DC offset causes performance degradation in signal processing systems especially for high-speed applications. A new offset cancellation method that relaxes the requirement for the offset of the circuit components in the differential analog data path to about 10 times larger is introduced. This method moves the adjusting target from analog-to-digital converter (ADC) to its input buffer and adjusts DC level of ADC input to its center before the final offset cancellation. It eliminates post-production adjustment such as fuse trimming, which increases the cost and TAT in manufacturing and testing. Execution and simulation times are shortened down to 1/9 for less settling time in buffer and with improved logic. An automatic quick offset calibration circuit is implemented in a small silicon space in a high-speed hard disk drive (HDD) channel with 0.25-µm four-layer metal CMOS process. The measured data show this method works effectively in this system.

The presence of a new surface-wave-like mode on CPWs of infinite width produces a complex transition region at the onset of leakage, involving the unusual simultaneous combination of a coupling region and a spectral gap. An examination of this region leads to a clear physical explanation of why sharp minima occur in the leakage behavior.

The applicability of composite materials containing laminar solid lubricants to sliding contacts was studied. Performances of several composite materials prepared by incorporating solid lubricants with the basic alloys of the Cu-Nb system and Cu-Sn system were investigated to test the suitability of the composite materials as sliding contacts. As a result, it was clarified that the composite materials based on Cu-Sn alloy were superior to those based on Cu-Nb alloy and those containing only WS2 and not MoS2 were more effective in reducing both the contact resistance and the coefficient of friction. Based on the relationship between the contact resistance and the coefficient of friction obtained in this experimental study, the author proposed a new model for electric contact of composite materials.

This paper presents a novel approach to pixel decimation for motion estimation in video coding. Early techniques of pixel decimation use regular pixel patterns to evaluate matching criterion. Recent techniques use adaptive pixel patterns and have achieved better efficiency. However, these adaptive techniques require an initial division of a block into a set of uniform regions and therefore are only locally-adaptive in essence. In this paper, we present a globally-adaptive scheme for pixel decimation, in which no regions are fixed at the beginning and pixels are selected only if they have features important to the determination of a match. The experiment results show that when no more than 40 pixels are selected out of a 1616 block, this approach achieves a better search accuracy by 13-22% than the previous locally-adaptive methods which also use features.

In this paper, we suggest the interference cancellation (IC) technique suitable for turbo coded code division multiple access (CDMA) systems, that merges IC processes into turbo decoding processes to improve system performance and reduce system complexity. To ensure the reliability of the temporary decision bits for cancellation, we use cyclic redundancy code (CRC) check as a measure. Prior to design turbo coded CDMA system, we first derive the optimized polynomials of low-rate turbo codes appropriate to CDMA systems. According to the simulation results with setting the processing gain (PG) to 120, the turbo coded CDMA system with the proposed IC technique can accommodate 60 users over additive white Gaussian noise (AWGN) channel when signal to noise ratio (SNR) is about 2. 5 dB and required frame error ratio (FER) is 10-2. Compared this result with the performance of single user's system, it requires only additional 1 dB SNR.

In this paper, we describe the implementation of the proposed single user type CDMA adaptive interference canceller (AIC) with RAKE structure in the developed testbed for the base station, and evaluate its performance in the multiuser and multipath fading environment. Laboratory experiment demonstrates that the AIC receiver is much more near-far resistant than the conventional matched filter (MF) receiver in the multiuser case. When the power of the other users is 6 dB larger than that of the desired user, the AIC receiver can achieve the BER of 10-3 at C/PG = 33. 3 % in the 2-path fading channel, while the MF receiver cannot achieve the BER at C/PG of more than 20. 8%. Furthermore, we evaluate the effect of transmission power reduction in the transmitter with transmission power control (TPC). The experimental result shows that the required transmission power can be greatly reduced by 3. 0 dB and 9. 2 dB with the AIC receiver at C/PG = 29. 2 % and 33. 3%, respectively.

