Time Parameterized Interval R-Tree for Tracing Tags in RFID Systems

Indexing of Tagged Moving Objects over Localized Trajectory with Time Intervals in RFID Systems

“…We previously reviewed the Time-Parameterized Interval R-tree (TPIR-tree) [2], which is one of the few indexing schemes that are capable of managing tag trajectories in RFID systems. The time-parameterized interval, or tpinterval, is dependent on the time in a reader.…”

“…The tpinterval has the form t id , x, y, t enter , now . The now element, which is the present time, is called now-interval and is denoted 'nowI' [2]. In TPIR-tree, if a tag is a point tag, the time of the tag must be extended to now when processing queries.…”

“…In TPIR-tree, if a tag is a point tag, the time of the tag must be extended to now when processing queries. The augmentation of the time-dimension results in the expansion of MBB [2]. From what has been outlined above, we can search a tag that possesses only an entry time in TPIR-tree.…”

“…TPIR-tree shows a much larger number of accesses because it searches for tags to be updated in topdown manner [4]. Another reason for the poor performance is that if a point tag (nowEntry in TPIR-tree) is encountered in a query, MBB is expanded to the present time [2] for the trajectory. If an MBB is expanded, it overlaps with other MBBs, which in turn causes a backtracking and increases the number of node accesses.…”

“…RFID tags are used for tracking inventory, container management at harbors, supply chain management, etc. One reason for attaching tags to objects is tracing [1], [2]. To trace and manage the movement of tagged objects requires a trajectory index that specifies both previous and current movements.…”