For on-chip matching Si-MMIC fabricated on a conventional low resistivity Si substrate, the loss of on-chip inductors is quite high due to the dielectric loss of the substrate. In order to reduce the loss of on-chip matching circuit, the use of high resistivity Si substrate is quite effective. By using electro-magnetic simulation, the relationship between coplanar waveguide (CPW) transmission line characteristics and the resistivity of Si substrate is discussed. Based on the simulated results, the resistivity of Si substrate is designed to achieve lower dielectric loss than conductor loss. The effectiveness of high resistivity Si substrate is evaluated by the extraction of equivalent circuit model parameters of the fabricated on-chip spiral inductors and the measurement of the fabricated on-chip matching Si-MMIC LNA's.

Mobile communication channels always suffer serious frequency-selective fading due to multipath effect. Traditional spreading codes are characterized by the fact that their time-domain orthogonality is based on fixed chip width across a code period. They often fail to perform well under frequency-selective fading. This paper proposes a new class of CDMA codes, wavelet-packet orthogonal codes capable to retain time-domain orthogonality as well as to offer intra-code subband diversity to mitigate frequency-selective fading. The new codes are constructed by congregating several wavelets with various dilations and shifts. The combination of the wavelets in different nodes in a wavelet-packet full binary tree enables frequency diversity capability. Owing to the even code length, they can be easily used in mobile communications for multi-rate streaming and multi-code spreading. The performance study is carried out using correlation statistics distribution convolution algorithm and the results reveal that wavelet-packet codes, combined with RAKE receiver, perform better than traditional spreading codes in frequency-selective fading channels.

Recently the effect of the angular spread caused by locally scattered signals in the vicinity of the mobile has received considerable attention. This paper proposes the Extended Array Mode Vector (EAMV) which represents the Instantaneous Angular Spread (IAS) as well as the Instantaneous Direction Of Arrival (IDOA) of the received signal at the Base Station (BS). Using the EAMV, MUSIC algorithm is generalized in order that it is possible to estimate both the IDOA and the IAS. In computer simulations, the estimates of the IDOA and the IAS in the fading situation are evaluated. The results show that the estimates for small angular spread agree well with the given values and demonstrate the validity of the proposed approach.

This paper describes a biometric-based key generation method and its application to a secure communication system. In the proposed method, a personal key which is unique to each user is generated by extracting his/her biometric information. Using the generated personal key, a secure communication system which has the functions of confidentiality and user authentication is realized. As an example of the proposed method, we introduce a personal key generation method based on one's handwriting, and a secure telewriting system which enables the encryption of handwriting information as well as the authentication of a writer. Some simulation results indicate the possibility of realizing the above functions by using a writer's personal key.

This paper proposes a fast algebraic codebook search for DSVD applications. In this method, the codebook search is simplified by reducing the number of possible position combinations using a mean-based track threshold multiplied by heuristically determined optimum threshold factor. And, to guarantee a complexity requirement of DSVD, the maximum number of searching position combinations is limited to 320. The proposed method reduced computational complexity considerably, compared with G.729 with a slight degradation of SNR. Particularly, it shows better speech quality with lower complexity than G.729A.

In this paper we propose a learning algorithm to enhance the fault tolerance of feedforward neural networks (NNs for short) by manipulating the gradient of sigmoid activation function of the neuron. We assume stuck-at-0 and stuck-at-1 faults of the connection link. For the output layer, we employ the function with the relatively gentle gradient to enhance its fault tolerance. For enhancing the fault tolerance of hidden layer, we steepen the gradient of function after convergence. The experimental results for a character recognition problem show that our NN is superior in fault tolerance, learning cycles and learning time to other NNs trained with the algorithms employing fault injection, forcible weight limit and the calculation of relevance of each weight to the output error. Besides the gradient manipulation incorporated in our algorithm never spoils the generalization ability.

