This paper proposes a fast encoding algorithm for iterated function system (IFS) coding of gray-level homogeneous fractal images. In order to realize IFS coding of high order fractal images, it is necessary to solve a set of simultaneous equations with many unknowns. Solving the simultaneous equations using a multi-dimensional, numerical root-finding method is however very time consuming. As preprocessing of numerical computation, the proposed algorithm employs univariate polynomial manipulation, which requires less computation time than multivariate polynomial manipulation. Moreover, the symmetry of the simultaneous equations with respect to the displacement coefficients enables us to derive an equation with a single unknown from the simultaneous equations using univariate polynomial manipulation. An experimental result is presented to illustrate that the encoding time of the proposed algorithm is about 5 seconds on a personal computer with a 400 MHz Pentium II processor.

In this paper, a new gradient-based adaptive algorithm for the estimation of discrete Fourier coefficients (DFC) of a noisy sinusoidal signal is proposed based on a summed least mean squared error criterion. This algorithm requires exactly the same number of multiplications as the conventional LMS algorithm, and presents much improved performance in both white and colored noise environments at the expense of some additional memories and additions only. We first analyze the performance of the conventional LMS algorithm in colored additive noise, and point out when its performance deteriorates. Then, a summed least mean squared error criterion is proposed, which leads to the above-mentioned new gradient-based adaptive algorithm. The performance of the proposed algorithm is also analyzed for a single frequency case. Simulation results are provided to support the analytical findings and the superiority of the new algorithm.

Wavelet filters used in usual applications are not time-varying filters. In this paper, we present a novel method to design biorthogonal wavelet filters which are orthogonal to the input signals. We call newly designed filters time-varying lifting wavelet filters (TVLWF). Their feature is to vary the wavelet filters adapting to the input signal by tuning free parameters contained in the lifting scheme developed by Sweldens. These filters are almost compact support and perfect reconstruction. By using TVLWF, we demonstrate an application to data compression of electrocardiogram (ECG) which is one of the semi-periodic time-series signals and show that the time-varying system can be constructed easily and the proposed method is very useful for data compression.

In the literature [9], the optimum discrete interpolation of one-dimensional signals is presented which minimizes various measures of approximation error simultaneously. In the discussion, the ratio λ of the weighted norm of the approximation error and that of the corresponding input signal plays an essential role to determine the structure of the set of signals. However, only the upper bound of λ is provided in [9]. In this paper, we will present more exact and systematic discussion of the optimum discrete interpolation of one-dimensional signals which minimizes various measures of approximation error at the same time. In this discussion, we will prove that the exact value of λ is identical with the upper limit, for ω (|ω| π), of the largest eigen value of a matrix including the weighting function W(ω) and the Fourier transforms of the optimum interpolation functions. Further, we will give a sufficient condition for W(ω) under which the ratio λ is equal to one, where the approximation error, if it is interpolated by sinc, is included in the set of band-limited signals defined by W(ω). Finally, as application of the presented approximation, we will propose a direction to interactive signal processing on Internet and a transmultiplexer system included in it. The transmultiplexer system included in this discussion can realize flexible arrangement of sub-bands which is inevitable in realizing the above proposal on interactive signal processing.

Fractal immittance, expressed by an admittance sa (0<|a|<1), is simulated by the analog circuits composed of finite numbers of conventional elements, resistance R, capacitance C and inductance L, based on the distributed-relaxation-time models. The correlation between the number of R-C or R-L pairs and the optimum pole interval to give the widest bandwidth is estimated for each a-value by the numerical calculation for each circuit against a given criterion with respect to the phase angle. It is found that the bandwidth of 5 decades with a phase-angle error of 1 can be composed for |a|=0.1-0.9 using eighteen pairs or less of the elements.

This paper reports on time-space conversion-based differential processing of optical signals using a high-resolution arrayed-waveguide grating (AWG) and a spatial filter at a wavelength of 1.55 µm. We clarify the advantages of the AWG device and show where it is applicable. In order to reduce loss at the spatial filter, we propose a new phase-only filter that functions as a differential filter. The difference between the exact differential filter and the proposed phase-only filter is calculated theoretically. We confirm experimentally that the optical pulse can be differentiated by the proposed filter. For application of differential processing, we also proposed a phase modulation to amplitude modulation (PM-AM) conversion and demonstrated the PM-AM conversion at 10 Gbit/s signals using a PSK-non-return-to-zero (NRZ) format.

