Dynamic Estimation of Optimum Path Loss Model in a RSS Positioning System

S. Mazuelas, F. A. Lago, D. Gonzalez, A. Bahillo, J. Blas and P. Fernandez

Abstract:	The development of location techniques in urban and indoor environments by using measurements of received signal strength (RSS) has as a main drawback the fact that in such environments the value of RSS depends on many unpredictable and changeable factors, not only on the actual distance between mobile station (MS) and the different base stations (BSs). In a specific propagation environment, received signal strength (on average) is proportional to the inverse of distance raised to a certain exponent. This exponent is known as path loss exponent or distance-power gradient. In free space propagation the value of this exponent is 2, but in general this value depends on specific propagation conditions present in each moment, so the values for this path loss exponent vary from values slightly lower than 2 (in some indoor environments) to values close to 6. Distance estimates will be accurate only if the propagation model used describes well specific propagation conditions present at each instant. So, the precision achieved on distances estimations from the RSS measurements depends directly on using a path loss exponent which fits well with the existing propagation conditions. Methods presented in other publications related to RSS location, need a previous exhaustive measurements campaign in the particular scenario where location takes place, or they use general propagation models which fit in the different environments. The first alternative achieves good accuracies, but it needs a costly previous stage to do the measurements campaign. Moreover this measurements campaign loses its validity if environment changes happen. On the other hand, the second alternative is quite simple but it offers very low accuracies, because the generic propagation model used does not describe with precision the dependence between distance and RSS.
Published in:	Proceedings of IEEE/ION PLANS 2008 May 6 - 8, 2008 Hyatt Regency Hotel Monterey, CA
Pages:	679 - 684
Cite this article:	Mazuelas, S., Lago, F. A., Gonzalez, D., Bahillo, A., Blas, J., Fernandez, P., "Dynamic Estimation of Optimum Path Loss Model in a RSS Positioning System," Proceedings of IEEE/ION PLANS 2008, Monterey, CA, May 2008, pp. 679-684. https://doi.org/10.1109/PLANS.2008.4569988
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