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- Mossberg, Magnus, 1971-, et al.
(författare)
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Fast estimators for large-scale fading channels from irregularly sampled data
- 2006
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Ingår i: IEEE Transactions on Signal Processing. - Karlstad Univ, Dept Elect Engn, SE-65188 Karlstad, Sweden. Univ Uppsala, Dept Syst & Control, SE-75105 Uppsala, Sweden. Karlstad Univ, Dept Math, SE-65188 Karlstad, Sweden.. - 1053-587X .- 1941-0476. ; 54:7, s. 2803-2808
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Tidskriftsartikel (refereegranskat)abstract
- The problem of estimating the power attenuation dynamics for large-scale lognormal fading channels in wireless communication systems, when the model is described as a mean reverting Ornstein-Uhlenbeck process, is studied in the paper. Fast and accurate estimators for the model parameters from irregularly sampled data are suggested for both offline and online applications. The Cramer-Rao bound for the estimation of the model parameters is derived, and the qualities of the proposed estimators are evaluated with respect to the bound.
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- Mossberg, Magnus, et al.
(författare)
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Long-term fading channel estimation from sample covariances
- 2009
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Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 45:5, s. 1126-1133
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Tidskriftsartikel (refereegranskat)abstract
- The power attenuation dynamics for long-term log-normal fading channels in wireless communication systems is modeled by a stochastic differential equation. Estimators for the model parameters based on sample covariances from data corrupted by discrete-time measurement noise are given. It is shown that the estimators are consistent, and variance expressions are derived and compared numerically to the Cramér–Rao bound. The estimation of the model parameters allows for the design of power control algorithms.
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- Jakobsson, Andreas, et al.
(författare)
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Exploiting temperature dependency in the detection of NQR signals
- 2006
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Ingår i: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 54:5, s. 1610-1616
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear quadrupole resonance (NQR) offers an unequivocal method of detecting and identifying land mines. Unfortunately, the practical use of NQR is restricted by the low signal-to-noise ratio (SNR), and the means to improve the SNR are vital to enable a rapid, reliable, and convenient system. In this paper, an approximate maximum-likelihood detector (AML) is developed, exploiting the temperature dependency of the NQR frequencies as a way to enhance the SNR. Numerical evaluation using both simulated and real NQR data indicate a significant gain in probability of accurate detection as compared with the current state-of-the-art approach.
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- Jakobsson, Andreas, et al.
(författare)
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Frequency-Selective Detection of Nuclear Quadrupole Resonance Signals
- 2005
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Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - 0196-2892 .- 1558-0644. ; 43:11, s. 2659-2665
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear quadrupole resonance (NQR) offers an unequivocal method of detecting and identifying both hidden explosives, such as land mines, and a variety of narcotics. Unfortunately, the practical use of NQR is restricted by a low signal-to-noise ratio (SNR), and means to improve the SNR are vital to enable a rapid, reliable, and convenient system. In this paper, we introduce a frequency-selective approximate maximum-likelihood (FSAML) detector, operating on a subset of the available frequencies, making it robust to the typically present narrow-band interference. The method exploits the inherent temperature dependency of the NQR frequencies as a way to enhance the SNR. Numerical evaluations, using both simulated and real NQR data, indicate a significant gain in probability of accurate detection as compared to a current state-of-the-art approach.
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