This paper proposes a scalable multiecho cancellation system based on multiple autonomic and distributed echo canceler units. The proposed system does not have any common control section. Distributed control sections are equipped with in multiple echo cancelers operating autonomically. Necessary information is transferred from one unit to the next one. When the number of echoes to be canceled is changed, the necessary number of echo canceler units, each of which may be realized on a single chip, are simply plugged in or unplugged. The proposed system also provides fast convergence thanks to the novel coefficient location algorithm which consists of flat-delay estimation and constrained tap-position control. The input signal is evaluated at each tap to determine when to terminate flat-delay estimation. The number of exchanged taps is selected larger in flat-delay estimation than in constrained tap-position control. The convergence time with a colored-signal input is reduced by approximately 50% over STWQ, and 80% over full-tap NLMS algorithm. With a real speech input, the proposed system cancels the echo by about 20 dB. Tap-positions have been shown to be controlled correctly.

In this paper, we propose a multiple access technique using a simple interference canceller for common code transmission. In the proposed system, we adopt a common code for a receiver oriented system. All the transmitters utilize the same pseudo noise (PN) code to communicate with a receiver. Here the receiver structure becomes very simple with only one matched filter (MF). The proposed system has two very important merits. One is to avoid packet collisions by means of an interference cancellation method based on a common code chip shift transmission technique. That is, in order to avoid interference, which occurs because all the received signals have the same PN code, the same data with different timing are transmitted in two channels. In this study, we define and evaluate three types of packet collision which can be reduced by the canceller. The other merit is to reduce the system degradation due to the correlation side-lobes by means of a side-lobe canceller. In spread spectrum (SS) communication systems with PN codes like M-sequences, the correlation side-lobes appear at the detector in the case of the polarity data changing from 1 to 1 . The side-lobes degrade the system quality. Therefore in this system a interference canceller operates to cancel the correlation side-lobes and attempts to reduce the system degradation. Finally, by our cancellation method it becomes possible to realize a simple multiple access using only one PN code under the condition of a receiver oriented system without a base station.

In this paper, we propose an adaptive lattice-transversal joint (LTJ) filter structure that is quite suitable for the practical implementation of the acoustic echo canceller. The structure maintains fast convergence of the lattice structure and low computational complexity of the transversal structure simultaneously. It is particularly more efficient in memory usage than any other existing fast-convergent algorithm for the acoustic echo cancellation.

In our current work, we attempt to make an automatic diagnostic system of lung cancer based on the analysis of the sputum color images. In order to form general diagnostic rules, we have collected a database with thousands of sputum color images from normal and abnormal subjects. As a first step, in this paper, we present a segmentation method of sputum color images prepared by the Papanicalaou standard staining method. The segmentation is performed based on an energy function minimization using an unsupervised Hopfield neural network (HNN). This HNN have been used for the segmentation of magnetic resonance images (MRI). The results have been acceptable, however the method have some limitations due to the stuck of the network in an early local minimum because the energy landscape in general has more than one local minimum due to the nonconvex nature of the energy surface. To overcome this problem, we have suggested in our previous work some contributions. Similarly to the MRI images, the color images can be considered as multidimensional data as each pixel is represented by its three components in the RGB image planes. To the input of HNN we have applied the RGB components of several sputum images. However, the extreme variations in the gray-levels of the images and the relative contrast among nuclei due to unavoidable staining variations among individual cells, the cytoplasm folds and the debris cells, make the segmentation less accurate and impossible its automatization as the number of regions is difficult to be estimated in advance. On the other hand, the most important objective in processing cell clusters is the detection and accurate segmentation of the nuclei, because most quantitative procedures are based on measurements of nuclear features. For this reason, based on our collected database of sputum color images, we found an algorithm for NonSputum cell masking. Once these masked images are determined, they are given, with some of the RGB components of the raw image, to the input of HNN to make a crisp segmentation by assigning each pixel to label such as Background, Cytoplasm, and Nucleus. The proposed technique has yielded correct segmentation of complex scene of sputum prepared by ordinary manual staining method in most of the tested images selected from our database containing thousands of sputum color images.