In this paper, we propose an adaptive video frame rate control method, called AFCON, that video encoders use in conjunction with explicit rate based congestion control in the network. First, an encoder buffer constraint which guarantees the end-to-end delay of video frames is derived under the assumption of bounded network transmission delay for every frame data. AFCON is based on the constraint and consists of future channel rate prediction, frame discarding, and frame skipping. Recursive Least-Squares (RLS) is used to predict the low-frequency component of the channel rate. Frame discarding prevents the delay violation of frames due to the prediction error of the channel rate. Frame skipping adapts the encoder output rate to the channel rate while avoiding abrupt quality degradation during the congestion period. From the simulation results, it is shown that AFCON can adapt to the time-varying rate channel with less degradation in temporal resolution and in PSNR performance compared to the conventional approach.

An accurate automatic personal identification is critical to a wide range of application domains such as access control, electronic commerce, and welfare benefits disbursement. Traditional personal identification methods (e.g., passwords, and PIN) suffer from a number of drawbacks and are unable to positively identify a person. Biometrics refers to automatic identification of an individual based on her distinct physiological and/or behavioral traits. While biometrics is not an identification panacea, it is beginning to provide very powerful tools for a variety of new applications (e.g., cellular phones, smart cards and international border control) requiring positive identification. This paper attempts to summarize important research issues in biometrics.

This paper presents a scale invariant face detection and classification method which uses shift invariant features extracted from a Log-Polar image. Scale changes of a face in an image are represented as shift along the horizontal axis in the Log-Polar image. In order to obtain scale invariant features, shift invariant features are extracted from each row of the Log-Polar image. Autocorrelations, Fourier spectrum, and PARCOR coefficients are used as shift invariant features. These features are then combined with simple classification methods based on Linear Discriminant Analysis to realize scale invariant face detection and classification. The effectiveness of the proposed face detection method is confirmed by experiments using face images captured under different scales, backgrounds, illuminations, and dates. To evaluate the proposed face classification method, we performed experiments using 2,800 face images with 7 scales under 2 different backgrounds and face images of 52 persons.

This paper presents a new approach to modeling speech spectra and pitch for text-independent speaker identification using Gaussian mixture models based on multi-space probability distribution (MSD-GMM). MSD-GMM allows us to model continuous pitch values of voiced frames and discrete symbols for unvoiced frames in a unified framework. Spectral and pitch features are jointly modeled by a two-stream MSD-GMM. We derive maximum likelihood (ML) estimation formulae and minimum classification error (MCE) training procedure for MSD-GMM parameters. The MSD-GMM speaker models are evaluated for text-independent speaker identification tasks. The experimental results show that the MSD-GMM can efficiently model spectral and pitch features of each speaker and outperforms conventional speaker models. The results also demonstrate the utility of the MCE training of the MSD-GMM parameters and the robustness for the inter-session variability.

Space division multiple access (SDMA) is an attractive technique to increase the channel capacity of wireless communication systems. In this paper, we first propose a new process to accomplish SDMA using an adaptive array at a base station receiver of broadband fixed wireless access (FWA) systems. Unlike other methods, the proposed process does not need highly accurate direction-of-arrival (DOA) estimation and is suitable to Directionally Constrained Minimization of Power (DCMP) algorithm in order to serve multiple fixed terminals. A newly modified DCMP with phase only control is proposed as well. The algorithm to control phase weights, uses only the array output power and does not require the complex baseband signals from individual array elements. The pattern measurement results in an anechoic chamber show that the proposed algorithm can direct a null to an interference while maintaining the gain to the desired signal.

Filtering and smoothing using a non-Gaussian state space model are proposed for motion trajectory of feature point in image sequence. A heavy-tailed non-Gaussian distribution is used for measurement noise to reduce the effect of outliers in motion trajectory. Experimental results are presented to show the usefulness of the proposed method.

The model to calculate high frequency C-V characteristics of ferroelectric capacitors that have not been modeled yet is presented. At first, P-V hysteresis model necessary to calculate C-V characteristics is improved by introducing two modification factors and by comparing with experimental results. Then, other parameters to express high frequency C-V characteristic of the metal/ferroelectric/metal structure are derived, in which the response for AC signal input is considered. Finally, it has been shown that these models predict well the C-V hysteresis shapes of the MFIS and the MFMIS structures.

