Enhanced Distance and Location Estimation for Broadband Wireless Networks

Abstract

In recent years, wireless positioning technologies have been widely integrated into new developments of telecom systems and services. As path loss characteristics are comprehensively investigated and adopted by international telecommunication union (ITU), received signal strength (RSS) is utilized as a type of measurement and can be properly transformed to obtain distance information. With the models and parameters addressed in the technical reports of 3GPP, the RSS-based distance and location estimation (RDLE) algorithm is proposed for mixed line-of-sight (LOS)/non-line-of-sight (NLOS) in LTE cellular networks. The proposed RDLE algorithm consists of a distance estimation method and a location estimation scheme. The particle-based distance estimation (PDE) method is proposed to estimate distances with RSS measurements under various environments and mixed sight conditions. Moreover, the geometry-improved location estimation (GILE) algorithm is proposed to explore geometric relationships between base stations (BSs) and mobile station (MS). A geometric constraint based on range differences which is related to time-difference-of-arrival (TDOA) information is constructed to confine MS\'s location estimation within a specific closed region. Moreover, a geometric reformation derived from minimizing the geometric dilution of precision (GDOP) is utilized as an assistance to increase the degree of freedom in space domain against the errors in location estimations. The theoretic Cramer-Rao lower bound is also derived as a benchmark to evaluate the precisions of positioning algorithms with range differences. The proposed RDLE algorithm is perceived to outperform other existing localization methods, especially under poor network topologies and insufficient measurement inputs.