We propose a soft decision Viterbi decoding scheme and a self-interference cancellation method applicable to a Parallel Combinatory CDMA (PC-CDMA) system. In this decoding scheme, branch metric is calculated for every bit by weighting the output levels of the PC-CDMA correlators so as to enable an effective soft decision capability to the system. The effectivity of this scheme is then further enhanced by the use of a simple pseudo-random bit interleaving scheme. Moreover, to increase the capacity of the PC-CDMA system, we propose a simple self-interference cancellation method for self-induced cross-correlation arising from the multipath environment. This further enhances the efficacy of the decoding scheme because the false contributions of the self-induced cross-correlation component are removed from the branch metric prior to soft decision Viterbi decoding. Finally, we simulated a possible PC-CDMA system with a user data rate of 1.92Mbps, transmitting it at a chip rate of 3.84Mcps and at 7.68Mcps under a multipath-Rayleigh fading interference environment. For a chip rate of 7.68Mcps, BER after Viterbi decoding is less than 3.2e-7 even without the use of interference cancellation. For a chip rate of 3.84Mcps, BER after Viterbi decoding with interference cancellation is 1.0e-4.

Spectral transform methods have been widely studied for classification and analysis of logic functions. Spectral methods have also been used for logic synthesis, and by use of BDDs, practical-sized synthesis problems have been solved. Wavelet theory has recently attracted the attention of researchers in the signal processing field. The Haar function is used in both spectral methods and in signal processing to obtain spectral coefficients of logic functions of signals. In this paper spectral transform-based analysis of neural nets verifying signal processing and discrete function is presented. A neural net element is defined as a discrete function with multi-valued input signals and multi-valued or binary outputs. The multi-valued variable is realized as a variable (V, W) formed by a pair of a binary value and a multi-value pulse width. The multi-valued encoding is used with the multi-valued Haar function to give meanings to the wavelet coefficients from the view of Boolean algebra. A design example shows that these conceptually different concepts are closely related.

We propose a new scanning method for image signals using a tree structure of automata. The tree is scanned selectively along the signal path for realizing both lower power consumption and a kind of image compression by skipping nonactive elements. We designed the node automata along with photo-detectors of 3232 in a 7.2 mm7.2 mm chip using a 1.5µm CMOS technology. We demonstrate applications of the tree structure using its feature of selective activation; a moving picture compression using inter-frame difference, an adaptive resolution scan like human eyesight and a motion compensation as examples.

Recently several dosimetric assessment procedures have been proposed to demonstrate the compliance of handheld mobile telecommuications equipment (MTE) with safety limits. However, for none of these procedures has an estimation of the overall uncertainty in assessing the maximum exposure been provided for a reasonable cross-section of potential users. This paper presents a setup and procedure based on a high-precision dosimetric scanner combined with a new phantom derived from an anatomical study. This allows the assessment of the maximum spatial peak SAR values occurring in approximately 90% of all MTE users, including children, with a precision of better than 25%. This setup and procedure therefore satisfies the requirements of the FCC, as well as those drafted by a CENELEC working group mandated by the European Union.

In this paper, a block implementation of high-speed IIR adaptive noise canceller is proposed. First, the block difference equation of an IIR filter is derived by the difference equation for high-speed signal processing. It is shown that the computational complexity for updating the coefficients of IIR adaptive filter can be reduced by using the relations between the elements of coefficient matrices of block difference equation. Secondly, the block implementation of IIR adaptive noise canceller is proposed in which the convergence rate is increased by successively adjusting filter Q-factors. Finally, the usefulness of proposed block implementation is verified by the computer simulations.

This paper describes the design and evaluation of fully scannable embedded memory arrays. A memory array, such as a register file, is made scannable by adding a small auxiliary circuit including a counter and multiplexers. Plural memory arrays can be chained into a single scan path along with ordinary flip-flops. Detailed configuration and implementation of the scannable CMOS and bipolar LCML register file macros are discussed. The overhead ratio of the CMOS register file macro with 16-word by 16-bit results in an 8.6% transistor count and a 6.4% die area. The access time overhaead is 7.8% and the set-up time increases by about 50ps. Bipolar LCML register file macros have been applied to gate array LSIs which have successfully achieved average stuck-at fault coverage of 99.2%.

