This paper proposes an adaptive noise canceller with low signal-distortion in the presence of crosstalk. The proposed noise canceller has two pairs of cross-coupled adaptive filters, each of which consists of the main filter and a sub filter. The signal-to-noise ratios (SNRs) of the primary and the reference signals are estimated by the sub filters. To reduce signal distortion at the output of the adaptive noise canceller, the step sizes for coefficient adaptation in the main filters are controlled according to the estimated SNRs. Computer simulation results show that the proposed noise canceller reduces signal distortion in the output signal by up to 15 dB compared to the conventional noise canceller.

In this paper, we propose an adaptive encoding method of fixed codebook in CELP coders and implement an adaptive fixed code-excited linear prediction (AF-CELP) speech coder as a low-bit-rate extension to the 8 kbit/s CS-ACELP. The AF-CELP can be implemented at low bit rates as well as low complexity by exploiting the fact that the fixed codebook contribution to the speech signal is periodic, as is the adaptive codebook (or pitch filter) contribution. Listening tests show that the 6.4 kbit/s AF-CELP has a comparable quality to the 8 kbit/s CS-ACELP under real environmental test conditions.

In the conventional antenna system for the handset, some gain degradation has been observed when an operator holds the handset. This is caused by the variation of the current on the conducting box used in the handset due to the body effect. This paper presents (1) design concept of antenna for the handset and (2) analysis of a newly proposed loop antenna system, which has the balance structure for the antenna feed to reduce the effect of currents on the conducting box. In order to confirm the effectiveness of using the balance-fed loop antenna, a simple model using a small loop antenna mounted on a ground plane is analyzed. The current distribution for the balance-fed loop antenna system is obtained calculatedly and also experimentally and is compared with that for the unbalance-fed loop antenna system. In a result, remarkable decrease in the current distribution on the ground plane for the case of the balance-fed antennas system is shown. Calculated results are in good agreement with measured results.

In microwave hyperthermia for cancer therapy, two power feeding techniques can be utilized: incoherent and coherent operations. In the incoherent operation, not-synchronized microwave power is fed into each array element, whereas the coherent operation is achieved by feeding synchronized microwave to the array elements. The authors have been studying the coaxial-slot antenna for interstitial microwave hyperthermia. The antenna is usually employed as an array applicator inserting several antennas into the tissue to generate large heating area. So far we have examined the control of the heating pattern by feeding techniques in order to obtain more uniform and enlarged heating region. Particularly, `tip-heating,' which means sufficient heating at the area near the tip of the applicator, is significant not to damage surrounding normal tissue in interstitial hyperthermia. In this paper, two feeding techniques are combined and calculated temperature distributions in a hexagonal array applicator are examined by solving Pennes bioheat transfer equation by finite difference method. As a result, in the coherent feeding, large heating area was obtained, while better tip-heating was achieved in the incoherent feeding. Moreover, an instance of sequential combination of two feeding techniques is depicted. In this case, temperature distribution had both characteristics of large heating area and tip-heating, therefore the ability of the control of heating characteristics by sequential combination of the coherent and the incoherent feedings was presented.

One effective way to make a large-capacity mobile communication system is to use a microcellular system. One way to do this is to place the base station antennas lower than the surrounding buildings. This result in what is called a street microcellular system. We previously presented basic simulation results evaluating the performance of a different-sized cell combination algorithm (DCC) designed to avoid the problems due to an unbalanced distribution of traffic in street microcellular systems. In this paper, we present the results of simulations evaluating the performance of an improved active different-sized cell combination method (ADCC) that controls the transmission power of each base station.

An efficient algorithm for reconstructing all polyhedral 3D objects from two orthographic views is presented. Since the two-view orthographic representation of a 3D object is ambiguous, it requires a numerous amount of combinatorial searches in the process of reconstruction. Also, multiple number of solutions in contrast to the designers intention can be existed in the problem. This paper proposes a two phase algorithm to reduce the search space and to select the most plausible solution described by the given projections. First, the partially constructed objects are reconstructed from the restricted candidate faces corresponding to each area on the two-view drawings in its first phase. Then the complete objects are obtained from the partially constructed objects by adding other candidates with geometrical validity in the second phase. The algorithm performs a combinatorial search based on the face decision rules along with two heuristics. Decision rules check geometrical validity and heuristic rules enhance the search speed. In addition, the reconstruction finds the most plausible 3D object that human observers are most likely to select first among the given multiple solutions. Several examples from a working implementation are given to show the completeness of the algorithm.

