Indoor and Urban Satellite Positioning Augmentation System based on UMTS

Paper number

IAC-05-B3.5.06

Author

Mr. Francisco A. Lago, University of Valladolid, Spain

Coauthor

Mr. Juan Blas, University of Valladolid, Spain

Coauthor

Dr. Evaristo J. Abril, University of Valladolid, Spain

Coauthor

Dr. Ruben M. Lorenzo, University of Valladolid, Spain

Coauthor

Mrs. Ana Torre, Spain

Year

2005

Abstract

The aim of this paper is to describe an indoor and urban satellite navigation augmentation system, based on the third generation mobile communications technology, UMTS (Universal Mobile Telecommunications System). The proposed system solves the problem of poor accuracy of satellite navigation in urban scenarios, and even provides capabilities of indoor positioning.

At present, with GLONASS at half operation capabilities, GPS fully operational, and its augmentation systems SBAS (Satellite Based Augmentation System) -like European EGNOS, American WAAS or Japanese SBAS- being deployed, another new satellite positioning system is being developed, the European Galileo. All these systems will be compatible and interoperable, which means that users will be able to use all the navigation systems at the same time, increasing the general performance and positioning precision.

Although these systems provide good performance in open field, one of the biggest problems in satellite navigation, even increasing the number of satellites and constellations, is the positioning in urban and indoor scenarios, due to the little power that arriving satellite signals have, which is not enough to pass through obstacles and buildings. Present urban navigation applications use information from other techniques and sensors, like odometers and gyroscopes, to overcome the lack of precision from satellite positioning, but even with these enhancements, they sometimes fail, and the precision is often too coarse. Regarding indoor positioning, it is obviously impossible with satellites, because no signal reaches the receiver.

A potential solution to indoor and urban positioning is the use of UMTS antennas as providers of positioning signals. An UMTS positioning antenna will send satellite-like signals that can be used by receivers to calculate their positions. 

The main information that receivers need from any positioning transmitter is the accurate transmitter location and a very precise clock reference. With them, the receiver can estimate the distance to the transmitter, and with several distances from different transmitters, it can determine its position. The necessary equipment for the antennas to be used as positioning transmitters is:

-A precise clock, to provide the accurate time reference for the signal sent to the receivers.

-A precise satellite positioning receiver, needed to extract the precise timing reference provided with satellite positioning in order to continuously synchronize the clock of the antenna with the satellite timing reference.

The UMTS antennas are usually placed on the roof of buildings, which guarantees a high number of satellites in view, and a very exact estimation of the satellite clock reference. It is also necessary to know the position of transmitter to send it to the receivers, and the exact location of the fixed antenna can be accurately known and remains always invariable, so the information needed to send to the receivers, the clock reference and the transmitter position, is available. 

The main advantage of this solution is that deployment costs are reasonable, because the infrastructure necessary, the antennas, is already deployed and capable of transmitting signals with enough power to provide high precision urban positioning (for precise vehicle navigation, tourist and pedestrian guidance, blind guidance), and even indoor positioning (which would be very useful in museums, monuments, public services buildings). The integration of positioning with UMTS also opens a great amount of possibilities and applications for service providers.

Preliminary simulation studies have been performed in order to compare the precision obtained with satellite navigation systems alone and together with UMTS positioning antennas in urban scenarios, showing the high performance improvement provided by the UMTS positioning enhancement. The simulation results are shown in the paper.

Abstract document

IAC-05-B3.5.06.pdf

Manuscript document

IAC-05-B3.5.06.pdf (🔒 authorized access only).

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