Figure 3From: Spatiotemporal correlations of handset-based service usagesSchematic diagram for deriving temporal boundaries from a sequence of cell records. Temporal boundaries {( c k , t k ( s ) , t k ( e ) )} (colored boxes) are derived from a sequence of cell records {( c k , t k )} (vertical black lines). It is assumed that the user stays in the cell c k from the moment of t k ( s ) to t k ( e ) . See the text for details.Back to article page