For the channel estimation in the pilot channel aided CDMA systems which can support a multi-code scheme, we consider a linear prediction using both pilot and traffic channels. After deriving a new form of the optimal Wiener filter which requires less computational load, for its practical implementation, we propose the decision-directed adaptive linear prediction filter (DD-ALPF). To prevent from falling into the false lock, the proposed DD-ALPF uses the conventional channel estimate obtained only from pilot channel as a baseline for checking the reliability of the filter output. It will be shown through computer simulation that the proposed method can improve the receiver performance and performs better in the fast fading environments, compared with the existing ones.

The problem of calculating parasitic capacitances between two interconnects is investigated dedicatedly for liquid crystal displays, with the main focus put on the approximate expressions of the capacitances caused at the intersection and the parallel running of two interconnects. To derive simple and accurate approximate expressions, the interconnects in these structures are divided into a few basic coupling regions in such a way that the electro-magnetic field in each region can be calculated by a 2-D capacitance model. Then the capacitance in such a region is represented by a simple expression adjusted to the results computed by an electro-magnetic field solver. The total capacitance obtained by summing the capacitances in all regions is evaluated in comparison with the one obtained by using a 3-D field solver, resulting in a relative error of less than 5%.

Usually, paintings are more appealing than photographic images. This is because paintings can incorporate styles based on the artist's subjective view of motif. This style can be distinguished by looking at elements such as motif, color, shape deformation and brush texture. In our work, we focus on the effect of "color" element and devise a method for transforming the color of an input photograph according to a reference painting. To do this, we consider basic color category concepts in the color transformation process. We assume that color transformations from one basic color category to another may cause peculiar feelings. Therefore, we restrict each color transformation within the same basic color category. For this, our algorithm first categorizes each pixel color of a photograph into one of eleven basic color categories. Next, for every pixel color of the photograph, the algorithm finds its corresponding color in the same category of a reference painting. Finally, the algorithm substitutes the pixel color with its corresponding color. In this way, we achieve large but natural color transformations of an image.

A Java execution environment is implemented, in which a hardware engine is operated in parallel with an embedded processor. This pair of hardware facilities together with an additional software kernel are devised for existing embedded systems, so as to execute Java applications more efficiently in such a way that 39 instructions are added to the original Java Virtual Machine to implement the software kernel. The exploration of design parameters is also attempted to attain a low hardware cost and high performance. The proposed hardware engine of a 6-stage pipeline can be integrated in a single chip using 30 k gates together with the instruction and data cache memories. The proposed approach improves the execution speed by a factor of 5 in comparison with the J2ME software implementation.

This paper focuses on the realization of low spurious responses by various bandpass filters (BPFs) using open-ended λ/2 resonators. The first part of this paper gives the resonance characteristics of the open-ended λ/2 resonators when the excitation methods are chosen. Secondly, various BPFs obtained with our methodology are provided. For constructing the BPF, (1) point-coupled resonators, (2) comb-line resonators, (3) quasi comb-line resonators and (4) parallel-coupled resonators are used. It is verified that the presented BPFs can be used to obtain low spurious responses both theoretically and experimentally.

The Communications Research Laboratory (CRL) started a new project named the New Generation Mobile Network Project in April 2002. The target of this project is the development of new technologies to enable seamless and secure integration of various wireless access networks such as 3rd and 4th generation cellular, wireless LAN, high-speed mobile wireless, wired communications, and broadcasting networks. This paper presents an overview of CRL's new generation mobile communication system that is called The Multimedia Integrated Network by Radio Access Innovation Plus (MIRAI+), as well as details the role of Software Radio Technology (SDR) in MIRAI+.

In relation to the Software Defined Radio (SDR) concept, an experimental simulation system was developed. Likewise, verification tests were performed in order to validate the envisaged SDR certification processes including its development, certification, distribution, and software installation assuming the future possibility of exchanging the software in the field.

