Performance of band-limited baseband synchronous CDMA using orthogonal Independent Component Analysis (ICA) spreading sequences is investigated. The orthogonal ICA sequences have an orthogonality condition in a synchronous CDMA like the Walsh-Hadamard sequences. Furthermore, these have useful correlation properties like the Gold sequences. These sequences are obtained easily by using the ICA which is one of the brain-style signal processing algorithms. In this study, the ICA is used not as a separator for received signal but as a generator of spreading sequences. The performance of the band-limited synchronous CDMA using the orthogonal ICA sequences is compared with the one using the Walsh-Hadamard sequences. For limiting bandwidth, a Root Raised Cosine filter (RRC) is used. We investigate means and variances of correlation outputs after passing the RRC filter and the Bit Error Rates (BERs) of the system in additive white Gaussian noise channel by numerical simulations. It is found that the BER in the band-limited system using the orthogonal ICA sequences is much lower than the one using the Walsh-Hadamard sequences statistically.

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This paper investigates whether the self-heating effect in short intra-block wires will become apparent with technology scaling. These wires seem to have good thermal radiation characteristics, but we validate that the self-heating effect in local signal wires will be greater than that in optimal repeater-inserted global wires. Our numerical experiment shows that the maximum temperature increase from the silicon junction temperature will reach 40.4°C in a steady state at a 14-nm process. Our attribution analysis also demonstrates that miniaturizing the area of wire cross-section exacerbates self-heating as well as using low-κ material and increased power dissipation in advanced technologies below 28nm. It is revealed that the impact of self-heating on performance in local wires is limited, while underestimating the temperature may cause an unexpected reliability failure.

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In the nanometer era, the power integrity problem has become one of the critical issues. Although checking this problem earlier can speed up the analysis, not so many tools are available now due to the limited design information at high levels. Most existing approaches at gate level require extra information of the cell library, which may require extra characterization efforts while migrating to new cell libraries. Therefore, an analytical approach is proposed in this paper to dynamically estimate the supply current waveforms at gate level using existing library information only, even for sequential circuits. The experimental results have shown that the estimation errors of such a quick approach are only 10% compared to HSPICE results.

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This paper proposes an efficient fingerprint recognition algorithm combining phase-based image matching and feature-based matching. In our previous work, we have already proposed an efficient fingerprint recognition algorithm using Phase-Only Correlation (POC), and developed commercial fingerprint verification units for access control applications. The use of Fourier phase information of fingerprint images makes it possible to achieve robust recognition for weakly impressed, low-quality fingerprint images. This paper presents an idea of improving the performance of POC-based fingerprint matching by combining it with feature-based matching, where feature-based matching is introduced in order to improve recognition efficiency for images with nonlinear distortion. Experimental evaluation using two different types of fingerprint image databases demonstrates efficient recognition performance of the combination of the POC-based algorithm and the feature-based algorithm.

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Many learning machines that have hierarchical structure or hidden variables are now being used in information science, artificial intelligence, and bioinformatics. However, several learning machines used in such fields are not regular but singular statistical models, hence their generalization performance is still left unknown. To overcome these problems, in the previous papers, we proved new equations in statistical learning, by which we can estimate the Bayes generalization loss from the Bayes training loss and the functional variance, on the condition that the true distribution is a singularity contained in a learning machine. In this paper, we prove that the same equations hold even if a true distribution is not contained in a parametric model. Also we prove that, the proposed equations in a regular case are asymptotically equivalent to the Takeuchi information criterion. Therefore, the proposed equations are always applicable without any condition on the unknown true distribution.

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An efficient noise reduction algorithm is proposed to improve speech recognition performance for human machine interfaces. In the algorithm, a probabilistic adaptation mode controller (AMC) is designed and adopted to the generalized sidelobe canceller (GSC). To detect target speech intervals, the proposed AMC calculates the inter-channel correlation and estimates speech absence probability (SAP). Based on the SAP, the adaptation mode of the adaptive filter in the GSC is decided. Experimental results show the proposed algorithm significantly improves speech recognition performances and signal-to-noise ratios in real noisy environments.

