The Global Positioning System allows most of today's phones to know where on the globe they currently are, often with accuracy measured in a few meters. This of course enables many interesting applications besides the obvious navigation use case.
However, there are still many scenarios where GPS is unable to provide the required accuracy. Since GPS requires your phone to communicate with satellites in space, it naturally works best when you have a clear view of the sky above. Accurate indoor positioning is not possible using GPS alone.
Investigate other techniques of positioning that could potentially be used where GPS is not enough. This includes but is not limited to:
The thesis work will likely include building some kind of prototype implementation on a mobile device.