We have developed and operated a newly conceived multiprobe scanning force microscope (SFM) using microfabricated piezoelectric cantilevers. An array of piezoelectric microcantilevers with a piezoelectric ZnO layer on an SiO2 film makes it possible to build a multiprobe SFM system. Multiprobe SFMs are required for the application of SFM to the probe lithography and high density data storage. Each cantilever probe of multiprobe system should have a detector for sensing of its own deflection and an actuator for positioning of its tip. The piezoelectric cantilever can detect its own vibration amplitude by measuring the piezoelectric current, and it can also drive its tip by applying a voltage to the piezoelectric layer. Therefore, the piezoelectric cantilever is suitable for each cantilever of the array in the multiprobe SFM. We have verified the applicability of the piezoelectric cantilever to each lever of the array by characterizing the sensitivities of the deflection sensing and actuation. The ZnO piezoelectric cantilever with the length of 125 µm works as the z scanner with the sensitivity of 20 nm/V. We have also fabricated an experimental piezoelectric microcantilever array with ten cantilevers. We have constructed parallel operation SFM system with two cantilevers of the fabricated array and successfully obtained parallel images of 1 µm pitch grating in constant height mode.

A new magnetostrictive thin-film cantilever actuator and a new thin-film walking mechanism were developed. The actuators were made of magnetostrictive amorphous Tb-Fe and Sm-Fe thin films, deposited on the opposite sides of a polyimide film substrate. These actuators need not power supply cables because they were remotely driven by external magnetic fields. The static deflection of a 3-mm-long cantilever actuator was as large as 100 µm at 300 Oe field. Moreover the application of ac resonant frequency field of the same intensity yielded deflection of above 500 µm. The walking mechanism ran as fast as in the order of cm/s. The forward and backward running were possible depending on the frequency of applied magnetic field. Such unique characteristics suggest that magnetostrictive thin-film actuators are useful in MEMS applications.

This paper presents a method of multiple fault diagnosis in sequential circuits by input-sequence pairs having sensitizing input pairs. We, first, introduce an input-sequence pair having sensitizing input pairs to diagnose multiple faults in a sequential circuit represented by a combinational array model. We call such input-sequence pair the sensitizing sequence pair in this paper. Next, we describe a diagnostic method for multiple faults in sequential circuits by the sensitizing sequence pair. From a relation between a sensitizing path generated by a sensitizing sequence pair and a subcircuit, the proposed method deduces the suspected faults for the subcircuits, one by one, based on the responses observed at primary outputs without probing any internal line. Experimental results show that our diagnostic method identifies fault locations within small numbers of suspected faults.

In this letter, a theoretical estimation of pick-up characteristics of the fiber probe of Photon Scanning Tunneling Microscopy based on the Wiener-Hopf technique taken account of the weakly guiding approximation are reported. As a result, it is found that diffracted waves by the extremity of the fiber probe mainly act on the mode excitation rather than transmitted waves, then the pick-up characteristics are well accordance with typical experiments quality and quantity.

When wireless multi-media information which includes speech, image, data and so on are transmitted, the defference in information rate, required quality as well as traffic performance should be taken into account. A wireless spread spectrum system can achieve a flexible balance of these differences because of the inherent asynchronous capability of CDMA. In this paper, we propose a wireless multi-media CDMA system based on a processing gain control in a dynamic traffic channel. According to the priority of each medium and channel measurement information i.e. traffic, the optimal processing gain can be controlled by using Nonlinear Programming. Numerical results demonstrate that the proposed method possesses higher flexible capacity than TDMA in a dynamic multi-medea traffic channel.

In this paper, a multiuser receiver using a Hopfield network (Hopfield network receiver) for asynchronous codedivision multiple-access systems is proposed. We derive a novel likelihood function for the optimum demodulation of a data subsequence whose length is far shorter than that of the entire transmitted data sequence. It is shown that a novel Hopfield network receiver can be derived by exploiting the likelihood function, and the derived receiver leads to a low complexity receiver. The structure of the proposed receiver consists of a bank of correlators and a Hopfield network where the number of units is proportional to both the number of users and the length of a data sequence demodulated at a time. Computer simulation results are presented to compare the performance of the proposed receiver with those of the conventional multiuser detectors. It is shown that the proposed receiver significantly outperforms the correlation receiver, decorrelating detector and multistage detector, and provides suboptimum performnace.

