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Weighted Least Squares Techniques for Improved Received Signal Strength Based Localization
Data Processing and Simulation Group, Universidad Politécnica de Madrid, ETSI. Telecomunicación, Avda. Complutense 30, 28040 Madrid, Spain
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Received: 1 August 2011; in revised form: 30 August 2011 / Accepted: 31 August 2011 / Published: 2 September 2011
Abstract: The practical deployment of wireless positioning systems requires minimizing the calibration procedures while improving the location estimation accuracy. Received Signal Strength localization techniques using propagation channel models are the simplest alternative, but they are usually designed under the assumption that the radio propagation model is to be perfectly characterized a priori. In practice, this assumption does not hold and the localization results are affected by the inaccuracies of the theoretical, roughly calibrated or just imperfect channel models used to compute location. In this paper, we propose the use of weighted multilateration techniques to gain robustness with respect to these inaccuracies, reducing the dependency of having an optimal channel model. In particular, we propose two weighted least squares techniques based on the standard hyperbolic and circular positioning algorithms that specifically consider the accuracies of the different measurements to obtain a better estimation of the position. These techniques are compared to the standard hyperbolic and circular positioning techniques through both numerical simulations and an exhaustive set of real experiments on different types of wireless networks (a wireless sensor network, a WiFi network and a Bluetooth network). The algorithms not only produce better localization results with a very limited overhead in terms of computational cost but also achieve a greater robustness to inaccuracies in channel modeling.
Keywords: localization; positioning; wireless networks; least squares; received signal strength; channel model estimation
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Tarrío, P.; Bernardos, A.M.; Casar, J.R. Weighted Least Squares Techniques for Improved Received Signal Strength Based Localization. Sensors 2011, 11, 8569-8592.
Tarrío P, Bernardos AM, Casar JR. Weighted Least Squares Techniques for Improved Received Signal Strength Based Localization. Sensors. 2011; 11(9):8569-8592.
Tarrío, Paula; Bernardos, Ana M.; Casar, José R. 2011. "Weighted Least Squares Techniques for Improved Received Signal Strength Based Localization." Sensors 11, no. 9: 8569-8592.