed. By using this method, the simulation results show the expectation of the coincidence with the calculated bounds at larger Eb/N0 for various conditions. Search results of optimum component code using proposed bound are shown.

In this letter, we propose a robust adaptive filter with a Variable Forgetting Factor (VFF) for impulsive noise suppression. The proposed method can restrict the perturbation of the parameters using M-estimator and adaptively reduce the error propagation caused by the impulsive noise using VFF. Simulations show that the performance of the proposed algorithm is less vulnerable to the impulsive noise than those of the conventional Kalman filter based algorithms.

We present a design method of the simulation probability density function for a trellis-coded modulation (TCM) in an impulsive noise environment. The upper bound evaluation method for the TCM scheme cannot be applied to the lognormally distributed impulsive noise, since the Chernoff bound cannot be defined. Thus the error probability can only be estimated by a computer simulation. For an evaluation of a low error probability, importance sampling (IS) is an efficient technique. A design method of the simulation probability density function, which plays an important role in IS, is proposed for the noise. The effectivity is shown by a numerical example.

Generating conditions of the optical feedback noise in self-pulsing lasers were experimentally examined. The noise charcteristics were determined by changing the operating power, the feedback distance and the feedback ratio for several types of self-pulsing lasers. The idea of the effective modulation index was introduced to evaluate the generating conditions in an uniform manner based on the mode competition theory. Validity of the idea was experimentally confirmed for generation of noise.

In this letter, the novel mapping network named self-organizing relationship (SOR) network, which can approximate the desired I/O relationship by employing the modified Kohonen's learning law, is proposed. In the modified Kohonen's learning law, the weight vectors are updated to be attracted to or repulsed from the input vector.

In this paper, we investigate the bit error rate (BER) performance of Direct Sequence-Code Division Multiple Access (DS-CDMA) systems under impulsive radio noise environments, and propose a novel DS-CDMA receiver which is designed to be robust against impulsive noise. At first, employing the Middleton's Class-A impulsive noise model as a typical model of impulsive radio noise, we discuss the statistical characteristics of impulsive radio noise and demonstrate that the quadrature components of impulsive noise are statistically dependent. Next, based on the computer simulation, we evaluate the BER performance of a conventional DS-CDMA system under a Class-A impulsive noise environment, and illustrate that the performance of the conventional DS-CDMA system is drastically degraded by the effects of the impulsive noise. To deal with this problem, motivated by the statistical dependence between the quadrature components of impulsive radio noise, we propose a new DS-CDMA receiver which can eliminate the effects of the channel impulsive noise. The numerical result shows that the performance of the DS-CDMA system under the impulsive noise environment is significantly improved by using this proposed receiver. Finally, to confirm the effectiveness of this proposed receiver against actual impulsive radio noise, we evaluate the BER performance of the DS-CDMA system employing the proposed receiver under a microwave oven (MWO) noise environment and discuss the robustness of the proposed receiver against MWO noise.

A turbo TCM system is applied to a channel with overall noise which is equal to the additive combination of impulsive Gaussian noise and Additive White Gaussian Noise (AWGN). By taking the distribution of the previously mentioned overall noise into account, a decoding algorithm for Poisson occurrence impulsive noise is derived as an extension of that for AWGN. A simulation result shows that Eb/N0 difference from Shannon limit to realize BER=10-4 is 0. 493 dB. To investigate the effect of burst noise, we discuss the case of additive impulsive noise with Markovian occurrence which is represented by Hidden Markov Model. A decoding algorithm for Markovian noise is proposed. In the iterative decoding for the Markovian channel, the decoding algorithms for Markovian and Poisson noise are applied separately to the two component decoders. The decoding algorithm for Markovian noise is used in the component decoder wherein received signal is directly fed, while the decoding algorithm for Poisson noise is used in the component decoder wherein received signal is fed after passing an interleaver. This paper also shows simulation results that include the effects of varying the noise parameters in the decoding. In the Markovian case, when smaller value of variance of impulsive noise is used, the observed flattening of BER performance is more serious compared to the effect in the Poisson noise channel. No flattening is observed when large value is used.

Theoretical calculations of the pulsing operation and the intensity noise under the optical feedback are demonstrated for operation of the self-sustained pulsation lasers. Two alternative models for the optical feedback effect, namely the time delayed injection model and the external cavity model, are applied in a combined manner to analyze the phenomena. The calculation starts by supposing the geometrical structure of the laser and the material parameters, and are ended by evaluating the noise. Characteristics of the feedback induced noise for variations of the operating parameters, such as the injection current, the feedback distance and the feedback ratio, are examined. A comparison to experimental data is also given to ensure accuracy of the calculation.

