Maximum Likelihood Position Location with a Limited Number of References

 

D. Munoz–Rodriguez*¹, L. Suarez–Robles², C. Vargas–Rosales³, J. R. Rodriguez–Cruz⁴

 

^1,2,3,4 Department of Electrical and Computer Engineering, ITESM–Monterrey. Av. Eugenio Garza Sada 2501 Sur, Monterrey, N.L., 64849, Mexico.*E–mail: dmunoz@itesm.mx

 

ABSTRACT

A Position Location (PL) scheme for mobile users on the outskirts of coverage areas is presented. The proposed methodology makes it possible to obtain location information with only two land–fixed references. We introduce a general formulation and show that maximum–likelihood estimation can provide adequate PL information in this scenario. The Root Mean Square (RMS) error and error–distribution characterization are obtained for different propagation scenarios. In addition, simulation results and comparisons to another method are provided showing the accuracy and the robustness of the method proposed. We study accuracy limits of the proposed methodology for different propagation environments and show that even in the case of mismatch in the error variances, good PL estimation is feasible.

Keywords: Position location, maximum likelihood, wireless networks.

 

RESUMEN

Se presenta un método de localización de la posición de dispositivos móviles en las fronteras de una región de cobertura. La metodología propuesta hace posible obtener la información de localización utilizando únicamente dos referencias fijas. Se introduce una formulación general y se muestra que la estimación de máxima verosimilitud puede proporcionar la información de localización de manera adecuada en este escenario. Se obtiene la caracterización del error de la posición por el valor rms del error y su distribución para diferentes escenarios de propagación. Además, a través de simulaciones y comparaciones con otros métodos, se muestra la exactitud y robustez de la metodología propuesta. Se estudian las limitaciones de exactitud de la metodología propuesta en diferentes ambientes de propagación y se muestra que aún en casos de diferencias en la varianza de los errores se obtiene una estimación de la posición con buena exactitud.

 

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