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Gerhard Wunder - One of the best experts on this subject based on the ideXlab platform.

  • ISIT - Generalized bounds on the Crest-Factor distribution of OFDM signals with applications to code design
    International Symposium onInformation Theory 2004. ISIT 2004. Proceedings., 2004
    Co-Authors: Simon Litsyn, Gerhard Wunder
    Abstract:

    In this paper bounds on the Crest-Factor (CF) distribution of OFDM signals are generalized as firstly, independent subcarriers a complete characterization of arbitrary complex constellations is derived; secondly, for dependent subcarriers bounds are derived in terms of the weight distribution and their duals of the underlying code. Implications on code design are also discussed. Generalizations to linear, binary codes are given in terms of the weight distribution

  • generalized bounds on the Crest Factor distribution of ofdm signals with applications to code design
    International Symposium on Information Theory, 2004
    Co-Authors: Simon Litsyn, Gerhard Wunder
    Abstract:

    In this paper bounds on the Crest-Factor (CF) distribution of OFDM signals are generalized as firstly, independent subcarriers a complete characterization of arbitrary complex constellations is derived; secondly, for dependent subcarriers bounds are derived in terms of the weight distribution and their duals of the underlying code. Implications on code design are also discussed. Generalizations to linear, binary codes are given in terms of the weight distribution

  • upper bounds on the statistical distribution of the Crest Factor in ofdm transmission
    IEEE Transactions on Information Theory, 2003
    Co-Authors: Gerhard Wunder, Holger Boche
    Abstract:

    This article analyzes the Crest-Factor behavior of an orthogonal frequency-division multiplexing (OFDM) modem. The behavior is characterized in terms of the complementary distribution function of the Crest-Factor (CDFC). The CDFC is a key parameter of OFDM systems, for example it provides limits on achievable information rates. Several approximations have been developed in the literature so far, but no true upper bounds dependent on the different constellations that are used in OFDM modulation have been derived. A new approach is given providing upper bounds that substitute for time-consuming simulations.

G. Wunder - One of the best experts on this subject based on the ideXlab platform.

  • ISIT - Crest-Factor analysis of carrier interferometry MC-CDMA and OFDM systems
    International Symposium onInformation Theory 2004. ISIT 2004. Proceedings., 2004
    Co-Authors: G. Wunder, K.g. Paterson
    Abstract:

    This paper describes the Crest-Factor analysis of carrier interferometry MC-CDMA and OFDM systems. The maximum Crest Factor of CF signals grows as log(N). Thus there appears to be an impressive reduction in the Crest Factor of CI signals. The Crest Factor performance for carrier interferometry systems is the same as in standard systems, in the sense that the statistical distributions of CF are identical. Hence, the carrier interferometry approach has no CF gain in the asymptotic regime. This analysis is advantageous in terms of BER and diversity.

  • Crest-Factor analysis of carrier interferometry MC-CDMA and OFDM systems
    International Symposium onInformation Theory 2004. ISIT 2004. Proceedings., 2004
    Co-Authors: G. Wunder, K.g. Paterson
    Abstract:

    This paper describes the Crest-Factor analysis of carrier interferometry MC-CDMA and OFDM systems. The maximum Crest Factor of CF signals grows as log(N). Thus there appears to be an impressive reduction in the Crest Factor of CI signals. The Crest Factor performance for carrier interferometry systems is the same as in standard systems, in the sense that the statistical distributions of CF are identical. Hence, the carrier interferometry approach has no CF gain in the asymptotic regime. This analysis is advantageous in terms of BER and diversity.

  • Generalized constellations with low Crest-Factor for OFDM
    IEEE International Symposium on Information Theory 2003. Proceedings., 2003
    Co-Authors: G. Wunder, H. Boche
    Abstract:

    Lowering the Crest-Factor (CF) in OFDM transmission is still an on-going research topic. Here, we provide a systematic approach for designing point sets in N-space (corresponding to the number of subcarriers in OFDM) with low CF that we call generalized constellations. In order to design codes that have both low CF and high diversity we propose a scheme based on properties of polynomials constituting the class of the so-called de la Vallee-Poussin kernels. The main idea is to use good codes that have small discrete-time Crest-Factor (for example trace codes) and to apply the interpolation.