In this paper, the bit error rate (BER) considering tracking performance is evaluated, by theoretical analysis and computer simulation, for a bi-orthogonal system using a synchronizing pseudo-noise (PN) sequence and co-channel interference cancellers. A system that improves on Tachikawa's system is proposed. It is found that the optimum ratio of the information signal energy to the synchronizing signal energy varies with Eb/No, and the canceller is better for small L than for large L (L = length of the sequence). Moreover, it is found that the BER considering synchronization performance improvse as the equivalent noise bandwidth Bn decreases.

New interference cancellation technique using time division reference signal is proposed for optical synchronous code-division multiple-access (CDMA) systems with modified prime sequence codes. In the proposed system one user in each group is not allowed to access the network at each time, and this unallowable user's channel is used as a reference signal for other users in the same group at the time. The performance of the proposed system using an avalanche photodiode (APD) is analyzed where the Gaussian approximation of the APD output is employed and the effects of APD noise, thermal noise, and interference for the receiver are included. The proposed cancellation techniqus is shown to be effective to improve the bit error probability performance and to alleviate the error floor when the number of users and the received optical power are not appreciably small.

In this letter, we propose a blind adaptive receiver with nonlinear structure for DS/CDMA communication systems. The proposed receiver requires the signature waveform and timing for only the desired user. It is shown that the blind adaptation is equivalent to the adaptation with the training signal and the function to be minimized has no local minima.

This paper evaluates the performance of DS/CDMA with diversity coding and multiuser interference (MUI) cancellation in fading multipath channel. The diversity technique considered in this paper, is different from the conventional scheme and transmits different information over different channels. It is shown that, this diversity scheme performs better than conventional diversity scheme, and when combined with MUI cancellation provides significant performance improvement. Effects of partial band jamming on the system are also considered.

An approach to design for testability using register-transfer level (RTL) partial scan selection is described. We define an RTL circuit model which enables efficient description in an electronic system design automation (ESDA) tool and testability analysis which leads to effective partial scan selection for RTL design including data path circuits and control circuits such as state machines. We also introduced a method of partial scan selection at RTL which selects critical registers and state machines based on RTL testability analysis. DFT techniques using gate level testability measures have been studied and concluded that they are not successful in achieving high fault coverage [15]. However, we started this work for the following reasons, 1) In sequential ATPG procedure, more than two memory elements belonging to a functional units such as registers and state machines are often required to be justified at a time. At RTL, state machines and registers are explicitly described and recognized as functional units while gate level memory elements are scattered over the circuit. 2) As discussed in [6], if the circuit is modified so that the test sequence which causes state transition between initial and final states of sequential ATPG can be easily obtained, ATPG results can be also improved. Complex state machines can be identified at RTL. According to the experimental results, our gate level DFT achieves high fault coverage comparable with the previously published most successful DFT methods, and DFT at RTL resulted in higher fault coverage than gate level DFT at much shorter CPU time.

A pilot symbol-assisted coherent multistage interference canceller (PSA-COMSIC) using recursive channel estimation is proposed for DS-CDMA mobile radio cellular systems. In the proposed scheme, since the channel variation due to fading is recursively estimated at each interference canceling stage, the accuracy of channel estimation is successively improved. The bit error rate (BER) performances against average Eb/N0 (signal energy per bit-to-noise power spectral density ratio) and capacity in the isolated cell are investigated by computer simulations. The simulations demonstrate that the capacity using the PSA-COMSIC with recursive channel estimation is about 1.6 times higher than that of the conventional matched filter receiver with channel coding and bit-interleaving in the interference-limited environments.

We have proposed a concept of low power drive system for a multi-media TFT-LCD using MFD in which a displayed image is divided into some interlaced subfield images and the number of interlaced subfields can be changed depending on the moving quantities of displayed images. This method has been applied to a 9.5" TFT-LCD and successful operation has been confirmed without moving image degradation.

This paper proposes a fast timing recovery method with a decision feedback equalizer for baudrate sampling. The proposed method features two special techniques. The first one is for coarse estimation of the sampling phase. Internal signals of the oversampled analog-to-digital converter at different phases are directly taken out for parallel evaluation. The second technique provides fine tuning with a phase-modification stepsize which is adaptively controlled by the residual intersymbol interference. Simulation results by a full-duplex digital transmission system with a multilevel line code show superiority of the proposed method. The coarse timing estimation and the fine tuning reduce 75% and 40% of the time required by the conventional method,respectively. The overall saving in timing recovery is almost 60% over the conventional method. The proposed method could easily be extended to other applications with a decision feedback equalizer.