The onboard antenna beam forming network (BFN) of the next-generation communication satellites must offer multiple beam forming and beam steering. The conventional BFN, which directly controls the array elements, is not suitable for a large-scale array antenna because of the difficulty of BFN control. This paper proposes a new BFN configuration that consists of three/four-way variable power dividers and a Butler matrix (FFT circuit). This BFN can offer continuous beam steering with fewer variable components. By introducing new techniques based upon excluding FFT periods and power evaluations by definite integration, the deviation in beamwidth is reduced by 75% or more and the maximum sidelobe level is improved by 10 dB or more.

The architecture design and test results of simulation facility named millimeter-wave Test Bed has been described. Contrast with a millimeter-wave sounder, the Test Bed proposed in this paper can characterize radio channels, received signals, target reflections and radio link performance at the millimeter-wave band of 60 GHz. For fixible simulation and analysis of the performances of newly designed millimeter-wave systems, major digital signal processing parts like a sophisticate waveform generator and an analyzer, a modulator, a demodulator, an encoder, a decoder, an equalizer in the Test Bed are implemented by a software using SPW. This software based Test Bed can be used as a "deign tool" for the simulation of the millimeter-wave communication systems very flexibly without hardware modification in different specifications. The Test Bed consists of a millimeter-wave transmitter, a receiver of 60 GHz, 1.95 GHz up/down converter as IF module and a digital signal processing module. The I/Q vector modulator and demodulator with a video bandwidth of 37.5 MHz in the Test Bed can simulate or test the application of high data rate communication systems of short distance.

In this paper, we present a simple codeword length generation algorithm and its hardware implementation. The proposed technique is based on the dividing the Huffman table as two parts; with leading 0'bits and following bits. The method is shown to be efficient in the memory requirement and searching speed since only logic gates are needed in the implementation and searching can be process parallel without looking up the memory table. The total equivalent gates for the implementation are about only 100 gates and critical path delay is 10 ns. The results of experiments show that the proposed algorithm has a very high speed and a good performance. The designed blocks are synthesized by Compass synthesis with 0.5 µm CMOS, 3.3V, technology.

In this paper, we investigate the bit error rate (BER) performance of Direct Sequence-Code Division Multiple Access (DS-CDMA) systems under impulsive radio noise environments, and propose a novel DS-CDMA receiver which is designed to be robust against impulsive noise. At first, employing the Middleton's Class-A impulsive noise model as a typical model of impulsive radio noise, we discuss the statistical characteristics of impulsive radio noise and demonstrate that the quadrature components of impulsive noise are statistically dependent. Next, based on the computer simulation, we evaluate the BER performance of a conventional DS-CDMA system under a Class-A impulsive noise environment, and illustrate that the performance of the conventional DS-CDMA system is drastically degraded by the effects of the impulsive noise. To deal with this problem, motivated by the statistical dependence between the quadrature components of impulsive radio noise, we propose a new DS-CDMA receiver which can eliminate the effects of the channel impulsive noise. The numerical result shows that the performance of the DS-CDMA system under the impulsive noise environment is significantly improved by using this proposed receiver. Finally, to confirm the effectiveness of this proposed receiver against actual impulsive radio noise, we evaluate the BER performance of the DS-CDMA system employing the proposed receiver under a microwave oven (MWO) noise environment and discuss the robustness of the proposed receiver against MWO noise.

The intermediate language (IL) modularizes a compiler into target processor independent and dependent parts, called the front-end and the back-end. By adding a new back-end, it is possible to port existing software from one processor to another. This paper presents a new efficient approach to achieve multiple targeting to quite different architectures using different processors as well, by translating from one IL into other existing ILs. This approach makes it possible to reuse existing back-ends. It has been successfully applied to a commercial-scale project for porting public switching system software. Since the target ILs were not predictable in advance, we provided an abstract syntax tree (AST) with attributes accessible by abstract data type (ADT) interface to convey the source language information from our front-end to back-ends. It was translated into several ILs that were developed independently. These translations made the compiler available in a very short time for different cross-target platforms and on several workstations we needed. The structure of this AST and the mapping to these ILs are presented, and retargeting cost is evaluated.

This letter proposes an efficient implementation method for a binary feedback switch, called EFCI/RELAY, which can reduce the feedback delay of the congestion status of a switch in multiple-hop network environments. At each transit switch, this method relays the EFCI-bit contained in an incoming data cell to the head-of-line cell with a corresponding VC which is waiting for transmission in the output buffer. Simulation results show that the proposed method can achieve a lower queue length while maintaining a higher link utilization.

