Rapid Initialization for Long Baseline RTK Positioning: Combined GPS+Galileo+BDS+QZSS+GLONASS with Partial Ambiguity Resolution

Introducing atmospheric delays in the GNSS RTK positioning model significantly weakens the ambiguity resolution performance, causing for instance long times to reliably fix the ambiguities when differential ionospheric delays have to be estimated. In order to overcome this problem, the combination of two strategies is proposed in this paper: the joint processing of five GNSS and partial ambiguity resolution. For GLONASS, the recently introduced integer estimable FDMA model from [1] is employed. We analyze two different partial ambiguity resolution schemes, both with simulations and real GNSS data from an 88.5 km baseline. The results show that instantaneous centimeter level positioning is possible with the ionosphere weighted model, and that on average only 3.5 epochs are required to reach the centimeter level with the ionosphere float model.