The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform

T. Taniguchi - One of the best experts on this subject based on the ideXlab platform.

  • Statistical Analysis of MIMO Keyhole Channels under Double Rayleigh and Double Nakagami-Rice Fadings
    IEICE Transactions on Communications, 2011
    Co-Authors: T. Taniguchi, Yoshio Karasawa, Makoto Tsuruta
    Abstract:

    This paper gives statistical analysis of double fading channels which are typically found in keyhole MIMO (multiple input multiple output) models. First, to investigate the potential of identically distributed double Nakagami-Rice MIMO keyhole channels including LOS (line of sight) environment, the density function of SNR (signal to noise ratio) which corresponds to the only one non-zero eigenvalue of channel correlation matrix is presented. In addition to the exact expression with an infinite series Form, an approximation Formula with a simple Monomial Form derived by substituting Nakagami m Formula for Rician distribution is also considered. Next, similar equations are introduced for double Rayleigh channels which have correlated branches in both the transmitter and receiver sides (independent but nonidentical case is included here). Through computer simulations, the effectiveness of the proposed Formulae is verified, and in double Nakagami-Rice fading case, the advantage of the approximated Formula particularly for large array size and/or large Rician factor is demonstrated.

  • Analysis and Approximation of Statistical Distribution of Eigenvalues in i.i.d. MIMO Channels under Rayleigh Fading
    IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences, 2008
    Co-Authors: T. Taniguchi, Shen Sha, Yoshio Karasawa
    Abstract:

    In multiple input multiple output (MIMO) communication systems, eigenvalues of channel correlation matrices play an essential role for the perFormance analysis, and particularly the investigation about their behavior under time-variant environment ruled by a certain statistics is an important problem. This paper first gives the theoretical expressions for the marginal distributions of all the ordered eigenvalues of MIMO correlation matrices under i.i.d. (independent and identically distributed) Rayleigh fading environment. Then, an approximation method of those marginal distributions is presented: We show that the theory of SIMO space diversity using maximal ratio combining (MRC) is applicable to the approximation of statistical distributions of all eigenvalues in MIMO systems with the same number of diversity branches. The derived approximation has a Monomial Form suitable for the calculation of various perFormance measures utilized in MIMO systems. Through computer simulations, the effectiveness of the proposed method is demonstrated.

  • PIMRC - An analysis method of double fading MIMO channels including LOS environments
    2008 IEEE 19th International Symposium on Personal Indoor and Mobile Radio Communications, 2008
    Co-Authors: T. Taniguchi, Yoshio Karasawa, Makoto Tsuruta
    Abstract:

    This paper gives an analysis method of i.i.d. (independent and identically distributed) double fading channels including LOS (line of sight) environment which are typically found in keyhole MIMO (multiple input multiple output) models. To investigate the potential of LOS double fading (double Rician fading) MIMO channels, the density function of SNR (Signal to Noise Ratio) which corresponds to the only one non-zero eigenvalue of channel correlation matrix is considered. After the description of the exact expression with an infinite series Form, an approximation Formula of SNR density with a simple Monomial Form is given utilizing Nakagami m approximation of Rician distribution. Through computer simulations, the effectiveness of the proposed Formulae is verified, and the advantage of the approximated Formula particular in case of large array size and/or large Rician factor is demonstrated.

  • EW - Analysis method of MIMO MRC systems under nakagami m fading environment
    2008 14th European Wireless Conference, 2008
    Co-Authors: T. Taniguchi, Makoto Tsuruta, Yoshio Karasawa
    Abstract:

    This paper presents an analysis method of i.i.d. (independent and identically distributed) MIMO (multiple input multiple output) channels under Nakagami m fading environment based on statistical distributions of the largest eigenvalue which is useful for the analysis of MRC (maximal ratio combining) communication systems. Given distribution Formulae are introduced utilizing the conversion of MIMO channels into equivalent SIMO models with the same number of diversity branches and total power equal to the per-branch largest eigenvalue mean. The derived density function has a simple Monomial Form which is suitable for calculations of various perFormance indices of MIMO systems. Through computer simulations, the effectiveness of the proposed approximated Formulae is demonstrated. Impact of antenna number and Nakagami factor representing the depth of fading on the approximation precision is also investigated. In addition, exact eigenvalue distribution of MIMO Nakagami m pinhole channel is described from the theoretical viewpoint.

