UPGRADE 2D Experimental Results for the RnS Approach

摘要

UPGRADE (Universal Positioning Theory Based on Global Positioning System) approaches have already been described [1], showing that it was theoretically feasible to use so-called "GPS repeaters" to implement an indoor positioning system which will allow a standard GPS receiver to give accurate indoor location information. The subject of this paper is now to present a practical new way to implement the approach that uses "RnS" repeaters, which transmit the signals of all the visible satellites from outdoors to indoors. We also present experimental results that confirm the possibility to achieve an indoor positioning system accurate to less than one meter (basically the same receiver accuracy as outdoors). To achieve a full positioning system, UPGRADE states that 4 such repeaters are required for a complete global system. Experiments with 3 have been carried out that allowed a 2-D location to be computed, assuming we are moving on a given floor of a building. For instance, a 1-meter accurate altimeter could be used to help in the determination of the floor. Experimental results have shown a typical accuracy of 1 meter in an open space (light multipath) environment such as a gymnasium, using an Ag132 Trimble receiver. Complementary experiments in a typical office building also show a less than 1 meter accuracy, using a Thales Navigation receiver. With these first results, we feel confident in designing a fully integrated GNSS receiver that will have indoor accuracy hitherto not achieved. The global indoor system architecture is still to be improved, taking into account different types of applications and environments, but the very simple theoretical method has proved to be a credible alternative to pseudolites or high sensitivity GNSS [2]. Furthermore, when thinking in terms of Assisted-GNSS, it is possible to use the most recent developments to improve our UPGRADE system further by using aid from a local communication network to provide useful information (location of repeaters, their specific characteristics, etc.). The next step is to achieve a full indoor positioning system, either by using 4 RnS repeaters, or by integrating additional sensors within the receiver (mainly altimeters and gyros).