The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform

P.p. Vaidyanathan - One of the best experts on this subject based on the ideXlab platform.

  • Cosine-Modulated FIR Filter Banks Satisfying
    1992
    Co-Authors: R.d. Koilpillai, P.p. Vaidyanathan
    Abstract:

    It is well known that FIR filter banks, satisfying the perfect reconstruction (PR) property, can be obtained by cosine modulation of a linear-phase prototype of length N = 2M (M is the number of channels) when certain constraints are imposed on the prototype. Recently, this result was extended for the case when N = 2mM (m is an arbitrary positive integer). In this paper, we obtain a necessary and sufficient condition on the 2M Polyphase Components of a linear-phase prototype filter of length N = 2mM, such that the Polyphase Component matrix of the modulated filter bank is lossless. The losslessness of the Polyphase Component matrix, in turn, is sufficient to ensure that the analysis/synthesis system satisfies PR. Using this result, a new design procedure is presented (based on the two-channel lossless lattice). This enables the design of a large class of FIR- PR filter banks (and includes the N = 2M case). It is shown that this approach requires fewer parameters to be optimized than in the pseudo-QMF designs and in the lossless lattice based PR-QMF designs (for equal length filters in the three designs). This advantage becomes significant when designing long filters for large M. The design procedure and its other advantages are described in detail. Design examples and comparisons are in- cluded.

  • Cosine-modulated FIR filter banks satisfying perfect reconstruction
    IEEE Transactions on Signal Processing, 1992
    Co-Authors: R.d. Koilpillai, P.p. Vaidyanathan
    Abstract:

    The authors obtain a necessary and sufficient condition on the 2M (M=number of channels) Polyphase Components of a linear-phase prototype filter of length N=2 mM (where m=an arbitrary positive integer), such that the Polyphase Component matrix of the modulated filter is lossless. The losslessness of the Polyphase Component matrix, in turn, is sufficient to ensure that the analysis/synthesis system satisfies perfect reconstruction (PR). Using this result, a novel design procedure is presented based on the two-channel lossless lattice. This enables the design of a large class of FIR (finite impulse response)-PR filter banks, and includes the N=2M case. It is shown that this approach requires fewer parameters to be optimized than in the pseudo-QMF (quadrature mirror filter) designs and in the lossless lattice based PR-QMF designs (for equal length filters in the three designs). This advantage becomes significant when designing long filters for large M. The design procedure and its other advantages are described in detail. Design examples and comparisons are included.

  • New results on cosine-modulated FIR filter banks satisfying perfect reconstruction
    [Proceedings] ICASSP 91: 1991 International Conference on Acoustics Speech and Signal Processing, 1991
    Co-Authors: R.d. Koilpillai, P.p. Vaidyanathan
    Abstract:

    The authors present a derivation of the necessary and sufficient condition on the Polyphase Components of a linear-phase prototype (length N=2 mM) such that the Polyphase Component matrix of the filter bank is lossless. This in turn ensures that the modulated filter bank satisfies the PR (perfect reconstruction) property. An efficient design procedure (which involves fewer parameters to be optimized than other approaches) is presented. By this approach, FIR (finite-impulse-response) PR filter banks can be designed for an arbitrary number of channels. Moreover, since both the analysis and synthesis filter banks are obtained by modulation, they can be implemented very efficiently (using the discrete cosine transform). The design procedure is outlined and a design example is presented.

  • Some results in the theory of crosstalk-free transmultiplexers
    IEEE Transactions on Signal Processing, 1991
    Co-Authors: R.d. Koilpillai, T.q. Nguyen, P.p. Vaidyanathan
    Abstract:

    The crosstalk-free transmultiplexer (CF-TMUX) focuses on crosstalk cancellation (CC) rather than on suppressing it. The authors present an analysis of the CF-TMUX based on the Polyphase Component matrices of the filter banks used in TDM to FDM and FDM to TDM conversions, respectively. Thus a necessary and sufficient condition for complete CC is obtained. It is shown that the filters for a CF-TMUX are the same as the filters for a 1-skewed alias free QMF bank. In addition, if the QMF bank satisfies the perfect reconstruction (PR) property, then the TMUX also satisfies PR. The relation between CF-TMUX filters and alias-free QMF banks is used to obtain a direct design procedure for CF-TMUX filters (both FIR and IIR). It is also shown that approximately crosstalk-free TMUX filters can be obtained from any approximately alias-free QMC bank. Design examples and comparison tables are included.