Advanced scientific and engineering problems require massively parallel computing. Critical to the designand ultimately the performanceof such computing systems is the interconnection network binding the computing elements, just as is the cardiovascular network to the human body. This paper develops a new interconnection network, "Tori connected mESHes (TESH)," consisting of k-ary n-cube connection of supernodes that comprise meshes of lower level nodes. Its key features are the following: it is hierarchical, thus allowing exploitation of computation locality as well as easy expansion (up to a million processors), and it appears to be well suited for 3-D VLSI implementation, for it requires far fewer number of vertical wires than almost all known multi-computer networks. Presented in the paper are the architecture of the new network, node addressing and message routing, 3-D VLSI/ULSI considerations, and application of the network to massively parallel computing. Specifically, we discuss the mapping on to the network of stack filtering, a hardware oriented technique for order statistic image filtering.

Microwave oven interference much degrades the performance of digital radio communication systems, and, in order to obtain a good error performance under microwave oven interference environment, the digital radio communication systems should be newly designed for microwave oven interference environment. In this paper, using the Middleton's canonical class-A impulsive noise model, we propose a statistical model of microwave oven interference and discuss the performance improvement achieved by an optimum reception based on this statistical model. As the results, although the first order statistic of microwave oven interference can be modeled by class-A impulsive noise, because of the burst high level interference, the performance of optimum receiver designed for class-A noise cannot achieve a good error performance under microwave oven interference environment. In order to eliminate the effect of burst high level interference, we introduce sample interleave scheme and show that the performance of optimum receiver can be much improved by using sample interleave scheme.

A method is presented for detecting impulsive noises in chaotic time series, based on a new nonlinear prediction algorithm. A multi-dimensional trajectory is reconstructed from a time series using delay coordinates. The future value of a point on the trajectory is predicted using a local approximation technique revised by adding the Biweight estimation method and then the prediction error is calculated. Impulsive noises are detected by examining the prediction errors for all points on the trajectory. The proposed method is applied to the time series of the pupil area and the refractive power of the lens in the human eye. The Lyapunov exponent analysis for thses time series is conducted. As a result, it is shown that the proposed method is effective in detecting impulsive noises caused by blinking in these time series.

This paper clarified fundamental aspects of both triboelectric processes and electrostatic discharge (ESD) phenomena to the electronic systems. A chance for ESD can occur if a charged metal object (steel piped chair, for example) contacts or collides with another metal objects at moderate speed. At metal-metal ESD event, the metal objects act as a radiation antenna in a very short time (some 100ps, for example) which emanates impulsive electromagnetic fields with unipolarity into the surrounding space. Because of ESD at low-voltage (3kV or less) conditions, the direction of electrons movement at the spark gap is always unidirectional and fixed. The spark gap works as a momentary switch and also as a "diode." The dominant fields radiated from the metal objects are impulsive electric fields or impulsive magnetic fields which depend on the metal object's electrical and geometric conditions. This impulsive electromagnetic fields penetrate electronic systems, causing electromagnetic interference (EMI) such as malfunctions or circuit upset. The difference between EMI actions in high-voltage ESD and low-voltage ESD is experimentally analyzed in terms of energy conversion/consumption. A series of experiments revealed that EMI actions due to the metal-metal ESD are not proportional to the charge voltage nor the discharge current. In order to capture single shot impulsive electromagnetic fields very close to the ESD point (wave source), a short monopole antenna as an ultra broad-band field sensor was devised. As for signal transmissions between the short monopole antenna and the instrument (receiver), micro/millimeter wave techniques were applied. The transmission line's minimum band width DC-18.5GHz is required for time domain measurements of low-voltage ESD.

High-performance ULSI devices require ultraclean silicon surfaces, the complete removal of native oxides, and atomic level flatness and stabilization of the cleaned surfaces against molecular contaminants. Dry cleaning techniques are an attractive alternative to conventional wet processing for future ULSI production using cluster chambers or multi-process cham-bers. Organic contaminants, including photoresist polymers, are effectively removed by photo-excited ozone cleaning. We have found photo-excited halogen radicals to be useful for removing trace metals and native oxides from silicon surfaces without damaging on silicon and silicon-dioxide surfaces. We success-fully terminated hydrogen on (100) silicon surfaces by annealing in pure hydrogen ambient. A dry cleaning system with these sequential processes will be useful in constructing fully-integrated mass-production lines of high-performance ULSI devices.

The pendulum equation with a periodic impulsive force is investigated. This model described by a second order differential equation is also derived from dynamics of the stepping motor. In this paper, firstly, we analyze bifurcation phenomena of periodic solutions observed in a generalized pendulum equation with a periodic impulsive force. There exist two topologically different kinds of solution which can be chaotic by changing system parameters. We try to stabilize an unstable periodic orbit embedded in the chaotic attractor by small perturbations for the parameters. Secondly, we investigate the intermittent drive characteristics of two-phase hybrid stepping motor. We suggest that the unstable operations called pull-out are caused by bifurcations. Finally, we proposed a control method to avoid the pull-out by changing the repetitive frequency and stepping rate.

