GNSS/Cellular Hybrid Positioning System for Mobile Users in Urban Scenarios

Abstract

This paper proposes a hybrid scheme for user positioning in an urban scenario using both a Global Navigation Satellite System (GNSS) and a mobile cellular network. To maintain receiver complexity (and costs) at a minimum, the location scheme combines the time-difference-of-arrival (TDOA) technique measurements obtained from the cellular network with GNNS pseudorange measurements. The extended Kalman filter (EKF) algorithm is used as a data integration system over the time axis. Simulated results, which are obtained starting from real measurements, demonstrate that the use of cellular network data may provide increased location accuracy when the number of visible satellites is not adequate. In every case, the obtained accuracy is within the limits required by emergency location services, e.g., Enhanced 911 (E911).

A survey of positioning techniques and location based services in wireless networks

“…Thus, inconsistent information is provided as entry when resolving the localization problem. Authors of [18] describe a hybrid positioning scheme that combines TDoA technique measurements obtained from the cellular network with GPS range information to improve the accuracy of mobile client position estimation. The obtained accuracy should be within the limits required by emergency location services.…”

“…Indeed, it is crucial for emergency location services. Hence, hybrid positioning systems, such as [18,19], are introduced to improve accuracy and reliability of the existing localization technologies.…”

Advanced Train Location Simulator (ATLAS) for developing, testing and validating on-board railway location systems

“…Both particle and Kalman filters are proposed in the literature as solutions to the problem of estimating a position using the measurement(s) received [7,10,22,38]. The modularity of the ATLAS platform allows evaluating different positioning strategies and algorithms, selecting the most adequate configuration.…”

“…With this strategy a final estimate is obtained when each of the positioning modules produces a partial position. An advanced integration of this option is to position only with GNSS and switch to another technology when this one is unavailable or deteriorated [10,22]. This data fusion is more time consuming and needs extra hardware for calculation of the partial positions.…”

“…Particularly, the LOCO-PROL [36] project reduces the positioning problem to the corresponding point in the track, thereby reducing the 3-dimensional position to only 1-dimension, a unique feature of the railway. The EATS [12] project proposes an on-board Smart Train Positioning System (STPS) based on the combination of different techniques proved useful for other industrial sectors with the aim of reaching ETCS level 3 requirements [10,26,32]: multi-antenna assembly to reduce multi-path effects and the combination of information sources such as GNSS, UMTS and GSM-Railway (GSM-R) which will provide full coverage on the tracks even in harsh environments. In general, the on-board hybridization of technologies will be a step forward towards European Train Control System (ETCS) level 3 minimizing track-side costs and maximizing track capacity.…”