In order to accommodate periodic and bursty sources into ATM networks effectively, we propose phase assignment control (PAC), which actively controls the phase of the new connection at its connection setup phase. To realize PAC, we develop an algorithm to find a good phase of the new connection in a short time. Simulation results show that the PAC can improve the system performance.

CTL (Computation Tree Logic) model checking is a formal method for design verification that checks whether the behavior of the verified system is contained in that of the requirements specification. If this check doesn't pass, the CTL model checker generates a subset of fair states which belongs to the system but not to the specification. In this letter, we present an incremental method which successively modifies the latest verification result each time the design is modified. Our incremental algorithm allows the designer to make changes in terms of addition or subtraction of fair CTL formulas, or fairness constraints on acceptable behavior from the problem statement. Then, these changes are adopted to update the set of fair states computed earlier. Our incremental algorithm is shown to be better than the current non-incremental techniques for CTL model checking. Furthermore, a conclusion supported by the experimental results is presented herein.

Multi-ary Trellis-Coded Modulation (TCM) schemes have been studied for use with digital radio communication systems. Among these TCM schemes, we have already reported the optimum signal constellation of a rate-3/4 trellis-coded (TC) 16-ary Amplitude and Phase Shift Keying (APSK) scheme and computed the minimum Euclidean distance: dfree. In this paper, we evaluate other performance parameters: Nfree and bit error rate (BER) over an additive white Gaussian noise channel, and further investigate the various signal constellations of rate-4/5 TC 32-APSK schemes. It is found that the BER performances of circular-type signal constellations are superior to that of rectangular-type in the TC 16-APSK, and a (24,8) circular type signal constellation is superior to other constellations in the TC 32-APSK.

An intrinsic property of a tapped resonator is elucidated here, and a novel bandpass filter (BPF) with improved skirt characteristics based on a tapped half-wavelength resonator is proposed by this intrinsic property. "Tapping" for both I/O and interstage couplings of the resonator is the key concept here because a resulting open-ended resonator makes shunt open stubs which give anti-resonance near the center frequency. Multiple attenuation poles appear near the center frequency, namely, close to the passband. A BPF is designed on the basis of the general filter theory with a narrow band approximation. An experiment is carried out to confirm the concept by using a coplanar structure. The expected bandpass characteristics with multiple attenuation poles have been obtained by the novel BPF designed by the present concept.

The feasibility of a dynamic zone configuration technique has been investigated. To make it easy to implement this technique in wireless communication systems, a simplified method for determining a suitable weight vector by using the least squares (LS) methods was developed. Simulations showed that the developed system is more effective than the present omni-directional zone system. Moreover, combining dynamic zone configuration technique with dynamic channel assignment strategy reduced blocking rate, forced call termination ratio, and required transmission power.

When designing microwave amplifiers, it is the task to select values of the source (input generator) and load reflection coefficients for the transistor, to achieve certain amplifier performance requirements and ensure stability. For unconditionally stable transistors, simultaneous conjugate matching can be achieved using well-known design formulae. Under this condition, the gain is maximised, and the input and output ports are matched. On the other hand when the transistor is conditionally stable, source and load reflection coefficients are selected using graphical design methods, involving gain and stability circles. To eliminate the reliance on graphical techniques, this paper shows the derivation of explicit design formulae that ensure maximum gain for a minimum specified safety margin, with one port matched. In this work, the safety margin is the distance between the chosen source or load reflection coefficient and its respective stability circle. In a production environment, where the circuit and transistor parameters are subject to random variations, the safety margin therefore makes allowance for such variations. This paper shows that the design problem for conditionally stable transistors can be reduced from the selection of values for two complex variables (port terminations) to the selection of the value for just one scalar variable.

In this paper, a novel design method for bandpass filter with attenuation poles (BAP) is presented. The changed inverter element values due to inserting either capacitors or inductors can be optimized using the linear relationship between inverter element values of a conventional bandpass filter (BPF) and those of the BAP using the Touchstone program. A 1800-1825 MHz bandpass filter with attenuation poles for duplexers is designed and fabricated using coaxial dielectric resonators. The validity of this design approach is demonstrated by a computer simulation. The resonators are simulated equivalently as shorted lossy transmission lines. The measured results of center frequency, bandwidth, and attenuation pole frequencies closely agree with the design values.

In this paper, the performance of dynamic channel assignment for cellular systems with an array antenna is evaluated assuming realistic beamformer. A new dynamic channel assignment algorithm is proposed to improve the performance by forming a directional beam pattern to cancel stronger co-channel interference with higher priority. Performance comparison is carried out by computer simulations. Conventional algorithm shows 2.7 fold capacity increase compared with an omni antenna system, whereas proposed algorithm shows around 3.3 fold capacity increase, at the point of 3 percent blocking probability. The simulation results also denote that a shorter reuse distance can be achieved by the proposed algorithm, which indicates a more efficient utilization of channel resource.

