Hardware Simulator Models and Methodologies for Indoor Performance Assessment of High Sensitivity Global Positioning Satellite Receivers

Simulation of weak GPS signals received in various environments has been proposed as a cost-efficient method of verifying the positioning performance of such mobile telephones. Recent results have demonstrated both the success and limitations of weak-signal and multipath models implemented in an advanced GPS hardware simulator. In particular, the lack of variability of multipath delay, as a function of time, is suspected to be a major reason for the discrepancy between simulator and field test results. This paper discusses how these model limitations have been addressed recently and demonstrates the improvement in the correlation between the simulator results and field test results. A high-sensitivity GPS receiver is used to collect data under two scenarios, near a building in an outdoor environment and inside a residence. These data are then used as a baseline to attempt to generate signals in the simulator that result in measurements with similar stochastic characteristics. An analysis of the results in terms of fading and position demonstrates the viability of this approach to test receivers under controlled environments.