Non-reporting (NR) vertex
A non-reporting (NR) vertex is a vertex (x, t) in the mobility graph satisfying both conditions:
- £\ (x, t) T > t,
- 0 „T t „T d(X0, x) „T £n.
A NR vertex represents a point which is reachable from the user last known location during its roaming interval, and in which the user should not transmit a registration message.