A Geometry-Assisted SSSD Positioning Method for Use in Urban Areas

Cellular Communications for public safety, emergency communications and delivery of location-based services (LBSs) to mobile terminal (MT) has been receiving a lot of attention in recent years. In our earlier work ( B. C. Liu, K. H. Lin, and J. C. Wu, IEEE Trans. Veh. Tech., Mar. 2006), a novel positioning method based on stationary signal-strength-difference (SSSD) measurements is proposed by using hyperbolic multilateration technique. The positioning accuracy obtained with this method, however, is degraded as a result of the large error in the estimated distance difference (DD). This paper contributes a geometry-assisted method to improve the positioning accuracy achieved by our earlier work. It is particularly useful for use in the urban areas where the propagation conditions are complicated and can not easily be parameterized. Through a field trial in a commercial cellular communication system, results show that the proposed method is able to estimate the MT position with better accuracy.