In this paper a digital frequency domain RFI (Radio Frequency Interference) cancellation scheme for DMT (Discrete Multitone) based VDSL (Very high speed Digital Subscriber Line) systems is presented. The proposed algorithm has been optimized and characterized in terms of complexity and performance. Optimizations were also performed from an implementation point of view by deducing key dependencies among our RFI model coefficients that let us drastically reduce the size of the memories involved. System simulations showed the effectiveness of the canceller: in terms of VDSL performance parameters such as bit rate, the optimized cancellation scheme recovers almost totally the performance degradation due to RFI.

In this paper, a joint adaptive interference canceller (AIC) and maximum likelihood (ML) decoder scheme is proposed for a space-time coded DS-CDMA system with the difference between arrival times from transmit antennas. As the arrival time difference causes not only ISI and MAI, but also inter-antenna interference, performance degradation in the space-time coded DS-CDMA system is more severe than that of a regular DS-CDMA system with single transmit antenna. To mitigate the effect of the interference during space-time decoding, a joint algorithm for the proposed scheme merges adaptation process of the AIC into a ML decoding algorithm. Performance of the proposed scheme is evaluated for QPSK space-time trellis codes with two transmit antennas. It is shown that the proposed scheme achieves better performance than the conventional ML decoding scheme.

To perform a high-speed measurement of a two-dimensional electric-field distribution, we developed an electric-field scanning system using a large-aperture electro-optic crystal and a laser-beam scanner. In the system, a two-dimensional electric-field image projected onto the crystal is read off using beam scanning through an electro-optic effect. With the imaging system, only 20 to 40 seconds are needed to obtain both millimeter-wave amplitude and phase images of a 20 30 mm area with a pixel spacing of 0.5 mm. We measured radiation patterns of a 10-GHz dipole antenna and compared them with simulation results to investigate a disturbance of the patterns inside the crystal. Profiles of a 120-GHz millimeter-wave beam were also measured to determine the effects of a dielectric lens used to focus the beam. Furthermore, we applied the system to imaging several objects with 180-GHz millimeter waves and experimentally showed that it is a valid means for a non-destructive inspection of hidden objects.

In order to increase the capacity of a DS-CDMA system, several kinds of interference suppression techniques have been studied, such as multiple access interference (MAI) cancellers and adaptive array antennas. However, their performance tends to degrade in high traffic-load situations. To compensate for the degradation, a receiver cascading an adaptive array antenna and a multistage parallel interference canceller (PIC) is studied in this paper. This receiver first uses an adaptive array antenna to suppress interference signals spatially, and uses a multistage PIC to suppress in-beam interference effectively. The performance of the cascaded receiver is evaluated with two schemes for antenna weight generation by computer simulations assuming a Rayleigh-distributed L-path channel. When antenna weights are generated for each user by an LMS algorithm, the cascaded receiver has shown better performance at the cost of a large number of pilot symbols and symbol by symbol weight update. Its performance degradation is 2.8 dB at the BER of 10-4 even when the number of users increases from one to 24. On the other hand, when antenna weights are generated for each path by a DMI algorithm, its performance is degraded due to the inaccurate weight generation which occurs when the SINR of the desired signal is small. This degradation can be mitigated by using all signals of the desired user received by all antenna patterns of desired user for RAKE combining when the difference among arrival angles of the paths of the desired user is small.

Discrete cosine transform (DCT) coding has been proven to be an efficient means of image compression coding. A lot of efforts have been made to improve the coding efficiency of DCT based coding. This paper presents an adaptive DCT coding based on geometrical edge representation. This scheme is designed to properly exploit the correlation between edge direction and distribution of DCT coefficients. Edges are extracted from original images first. Then, sub-optimal block-size and scanning order are determined at each block based on the extracted edges. In this way an adaptive DCT scheme taking account of local characteristics of image can be achieved. It is shown through the simulations that the proposed algorithm outperforms a conventional coding scheme in terms of coding efficiency by 10-15%.

The interconnection problem of binary circuits becomes seriously as the exponential growth of the circuits complexity has been driven by a combination of down scaling of the device size and up scaling of the chip size. Motivated by the problem, there is much research of circuits based on multiple-valued logic. On the other hand, caused by the signal propagation delay, there exist hazards in binary logic circuits. To analyze hazards in binary logic circuits, many multiple-valued logics have been proposed, and studied on their mathematical properties. The paper will discuss on a multiple-valued logic which is suitable for treating static hazards in multiple-valued logic circuits. Then, the paper will show that the prime implicants expressions of r-valued logic functions realize static hazards free r-valued logic circuits.