A low loss magnetic plate positioned near an antenna is proposed to increase radiation efficiency of cellular phones. This magnetic plate is used to control the nearby magnetic field around the cellular phone's antenna, and this field controlling is shown to be effective for the improvement of radiation efficiency and far-field pattern. As for the material design of the plate, a magnetic plate having high µr and low µr" (complex relative permeability: µr = µr - j µr") is found to be effective for achieving high performance. In our sample fabrication, a low loss magnetic sample with µr = 5.7 - j 0.7 at 900 MHz is realized. It is demonstrated that this low loss sample contributes to increased efficiency and improved far-field characteristics.

This paper proposes an automatic system which can perform the entire diagnostic process from the extraction of the liver to the recognition of a tumor. In particular, the proposed technique uses shape information to identify and recognize a lesion adjacent to the border of the liver, which can otherwise be missed. Because such an area is concave like a bay, morphological operations can be used to find the bay. In addition, since the intensity of a lesion can vary greatly according to the patient and the slice taken, a decision on the threshold for extraction is not easy. Accordingly, the proposed method extracts the lesion by means of a Fuzzy c-Means clustering technique, which can determine the threshold regardless of a changing intensity. Furthermore, in order to decrease any erroneous diagnoses, the proposed system performs a 3-D consistency check based on three-dimensional information that a lesion mass cannot appear in a single slice independently. Based on experimental results, these processes produced a high recognition rate above 91%.

This letter presents a method which attempts to minimize the number of spill codes to resolve usage conflicts of distributed registers in application specific DSPs. It searches for a set of ordering restrictions among operations which sequentialize the lifetimes of the values residing in the same register as much as possible. Experimental results show that the proposed analysis method reduces the number of register spills into 28%.

This paper reviews device technologies of flash memories, whose market has grown explosively due to the advantages of: (1) their low cost provided by availability of the single-transistor type cell with adoption of block-erase operation; (2) high functionality as electrically erasable and programmable non-volatile memories; and (3) high reliability with the mature floating gate technology. As for fast-random-access flash memories, their scaling issue, including a multi-level-cell technology, is discussed, and technologies for low power consumption, which is highly demanded for mobile electronic equipment, their major application, are described. Furthermore, device technologies of serial-access flash memories, which have achieved low cost with cell-size reduction, are also reviewed. Finally, a future promising technology of the NROM concept, which achieves a multi-storage-cell with low voltage operation and a simple process, is introduced.

This paper proposes an LDMOSFET (Lateral Double-diffused MOSFET) that has the robustness against the hardest ESD (Electrostatic Discharge) requirement for automobile ECUs (Electronic Control Units) of discharging 25 kV 150 pF through 150 ohm 1 µH without external protecting circuits. The basic idea to achieve this is to add a novel discharge circuit to an LDMOSFET, which turns on when Human Body Model (HBM) type ESD is applied, and to consume the discharge energy in SOA (Safe Operating Area) in the LDMOSFET, avoiding localized current crowding of a parasitic bipolar transistor which causes the conventional ESD device failure. First, dynamics of current crowding when a grounded gate LDMOSFET is exposed to ESD stress is described by means of a circuit level SPICE simulation on a parallel distributed device model. Then a novel ESD turn-on LDMOSFET with a discharge MOSFET is proposed, which has ESD robustness of 25 kV. Finally the ESD measurements of the new device are shown to be in good accordance with estimation and to satisfy the target.

We have developed a new scheme to provide Diffserv-based QoS over ATM access networks. Well-known Diffserv over ATM scheme requires some extension for conventional routers with ATM interfaces. The routers must map their Diffserv classes of services into ATM QoS classes and forward IP packets into prioritized VCs based on DSCP (DiffServ Code Point). The purpose of this work is to provide Diffserv-based QoS over ATM network using conventional IP over ATM interfaces on routers. We propose DSCP snooping at ATM edge nodes, which differentiates services over a single VC between two IP domains. A prototype circuit was used to evaluate this scheme.

In this paper, we survey the fairness issues in the congestion control mechanisms of TCP, which is one of most important service aspects in the current and future Internet. We first summarize the problems from a perspective of the fair service among connections. Several solution methods are next surveyed. Those are modifications of TCP congestion control mechanism and router support for achieving the fair service among TCP connections. We finally investigate the fair share of resources at endhosts.