An iterative decoder of turbo code over an inter-symbol interference channel is proposed. A component decoder realizes decoding and equalization simultaneously with the soft-output Viterbi algorithm (SOVA). A decoding algorithm and simulation results are shown.

Nonlinear behavior of electromagnetic surface waves propagating along a tangentially magnetized ferrite slab is investigated. The nonlinear Schrodinger equation (NLSE) which describes the temporal evolution of the electromagnetic wave pulses has been derived directly from the Maxwell equations and the equation of precessional motion for the magnetization in the ferrite slab with the aid of the reductive perturbation method without magnetostatic approximation. Based on the formula derived, we have numerically evaluated the frequency-dependence of the nonlinear coefficient in the NLSE for both a magnetostatic surface wave mode and a dynamic mode. As a result, we have confirmed the possibility of the propagation of solitons in the waveguide.

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.

Multi-user uniquely decodable (UD) k-ary coding for the multiple-access adder channel is investigated. It is shown that a Tf+g+1-user UD k-ary affine code with code length f+g+1 can be obtained from two Tf-user and Tg-user UD k-ary affine codes. This leads to construct recursively a Tn-user UD k-ary affine code with arbitrary code length n. The total rate of the code tends to be higher than those of all the multi-user UD k-ary codes reported previously as the number of users increases.

In this paper, we discuss on the realization of reduced peak power transmission for the multicarrier systems. Since the signals have large amplitude fluctuations in conventional multicarrier systems, signals amplified by a nonlinear amplifier are greatly distorted, resulting in severe performance degradation. In order to avoid this large amplitude fluctuation, we propose a scheme for reducing the nonlinear distortion by using the set of the signal point series which show low peak to mean envelope power ratio (PMEPR) value. In this system, one symbol is transmitted with multicarriers and the received signal is detected with maximum likelihood sequence detection.

A modified sequential acquisition scheme is proposed in this letter to avoid the significant high error probabilities (false alarm and missing probabilities) occurring with the conventional sequential acquisition scheme in direct-sequence spread-spectrum systems while a high frequency offset is present. A new estimator of Ek/N0 is also designed to effectively solve the problems caused by the channel fading effects. Extensive computer simulation results have indicated that the proposed technique can achieve the desired low error probabilities, and furthermore its performance is very close to that with the perfect channel estimation.

A sufficient condition for a code to be optimum on discrete channels with finite input and output alphabets is given, where being optimum means achieving the minimum decoding error probability. This condition is derived by generalizing the ideas of binary perfect and quasi-perfect codes, which are known to be optimum on the binary symmetric channel. An application of the sufficient condition shows that the code presented by Hamada and Fujiwara (1997) is optimum on the q-ary channel model proposed by Fuja and Heegard (1990), where q is a prime power with some restriction. The channel model is subject to two types of additive errors of (in general) different probabilities.

In this paper we study general complex eigenvalue problems in engineering fields. The eigenvalue problems can be transformed into the associated problems for solving large systems of nonlinear ordinary differential equations (dynamic equations) by optimization techniques. The known waveform relaxation method in circuit simulation can then be successfully applied to compute the resulting dynamic equations. The approach reported here, which is implemented on a message passing multi-processor system, can determine all eigenvalues and their eigenvectors for general complex matrices without any restriction on the matrices. The numerical results are provided to confirm the theoretical analysis.

An optical spectral coding scheme is devised for fiber-optic code-division multiple-access (FO-CDMA) networks. The spectral coding is based on the pseudo-orthogonality of FO-CDMA codes properly written in the fiber Bragg grating (FBG) devices. For an incoming broadband optical signal having spectral components equal to the designed Bragg wavelengths of the FBG, the spectral components will be reflected and spectrally coded with the written FO-CDMA address codes. Each spectral chip has different central wavelength and is distributed over the spectrum of the incoming light source. Maximal-length sequence codes (m-sequence codes) are chosen as the signature or address codes to exemplify the coding and correlation processes in the FO-CDMA system. By assigning the N cycle shifts of a single m-sequence code to N users, we get an FO-CDMA network that can theoretically support N simultaneous users. To overcome the limiting factor of multiple-access interference (MAI) on the performance of the FO-CDMA network, an FBG decoder is configured on the basis of orthogonal correlation functions of the adopted pseudo-orthogonal codes. An intended receiver user that operates on the defined orthogonal correlation functions will reject any interfering user and obtain quasi-orthogonality between the FO-CDMA users in the network. Practical limiting issues on networking performance, such as non-flattened source spectra, optical path delay, and asynchronous data accesses, are evaluated in terms of the bit-error-rate versus the number of active users. As expected, the bit-error-rate will increase with the number of active users. Increasing the flatness parameter of optical signal will lead to a lower average error probability, since we are working in a part of the more flattened optical spectrum. In contrast, reducing the encoded bandwidth will reduce the total received power, and this will necessitate higher resolution of fiber Bragg gratings.

