In addition to additive thermal noise, a received direct-sequence spread spectrum (DS/SS) signal may suffer from intersymbol interference (ISI) and interference caused by cochannel narrowband users or other narrowband radio frequency interference (RFI). This paper presents a workable solution for removing narrowband interference (NBI) and reducing ISI or inter-chip interference (ICI) when the communication channel can be modeled as an FIR filter and the NBI comes from multiple CW tones, an AR-modeled Gaussian process, or a BPSK signal. Unlike earlier solutions, the proposed scheme is capable of performing the functions of NBI-rejection, ISI/ICI suppression and data detection (code despreading) simultaneously. It is easy to implement and, more importantly, it yields lower bit error rate (BER) and smaller mean squared error (MSE).

In general cases of pattern recognition, a pattern to be recognized is first represented by a set of features and the measured values of the features are then classified. Finding features relevant to recognition is thus an important issue in recognizer design. As a fundamental design framework taht systematically enables one to realize such useful features, the Subspace Method (SM) has been extensively used in various recognition tasks. However, this promising methodological framework is still inadequate. The discriminative power of early versions was not very high. The training behavior of a recent discriminative version called the Learning Subspace Method has not been fully clarified due to its empirical definition, though its discriminative power has been improved. To alleviate this insufficiency, we propose in this paper a new discriminative SM algorithm based on the Minimum Classification Error/Generalized Probabilistic Descent method and show that the proposed algorithm achieves an optimal accurate recognition result, i.e., the (at least locally) minimum recognition error situation, in the probabilistic descent sense.

This paper proposes a direct-sequence spread spectrum (DS/SS) communication system with a new diversity technique designed for indoor multi-path fading channels where path diversity isn't available. In this system, the transmitter sends a same signal from multiple antennas at the same time with intentional time delays, which allows the receiver to distinguish and combine the signals from different antennas. We also consider the combination of this scheme with the conventional receiving antenna diversity for additional diversity gain. Furthermore, it is found that the use of the multiple transmitting antennas decreases the effect of the multiple access interference.

In this paper an algorithm for numerical investigation of the transmission line having a generalized polygonal cross-section and open interface is proposed. Solution of the eigenmode problem is based on the method called the domain product technique, which employs a Mathieu function expansion and provides an efficient technique to the analysis of the structures with multiangular boundaries. An agreement at the obtained numerical results with existing data confirms the applicability of the theoretical analysis given in the paper.

Coupling in time domain between two non-parallel transmission lines of finite length is analyzed by using a circuit concept. Coupling equations based on the Maxwell's equations for lossless transmission lines in a homogeneous medium are written by a set of non-homogeneous differential equations including distributed source terms produced by external electromagnetic fields. The forcing terms are expressed by vector potentials generated by currents in the line section and at the transitions. A set of solutions in frequency domain is obtained by a four-port network expression with regard to the terminal voltages and currents, and can be applied to estimation of the frequency-domain crosstalk. Utilizing the inverse fast Fourier transform (FFT), the crosstalk responses between the lines is studied in time domain. Comparison of theoretical and experimental results shows the validity of the method.

The main defficulty in recognizing 3-D objects from 2-D images is matching 2-D information to the 3-D object representation. The multiple-view approach makes this problem easy to solve by reducing the problem to 2-D to 2-D matching problem. This approach models each 3-D object by a collection of 2-D views from various viewing angles and recognizes an object in the image by finding a 2-D view that has the best match to the image. However, if the size of the model database becomes large, the approach requires long time for the recognition of objects. In this paper we present a 3-D object recognition algorithm based on multiple-view approach. To reduce the recognition time, the proposed algorithm uses the coarse-to-fine process previously proposed by the authors and a genetic algorithm-based search scheme for the selection of a best matched model in the database. And, we could verify from the results of the experiments that the algorithm proposed in this paper is useful to speed up the recognition process in multiple-view based object recognition systems.

Turbo codes have fascinated many coding researchers because of thier near-Shannon-limit error correction performance. In this paper, we discuss multi-dimensional turbo codes which are parallel concatenation of multiple constituent codes. The average upper bound to bit error probability of multidimensional turbo codes is derived. The bound shows that the interleaver gains of this kind of codes are larger than that of conventional two-dimensional turbo codes. Simplified structures of multi-dimensional turbo encoder and decoder are proposed for easier implementation. Simulation results show that for a given interleaver size, by increasing the dimension, great performance improvement can be obtained.