A new IC interconnect transmission line parameter determination methodology and a novel fast simulation technique for non-uniform transmission lines are presented and verified. The capacitance parameter is a strong function of a shielding effect between the layers, while silicon substrate has a substantial effect on inductance parameter. Thus, they are taken into account to determine the parameters. Then the virtual straight-line-based per unit length parameters are determined in order to perform the fast transient simulation of the non-uniform transmission lines. It was shown that not only the inductance effect due to a silicon substrate but also the shielding effect between the layers are too significant to be neglected. Further, a model order reduction technique is integrated into Berkeley SPICE in order to demonstrate that the virtual straight-line-based per-unit-length parameters can be efficiently employed for the fast transient response simulation of the complicated multi-layer interconnect structures. Since the methodology is very efficient as well as accurate, it can be usefully employed for IC CAD tools of high-performance VLSI circuit design.

From our previous studies, we derived the worst case cell delay within an ATM switch and thus can find the worst case end-to-end delay for a set of real-time connections. We observed that these delays are sensitive to the priority assignment of the connections. With a better priority assignment scheme within the switch, the worst case delay can be reduced and provide a better network performance. We extend our previous work on the closed form analysis to conduct more experimental study of how different priority assignments and system parameters may affect the performance. Furthermore, from our worst case delay analysis on a regulated ATM switch, network traffic can be smoothed by a leaky bucket at the output controller for each connection. With the appropriate setting on the leaky bucket parameter, the burstiness of the network traffic can be reduced without increasing the delay in the switch. Therefore, fewer buffers will be required for each active connection within the switch. In this paper, our experimental results have shown that the buffer requirement can be reduced up to 5.75% for each connection, which could be significant, when hundreds of connections are passing through the switches within a regulated ATM network.

This paper discusses the classification of targets buried in the underground by radar polarimetry. The subsurface radar is used for the detection of objects buried beneath the ground surface, such as gas pipes, cables and cavities, or in archeological exploration operation. In addition to target echo, the subsurface radar receives various other echoes, because the underground is inhomogeneous medium. Therefore, the subsurface radar needs to distinguish these echoes. In order to enhance the discrimination capability, we first applied the polarization anisotropy coefficient to distinguish echoes from isotropic targets (plate, sphere) versus anisotropic targets (wire, pipe). It is straightforward to find the man-made target buried in the underground using the polarization anisotropy coefficient. Second, we tried to classify targets using the polarimetric signature approach, in which the characteristic polarization state provides the orientation angle of an anisotropic target. All of these values contribute to the classification of a target. Field experiments using an ultra-wideband (250 MHz to 1 GHz) FM-CW polarimetric radar system were carried out to show the usefulness of radar polarimetry. In this paper, several detection and classification results are demonstrated. It is shown that these techniques improve the detection capability of buried target considerably.

Design concepts and backgrounds of a 3-dimensional semiconductor process simulator are presented. It is designed to become a basis of developing semiconductor process models. An input language is designed to realize flexibly controlling simulation sequence, and its interpreter program is designed to accept external software to be controlled and to be integrated into a system. To realize data-exchanges between the process simulator and other software, a self-describing data-file format is designed and related program libraries are developed. A C++ class for solving drift-diffusion type partial-differential-equation in a three-dimensional space is developed.

A new design hierarchy in TCAD is discussed with emphasis on a design of IC interconnects and gate patterns. Two design methodologies for gate patterns at a CMOS cell level and multilevel interconnect scheme at a chip level are proposed. This approach generates the layout design rules of gate patterns, considering the fabrication process and pattern layout dependency, and allows a design of multilevel interconnect scheme at the initial phase of technology development.

A new practical coherent detection scheme for biorthogonal signals, which uses multi-symbol observation interval, is proposed and its performances are analyzed and simulated. The technique jointly estimates both the demodulated data and the channel from received signal only while reducing computation complexity by an approximate maximum-likelihood sequence estimation rather than symbol-by-symbol detection as in previous noncoherent detection. The scheme achieves performance close to that of ideal coherent detection with perfect channel estimates when select the appropriate observation symbol interval N in the given symbol alphabet size M. What is particularly interesting is that the required average signal-to-noise ratio per bit γb can be reduced by as much as 1.4 dB and the capacity can be increased by as much as 38% when we use this system in the CDMA cellular reverse link.