Real-Time Phase Ambiguity Resolution in Global Navigation Satellite Systems

Abstract

This dissertation focuses on real-time carrier phase ambiguity resolution for high precision solutions in Global Navigation Satellite Systems (GNSS). In order to exploit the full accuracy potential, one must be able to account for the unknown integer ambiguity related to the carrier phase observable. Solving this integer ambiguity with a sufficient level of reliability and integrity is perhaps one of the most challenging tasks in real-time processing of GNSS observations.

The integrated use of GNSS introduces the problem of modeling the various inter-system biases involved. In order to identify the integer nature of the ambiguities in a common high precision solution utilizing the carrier phase observable, one must in general be able to address all biases and measurement errors down to a sufficient level of accuracy.

During the last decade much effort has been put into research and development of methods to determine this integer ambiguity, realizing that fixing the integer ambiguities to their correct values, aiming at high computational efficiency and high success rate, is a non-trivial problem.

This thesis contains the following contributions:

• Defining the integer optimization problem and identifying its complexity.

• Introducing the reduced basis method for ambiguity resolution.

• Introducing models for the integrated use of GNSS, with emphasis on the preservation of the integer nature of the ambiguities.

• Comparing the performance of the reduced basis method and the LAMBDA method for ambiguity resolution on observations from various campaigns.