At the beginning of the 21st century, 1 Gb DRAMs will be in practical use, and sufficient in terms of memory capacity for most memory applications systems. The key technologies for multimedia systems include data compression, communication, storage, and human interfaces. Image data processing, ATM switch, and microprocessor in multimedia applications require the high data transfer rate from several 100 Mbits/s to Tbits/s. Storage systems, on the other hand, require the reduction of the price per bit to less than 10 cents/Mbytes. Application specific design approaches towards a system-on-chip are strongly needed for ULSI memories in the multimedia era.

A high-speed high-density self-aligned pnp technology for complementary bipolar ULSIs has been developed to achieve high-speed and low-power performance simultaneously. It is fully compatible with the npn process. A low sheet-resistance p+ buried layer and a low sheet-resistance extrinsic n+ polysilicon layer with U-grooved isolation enable the transistor size to be scaled down to about 20 µm2. Current gain of 85 with 4-V collector-emitter breakdown voltage was obtained without any leakage current arising from emitter-base forward tunneling or recombination, which indicates no extrinsic base encroachment problem. A shallow emitter junction depth of 45 nm and narrow base width of 30 nm, obtained by utilizing an optimized retrograded p-well, an arsenic-implanted intrinsic base, and emitter diffusion from BF2-implanted polysilicon, improve the maximum cutoff frequency to 35 GHz. The power dissipation of the pnp pull-down complementary emitter-follower ECL circuit with load capacitances is calculated to be reduced to 20-40% of a conventional ECL circuit.

In this paper, a design of TCM signals for Middleton's class-A impulsive noise environment is investigated. The error event characteristics under the impulsive noise is investigated, and it is shown that the length of the signal sequence is more important than Euclidean distance between the signal sequences. Following this fact, we introduce the shortest error event path length as a measure of the signal design. In order to make this value large, increasing of states of convolutional codes is employed, and the performance improvement achieved by this method is evaluated. Numerical results show the great improvement of the error performance and conclude that the shortest error event path length is a good measure in the design of TCM signals under impulsive noise environment. Moreover, the capacity of class-A impulsive noise channel is evaluated, and the required signal sets expansion rates to obtain the achievable coding gain is discussed.

We propose a smart design methodology for advanced ULSI memories to reduce the turn around time(TAT) for circuit revisions with no area penalty. This methodology was executed by distributing extra gate-arrays, which were composed of the n-channel and p-channel transistors, under the power line and the signal line. This method was applied to the development of a 16 Mb DRAM with double metal wiring. The design TAT can be reduced to 1/8 using 1500 gates. This design methodology has been confirmed to be very effective.

If a perspective of the "256M/1G era" were to be made from this present, namely the last stage of the development of 64 M DRAMs, the process technologies will show a variety of progress. Some of them would remain only in the extension of the present ones, but others would show a fundamental change including their technological constitutions. The optical lithography will survive even the "256M/1G era" mainly with the innovations of mask technologies. The etching technologies will remain basically the same as the present ones, but will be much more refined. The studies on plasma/redical related surface reactions, however, will bring a variety of surface treatment technologies of new function. The interconnection technologies will encounter various kinds of difficulties both in materials and in processign, and mechanical processing will become one of ULSI processing technologies. The shallow junction technology will merge with the metallization and epitaxial growth technology. The thin dielectrics will approach a critical situation, and it might enhance the device structural change to three dimensional ones. Corresponding to this, the necessity of "vertical processing" will become larger. The bonding SOI technology might overcome these situations of increasing difficulties. On the other hand, the contamination control will be the base of these technology innovations and improvements, exploring a new technology field in addition to the conventional process technology fields.

In the maximum-likelihood decoding under a non-Gaussian noise, the decoding region is bounded by complex curves instead of a perpendicular bisector corresponding to the Gaussian noise. Therefore, the error rate is not evaluated by the Euclidean distance. The Bhattacharyya distance is adopted since it can evaluate the error performance for a noise with an arbitrary distribution. Upper bound formulae of a bit error rate and an event error rate are obtained based on the error-weight-profile method proposed by Zehavi and Wolf. The method is modified for a non-Gaussian channel by using the Bhattacharyya distance instead of the Euclidean distance. To determine the optimum code for an impulsive noise channel, the upper bound of the bit error rate is calculated for each code having an encoder with given shift-register lehgth. The best code is selected as that having the minimum upper bound of the bit error rate. This method needs much computation time especially for a code with a long shift-register. To lighten the computation burden, a suboptimum search is also attempted. For an impulsive noise, modeled from an observation in digital subscriber loops, an optimum or suboptimum code is searched for among codes having encoders with a shift-register of up to 4 bits. By using a code with a 4-bit encoder, a coding gain of 20 dB is obtained at the bit error rate 10-5. It is 11 dB more than that obtained by Ungerboeck's code.