This paper proposes a general expansion architecture for constructing large-scale multicast ATM switches with any type of small multicast switch, called the multicast Universal Multistage Interconnection Network (multicast UniMIN). The proposed architecture consists of a buffered distribution network that can perform cell routing and replication simultaneously, and a column of output switch modules (OSMs). The adoption of channel grouping and virtual first-in-first-out (FIFO) buffers results in high delay/throughput performance, and the distributed lookup table scheme for multicast addressing greatly reduces the size of a single lookup table. Analytical and simulation results show that high delay/throughput performance is obtained for both unicast and multicast traffic, and the proposed architecture yields an even better performance for multicast traffic than for unicast traffic. In addition, the multicast UniMIN switch has such good features as modular expandability, simple hardware, and no internal speed-up operation.

This paper analyzes mechanisms of radiated emissions from multilayer printed circuit boards (PCBs) and presents a model to describe the characteristics of such radiation. The radiation mechanism from a four-layer PCB, including the internal power and ground planes, is investigated using a time-domain magnetic field measurement near the PCB. Measurement of the waveform indicates that the main source of radiation is in the power distribution planes. To investigate the characteristics of the radiation from the power distribution, the S21s of the board are measured; the board impedance and the transmission characteristics of the power distribution planes are found to be directly related to the S21 between the two points in the board. The results indicate that the power distribution acts as a transmission line at frequencies higher than 100 MHz. A model that can explain well the radiation properties of these planes treats them as a parallel-plate transmission line interconnected by decoupling circuit comprising a decoupling capacitor and interconnect inductance. From the transmission line theory it is deduced that the line resonance gives rise to strong radiated emissions. The interconnect inductance is an important factor in determining the radiation characteristics.

Generalized minimum-distance (GMD) decoding is well-known as a soft decision decoding technique for such linear block codes as BCH and RS codes. The GMD decoding algorithm generates a set of candidate codewords and selects as a decoded codeword that candidate with the smallest reliable distance. In this paper, for a GMD decoder of RS and BCH codes, we present a new sufficient condition for the decoded codeword to be optimal, and we show that this sufficient condition is less stringent than the one presented by Taipale and Pursely.

A Bitplane Tree Weighting (BTW) method with arithmetic coding is proposed for lossless coding of gray scale images, which are represented with multiple bitplanes. A bitplane tree, in the same way as the context tree in the CTW method, is used to derive a weighted coding probability distribution for arithmetic coding with the first order Markov model. It is shown that the proposed method can attain better compression ratio than known schemes with MDL criterion. Furthermore, the BTW method can be extended to a high order Markov model by combining the BTW with the CTW or with prediction. The performance of these modified methods is also evaluated. It is shown that they attain better compression ratio than the original BTW method without increasing memory size and coding time, and they can beat the lossless JPEG coding.

The integral kernel expansion method is applied to an analysis of scattering of magnetostatic forward volume waves (MSFVWs) by an array with any number of metal strips. In this method, first the integral kernel of the Fourier integral is expanded in terms of orthogonal polynomials to obtain moment equations. Then a system of algebraic equations is derived by applying the Galerkin's method. In the process, interaction between strips is naturally taken into account and real current distributions on the strips are determined such that boundary conditions are satisfied. Calculus confirmation through the energy conservation principle shows that numerical results are quite satisfactory. A comparison shows that theoretical results are in good agreement with experimental ones except the vicinity of lower and upper limits of the MSFVW band. It is shown that an infinite number of propagation modes is excited even if a wave of single mode is incident. Dependence of the scattering on dimension of arrays and on frequency and mode of an incident wave is obtained.

Polarization transformation characteristics of a statified slab consisting of uniaxial chiral layers are investigated. It is assumed that a plane electromagnetic wave with arbitrary polarization is normally incident from free space on the stratified slab, which is located on a dielectric substrate. Note that the electric field inside a uniaxial chiral layer is expressed as a sum of four plane waves with different wavenumbers. The wavenumbers are found by seeking non-trivial solutions of the constitutive relations with Maxwell's equations. The electric field components of the transmitted and reflected waves can be obtained from a chainmatrix formalism. The powers and the Stokes parameters of the two waves are represented in terms of their electric field components. As is well known, the Stokes parameters uniquely describe every possible state of polarization of a plane wave. Numerical results are presented for two types of uniaxial chiral structure. The cross- and co-polarized powers and the Stokes parameters of the transmitted and reflected waves are computed for the incident plane wave of linear polarization. The results demonstrate a significant polarization transformation of the transmitted wave. Then it is shown that the stratified slab can be used as efficient polarization-transformation transmission filters active at some frequency band.