Dacheng Yang - One of the best experts on this subject based on the ideXlab platform.

  • VTC Fall - SVD-Based Frequency Domain Equalizer for MIMO-CDMA Systems Using Virtual Antennas
    2008 IEEE 68th Vehicular Technology Conference, 2008
    Co-Authors: Hui Lu, Qixing Wang, Yongyu Chang, Dacheng Yang
    Abstract:

    This paper proposes a new approach to apply singular value decomposition (SVD) in fractionally spaced frequency domain equalizer (FSFDE) for the single carrier MIMO-CDMA systems. Multiple data streams can be reliably transmitted through the parallel subchannels by using SVD, which can improve the capacity effectively without increasing frequency bandwidth or the average transmit power. Fractional sampling at the receiver is equivalent to having multiple virtual receive antennas with correlated channel gains and colored noise, which may be seen as a virtual receive diversity. Therefore, each Polyphase Component is denoted as a virtual antenna, and it is also called fractionally spaced system as virtual antennas system. Simulations show that high performance can be achieved by using SVD with virtual antennas.

  • SVD-Based Frequency Domain Equalizer for MIMO-CDMA Systems Using Virtual Antennas
    2008 IEEE 68th Vehicular Technology Conference, 2008
    Co-Authors: Hui Lu, Qixing Wang, Yongyu Chang, Dacheng Yang
    Abstract:

    This paper proposes a new approach to apply singular value decomposition (SVD) in fractionally spaced frequency domain equalizer (FSFDE) for the single carrier MIMO-CDMA systems. Multiple data streams can be reliably transmitted through the parallel subchannels by using SVD, which can improve the capacity effectively without increasing frequency bandwidth or the average transmit power. Fractional sampling at the receiver is equivalent to having multiple virtual receive antennas with correlated channel gains and colored noise, which may be seen as a virtual receive diversity. Therefore, each Polyphase Component is denoted as a virtual antenna, and it is also called fractionally spaced system as virtual antennas system. Simulations show that high performance can be achieved by using SVD with virtual antennas.

  • Layered Space-Frequency Detection for MIMO-CDMA Systems Using Virtual Antennas
    2007 IEEE 65th Vehicular Technology Conference - VTC2007-Spring, 2007
    Co-Authors: Qixing Wang, Yongyu Chang, Baojin Li, Dacheng Yang
    Abstract:

    This paper proposes a new approach to apply fractionally spaced frequency-domain equalizer (FSFDE) for the single carrier MIMO-CDMA systems. The complexity of this equalizer can be significantly reduced with the help of performing the equalization in the frequency domain. Analogous to the previously developed layered space-time architectures, we proposed layered space-frequency detection (LSFD) which is performed layer by layer in a successive way. In this work, the concept of virtual antennas is also introduced. Oversampling at the receiver is equivalent to having multiple virtual receive antennas with the correlated channel gains and the colored noise. This may be viewed as a virtual receive diversity, and therefore, each Polyphase Component is denoted as a virtual antenna. Simulations demonstrate that high performance can be achieved by using the proposed detection with virtual antennas.

Paraskevas Argyropoulos - One of the best experts on this subject based on the ideXlab platform.