  • On the statistical distribution of the Crest-Factor of codes in OFDM transmission
    Proceedings 2003 IEEE Information Theory Workshop (Cat. No.03EX674), 2003
    Co-Authors: G. Wunder, S. Litsyn
    Abstract:

    The paper presents a new approach to the calculation of the Crest-Factor (CF) distribution in coded OFDM systems. The approach reveals an interesting connection between the weight distribution and the CF distribution of linear, binary codes that can be exploited to give an upper bound. The weight distribution of codes has attracted a great deal of attention in the past and many expressions and bounds are known. Thus we can expect to obtain a large number of bounds on the CF distribution. The upper bounds can serve as approximate curves for the CF distribution in the low probability region.

Holger Boche - One of the best experts on this subject based on the ideXlab platform.

  • upper bounds on the statistical distribution of the Crest Factor in ofdm transmission
    IEEE Transactions on Information Theory, 2003
    Co-Authors: Gerhard Wunder, Holger Boche
    Abstract:

    This article analyzes the Crest-Factor behavior of an orthogonal frequency-division multiplexing (OFDM) modem. The behavior is characterized in terms of the complementary distribution function of the Crest-Factor (CDFC). The CDFC is a key parameter of OFDM systems, for example it provides limits on achievable information rates. Several approximations have been developed in the literature so far, but no true upper bounds dependent on the different constellations that are used in OFDM modulation have been derived. A new approach is given providing upper bounds that substitute for time-consuming simulations.

Tong G. Zhou - One of the best experts on this subject based on the ideXlab platform.

  • Time-domain impulse injection method for Crest Factor reduction of OFDM signals
    2012 IEEE Statistical Signal Processing Workshop (SSP), 2012
    Co-Authors: Zhenhua Yu, Robert J. Baxley, Tong G. Zhou
    Abstract:

    This paper treats the problem of Crest Factor reduction (CFR) for orthogonal frequency division multiplexing (OFDM) signals. The proposed impulse injection method reduces the Crest Factor of the time-domain signal by injecting judiciously designed complex-valued impulse in selected discrete-time locations while keeping both the in-band error vector magnitude (EVM) and out-of-band spectral emission under control. Numerical examples are provided to demonstrate the effectiveness of the proposed method.

  • Constrained Clipping for Crest Factor Reduction in Multiple-user OFDM
    2007 IEEE Radio and Wireless Symposium, 2007
    Co-Authors: Chunming Zhao, Robert J. Baxley, Tong G. Zhou, Deepak Boppana, Stevenson J. Kenney
    Abstract:

    Crest Factor reduction (CFR) techniques aim to solve the high peak-to-average power ratio (PAR) problem encountered in the transmission of modern communication signals such as orthogonal frequency division multiplexing (OFDM). Constrained clipping is a promising CFR technique that is capable of large PAR reductions while guaranteeing that EVM and spectral mask constraints are met. In this paper, we analyze the computational complexity of constrained clipping and show that it is a practical technique that can be readily implemented. We then demonstrate its performance in a multiple-user OFDM environment such as the IEEE 802.16 OFDMA forward link. More than 5 dB of PAR reduction can be achieved in a four-user scenario

  • Low Complexity Crest Factor Reduction for Forward Link CDMA using IQ Offset
    2007 IEEE SP 14th Workshop on Statistical Signal Processing, 2007
    Co-Authors: Hua Qian, Chunming Zhao, Tong G. Zhou
    Abstract:

    Forward link code division multiple access (CDMA) signals generally have large Crest Factors, giving rise to low power efficiency of the transmission system. Crest Factor reduction (CFR) for forward link CDMA is called for to improve the system power efficiency. In this paper, we propose a CFR algorithm that reduces the probability of simultaneous occurrences of high peaks between the in-phase and the quadrature branches. The proposed algorithm is distortionless, offers good CFR capability with little modification to the existing system and has low computational complexity. Simulation results are provided to demonstrate the performance of the proposed CFR technique.

  • Constrained Clipping for Crest Factor Reduction in OFDM
    IEEE Transactions on Broadcasting, 2006
    Co-Authors: Robert J. Baxley, Chunming Zhao, Tong G. Zhou
    Abstract:

    In this paper, we propose a constrained clipping method for reducing the peak to average power ratio (PAR) or Crest Factor of an orthogonal frequency division multiplexing (OFDM) signal. This is a transmitter-side processing technique that does not impose any modification at the receiver. Specifically, constrained clipping achieves PAR reduction while simultaneously satisfying spectral mask and error vector magnitude (EVM) constraints which are specified by most modern communications standards. Our proposed constrained clipping method consists of two independent processing units, one to satisfy the in-band EVM constraint and the other to satisfy the out-of-band spectral constraint. Achievable PAR reduction results vary depending on the particular standards' requirements, but we show that by using constrained clipping on a QPSK WiMax signal with 256 subcarriers, a 4.5 dB PAR reduction at the 10-2 complementary cumulative distribution function (CCDF) level can be obtained

Robert J. Baxley - One of the best experts on this subject based on the ideXlab platform.