  • PIMRC - Approximation of Largest Eigenvalue Distribution in Rician MIMO Channels
    2007 IEEE 18th International Symposium on Personal Indoor and Mobile Radio Communications, 2007
    Co-Authors: T. Taniguchi, Shen Sha, Yoshio Karasawa, Makoto Tsuruta
    Abstract:

    This paper presents approximation Formulae of statistical distributions of the largest eigenvalue of i.i.d. (independent and identically distributed) MIMO (multiple input multiple output) channel correlation matrices under Rician (Nakagami- Rice) fading environment. The proposed Formulae are based on space diversity theory adopting MRC (maximal ratio combining) scheme under Nakagami m fading channel which is known as a good approximation of Nakagami-Rice fading, hence it well approximates the largest eigenvalue distribution in MIMO Rician channels. The derived marginal distributions have a simple Monomial Form which is suitable for calculations of various perFormance indices of MIMO systems. Computer simulations show that the proposed approximation Formulae are effective and have a better precision than conventional one.

Natasha Dejdumrong - One of the best experts on this subject based on the ideXlab platform.

  • The Analysis of PIA Algorithm Efficiency in Converting Rational Bézier Curves into Corresponding Non-rational Curves
    2014 11th International Conference on Computer Graphics Imaging and Visualization, 2014
    Co-Authors: Anchisa Chantakamo, Natasha Dejdumrong
    Abstract:

    This paper presents an efficient method to approximate a rational Bezier curve by the corresponding Non- Rational Bezier curve using Progressive Iterative Approximation (PIA) with the algorithm efficiency analysis. The proposed method samples the input curve into data points and uses a PIA algorithm to calculate new control points for the nonrational curve. The experimental results show that the proposed method has less computational complexity, which yields less computational time, than other methods which approximate the curve using power basis or Monomial Form conversion. This work also presents the method to find the appropriate degree of the output non-rational curve for each degree-n rational curve input.

  • Relationship of Interpolation and Approximation Curve Conversion Based on Monomial Form
    2014 11th International Conference on Computer Graphics Imaging and Visualization, 2014
    Co-Authors: Dilokvith Savetseranee, Natasha Dejdumrong
    Abstract:

    In Computer Aided Geometric Design (CAGD), the utilization of using curves for geometric design and modeling is undertaken by most research works. Due to the high degree of shape preservation of the approximation curve and ease of configuration of the interpolation curve, they are commonly used in CAD and CAM application. However, there are very few works that pay attention to the integration and transFormation of those types of curve in graphical modeling tools. In 2010, Aphirukmatakun et al [1] proposed the transFormation scheme based on Monomial Form technique to transForm the CAGD curve into Newton-Lagrange curve and vice versa. However, Newton-Lagrange has a limitation in dealing with loops curve and zigzag. In this paper, we propose an interpolation and approximation curve conversion scheme to provide more flexible and efficient conversion between them. To this end, we combine Chebyshev polynomial representation and Monomial matrix conversion to develop a set of conversion algorithms. The paper presents how the curves are converted and it is considered to be feasible and sound to implement in CAGD application.

  • CGIV - New Monomial Forms Approach for DP and NB1 Curves with Their Proofs
    2013 10th International Conference Computer Graphics Imaging and Visualization, 2013
    Co-Authors: Dilokvith Savetseranee, Natasha Dejdumrong
    Abstract:

    There are several methods used to construct curves in CAGD, e.g., the de Casteljaus algorithm, DP algorithm, and NB1 algorithm. However, they are represented in the Forms that are not suitable for perForming geometric modeling. A proposed approach for evaluating DP curve, NB1 Curve by using Monomial Form was introduced by Aphirukmatakun and Dejdumrong in 2009. The authors did not provide any proofs for their propositions. Thus, this paper shows the proofs for the conversions from DP polynomial into its Monomial Form as well as NB1 polynomial.

