Sensitivity of projection-based near-far mitigation techniques in high-sensitivity GNSS software receivers

Abstract

One of the difficulties faced by high-sensitivity GNSS receivers is the so-called near-far problem, where the acquisition of weak signals is hampered by the presence of more powerful signals. If countermeasures are not implemented, the presence of near-far may result in loss or false acquisition of weak signals, and consequently the user's position may exhibit a huge error. In this sense, subspace projection techniques become an attractive choice for near-far mitigation purposes due to their effectiveness and low-complexity. However, many questions still remain open to make the techniques implementable in real handheld receivers such as mobile phones, which have not yet been addressed in the literature. This paper contributes with an analysis of the robustness of projection-based mitigation techniques when the synchronization parameters or the data bits of the interferences are not perfectly estimated. On the other hand, the paper also analyses the impact that signal filtering and quantization at the receiver front-end may also have on the near-far mitigation performance. The approaches presented in this paper give an actual idea of what would happen in practice in a real GNSS receiver. To analyse these effects, an extensive simulation campaign was conducted for Galileo E1 signals.