  • Digital spur mitigation in high-speed block-parallel digital filter realizations
    2015 IEEE International Symposium on Circuits and Systems (ISCAS), 2015
    Co-Authors: Paraskevas Argyropoulos
    Abstract:

    An intuitive procedure for determining the location as well as reducing the effect of digital spurs in block-parallel digital filter realizations is proposed. The method is based on modeling voltage/current waveforms generated by the switching activity of digital clocks in each Polyphase Component of a blockparallel digital filter as electromagnetic waves travelling over a linear medium. Using superposition, frequency analysis as well as information regarding the area (size) and layout (placement) of the synthesized Polyphase filter, the spurs generated at the output of the overall system are modeled as a weighted sum of voltage/current interference waveforms. Digital spur mitigation is achieved by calculating a strategic clock phasing scheme based on the contribution of these weighting coefficients. The technique and examples presented are intended to serve as a high-speed filter realization reference for Digital and DSP ASIC developers.

  • ISCAS - Digital spur mitigation in high-speed block-parallel digital filter realizations
    2015 IEEE International Symposium on Circuits and Systems (ISCAS), 2015
    Co-Authors: Paraskevas Argyropoulos
    Abstract:

    An intuitive procedure for determining the location as well as reducing the effect of digital spurs in block-parallel digital filter realizations is proposed. The method is based on modeling voltage/current waveforms generated by the switching activity of digital clocks in each Polyphase Component of a blockparallel digital filter as electromagnetic waves travelling over a linear medium. Using superposition, frequency analysis as well as information regarding the area (size) and layout (placement) of the synthesized Polyphase filter, the spurs generated at the output of the overall system are modeled as a weighted sum of voltage/current interference waveforms. Digital spur mitigation is achieved by calculating a strategic clock phasing scheme based on the contribution of these weighting coefficients. The technique and examples presented are intended to serve as a high-speed filter realization reference for Digital and DSP ASIC developers.

R.d. Koilpillai - One of the best experts on this subject based on the ideXlab platform.

  • Cosine-Modulated FIR Filter Banks Satisfying
    1992
    Co-Authors: R.d. Koilpillai, P.p. Vaidyanathan
    Abstract:

    It is well known that FIR filter banks, satisfying the perfect reconstruction (PR) property, can be obtained by cosine modulation of a linear-phase prototype of length N = 2M (M is the number of channels) when certain constraints are imposed on the prototype. Recently, this result was extended for the case when N = 2mM (m is an arbitrary positive integer). In this paper, we obtain a necessary and sufficient condition on the 2M Polyphase Components of a linear-phase prototype filter of length N = 2mM, such that the Polyphase Component matrix of the modulated filter bank is lossless. The losslessness of the Polyphase Component matrix, in turn, is sufficient to ensure that the analysis/synthesis system satisfies PR. Using this result, a new design procedure is presented (based on the two-channel lossless lattice). This enables the design of a large class of FIR- PR filter banks (and includes the N = 2M case). It is shown that this approach requires fewer parameters to be optimized than in the pseudo-QMF designs and in the lossless lattice based PR-QMF designs (for equal length filters in the three designs). This advantage becomes significant when designing long filters for large M. The design procedure and its other advantages are described in detail. Design examples and comparisons are in- cluded.

  • Cosine-modulated FIR filter banks satisfying perfect reconstruction
    IEEE Transactions on Signal Processing, 1992
    Co-Authors: R.d. Koilpillai, P.p. Vaidyanathan
    Abstract:

    The authors obtain a necessary and sufficient condition on the 2M (M=number of channels) Polyphase Components of a linear-phase prototype filter of length N=2 mM (where m=an arbitrary positive integer), such that the Polyphase Component matrix of the modulated filter is lossless. The losslessness of the Polyphase Component matrix, in turn, is sufficient to ensure that the analysis/synthesis system satisfies perfect reconstruction (PR). Using this result, a novel design procedure is presented based on the two-channel lossless lattice. This enables the design of a large class of FIR (finite impulse response)-PR filter banks, and includes the N=2M case. It is shown that this approach requires fewer parameters to be optimized than in the pseudo-QMF (quadrature mirror filter) designs and in the lossless lattice based PR-QMF designs (for equal length filters in the three designs). This advantage becomes significant when designing long filters for large M. The design procedure and its other advantages are described in detail. Design examples and comparisons are included.

