• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.11
• /
• pp.2108-2113
• /
• 2010

The Long Term Evolution (LTE) system is based on the Orthogonal Frequency Division Multiplexing (OFDM) and relies its channel estimation on the lattice-type pilot samples in the multipath fading channel environment. The estimation of the channel frequency response (CFR) makes use of the least squares estimate (LSE) for each pilot samples, followed by an interpolation both in time- and in frequency-domain to fill up the channel estimates for subcarriers corresponding to data samples. Any interpolation scheme could be adopted for this purpose. Depending on the requirements of the target system, we may choose a simple linear interpolation or a sophisticated one. For any choice of an interpolation scheme, these is a trade-off between estimation accuracy and numerical cost. For those wireless communication systems based on the OFDM and the preamble-type pilot structure, the DFT-based channel estimation and its variants have been successfully. Yet, it may not be suitable for the lattice-type pilot structure, since the pilot samples are not sufficient to provide an accurate estimate and it is known to be sensitive to the location as well as the length of the time-domain window. In this paper, we propose a simple interpolated based on the upsampling mechanism in the multirate signal processing. The proposed method provides an excellent alternative to the DFT-based methods in terms of numerical cost and accuracy. The performance of the proposed technique is verified on a multipath environment suggested on a 3GPP LTE specification.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.442-447
• /
• 2005

This paper presents an application of overlapping-grid technique for probe feeding simulation. The overlapping grid technique is used to solve contour path problem. In this technique, field interpolation is very important to make communication between two coordinates. By applying overlapping-grid technique, error of contour path in probe feeding simulation is reduced.

• Journal of Mechanical Science and Technology
• /
• v.14 no.1
• /
• pp.84-92
• /
• 2000

A new bounce back boundary method of the second order in error is proposed for the lattice Boltzmann fluid simulation. This new method can be used for the arbitrarily irregular lattice geometry of a non-slip boundary. The traditional bounce back boundary condition for the lattice Boltzmann simulation is of the first order in error. Since the lattice Boltzmann method is the second order scheme by itself, a boundary technique of the second order has been desired to replace the first order bounce back method. This study shows that, contrary to the common belief that the bounce back boundary condition is unilaterally of the first order, the second order bounce back boundary condition can be realized. This study also shows that there exists a generalized bounce back technique that can be characterized by a single interpolation parameter. The second order bounce back method can be obtained by proper selection of this parameter in accordance with the detailed lattice geometry of the boundary. For an illustrative purpose, the transient Couette and the plane Poiseuille flows are solved by the lattice Boltzmann simulation with various boundary conditions. The results show that the generalized bounce back method yields the second order behavior in the error of the solution, provided that the interpolation parameter is properly selected. Coupled with its intuitive nature and the ease of implementation, the bounce back method can be as good as any second order boundary method.

• The Journal of the Korea Contents Association
• /
• v.14 no.4
• /
• pp.9-18
• /
• 2014

Recently, many researches have been focused on multi-view video applications and services such as wireless video surveillance networks, wireless video sensor networks and wireless mobile video. In multi-view video signal processing, to exploit the strong correlation between images acquired by different cameras plays great role in developing a core technique of multi-view video coding. This paper proposes an adaptive multi-view video interpolation technique which is applicable for multi-view distributed video coding without requiring any cooperation amongst the cameras. The proposed algorithm estimates the non-linear moving blocks and employs disparity compensated view prediction, and then fills in the unreliable blocks. Through computer simulations, it is shown that the proposed method outperforms the conventional methods.

• The Journal of the Korea Contents Association
• /
• v.12 no.3
• /
• pp.1-8
• /
• 2012

Video FRUC (Frame Rate Up Conversion) has been a technique of great interest due to its diversified applications in consumer electronics. Most advanced FRUC algorithms adopt a motion interpolation technique to determine the motion vector field of interpolated frames. But, in some applications, it is necessary to evaluate how well the MCI (Motion Compensated Interpolation) frame is reconstructed. For this aim, this paper proposes a distortion estimation for motion compensated interpolation frame using frame-adaptive distortion estimation. The proposed method is applied for the symmetric motion estimation and compensated scheme and then analyzed by three different approaches, that is, forward estimation, backward estimation and adaptive bi-directional estimation schemes. Through computer simulations, it is shown that the proposed bi-directional estimation method outperforms others and can be effectively applied for FRUC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.9
• /
• pp.906-913
• /
• 2004

FFT algorithm is the most popular ISAR imaging technique from radar data. It requires polar formatting technique to make a focused image of the target as MTRC(Moving Through Resolution Cell) causes a blurred image when the data is from the wide azimuth angle. But there exits the angle limit for the application of the polar formatting and we cannot obtain clear images if the range of the azimuth angle is too wide to process with polar, formatting. This paper analyses the relative merits of the polar formatting algorithm accompanied by interpolation to the CDT algorithm that needs not the interpolation.

• The Journal of the Acoustical Society of Korea
• /
• v.19 no.3
• /
• pp.72-76
• /
• 2000

A calibration technique is proposed to improve the performance of 2-D towed array shape estimation using the Kalman filter. In the case of using displacement sensors, 2-D hydrophone positions estimated by the Kalman filter are calculated by assuming that the adjacent hydrophones are horizontally equi-spaced so that maximum distance is equal to the array length. The assumption causes errors in estimating hydrophone positions. The proposed technique using linear model approximation or spline interpolation can reduce the errors by exploiting the fact that the whole length of array is preserved whatever the array shape is. The numerical experiments show that the proposed method is very effective.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.4
• /
• pp.1305-1315
• /
• 2000

It is known that a digital image enlargement technique can increase the size of he image but the practical enhancement of resolution is trifle because the frequency bandwidth of the original image is basically limited. To solve this problem, this paper proposes the digital image enlargement technique which interpolates the interpolation points of horizontal and vertical direction by weighting according to the direction of edge information with the component of FOI(First Order Interpolation)and output of the pseudomedian filter for image enlargement and interpolates the interpolation points of diagonal direction by selectively transposing the direction of the subwindows of the pseudomedian filter according to the distribution of neighbored pixels thereto in the extended image. According to the proposed methods, the digital image enlargement which preserves the characteristic of the pseudomedian filter capable of keeping the reconstruction of edge information and reflects the advantage of FOI can be performed. Therefore, visual artifacts could be effectively suppressed, and most characteristics and shape of the original image can be reconstructed as well.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.9C
• /
• pp.725-733
• /
• 2008

This paper proposed a novel do-interlacing algorithm using all direction edges estimation technique. In the proposed algorithm. previously developed the DOI(Direction-Oriented Interpolation) algorithm was used as a basis. The do-interlacing method was divided into two main parts. First, we should estimate edge direction. Then, missing pixel: were interpolated along with the decided edge. In this paper, after estimating the edge through the DOI algorithm considering high angle edge direction, missing pixels were interpolated by using the median filter. Experimental results indicate that the proposed algorithm is superior to the conventional algorithms in terms of the objective and subjective criteria.

• Proceedings of the IEEK Conference
• /
• 2007.07a
• /
• pp.363-364
• /
• 2007

In this paper, we present a novel motion-compensated interpolation technique for non-moving caption region to prevent the block artifacts due to the failure of conventional block-based motion estimation algorithm on the block is consist of non-moving caption and moving object. Experimental results indicate good performance of the proposed scheme with significantly reduced block artifacts on image sequence that include non-moving caption. Also the proposed method is simple and adequate for hardware implementation.