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Träfflista för sökning "LAR1:cth ;pers:(Viberg Mats 1961);srt2:(2010-2011)"

Sökning: LAR1:cth > Viberg Mats 1961 > (2010-2011)

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  • Cerullo, Livia, 1982-, et al. (författare)
  • Determination of model order for inverse scattering applications
  • 2010
  • Ingår i: Proceedings of the V European Conference on Computational Fluid Dynamics ECCOMAS CFD 2010 J. C. F. Pereira, A. Sequeira and J. M. C. Pereira (Eds) Lisbon, Portugal,14-17 June 2010. - 978-989-96778-1-4
  • Konferensbidrag (refereegranskat)
  • Chung, P. J., et al. (författare)
  • Broadband ML estimation under model order uncertainty
  • 2010
  • Ingår i: Signal Processing. - 0165-1684. ; 90:5, s. 1350-1356
  • Tidskriftsartikel (refereegranskat)abstract
    • The number of signals hidden in data plays a crucial role in array processing. When this information is not available, conventional approaches apply information theoretic criteria or multiple hypothesis tests to simultaneously estimate model order and parameter. These methods are usually computationally intensive, since ML estimates are required for a hierarchy of nested models. In this contribution, we propose a computationally efficient solution to avoid this full search procedure and address issues unique to the broadband case. Our max-search approach computes ML estimates only for the maximally hypothesized number of signals, and selects relevant components through hypothesis testing. Furthermore, we introduce a criterion based on the rank of the steering matrix to reduce indistinguishable components caused by overparameterization. Numerical experiments show that despite model order uncertainty, the proposed method achieves comparable estimation and detection accuracy as standard methods, but at much lower computational expense. (C) 2009 Elsevier B.V. All rights reserved.
  • Johansson, Eija, 1982-, et al. (författare)
  • Interpolation based on stationary and adaptive AR(1) modeling
  • 2011
  • Ingår i: 36th IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2011; Prague; 22 May 2011 through 27 May 2011. - 15206149. - 978-145770539-7 ; s. 4052-4055
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we describe a minimal mean square error (MMSE) optimal interpolation filter for discrete random signals. We explicitly derive the interpolation filter for a first-order autoregressive process (AR(1)), and show that the filter depends only on the two adjacent points. The result is extended by developing an algorithm called local AR approximation (LARA), where a random signal is locally estimated as an AR(1) process. Experimental evaluation illustrates that LARA interpolation yields a lower mean square error than other common interpolation techniques, including linear, spline and local polynomial approximation (LPA).
  • Khademi, Seyran, 1981-, et al. (författare)
  • Peak-to-Average-Power-Ratio (PAPR) reduction in WiMAX and OFDM/A systems
  • 2011
  • Ingår i: EURASIP Journal on Advances in Signal Processing. - 1687-6180.
  • Tidskriftsartikel (refereegranskat)abstract
    • A peak to average power ratio (PAPR) reduction method is proposed that exploits the precoding or beamforming mode in WiMAX. The method is applicable to any OFDM/A systems that implements beamforming using dedicated pilots which use the same beamforming antenna weights for both pilots and data. Beamforming performance depends on the relative phase shift between antennas, but is unaffected by a phase shift common to all antennas. PAPR, on the other hand, changes with a common phase shift and this paper exploits that property. An effective optimization technique based on sequential quadratic programming is proposed to compute the common phase shift. The proposed technique has several advantages compared with traditional PAPR reduction techniques in that it does not require any side-information and has no effect on power and bit-error-rate while providing better PAPR reduction performance than most other methods.
  • Lioliou, Panagiota, 1982-, et al. (författare)
  • Bayesian Channel Estimation Techniques for AF MIMO Relaying Systems
  • 2011
  • Ingår i: IEEE VTS Vehicular Technology Conference Proceedings. VTC 2011 - Fall. - 1090-3038. - 978-1-4244-8327-3
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, we consider the fundamental problem of channel estimation in multiple-input multiple-output (MIMO) amplify-and-forward (AF) relaying systems operating over random channels. Using the Bayesian framework, linear minimum mean square error (LMMSE) and expectation-maximization (EM) based maximum a posteriori (MAP) channel estimation algorithms are developed, that provide the destination with full knowledge of all channel parameters involved in the transmission. The performance of the proposed algorithms is evaluated in terms of the mean square error (MSE) as a function of the signal-to-noise ratio (SNR) during the training interval. Our simulation results show that the incorporation of prior knowledge into the channel estimation algorithm offers improved performance, especially in the low SNR regime.
  • Mecklenbräuker, Christoph F., et al. (författare)
  • Eigenbeam transmission over line-of-sight MIMO channels for fixed microwave links
  • 2011
  • Ingår i: Proceedings - ITG/IEEE Workshop on Smart Antennas (WSA). - 978-161284074-1
  • Konferensbidrag (refereegranskat)abstract
    • We propose and analyze eigenbeam transmission over line-of-sight (LOS) multiple-input multiple-output (MIMO) channels with linear reception. In particular, we consider fixed point-to-point microwave links for which the singular value decomposition of the LOS MIMO channel matrix is analytically derived. We demonstrate that the Tx eigenbeams can be defined without channel state information at the transmitter and that the beams admit an insightful physical interpretation. We also evaluate the performance of a lattice-reduction aided linear receiver through numerical simulations.
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