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- Irshad, Yasir, 1977-
(författare)
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On some continuous-time modeling and estimation problems for control and communication
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The scope of the thesis is to estimate the parameters of continuous-time models used within control and communication from sampled data with high accuracy and in a computationally efficient way.In the thesis, continuous-time models of systems controlled in a networked environment, errors-in-variables systems, stochastic closed-loop systems, and wireless channels are considered. The parameters of a transfer function based model for the process in a networked control system are estimated by a covariance function based approach relying upon the second order statistical properties of input and output signals. Some other approaches for estimating the parameters of continuous-time models for processes in networked environments are also considered. The multiple input multiple output errors-in-variables problem is solved by means of a covariance matching algorithm. An analysis of a covariance matching method for single input single output errors-in-variables system identification is also presented. The parameters of continuous-time autoregressive exogenous models are estimated from closed-loop filtered data, where the controllers in the closed-loop are of proportional and proportional integral type, and where the closed-loop also contains a time-delay. A stochastic differential equation is derived for Jakes's wireless channel model, describing the dynamics of a scattered electric field with the moving receiver incorporating a Doppler shift.
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| 2. |
- Irshad, Yasir, 1977-
(författare)
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Some problems of modeling and parameter estimation in continous-time for control and communication
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stochastic system identification is of great interest in the areas of control and communication. In stochastic system identification, a model of a dynamic system is determined based on given inputs and received outputs from the system, where stochastic uncertainties are also involved. The scope of the report is to consider continuous-time models used within control and communication and to estimate the model parameters from sampled data with high accuracy in a computational efficient way. Continuous-time models of systems controlled in a networked environment, stochastic closed-loop systems, and wireless channels are considered. The parameters of a transfer function based model for the process in a networked control system are first estimated by a covariance function based approach, relying upon the second order statistical properties of the output signal. Some other approaches for estimating the parameters of continuous-time models for processes in networked environments are also considered. Further, the parameters of continuous-time autoregressive exogenous models are estimated from closed-loop filtered data, where the controllers in the closed-loop are of proportional and proportional integral type, and where the closed-loop also contains a time-delay. Moreover, a stochastic differential equation is derived for Jakes's wireless channel model, describing the dynamics of a scattered electric field with the moving receiver incorporating a Doppler shift.
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| 7. |
- 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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| 9. |
- 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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