  • Monomial Forms of two generalized ball curves and their proofs
    The 2013 10th International Joint Conference on Computer Science and Software Engineering (JCSSE), 2013
    Co-Authors: Dilokvith Savetseranee, Natasha Dejdumrong
    Abstract:

    There are several methods used to construct curves in CAGD, e.g., the de Casteljau's algorithm, Wang algorithm, Said-Ball algorithm. However, they are represented in the Forms that are not suitable for perForming geometric modeling. A proposed approach for evaluating Said-Ball and Wang-Ball curves by using Monomial Form was introduced by Aphirukmatakun and Dejdumrong in 2009. The authors did not provide any proofs for their propositions. Thus, this paper shows the proofs for the conversions from Said-Ball polynomials into its Monomial Form as well as that of the Wang-Ball polynomials.

  • CGIV - Modeling of Bézier Curves Using a Combination of Linear and Circular Arc Approximations
    2012 Ninth International Conference on Computer Graphics Imaging and Visualization, 2012
    Co-Authors: Pongrapee Kaewsaiha, Natasha Dejdumrong
    Abstract:

    This paper presents the new approach of the Bezier curve rendering using linear and circular arc approximations, instead of a recursive method that calculates all points on the curve pixel by pixel. The new developed algorithm also works better than a pure-linear approximation which generates rough output, and a pure-circular-arc approximation which involves with too many parameters. The purposed algorithm subdivides the curve into a series of lines and arcs satisfying the user-defined tolerance. This new method can reduce the number of points involved with the calculation and also decrease the computational time since the software built-in line and arc functions calculate faster than the recursive method. This algorithm is based on the Monomial Form approach which can provides more efficiency and flexibility, compare with traditional methods that are mostly based on a polynomial basis or the de Casteljau's algorithm.

Yoshio Karasawa - One of the best experts on this subject based on the ideXlab platform.

  • Statistical Analysis of MIMO Keyhole Channels under Double Rayleigh and Double Nakagami-Rice Fadings
    IEICE Transactions on Communications, 2011
    Co-Authors: T. Taniguchi, Yoshio Karasawa, Makoto Tsuruta
    Abstract:

    This paper gives statistical analysis of double fading channels which are typically found in keyhole MIMO (multiple input multiple output) models. First, to investigate the potential of identically distributed double Nakagami-Rice MIMO keyhole channels including LOS (line of sight) environment, the density function of SNR (signal to noise ratio) which corresponds to the only one non-zero eigenvalue of channel correlation matrix is presented. In addition to the exact expression with an infinite series Form, an approximation Formula with a simple Monomial Form derived by substituting Nakagami m Formula for Rician distribution is also considered. Next, similar equations are introduced for double Rayleigh channels which have correlated branches in both the transmitter and receiver sides (independent but nonidentical case is included here). Through computer simulations, the effectiveness of the proposed Formulae is verified, and in double Nakagami-Rice fading case, the advantage of the approximated Formula particularly for large array size and/or large Rician factor is demonstrated.

  • Analysis and Approximation of Statistical Distribution of Eigenvalues in i.i.d. MIMO Channels under Rayleigh Fading
    IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences, 2008
    Co-Authors: T. Taniguchi, Shen Sha, Yoshio Karasawa
    Abstract:

    In multiple input multiple output (MIMO) communication systems, eigenvalues of channel correlation matrices play an essential role for the perFormance analysis, and particularly the investigation about their behavior under time-variant environment ruled by a certain statistics is an important problem. This paper first gives the theoretical expressions for the marginal distributions of all the ordered eigenvalues of MIMO correlation matrices under i.i.d. (independent and identically distributed) Rayleigh fading environment. Then, an approximation method of those marginal distributions is presented: We show that the theory of SIMO space diversity using maximal ratio combining (MRC) is applicable to the approximation of statistical distributions of all eigenvalues in MIMO systems with the same number of diversity branches. The derived approximation has a Monomial Form suitable for the calculation of various perFormance measures utilized in MIMO systems. Through computer simulations, the effectiveness of the proposed method is demonstrated.

