This time we will give you a brief overview of an LTE Tracking Area (TA) and Tracking Area Update (TAU).
While an LTE device (UE) is in active state (i.e. while communicating, or while in EMM-Registered/ECM-Connected/RRC-Connected state in LTE terms), its location is known by the LTE network at cell level (i.e. on a cell granularity), e.g. in cell2 in eNB1.
However, while the UE is in idle...