A minor component analysis approach based on the generalized sidelobe canceler is presented to realize the blind suppression of multiple-access interference in multicarrier code division multiple access systems. With a rough user-code and timing estimations, this proposed method of less computation performs the same as minimum mean square error detectors and outperforms existing blind detectors. Simulation results illustrate the effectiveness of the blind multiuser detection.

We propose a new detection method of a 2-dimensional pH image to measure the pH distribution of test materials by illuminating a frequency modulated light to LAPS using a chopping wheel. It could simultaneously measure signals in one line by applying a modulated light with a different frequency for each pixel, using a chopping wheel for modulating the frequency, and calculating an amplitude with respect to a frequency component by the light source. To test the proposed method, we implement a chopping wheel in consideration of a LAPS's characteristic, and reconstructed an image by frequency analysis using the implemented chopping wheel and 4 mm test pattern image. As a result, we verified that the proposed method using the chopping wheel was able to detect 30 times faster a 3030 pixels pH image having a PSNR more than 22 dB above the conventional method.

The authors have been interested in a Scanning Laser Microscope (SLM) and applied it to studies of contact phenomena. In particular, a digital SLM is being currently used, and confirmed to be a successful tool for investigating the contact phenomena. In this paper, the theory and mechanism of a digital SLM are briefly explained, and some actual data obtained with the digital SLM are presented for demonstrating its usefulness for studies of contact phenomena.

In recent years, sliding electric contacts came to be often used under very severe conditions such as high temperature, extremely low temperature, high vacuum, etc. Conventionally, solid lubricants having excellent properties in lubricating performance are generally used compositely with a metal of high electric conductivity, because of their high electrical resistivity. In the present study, we proved that more excellent sliding electrical contacts can be produced with a design made by controlling the distribution on contact surface of a solid lubricant having excellent lubricating performance and of a metal with high electric conductivity through expansion of Greenwood's theory.

In this paper, we propose a new computer-aided diagnosis system which can extract specific features from hematoxylin and eosin (HE)-stained breast tumor images and evaluate the type of tumor using artificial organisms. The gene of the artificial organisms is defined by three kinds of texture features, which can evaluate the specific features of the tumor region in the image. The artificial organisms move around in the image and investigate their environmental conditions during the searching process. When the target pixel is regarded as a tumor region, the organism obtains energy and produces offspring; organisms in other regions lose energy and die. The searching process is iterated until the 30th generation; as a result, tumor regions are filled with artificial organisms. Whether the detected tumor is benign or malignant is evaluated based on the combination of selected genes. The method developed was applied to 27 test cases and the distinction between benign and malignant tumors by the artificial organisms was successful in about 90% of tumor images. In this diagnosis support system, the combination of genes, which represents specific features of detected tumor region, is selected automatically for each tumor image during the searching process.

An automatic LSI package lead inspection system for backside lead specification is proposed. The proposed system inspects not only lead backside contamination but also the mechanical lead specification such as lead pitch, lead offset and lead overhangs (variations in lead lengths). The total inspection time of a UQFP package with a lead count of 256 is less than the required time of 1 second. Our proposed method is superior to the threshold method used usually, especially for the defect between leads.

In this letter, base station placement is automatically determined from pre-defined candidate sites using a genetic approach, and the transmit power is obtained taking the interference situation into account in cases of interference-dominant systems. In order to apply a genetic algorithm to the base station placement problem, a real-valued representation scheme is proposed. Corresponding operators such as crossover and mutation are also introduced. The proposed algorithm is applied to an inhomogeneous traffic density environment, where a base station's coverage may be limited by offered traffic loads. An objective function is designed for performing the cell planning in a coverage- and cost-effective manner.

In this paper, we discuss crosstalk equalization technique for high-speed digital transmission systems. This equalization technique makes use of the cyclostationarity of the crosstalk interferer. We first analyze the eigenstructure of the equalizer in the presence of cyclostationary crosstalk interference. It is shown that the eigenvalues of the equalizer depend upon the folded signal and interferer power spectra, and the cross power spectrum between the signal and the interferer. The expressions of the minimum mean square error (MMSE) and the excess MSE are then obtained by using the equalizer's eigenstructure. Analysis and simulation results indicate that such peculiar equalizer's eigenstructure in the presence of cyclostationary interference results in significantly different initial convergence and steady-state behaviors as compared with the stationary noise case. We also show that the performance of the equalizer varies depending on the relative clock phase of the symbol clocks used by the signal and the crosstalk interferer.