  • New results on cosine-modulated FIR filter banks satisfying perfect reconstruction
    [Proceedings] ICASSP 91: 1991 International Conference on Acoustics Speech and Signal Processing, 1991
    Co-Authors: R.d. Koilpillai, P.p. Vaidyanathan
    Abstract:

    The authors present a derivation of the necessary and sufficient condition on the Polyphase Components of a linear-phase prototype (length N=2 mM) such that the Polyphase Component matrix of the filter bank is lossless. This in turn ensures that the modulated filter bank satisfies the PR (perfect reconstruction) property. An efficient design procedure (which involves fewer parameters to be optimized than other approaches) is presented. By this approach, FIR (finite-impulse-response) PR filter banks can be designed for an arbitrary number of channels. Moreover, since both the analysis and synthesis filter banks are obtained by modulation, they can be implemented very efficiently (using the discrete cosine transform). The design procedure is outlined and a design example is presented.

Qixing Wang - One of the best experts on this subject based on the ideXlab platform.

  • VTC Fall - SVD-Based Frequency Domain Equalizer for MIMO-CDMA Systems Using Virtual Antennas
    2008 IEEE 68th Vehicular Technology Conference, 2008
    Co-Authors: Hui Lu, Qixing Wang, Yongyu Chang, Dacheng Yang
    Abstract:

    This paper proposes a new approach to apply singular value decomposition (SVD) in fractionally spaced frequency domain equalizer (FSFDE) for the single carrier MIMO-CDMA systems. Multiple data streams can be reliably transmitted through the parallel subchannels by using SVD, which can improve the capacity effectively without increasing frequency bandwidth or the average transmit power. Fractional sampling at the receiver is equivalent to having multiple virtual receive antennas with correlated channel gains and colored noise, which may be seen as a virtual receive diversity. Therefore, each Polyphase Component is denoted as a virtual antenna, and it is also called fractionally spaced system as virtual antennas system. Simulations show that high performance can be achieved by using SVD with virtual antennas.

  • SVD-Based Frequency Domain Equalizer for MIMO-CDMA Systems Using Virtual Antennas
    2008 IEEE 68th Vehicular Technology Conference, 2008
    Co-Authors: Hui Lu, Qixing Wang, Yongyu Chang, Dacheng Yang
    Abstract:

    This paper proposes a new approach to apply singular value decomposition (SVD) in fractionally spaced frequency domain equalizer (FSFDE) for the single carrier MIMO-CDMA systems. Multiple data streams can be reliably transmitted through the parallel subchannels by using SVD, which can improve the capacity effectively without increasing frequency bandwidth or the average transmit power. Fractional sampling at the receiver is equivalent to having multiple virtual receive antennas with correlated channel gains and colored noise, which may be seen as a virtual receive diversity. Therefore, each Polyphase Component is denoted as a virtual antenna, and it is also called fractionally spaced system as virtual antennas system. Simulations show that high performance can be achieved by using SVD with virtual antennas.

  • Layered Space-Frequency Detection for MIMO-CDMA Systems Using Virtual Antennas
    2007 IEEE 65th Vehicular Technology Conference - VTC2007-Spring, 2007
    Co-Authors: Qixing Wang, Yongyu Chang, Baojin Li, Dacheng Yang
    Abstract:

    This paper proposes a new approach to apply fractionally spaced frequency-domain equalizer (FSFDE) for the single carrier MIMO-CDMA systems. The complexity of this equalizer can be significantly reduced with the help of performing the equalization in the frequency domain. Analogous to the previously developed layered space-time architectures, we proposed layered space-frequency detection (LSFD) which is performed layer by layer in a successive way. In this work, the concept of virtual antennas is also introduced. Oversampling at the receiver is equivalent to having multiple virtual receive antennas with the correlated channel gains and the colored noise. This may be viewed as a virtual receive diversity, and therefore, each Polyphase Component is denoted as a virtual antenna. Simulations demonstrate that high performance can be achieved by using the proposed detection with virtual antennas.