  • EW - Analysis method of MIMO MRC systems under nakagami m fading environment
    2008 14th European Wireless Conference, 2008
    Co-Authors: T. Taniguchi, Makoto Tsuruta, Yoshio Karasawa
    Abstract:

    This paper presents an analysis method of i.i.d. (independent and identically distributed) MIMO (multiple input multiple output) channels under Nakagami m fading environment based on statistical distributions of the largest eigenvalue which is useful for the analysis of MRC (maximal ratio combining) communication systems. Given distribution Formulae are introduced utilizing the conversion of MIMO channels into equivalent SIMO models with the same number of diversity branches and total power equal to the per-branch largest eigenvalue mean. The derived density function has a simple Monomial Form which is suitable for calculations of various perFormance indices of MIMO systems. Through computer simulations, the effectiveness of the proposed approximated Formulae is demonstrated. Impact of antenna number and Nakagami factor representing the depth of fading on the approximation precision is also investigated. In addition, exact eigenvalue distribution of MIMO Nakagami m pinhole channel is described from the theoretical viewpoint.

  • PIMRC - An analysis method of double fading MIMO channels including LOS environments
    2008 IEEE 19th International Symposium on Personal Indoor and Mobile Radio Communications, 2008
    Co-Authors: T. Taniguchi, Yoshio Karasawa, Makoto Tsuruta
    Abstract:

    This paper gives an analysis method of i.i.d. (independent and identically distributed) double fading channels including LOS (line of sight) environment which are typically found in keyhole MIMO (multiple input multiple output) models. To investigate the potential of LOS double fading (double Rician fading) MIMO channels, the density function of SNR (Signal to Noise Ratio) which corresponds to the only one non-zero eigenvalue of channel correlation matrix is considered. After the description of the exact expression with an infinite series Form, an approximation Formula of SNR density with a simple Monomial Form is given utilizing Nakagami m approximation of Rician distribution. Through computer simulations, the effectiveness of the proposed Formulae is verified, and the advantage of the approximated Formula particular in case of large array size and/or large Rician factor is demonstrated.

  • PIMRC - Approximation of Largest Eigenvalue Distribution in Rician MIMO Channels
    2007 IEEE 18th International Symposium on Personal Indoor and Mobile Radio Communications, 2007
    Co-Authors: T. Taniguchi, Shen Sha, Yoshio Karasawa, Makoto Tsuruta
    Abstract:

    This paper presents approximation Formulae of statistical distributions of the largest eigenvalue of i.i.d. (independent and identically distributed) MIMO (multiple input multiple output) channel correlation matrices under Rician (Nakagami- Rice) fading environment. The proposed Formulae are based on space diversity theory adopting MRC (maximal ratio combining) scheme under Nakagami m fading channel which is known as a good approximation of Nakagami-Rice fading, hence it well approximates the largest eigenvalue distribution in MIMO Rician channels. The derived marginal distributions have a simple Monomial Form which is suitable for calculations of various perFormance indices of MIMO systems. Computer simulations show that the proposed approximation Formulae are effective and have a better precision than conventional one.

Makoto Tsuruta - One of the best experts on this subject based on the ideXlab platform.

  • Statistical Analysis of MIMO Keyhole Channels under Double Rayleigh and Double Nakagami-Rice Fadings
    IEICE Transactions on Communications, 2011
    Co-Authors: T. Taniguchi, Yoshio Karasawa, Makoto Tsuruta
    Abstract:

    This paper gives statistical analysis of double fading channels which are typically found in keyhole MIMO (multiple input multiple output) models. First, to investigate the potential of identically distributed double Nakagami-Rice MIMO keyhole channels including LOS (line of sight) environment, the density function of SNR (signal to noise ratio) which corresponds to the only one non-zero eigenvalue of channel correlation matrix is presented. In addition to the exact expression with an infinite series Form, an approximation Formula with a simple Monomial Form derived by substituting Nakagami m Formula for Rician distribution is also considered. Next, similar equations are introduced for double Rayleigh channels which have correlated branches in both the transmitter and receiver sides (independent but nonidentical case is included here). Through computer simulations, the effectiveness of the proposed Formulae is verified, and in double Nakagami-Rice fading case, the advantage of the approximated Formula particularly for large array size and/or large Rician factor is demonstrated.

