Evaluation of a GNSS Receiver Performance in Different Multipath Environments with a Novel Real-time Multipath Simulation System

Abstract

Multipath can be one of the main sources of error in a GNSS receiver in urban environment. Multipath errors can vary from a few meters to hundreds of meters according to the geometry of the satellites and environmental conditions. The characterization and study of multipath is complex but important when its effect needs to be compensated in the position or navigation solution. The disruption caused in the received GNSS signal by the surrounding environment can be assessed in simulation. In fact, simulation is a powerful tool to test the performances of GNSS systems and services in controlled and repeatable conditions. Furthermore, simulations provide users with a method to characterize the multipath, to study and test advanced and new techniques for multipath rejection, to evaluate the reception in a given location and at a specific time (i.e. mission planning), and to simplify the analysis of specific events (i.e. for mission debriefing). The aim of this paper is to analyze the performances of a GNSS receiver with an innovative real-time system that allows the reproduction of an authentic multipath environment. The system combines a state-of-the-art GNSS simulator and an advanced GNSS propagation model. The propagation model relies on a 3D-model reconstruction of the urban environment, which allows the generation of a multipath signature that strictly depends on the location of the receiver’s antenna. This becomes important for a moving vehicle since it may be affected by very different multipath conditions depending on the trajectory and location. Then, the performances of a GNSS receiver are compared between simulated and field test data. The results show that it is possible to simulate realistically the multipath environment and to obtain performances that are comparable to a real case scenario.