[hxsvui]

These attacks are valuable inputs for new generations, but no cause to consider 3G and 4G insecure in practice.

The authors learn about user's activity and location. But the comments often lack understanding what that means in context of mobile networks. Usually, it simply means:

* Is the user currently active in the cell?

If yes, the user's location is known (somewhere in this cell) and also his activity (he's online, otherwise he wouldn't be present). The authors here present an issue where the authentication procedure allows tracking with some probability.