  • SSP - Time-domain impulse injection method for Crest Factor reduction of OFDM signals
    2012 IEEE Statistical Signal Processing Workshop (SSP), 2012
    Co-Authors: Zhenhua Yu, Robert J. Baxley, G. Tong Zhou
    Abstract:

    This paper treats the problem of Crest Factor reduction (CFR) for orthogonal frequency division multiplexing (OFDM) signals. The proposed impulse injection method reduces the Crest Factor of the time-domain signal by injecting judiciously designed complex-valued impulse in selected discrete-time locations while keeping both the in-band error vector magnitude (EVM) and out-of-band spectral emission under control. Numerical examples are provided to demonstrate the effectiveness of the proposed method.

  • Time-domain impulse injection method for Crest Factor reduction of OFDM signals
    2012 IEEE Statistical Signal Processing Workshop (SSP), 2012
    Co-Authors: Zhenhua Yu, Robert J. Baxley, Tong G. Zhou
    Abstract:

    This paper treats the problem of Crest Factor reduction (CFR) for orthogonal frequency division multiplexing (OFDM) signals. The proposed impulse injection method reduces the Crest Factor of the time-domain signal by injecting judiciously designed complex-valued impulse in selected discrete-time locations while keeping both the in-band error vector magnitude (EVM) and out-of-band spectral emission under control. Numerical examples are provided to demonstrate the effectiveness of the proposed method.

  • Constrained Clipping for Crest Factor Reduction in Multiple-user OFDM
    2007 IEEE Radio and Wireless Symposium, 2007
    Co-Authors: Chunming Zhao, Robert J. Baxley, Tong G. Zhou, Deepak Boppana, Stevenson J. Kenney
    Abstract:

    Crest Factor reduction (CFR) techniques aim to solve the high peak-to-average power ratio (PAR) problem encountered in the transmission of modern communication signals such as orthogonal frequency division multiplexing (OFDM). Constrained clipping is a promising CFR technique that is capable of large PAR reductions while guaranteeing that EVM and spectral mask constraints are met. In this paper, we analyze the computational complexity of constrained clipping and show that it is a practical technique that can be readily implemented. We then demonstrate its performance in a multiple-user OFDM environment such as the IEEE 802.16 OFDMA forward link. More than 5 dB of PAR reduction can be achieved in a four-user scenario

  • Comparison of Selected Mapping and Partial Transmit Sequence for Crest Factor Reduction in OFDM
    MILCOM 2006, 2006
    Co-Authors: Robert J. Baxley, G.t. Zhou
    Abstract:

    Selected mapping (SLM) and partial transmit sequence (PTS) are two existing distrotionless Crest Factor reduction (CFR) schemes that have been proposed for orthogonal frequency division multiplexing (OFDM). Previously, it was argued that SLM and PTS have comparable CFR performance but that the latter has lower computational complexity because it uses fewer IFFTs. In this paper, we show that the overall computational complexity of PTS may be higher than that of SLM, but that SLM always has better CFR performance as quantified through a per unit of complexity metric.

  • Constrained Clipping for Crest Factor Reduction in OFDM
    IEEE Transactions on Broadcasting, 2006
    Co-Authors: Robert J. Baxley, Chunming Zhao, Tong G. Zhou
    Abstract:

    In this paper, we propose a constrained clipping method for reducing the peak to average power ratio (PAR) or Crest Factor of an orthogonal frequency division multiplexing (OFDM) signal. This is a transmitter-side processing technique that does not impose any modification at the receiver. Specifically, constrained clipping achieves PAR reduction while simultaneously satisfying spectral mask and error vector magnitude (EVM) constraints which are specified by most modern communications standards. Our proposed constrained clipping method consists of two independent processing units, one to satisfy the in-band EVM constraint and the other to satisfy the out-of-band spectral constraint. Achievable PAR reduction results vary depending on the particular standards' requirements, but we show that by using constrained clipping on a QPSK WiMax signal with 256 subcarriers, a 4.5 dB PAR reduction at the 10-2 complementary cumulative distribution function (CCDF) level can be obtained