The detection performance of coherent OFDM receivers significantly depends on the accuracy of channel estimation. The accuracy of channel estimation can be improved by properly post-processing the channel estimate using a so-called channel estimation filter (CEF). Minimum mean-squared error (MMSE) filter is known optimum as the CEF, but it may not be practical due to its implementation complexity. We consider the use of a reduced-complexity CEF whose tap coefficient is real-valued and symmetrically weighted (RSW). The optimum RSW CEF is analytically designed using the SNR and multi-path intensity profile of the channel. For further improvement, we also propose a method to adapt the coefficient of the RSW CEF to the channel condition. Numerical results show that the proposed RSW CEF can provide channel estimation performance comparable to that of linear MMSE filter, while significantly reducing the computational complexity. In addition, the proposed RSW CEF can provide performance robust to unknown timing offset with a fractional dB loss compared to the optimum one.

In this paper, we propose a new predictive location management strategy that reduces the update cost while restricting the paging load optimized for mobiles roaming with traceable patterns. Enhanced with directional predictive capabilities offered by Kalman filtering, new update boundaries are assigned to better reflect the movement patterns of individual mobiles upon location registration. Thus, while complying with the required delay constraints, QoS measures such as throughput will not need to be sacrificed as a result of increasing update threshold. The contribution of this paper is two-fold: (1) to propose a distribution model that is capable of describing a wide range of movement patterns with varying correlation between traveling directions and (2) to show the capabilities (in terms of reliable performances) of the Kalman filter in predicting future movement patterns. Simulation results have successfully demonstrated the ability of the Kalman filter in assigning update boundaries capable of reflecting a mobile's roaming characteristics. The performance gains achieved mainly through a significant reduction in the number of updates indicate its potential for promoting better bandwidth conservation.

Multi-Code CDMA (MC-CDMA) can not only be integrated easily with a conventional CDMA system, but also achieve good spectral efficiency and high processing gain. MC-CDMA requires a linear amplifier due to the increasing value of its peak-to-average power ratio (PAPR) as the number of codes increases. As such, a multi-phased MC-CDMA (MP-CDMA) system is proposed to provide a variable rate service that is not susceptible to the nonlinear characteristics of an amplifier. A clipping technique is used between the output of a multi-code modulator and the input of an MPSK modulator to improve the performance of the MPSK chip demodulator and reduce the system's complexity. System performance is analyzed and compared with the number of codes and clipping levels. The optimum clipping level is also evaluated for the number of codes on both AWGN and flat fading channels.

It is expected that per-user customized services are widely used in next generation Personal Communication Network. To provide personalized services for each call, per-user service profiles are frequently referenced, so efficient service profile management is essentially required. To provide service profile based services, typically two schemes can be employed: One is Intelligent Network based Central scheme and the other is IMT-2000 based full replication scheme, we refer to as Follow-Me Replication Unconditional (FMRU). Since the Central scheme only depends on the service call rate and the FMRU is merely dependent on the movement rate, it is apparent that the FMRU scheme outperforms the Central scheme if the call-to-mobility ratio (CMR) is large, and vice versa. In this paper, we propose a new service profile replication schemes, Adaptive Follow-Me Replication Conditional (AFMRC) that determine replication automatically according to the user's varying CMR in real-time. We compared the performance of the AFMRC with the previous non-adaptive Follow-Me Replication Conditional (FMRC) scheme. Performance results indicate that as the CMR of a user changes, AFMRC adapts well compared to the existing schemes.

A special group of voice application services (VASs) are promising contents for wireless as well as wireline networks. Without a designated call admission policy, VAS calls are expected to suffer from relatively high probability of blocking since they normally require better signal quality than ordinary voice calls. In this letter, we consider a prioritized call admission design in order to reduce the blocking probability of VAS calls, which makes the users feel the newly-provided VAS in belief. The VAS calls are given a priority by reserving a number of channel-processing hardwares. With the reservation, the blocking probability of prioritized VAS calls can be evidently reduced. That of ordinary calls, however, is increasing instead. This letter provides a system model that counts the blocking probabilities of VAS and ordinary calls simultaneously, and numerically examines an adequate level of the prioritization for VAS calls.

This letter presents a lower bound and approximation for the coverage probability of the pilot channel that can be used for a CDMA downlink design. The approximation of a compound truncated Poisson distribution is used to obtain a closed form equation for the coverage probability of the pilot channel. Computer simulations show that our lower bound curve is truly less than the empirical curve, and our proposed approximation agrees well with the empirical result.