The purpose of this report is to predict far-field EMI spectrum emitted from a signal line on a digital PCB based on near-field EMI measurement. The relation between near magnetic field and far electric field is shown. A method of predicting far electric field from near magnetic field is proposed. Current flowing along a signal line is calculated from measured near magnetic field. Far electric field is estimated from the current. Measurement and prediction of EM emission are carried out using a simple PCB. The result of prediction and measurement of far-field EMI spectrum coincide within the error of 3 dB.

In this paper, we illustrate the analysis of microstrip structures with a large number of unknowns using the sparse-matrix/canonical grid method. This fast Fourier thansform (FFT) based iterative method reduces both CPU time and computer storage memory requirements. We employ the Mixed-Potential Integral Equation (MPIE) formulation in conjunction with the RWG triangular discretization. The required spatial-domain Green's functions are obtained efficiently and accurately using the Complex Image Method (CIM). The impedance matrix is decomposed into a sparse matrix which corresponds to near interactions and its complementary matrix which corresponds to far interactions among the subsectional current elements on the microstrip structures. During the iterative process, the near-interaction portion of the matrix -vector multiplication is computed directly as the conventional MPIE formulation. The far-interaction portion of the matrix-vector multiplication is computed indirectly using fast Fourier transforms (FFTs). This is achieved by a Taylor series expansion of the Green's function about the grid points of a uniformly-spaced canonical grid overlaying the triangular discretization.

Bit-interleaving can enhance performance of a trellis coded modulation system over a fading channel. A combined system with decision feedback equalization is proposed. In the system, TCM decoded symbols are fed back for equalization. To avoid a bad effect of decoding delay, a deinterleaver is utilized effectively. Information sequence is divided into three subsequences and encoded by three encoders. Among the 3 code vectors from the encoders, bits are interleaved and decoding proceeds in parallel. Simulation results show that the proposed system realizes 0.6 dB more coding gain than a symbol interleaved system. A calculation method of a branch metric for decoding is proposed. Performance with the branch metric is shown to be nearly independent from the desired/undesired power ratio of a intersymbol interference channel. An approximate upper bound is analyzed for the proposed system, and the optimum code is searched.

This paper describes a vision system with dual viewing angles, i. e., wide and narrow viewing angles, and a scheme of user-friendly speech dialogue environment based on the vision system. The wide viewing angle provides a wide viewing field for wide range motion tracking, and the narrow viewing angle is capable of following a target in wide viewing field to take the image of the target with sufficient resolution. For a fast and robust motion tracking, modified motion energy (MME) and existence energy (EE) are defined to detect the motion of the target and extract the motion region at the same time. Instead of using a physical device such as a foot switch commonly used in speech dialogue systems, the begin/end of an utterance is detected from the movement of user's mouth in our system. Without recognizing the movement of lips directly, the shape variation of the region between lips is tracked for more stable recognition of the span of a dialogue. The tracking speed is about 10 frames/sec when no recognition is performed and about 5 frames/sec when both tracking and recognition are performed without using any special hardware.

In this paper, we present a lower bound for the dimension of subfield subcodes of residue Goppa codes on the curve Cab, which exceeds the lower bound given by Stichtenoth when the number of check symbols is not small. We also give an illustrative example which shows that the proposed bound for the dimension of certain residue Goppa code exceeds the true dimension of a BCH code with the same code length and designed distance.

A hybrid mo-demodulation approach, fully insensitive to the phase noise induced by the sources, is described for CDMA applications at optical frequencies. It is analytically demonstrated that, using bipolar codes in conjunction with polarisation modulation, the considered system can improve the performance of coherent schemes with not negligible laser linewidths, as well as the performance of more conventional noncoherent schemes based on intensity modulation and unipolar codes.

Minato has proposed canonical representation for polynomial functions using zero-suppressed binary decision diagrams (ZBDDs). In this paper, we extend binary moment diagrams (BMDs) proposed by Bryant and Chen to handle variables with degrees higher than l. The experimental results show that this approach is much more efficient than the previous ZBDDs' approach. The proposed approach is expected to be useful for various problems, in particular, for computer algebra.