The phase and frequency commands of a rotating radar system, that utilizes the frequency scanning and phase shifters to steer the beam in the azimuth and elevation directions, respectively, are derived in terms of the angles of the ground based coordinate system. The frequency equation derived is approximated to a simple form to reduce the calculation time for real time multi-function radar systems. It is shown that the approximate frequency commands are in good agreement with the exact ones if the range of the azimuth scanning is not too wide.

This paper discusses a design technique for multidimensional (M-D) multirate filters which cause no checkerboard distortion. In the first part of this paper, a necessary and sufficient condition for M-D multirate filters to be checkerboard-distortion-free is derived in the frequency domain. Then, in the second part, this result is applied to a scanning line conversion system for television signals. To confirm the effectiveness of the derived condition, band-limiting filters with and without considering the condition are designed, and the results by these filters are compared. A reducibility of the number of delay elements in such a system is also considered to derive efficient implementation.

Direct sequence code division multiple access (DS-CDMA) is attractive for mobile radio use because of its inherently high capacity. There is great demand for mobile radio to offer multimedia services. This means that various service rates and qualities should be supported. DS-CDMA systems are flexible and can accommodate various user rates easily so these demands can be met. As many users will occupy the same frequency band simultaneously, the traffic capacity of a DS-CDMA system is determined by interference power. Interference cancellation is one of the important techniques in decreasing interference power at the demodulation stage and thus increasing traffic capacity. In this paper, we propose the delayed symbol combining interference canceller which can suppress the interference from various users sending at different information rates. Performance of the proposed method is calculated by computer simulations. Furthermore, the effect of adding forward error correction to the proposed canceller is also evaluated by computer simulations. In the quasi static flat fading environment, it is found that the Eb/No degradation due to interference is suppressed to 3 dB at BER=10-3 with 24 users. In the quasi static frequency selective fading environment, it is found that the required Eb/No of the frequency selective fading canceller is about 11 dB better than that of the flat fading canceller for the target BER of 10-3. It is found that BER<10-3 is achieved with forward error correction and bit interleaving even when the maximum Doppler frequency normalized by low data bit rate is 0. 0008 and Eb/No is 20 [dB] in frequency selective fading and 30 [dB] in flat fading.

The Future Public Land Mobile Telecommunication Systems (FPLMTS) standards have made it quite clear that in the near future, the capability in doing wireless data transmission will become necessary in order to make the tether-free use of multimedia applications possible. CDMA is considered the most appropriate and probable radio access method of FPLMTS for its high capacity and flexibility in accommodation of multimedia and variable rate users. In order to further increase the capacity of CDMA system, several techniques have been studied and proposed such as an interference canceller and adaptive array antenna. We propose the novel multi-user detection type interference cancellation technique named SRIC (Symbol Ranking type IC) in this paper. SRIC is very feasible for its small amount of operation compared with other multi-user detection type ICs and can be added to a base station with slight alteration according to the requirement of higher capacity. The performance of SRIC depends on the method of calculating the likelihood. We studied three methods. In order to reduce the operations, we tried to propose two more methods. We confirmed that SRIC can make the system capacity about three times greater than that of a conventional RAKE receiver. We also confirmed that SRIC can be reduce its operations very much at some sacrifice of their performance. There are nine variants of SRIC, which have a trade off between performance and amount of operation. We can choose one of them which is most fit to our requirement. The first operation of SRIC is common with that of a conventional RAKE receiver. Therefore, SRIC can be introduced to conventional systems afterwards by inserting the interference canceller block which functions replica generation, removal, and ranking between output of a RAKE receiver and FEC decoder.

We present a high-level synthesis scheme that considers weak testability of generated register-transfer level (RTL) data paths, as well as their area and performance. The weak testability, proposed in our previous work, is a testability measure of RTL data paths for non-scan design. In our scheme, we first extract a condition on resource sharing sufficient for weak testability from a data flow graph before synthesis, and treat the condition as design objectives in the following synthesis tasks. We propose heuristic synthesis algorithms which optimize area and the design objectives under the performance constraint.