Some new differential input ideal differentiator and integrator function circuits using the current feedback amplifier (CFA) device are presented. The time constant (τo) is tunable by the control voltage (Vc) of a multiplier element connected appropriately around the feedback loop. The CFA device port errors () have insignificant effects on (τo). Test results based on hardware implementation and macromodel simulation are included; the proposed circuits exhibited good high frequency response with low phase errors (θe 2) upto about 450 kHz.

The performance of a mobile ad hoc network (MANET) is related to the efficiency of the routing protocol in adapting to changes in the network topology and the link status. However, the use of many different mobility models without a unified quantitative "measure" of the mobility has made it very difficult to compare the results of independent performance studies of routing protocols. In this paper, a mobility measure for MANETs is proposed that is flexible and consistent. It is flexible because one can customize the definition of mobility using a remoteness function. It is consistent because it has a linear relationship with the rate at which links are established or broken for a wide range of network scenarios. This consistency is the strength of the proposed mobility measure because the mobility measure reliably represents the link change rate regardless of network scenarios.

Recently, Zhu et al. proposed an password-based authenticated key exchange protocol based on RSA such that it is efficient enough to be implemented on most of the target low-power devices such as smart cards and low-power Personal Digital Assistants in wireless networks. They claimed that the proposed scheme is secure against dictionary attacks. In this paper, we show that the scheme proposed by Zhu et al. is insecure against undetectable on-line password guessing attacks. Furthermore, we examine Zhu et al.'s protocol and find that Zhu et al.'s protocol does not achieve explicit key authentication. An improved version is then proposed to defeat the undetectable on-line password guessing attacks and also provide explicit key authentication.

We propose and demonstrate a directly modulated AM-VSB CATV system employing split-band and optical vestigial sideband (VSB) modulation techniques. Systems' performance can be improved by using optical VSB modulation and split-band techniques simultaneously. Our proposed directly modulated transmission system is simpler and more cost-effective than conventional externally modulated transmission system because of external modulator and complicated stimulated Brillouin scattering (SBS)-suppression method are not required.

In this paper, an efficient optimization algorithm for solving the inverse problem of a two-dimensional lossless homogeneous dielectric object is investigated. A lossless homogeneous dielectric cylinder of unknown permittivity scatters the incident wave in free space and the scattered fields are recorded. Based on the boundary condition and the incident field, a set of nonlinear surface integral equation is derived. The imaging problem is reformulated into optimization problem and the steady-state genetic algorithm is employed to reconstruct the shape and the dielectric constant of the object. Numerical results show that the permittivity of the cylinders can be successfully reconstructed even when the permittivity is fairly large. The effect of random noise on imaging reconstruction is also investigated.

We have obtained high performance and low voltage driving OCB panel by reducing the critical voltage and retardation matching between liquid crystal layer and compensation films. Flattening color filter layer and optimizing rubbing process have minimized the critical voltage in the panel. In addition, an appropriate retardation of the film and LC layer has scanned to achieve low driving voltage and high transmission. Especially, by adopting new driving scheme, we considerably reduced the initial bend transition time, which is known as one of drawbacks in OCB mode. As a result, we developed the proto-type 17" WXGA OCB panel with less than 5 V drive, over 90% of TN light efficiency and over 80 degree for all viewing direction except for rubbing direction including color shift as well as high-speed response time.

The boundary element method (BEM), a representative method of numerical calculation of electromagnetic wave scattering, has been used for solving boundary integral equations. Using BEM, however, we finally have to solve a linear system of L equations expressed by dense coefficient matrix. The floating-point operation is O(L2) due to a matrix-vector product in iterative process. Greengard-Rokhlin's fast multipole algorithm (GRFMA) can reduce the operation to O(L). In this paper, we describe GRFMA and its floating-point operation theoretically. Moreover, we apply the fast Fourier transform to the calculation processes of GRFMA. In numerical examples, we show the experimental results for the computation time, the amount of used memory and the relative error of matrix-vector product expedited by GRFMA. We also discuss the convergence and the relative error of solution obtained by the BEM with GRFMA.