Huerta, J.; Vidal, J.; Giremus, A.; Tourneret, J. IEEE journal on selected topics in signal processing Vol. 3, num. 5, p. 874-888 DOI: 10.1109/JSTSP.2009.2027804 Data de publicació: 2009-10 Article en revista
The performance of localization techniques in a wireless communication system is severely impaired by biases induced in the range and angle measures because of the non-line-of-sight (NLOS) situation, caused by obstacles in the transmitted signal path. However, the knowledge of the line-of-sight (LOS) or NLOS situation for each measure can improve the final accuracy. This paper studies the localization of mobile terminals (MT) based on a Bayesian model for the LOS-NLOS evolution. This Bayesian model does not require having a minimum number of LOS measures at each acquisition. A tracking strategy based on a particle filter (PF) and an unscented Kalman filter (UKF) is used both to estimate the LOS-NLOS situation and the MT kinetic variables (position and speed). The approach shows a remarkable reduction in positioning error and a high degree of scalability in terms of performance versus complexity.
This paper shows the analysis and implementation of a hybrid DC–DC power converter. The proposed topology consists of a series linear voltage regulator in parallel with a switching step-down converter. This topology can provide small ripple at the output voltage, fast responses for load variations and high efficiency for high load current conditions. In the hybrid structures there is not a classical feedback loop as in DC-DC converters, but they are feedback systems too. Therefore, their smallsignal analysis is important to assure stability of the implemented power supply system. From the analysis proposed we deduce the critical components that induce instability to the converter and how to improve the final design.