On the capability of high sensitivity GPS for precise indoor positioning

High-sensitivity GPS receivers allow to track very weak GPS signals (-180 dBW or even below) that are due to strong signal attenuation by e.g. foliage or constructive materials. Consequently, they outperform classical geodetic receivers of more than 30 dB and enable the signal tracking and positioning even indoors. This increase of GPS availability opens up new applications such as seamless outdoor-indoor positioning and navigation. However the positioning accuracy is often poor. In this paper, we use an exemplary data set from our GPS indoor test network to analyse the capability of high sensitivity GPS receivers for precise indoor positioning. A general study of the performance parameters (e.g. DOP factors, C/No-values) gives a first impression of the improved availability. The detailed analysis of the observed-computed values of the pseudo-ranges quantify the indoor delay which can reach up to 100 m. Considering the positioning solution, it is shown that a C/N₀- based signal weighting can improve the accuracy of about 70 % for the mean value over 40 min observation time and up to 40% for the scatter of the coordinate time series.