In this paper, we propose several novel methods to decrease propagation error for multiple access interference cancellation techniques in asynchronous DS/CDMA. To increase spectral efficiency, the system wherein transmitting signal power of each user is assigned with exponential law and multiple access interference successive cancellation is used in the receiver has been discussed. However, when the number of active users is increased, propagation error occurs in the receiver. Thus, the improvement effect of spectral efficiency in the system has been degraded. In this paper, we propose novel methods to decrease these propagation errors for the system. These novel methods are quasi-maximum likelihood method that means maximum likelihood in considering the signal of the next user when the signal of the arbitrary user is demodulated, feedback method that means the demodulation error of the stronger users in transmitting signal power is estimated after several users, demodulations and the error is corrected, and combination method that is a combination of quasi-maximum likelihood method and feedback method. And we evaluate their performances by computer simulation and show that the combination method is effective for the reduction of the propagation error.

We will present a partial scan design method based on n-fold line-up structures in order to achieve high fault efficiency and reduce test pattern generation time for practical LSIs. We will also present a partial scan design method based on the state justification of pure load/hold FFs in order to achieve high fault efficiency and reduce the number of scan FFs for practical LSIs with lots of load/hold FFs. Experimental results for practical LSIs show that our presented methods can achieve high fault efficiency (more than 99%) and reduce the number of scan FFs for the LSI with lots of load/hold FFs.

To further increase the capacity of the DS-CDMA reverse-link, this paper investigates the effectiveness of interference rejection weight control (IRWC) for the pilot symbol-assisted coherent multistage interference canceller (PSA-COMSIC) using recursive channel estimation (RCE). First, a bit error rate (BER) expression of the serial (successive) and parallel type hard decision multistage interference canceller (MSIC) with IRWC using Gaussian approximation for multiple access interference (MAI) are presented for no fading channels. It is theoretically shown that IRWC is effective in mitigating the interference replica generation error in hard decision MSIC. Next, the BER performance of PSA-COMSIC using IRWC in a multipath Rayleigh fading channel when channel coding is applied is evaluated by computer simulations. The BER performance and capacity are evaluated not only for the conventional serial and parallel types but also for serial/parallel (S/P) hybrid type and non-linear/linear (N/L) hybrid type schemes, both of which are effective in significantly reducing the demodulation processing delay. The simulation results demonstrate that, in interference-limited channels where the back ground noise is negligible, the capacity of serial type PSA-COMSIC using IRWC is about 10% higher than that without IRWC. It is also found that if we can accept a slight capacity degradation compared to the serial type PSA-COMSIC, S/P hybrid schemes are effective in reducing the demodulation processing delay.

Co-channel interference is a major deteriorating factor limiting the capacity of mobile communication systems. To mitigate the effect of the interference, a kind of nonlinear interference canceller named trellis-coded co-channel interference canceller (TCC) has been proposed. In TCC the trellis-coded modulation (TCM) is introduced to both the desired signal and the interference signal in order to enhance the cancelling performance. In this paper, the bit error rate (BER) performance of TCC in static channel is theoretically evaluated for the first time. An equivalent TCM (E-TCM) model is firstly established, and a BER asymptotic estimate (AE) and a BER upper bound (UB) of TCC are then evaluated respectively by analyzing E-TCM. In the evaluation of AE, the BER performance is calculated as a function of phase difference between the desired signal and the interference signal (φ), subsequently the average BER performance over φ can be evaluated. The UB of BER is calculated using a transfer function based on the matrix representation. This paper also demonstrates that AE gives higher accuracy and less calculation complexity than UB. Performance comparisons reveal the consistency of these theoretical results with that of computer simulations.

It is important to test the various kinds of interconnect faults between chips on a card/module. When boundary scan design techniques are adopted, the chip to chip interconnection test generation and application of test patterns is greatly simplified. Various test generation algorithms have been developed for interconnect faults. A new interconnect test generation algorithm is introduced. It reduces the number of test patterns by half over present techniques. It also guarantees the complete diagnosis of multiple interconnect faults.