We have developed a highly integrated liquid-crystal-on-silicon microdisplay for virtual reality applications. The silicon panel of 704 576 pixels was designed and fabricated by a custom 0.35 µm complementary metal oxide semiconductor (CMOS) technology with emphasis on surface planarization. Topographic variation of less than 100 within the pixels was achieved. The pixel pitch was 9.6 µm, fill factor was 88% and display area was 0.36" in diagonal. Eight-bit digital data drivers and gamma-correction circuitry were integrated onto the silicon panel for true gray scale and full color representation. The display panel was assembled with a mixed twisted nematic and birefringence liquid crystal cell for high contract at CMOS compatible voltage. Chromatic characterization of the display using 3-color-in-1 light emitting diode (LED) as light source was performed. Contrast ratios on the pixel array were 95, 72 and 56, respectively, for red, green and blue colors at 3 V root-mean-squared voltage. In addition, a three-dimensional (3D) video stream in interlaced format was generated by a 3D modeling code for test and demonstration. Control logic was implemented to extract the left and right video frames and perform system timing synchronization. The silicon microdisplay was driven in frame inversion and by color sequence. With two sets of silicon microdisplays and eyepieces for each eye, we have demonstrated a 3D stereoscopic display based on the silicon microdisplay technology.

In this paper, we propose an adaptive IIR equalizer based on prefiltering techniques. The proposed equalizer has a cascade structure of an ARMA prefilter and an adaptive FIR equalizer. The ARMA prefilter is designed based on the transfer function estimated by the gradient-type instrumental variable algorithm. Simulation results are shown to confirm the performance of the proposed adaptive IIR equalizer.

This paper describes a novel IDDQ sensor circuit that is driven by only an abnormal IDDQ. The sensor circuit has relatively high sensitivity and can operate at a low supply voltage. Based on a very simple idea, it requires two additional power supplies. It can operate at either 5-V or 3.3-V VDD with the same design. Simulation results show that it can detect a 16-µA abnormal IDDQ at 3.3-V VDD. This sensor circuit causes a smaller voltage drop and smaller performance penalty in the circuit under test than other ones.

A new method is introduced for sequential estimation of TDOA (time delay of arrival) and FDOA (frequency delay of arrival) in a two sensor array. The proposed scheme is basically a two step algorithm utilizing 1-dimensional slice functions of the third order cumulants between two signal measurements, and is capable of suppressing the effect of correlated Gaussian measurement noises. It is demonstrated that the proposed algorithm outperforms existing TDOA/FDOA estimation algorithms from the viewpoint of computational burden and in the sense of mean squared error as well.

A novel fabrication process and materials of LC layers have been developed for three layer LCDs. It is based on LC/resist composite that can be applied to patterning LC layers with high resolution by conventional photolithography processes. Using this process, we fabricated a 2" matrix panel of three GH-LC layers stacked on a substrate for the fist time.

Voltage holding property of liquid crystal (LC) cell for long period was investigated and the experimantal results were analyzed using a microscopic model considered the movement of ions in LC layer. The time dependent voltage decay curve observed in the experiment, which is not driven by the analysis with the conventional equivalent circuit comprised of the capacitance and the resistance, can be well explained by the microscopic model.

Loop optimization plays an important role in compiler optimization and program transformation. Many sophisticated techniques such as loop-invariance code motion, loop restructuring and loop fusion have been developed. This paper introduces a novel technique called loop quasi-invariance code motion. It is a generalization of standard loop-invariance code motion, but based on loop quasi-invariance analysis. Loop quasi-invariance is similar to standard loop-invariance but allows for a finite number of iterations before computations in a loop become invariant. In this paper we define the notion of loop quasi-invariance, present an algorithm for statically computing the optimal unfolding length in While-programs and give a transformation method. Our method can increase the accuracy of program analyses and improve the efficiency of programs by making loops smaller and faster. Our technique is well-suited as supporting transformation in compilers, partial evaluators, and other program transformers.

With the continuing growth of the World Wide Web (WWW) services over the Internet, the demands for rapid image transmission over a network link of limited bandwidth and economical image storage of a large image database are increasing rapidly. In this paper, a classified binary-tree-structured Self-Organizing Feature Map neural network is proposed to design image vector codebooks for quantizing images. Simulations show that the algorithm not only produces codebooks with lower distortion than the well-known CVQ algorithm but also can minimize the edge degradation. Because the adjacent codewords in the proposed algorithm are updated concurrently, the codewords in the obtained codebooks tend to be ordered according to their mutual similarity which means more compression can be achieved with this algorithm. It should also be noticed that the obtained codebook is particularly well suited for progressive image transmission because it always forms a binary tree in the input space.

In this work, a temperature stable voltage-to-frequency converter (VFC) in which the output frequency is proportional to the input voltage is proposed. The output frequency range is from 22 kHz to 60 kHz and the difference between simulated and calculated values is less than about 5% for this range of output frequency. The temperature variation of sample output frequencies is less than 0.5% in the temperature range -25C to 75C.

We generalize the construction of quantum error-correcting codes from F4-linear codes by Calderbank et al. to pm-state systems. Then we show how to determine the error from a syndrome. Finally we discuss a systematic construction of quantum codes with efficient decoding algorithms.

An airborne X- and L-band synthetic aperture radar system was developed by the Communications Research Laboratory and the National Space Development Agency of Japan in their joint project from 1993 to 1996. It is installed in the airplane, Gulfstream II. In both the azimuth and range directions, the resolution is 1.5 m for the X-band and 3 m for the L-band. Both SARs can make fully polarimetric observations. The X-band SAR has a cross-track interferometric function. In this paper we describe the SAR system, its ground processing system, and its performance. We also discuss motion compensation and interferogram quality.