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We propose two methods for avoiding the checkerboard distortion which is caused by finite word length error. The first method derives the bit length of filter coefficients required for avoiding the checkerboard distortion under a certain word length. In the second method, the checkerboard distortion can be avoided by using the cascade structure which consists of zero-hold kernel and a time-invariant filter factorized from a filter with structure for avoiding the checkerboard distortion under linear systems. It is demonstrated by simulations that we can avoid the checkerboard distortion by using these proposed methods.

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In this Letter, we explore semi-definite relaxation (SDR) program for finding the real roots of a real polynomial. By utilizing the square of the polynomial, the problem is approximated using the convex optimization framework and a real root is estimated from the corresponding minimum point. When there is only one real root, the proposed SDR method will give the exact solution. In case of multiple real roots, the resultant solution can be employed as an accurate initial guess for the iterative approach to get one of the real roots. Through factorization using the obtained root, the reminding real roots can then be solved in a sequential manner.

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A method to construct Boolean functions with maximum algebraic immunity have been proposed in [1]. Based on that method, we propose a different method to construct Boolean functions on even variables with maximum algebraic immunity in this letter. By counting on our construction, a lower bound of the number of such Boolean functions is derived, which is the best among all the existing lower bounds.

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Antenna selection is a practical way to decrease system complexity and the hardware cost of radio frequency (RF) chains in multiple input multiple output (MIMO) system. In this study, we give a simple characterization of the optimal diversity and multiplexing tradeoff (DMT) curve of the MIMO system with antenna subset selection at both the transmitter and the receiver for Rayleigh fading channel.

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In this letter, we propose an integer carrier frequency offset (IFO) estimator in the presence of symbol timing error for an ultra-wideband multi-band orthogonal frequency division multiplexing (UWB MB-OFDM) system. The proposed IFO estimator uses frequency-domain spreaded data symbol which is provided in the MB-OFDM system. To demonstrate the accuracy of the proposed IFO estimator, comparisons are made with conventional estimators via computer simulation.

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This paper considers the use of an antenna selection mechanism to reduce the cost of multiple analog transmit/receive chains in multiple-input multiple-output (MIMO) systems. With the optimal antenna selection scheme, radio-frequency chains can optimally connect with the best subset of transmitter and/or receiver antennas. However, the optimal antenna selection algorithm requires an exhaustive search of all possible combinations to find the optimum subset at the transmitter and/or receiver, thus resulting in high complexity. In order to reduce the computational load while still maximizing channel capacity, we introduce the simulated annealing (SA) method, an effective algorithm that solves various combinatorial optimization problems, to search the optimal subset. The simulation results show that the performance of the proposed SA method provides almost the same channel capacity as that of the optimal exhaustive search algorithm while maintaining low complexity.

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A stochastic quasi-gradient algorithm is applied to design linear dispersion (LD) codes for two-way wireless relay networks under Rayleigh fading channels. The codes are designed to minimize an upper bound of the average pairwise error probability. Simulation results show that the codes obtained by the optimization technique achieve a coding gain over codes that are randomly generated based on the isotropic distribution.

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The rate-distortion optimization (RDO) method in the H.264/AVC encoder is an informative technology that improves the coding efficiency, but increases the computational complexity. In this letter, a fast Intra mode decision algorithm using DCT (Discrete Cosine Transform) coefficients distribution is proposed to reduce the H.264 encoder complexity. The proposed method reduces the encoder complexity on average 63.44%, while the coding efficiency is slightly decreased compared with the H.264/AVC encoder.

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This study employs a simple measurement methodology that is based on the de-convolution of a square test stimulus to measure the transmission characteristics of the human body channel in an electrostatic-coupling intra body communication system. A battery-powered square waveform generator was developed to mimic the electrostatic-coupling intra body communication system operating in the environment of the ground free. The measurement results are then confirmed using a reliable measuring method (single tone) and spectral analysis. The results demonstrate that the proposed measurement approach is valid for up to 32.5MHz, providing a data rate of over 16Mbps.

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