Challenges in ambiguity resolution: Biases, weak models, and dimensional curse

Next generation Global Navigation Satellite Systems will open the door to a whole new field of applications, for example in Earth observation, construction, and safety-of-life navigation. This implies very high requirements not only on precision and availability, but also on reliability. Integer carrier phase ambiguity resolution is the key to (near) real-time and high-precision GNSS positioning and navigation. The reliability of integer ambiguity estimation depends on the strength of the underlying GNSS model and on the applied integer estimation method. This brings certain challenges and limitations that need to be addressed and have not all been solved so far. The aim of this contribution is to address these remaining challenges and limitations: it will be explained why it is important to do so, and how solutions can be obtained. Experimental results will be used to underpin the importance and potential improvement in terms of precision and/or reliability.