Figure 1.

Illustrative example of Call Detail Records (CDRs), eXtended Detail Records (XDRs) and Control Plane Records (CPRs) of a user u. The hexagons represent mobile phone towers and black dots the positions where the user starts a call (CDRs), a download/upload operation (XDRs), or a network event (CPRs). Red dots indicate calls, green dots indicate download/upload operations, blue dots, green squares and green triangles indicate network events. The dotted line indicates the real movement of the user, from the left to the right, within each panel. The dark grey tower indicates the tower in which the user has the highest number of records. From this example, we observe that: 1) CDRs are the most sparse and CPRs the most dense data stream; 2) when u does not perform any call or download/upload operation in the area covered by a tower, there is no information about the user’s position in CDRs and XDRs; 3) CPRs is the only type of records that can describe all the towers u passed through