The rosette-scanning infrared seeker (RSIS) is a tracker that a single infrared detector scans the total field of view (TFOV) in a rosette pattern, and then produces 2D image about a target. Since the detected image has various shapes in accordance with the target position in the TFOV, it is difficult to determine a precise target position from the obtained image. In order to track this type of target, therefore, we propose an efficient tracking method using the K-means algorithm (KMA). The KMA, which classifies image clusters and calculates their centers, is used to cope with an countermeasure (CM) such as an IR flare. To evaluate the performance of the RSIS using the KMA dynamically, we simulate the RSIS in the various conditions, and discuss the tracking results.

Secret information stored in a tamperfree device is revealed during the decryption or signature generation processes due to fault-based attack. In this paper, based on the coding approach, we propose a new fault-resistant system which enables any fault existing in modular multiplication and exponentiation computations to be detected with a very high probability. The proposed method can be used to implement all crypto-schemes whose basic operations are modular multiplications for resisting both memory and computational fault-based attacks with a very low computational overhead.

In this paper, we introduce a lower bound for the generalized Hamming weights, which is applicable to arbitrary linear code, in terms of the notion of well-behaving. We also show that any [n,k] linear code C over a finite field F is the t-th rank MDS for t such that g(C)+1 t k where g(C) is easily calculated from the basis of Fn so chosen that whose first n-k elements generate C. Finally, we apply our result to Reed-Solomon, Reed-Muller and algebraic geometry codes on Cab, and determine g(C) for each code.

We introduce an extended EZW coder that uses flexible zerotree coding of wavelet coefficients. A flexible parent-child relationship is defined so as to exploit spatial dependencies within a subband as well as hierarchical dependencies among multi-scale subbands. The new relationship is based on a particular statistics that a large coefficient is more likely to have large coefficients in its neighborhood in terms of space and scale. In the flexible relationship, a parent coefficient in a subband relates to four child coefficients in the next finer subband in the same orientation. If each of the children is larger than a given threshold, the parent extends its parentship to the neighbors close to its conventional children. A probing bit is introduced to indicate whether a significant parent has significant children to be scanned. This enables us to avoid excessive scan of insignificant coefficients. Also, produced symbols are re-symbolized into simple variable-length binary codes to remove some redundancy according to a pre-defined rule. As a result, the wavelet coefficients can be described with a small number of binary symbols. This binary symbol stream gives a competitive performance without an additional entropy coding and thus a fast encoding/decoding is possible. Moreover, the binary symbols can be more compressed by an adaptive arithmetic coding. Our experimental results are given in both binary-coded mode and arithmetic-coded mode. Also, these results are compared with those of the EZW coder.

A device simulator that simulates device performance in the cyclic bias steady state was developed, and it was applied to GaAs hetero-junction FET (HJFET) pulse pattern effect. Although there is a large time-constant difference between the pulse signals and deep trap reactions, the simulator searches the cyclic bias steady states at about 30 iterations. A non-linear shift in the drain current level with the mark ratio was confirmed, which has been estimated from the rate equation of electron capture and emission based on Shockley-Read-Hall statistics for deep traps.

The full-band Monte Carlo technique is currently the most accurate device simulation method, but its usefulness is limited because it is very CPU intensive. This work describes efficient algorithms in detail, which raise the efficiency of the full-band Monte Carlo method to a level where it becomes applicable in the device design process beyond exemplary simulations. The k-space is discretized with a nonuniform tetrahedral grid, which minimizes the discretization error of the linear energy interpolation and memory requirements. A consistent discretization of the inverse mass tensor is utilized to formulate efficient transport parameter estimators. Particle scattering is modeled in such a way that a very fast rejection technique can be used for the generation of the final state eliminating the main cause of the inefficiency of full-band Monte Carlo simulations. The developed full-band Monte Carlo simulator is highly efficient. For example, in conjunction with the nonself-consistent simulation technique CPU times of a few CPU minutes per bias point are achieved for substrate current calculations. Self-consistent calculations of the drain current of a 60nm-NMOSFET take about a few CPU hours demonstrating the feasibility of full-band Monte Carlo simulations.

This paper reports the evaluation results of the channel boron distribution in the deep sub-0.1 [µm] n-MOSFETs for the first time. It has been found that the boron depletion effect becomes dominant and the reverse short channel effect becomes less significant in the deep sub-0.1 [µm] n-MOSFETs. It has been also found that the sheet charge distribution responsible for the reverse short channel effect is localized within a distance of 100 [nm] from the source/drain-extension junction.

This paper presents a method of calculating an interval including a bifurcation point. Turning points, simple bifurcation points, symmetry breaking bifurcation points and hysteresis points are calculated with guaranteed accuracy by the extended systems for them and by the Krawczyk-based interval validation method. Taking several examples, the results of validation are also presented.