This paper describes a low-power-supply 2-GHz CMOS up-converter. A current-mode mixing method using current adding and self-switching mixers is proposed for 1-V operation. The current-mode up-converter achieves conversion gain of 6.7 dB and linearity of 6.5-dBm OIP3 at 1 V. Balanced configuration and DC offset canceller reduce LO leakage below -40 dBc even with 20-mV Vth mismatches. The bias circuit of the IC is designed to maintain constant conversion gain for variation of temperature for practical usage. The measurement results indicate the proposed up-converter is applicable for future wireless systems.

A slot pair array using a post-wall waveguide is a promising candidate for a Fixed Wireless Access (FWA) sector antenna to be used in a base station. This array is formed by a traveling wave antenna, and therefore its main beam direction varies with frequency. To overcome this difficulty, we propose a new structure that comprises of a cosecant array and an additional Talor array. This structure can fix the main beam in a constant direction whilst maintaining a cosecant radiation pattern. We conducted an investigation based on an array factor, and the validity of the method was confirmed by experiment.

In this paper, two types of multi-stage partial parallel interference cancellation (PIC) receivers are considered for multi-rate DS-CDMA system: multi-stage PIC receiver with partial cancellation factors and multi-stage PIC receiver with decision thresholds. Bit error rate (BER) of the multi-stage partial PIC receivers is obtained by simulation in a Rayleigh fading channel. It is shown that the multi-stage partial PIC receivers achieve smaller BER than the matched filter (MF) receiver, multi-stage PIC receiver, group-wise successive interference cancellation (GSIC) receiver, and extended GSIC receiver (EGSIC) for the multi-rate DS-CDMA system in a Rayleigh fading channel.

This paper proposes a multipath interference canceller (MPIC) employing multipath interference (MPI) replica generation (MIG) utilizing previously transmitted packet combining (PTPC), which is well-suited to incremental redundancy, in order to achieve a peak throughput of nearly 8 Mbps in a multipath fading environment in high-speed downlink packet access (HSDPA). In our scheme, more accurate MPI replica generation is possible by generating MPI replicas utilizing the soft-decision symbol sequence of the previously transmitted packets in addition to that of the latest transmitted packet. Computer simulation results elucidate that the achievable throughput of the MPIC employing MIG-PTPC is increased by approximately 100 kbps and 200 kbps and the required average received signal energy per symbol-to-background noise power spectrum density ratio (Es/N0) per antenna at the throughput of 0.8 normalized by the maximum throughput is improved by about 0.3 and 0.7 dB compared to that of the MPIC using the soft-decision symbol sequence after Rake combining of the last transmitted packet both in 2- and 3-path Rayleigh fading channels for QPSK and 16QAM data modulations, respectively. Furthermore, we clarify that the maximum peak throughput using the proposed MPIC with MIG-PTPC coupled with incremental redundancy achieves approximately 7 Mbps and 8 Mbps with 16QAM and 64QAM data modulations in a 2-path Rayleigh fading channel, respectively, within a 5-MHz bandwidth.

We study the influence of decoding order on the capacity of multimedia DS-CDMA system employing imperfect successive interference cancellation. We prove that the capacity is maximized by decoding users according to the ascending order of cancellation errors. We also prove that this capacity-optimal decoding order makes total residual interference minimum at the same time.

Interference Cancellation (IC) receivers can be used in CDMA cellular systems to improve the capacity. The IC receivers can be divided into two main categories, Single-User Detectors (SUD) and Multi-User Detectors (MUD). They have different characteristics in terms of intra-cell and inter-cell interference cancellation ability. In this paper we propose two new IC receivers that combines the properties of SUD and MUD receivers. The first one is a Serial IC receiver followed by the Normalized Griffiths' algorithm (SING). The second one is an Integrated Serial IC and Normalized Griffiths' algorithm (iSING). We first compare their basic single-cell performance with the conventional RAKE receiver, the Serial IC and the Normalized Griffiths' Algorithm. Next, we examine their multi-cell performance by doing multi-cell link-level simulations. The results show that even though the Serial IC receiver has good single-cell performance, the proposed receivers have as much as 35-40% higher capacity than the Serial IC receiver in the multi-cell case under the ideal conditions assumed in this paper.