Collaborative Code-Based Differential GNSS for Multi-User Positioning

Kurzfassung

This paper introduces a collaborative differential GNSS (C-DGNSS) method designed to enhance positioning accuracy in scenarios with limited satellite visibility, relying solely on GNSS pseudorange measurements and requiring no inter-ranging information. C-DGNSS exploits the correlation among single difference observations from multiple users to a common base station, which are not leveraged by conventional DGNSS. The estimation problem is formulated as an iterative weighted least squares (WLS) estimator, known to be optimal under the Gaussian assumption, and its variance lower bound is derived from the Cramér-Rao bound (CRB). C-DGNSS is compared against conventional DGNSS and the ideal DGNSS bound, the latter assuming noiseless pseudorange measurements for the base station. We evaluate the impact of the number aiding users, their geometry, and measurement precision on positioning error, as well as the effect of favorable and poor geometric dilution of precision (GDOP) for the aided users. Simulation results demonstrate that the proposed scheme outperforms standard DGNSS even with a single aiding user, approaching the ideal bound as the number of aiding users grows and their geometry improves. Accuracy gains of up to 28.5\% are achieved.