  • EW - Analysis method of MIMO MRC systems under nakagami m fading environment
    2008 14th European Wireless Conference, 2008
    Co-Authors: T. Taniguchi, Makoto Tsuruta, Yoshio Karasawa
    Abstract:

    This paper presents an analysis method of i.i.d. (independent and identically distributed) MIMO (multiple input multiple output) channels under Nakagami m fading environment based on statistical distributions of the largest eigenvalue which is useful for the analysis of MRC (maximal ratio combining) communication systems. Given distribution Formulae are introduced utilizing the conversion of MIMO channels into equivalent SIMO models with the same number of diversity branches and total power equal to the per-branch largest eigenvalue mean. The derived density function has a simple Monomial Form which is suitable for calculations of various perFormance indices of MIMO systems. Through computer simulations, the effectiveness of the proposed approximated Formulae is demonstrated. Impact of antenna number and Nakagami factor representing the depth of fading on the approximation precision is also investigated. In addition, exact eigenvalue distribution of MIMO Nakagami m pinhole channel is described from the theoretical viewpoint.

  • PIMRC - An analysis method of double fading MIMO channels including LOS environments
    2008 IEEE 19th International Symposium on Personal Indoor and Mobile Radio Communications, 2008
    Co-Authors: T. Taniguchi, Yoshio Karasawa, Makoto Tsuruta
    Abstract:

    This paper gives an analysis method of i.i.d. (independent and identically distributed) double fading channels including LOS (line of sight) environment which are typically found in keyhole MIMO (multiple input multiple output) models. To investigate the potential of LOS double fading (double Rician fading) MIMO channels, the density function of SNR (Signal to Noise Ratio) which corresponds to the only one non-zero eigenvalue of channel correlation matrix is considered. After the description of the exact expression with an infinite series Form, an approximation Formula of SNR density with a simple Monomial Form is given utilizing Nakagami m approximation of Rician distribution. Through computer simulations, the effectiveness of the proposed Formulae is verified, and the advantage of the approximated Formula particular in case of large array size and/or large Rician factor is demonstrated.

  • PIMRC - Approximation of Largest Eigenvalue Distribution in Rician MIMO Channels
    2007 IEEE 18th International Symposium on Personal Indoor and Mobile Radio Communications, 2007
    Co-Authors: T. Taniguchi, Shen Sha, Yoshio Karasawa, Makoto Tsuruta
    Abstract:

    This paper presents approximation Formulae of statistical distributions of the largest eigenvalue of i.i.d. (independent and identically distributed) MIMO (multiple input multiple output) channel correlation matrices under Rician (Nakagami- Rice) fading environment. The proposed Formulae are based on space diversity theory adopting MRC (maximal ratio combining) scheme under Nakagami m fading channel which is known as a good approximation of Nakagami-Rice fading, hence it well approximates the largest eigenvalue distribution in MIMO Rician channels. The derived marginal distributions have a simple Monomial Form which is suitable for calculations of various perFormance indices of MIMO systems. Computer simulations show that the proposed approximation Formulae are effective and have a better precision than conventional one.

Taoufik Ouali - One of the best experts on this subject based on the ideXlab platform.

  • Dynamical System Study of Nonminimal Tachyon Field within Holographic Cosmology
    Gravitation and Cosmology, 2020
    Co-Authors: Farida Bargach, Aatifa Bargach, Taoufik Ouali
    Abstract:

    We use the dynamical system method in order to investigate the dynamics of a non-minimally coupled tachyon field within induced gravity on the brane in a holographic cosmological context. Assuming an exponential potential and a Monomial Form of the nonminimal coupling function, we construct the phase space of the model. Two possible cases, namely, the minimal and nonminimal coupling, are investigated. Using dynamical systems tools, it is found that the model can describe an attractor solution which corresponds to the inflationary era in the non-minimal coupling case.

  • Dynamical system approach of non-minimal coupling in holographic cosmology
    Nuclear Physics B, 2019
    Co-Authors: Aatifa Bargach, Farida Bargach, Taoufik Ouali
    Abstract:

    Abstract We study the dynamical system approach of non-minimally coupled scalar field to induced gravity on the brane in the framework of holographic cosmology. In this context, we derive the modified Friedmann equation and the equation of motion. The dynamics of this model are studied by rewriting the cosmological field equations in the Form of a system of autonomous differential equations. In particular, the analysis is considered by investigating an exponential potential and a Monomial Form of the non-minimal coupling function. We show that, for sufficient conditions, a past de Sitter attractor solution is obtained in the case of a minimal coupling, meanwhile a future de Sitter attractor solutions is obtained for a conFormal coupling and for a non-minimal coupling.