Improvement of Augmented Multi-Constellation Satellite-Based Precise Positioning in a Wide Range of Environments

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Although GPS was the first widely available satellite navigation system, it has now been joined by the Russian GLONASS system, and will soon be joined by the European Galileo system, the Chinese BeiDou system and the Japanese QZSS-all of which have test satellites now in orbit. There are a number of interesting problems to be solved in gaining maximum benefits from this plethora of global navigation satellite systems (GNSS) for precise positioning and navigation, and my proposed Discovery Grant research will address a number of them.**By using observations from all available satellites, regardless of constellation, we have the possibility of significantly improving navigation availability and continuity in restricted environments where signals from some directions might be blocked. We also have the potential for improved positioning accuracy due to the availability of more observations with more favourable geometry. We have already demonstrated this by combining GPS observations with those from one of the Galileo test satellites. Research is needed on how to best combine measurements from the different systems with different reference datums, reference time systems, system biases, signal types, and measurement accuracies and precisions. The algorithms and associated software for optimally processing the observations also need to be developed. We have already achieved an optimum approach for combining GPS and GLONASS legacy signal data and will extend it for data from the other constellations.**High-accuracy GNSS positioning in sub-par environments is hampered by other difficulties besides access to augmentation data. For example, in the auroral and polar regions, the ionosphere can be often disturbed resulting in scintillating observations that frequently include cycle slips or jumps in the recorded carrier-phase data. My research group has made significant progress in developing approaches for the detection and repair of cycle slips. However, the techniques are not infallible and further research into the problem of cycle slips is required. **The new GNSS along with modernized GPS will offer new signal structures on multiple frequencies that will greatly benefit positioning and navigation. My group has done some pioneering work to demonstrate some of the advantages and we will carry out further investigations as the GPS Block IIF/III, Galileo, and BeiDou constellations are built up along with the use of the new signals to be implemented for the GLONASS constellation.**Our work will also involve enhanced modelling of atmospheric effects. We will be investigating GNSS receiver performance in disturbed ionospheric conditions, including the use of GPS as a remote-sensing tool for studying the morphology of the electron distribution. This part of our work will make use of data from terrestrial GPS receivers including those of the expanded Canadian High Arctic Ionospheric Network currently being deployed by UNB. We will also begin the analysis of data from our GPS-based instrument on the Canadian CASSIOPE scientific satellite launched at the end of September 2013.**Some of our work will be coordinated with the International GNSS Service (IGS) Multi-GNSS Experiment and the IGS Real Time Pilot Project-two IGS activities in which we already participate.**All of our proposed GNSS research will be of significant benefit for positioning and navigation in Canada and worldwide.