1 / 41

Identifying the Missing Tags in a Large RFID System

Identifying the Missing Tags in a Large RFID System. Tao Li (University of Florida, US) Shigang Chen (University of Florida, US) Yibei Ling (Telcordia Technologies, US). Outline. Introduction System Model Missing-tag Detection Protocols Simulation Results Conclusion. Introduction.

alcina
Télécharger la présentation

Identifying the Missing Tags in a Large RFID System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Identifying the Missing Tags in a Large RFID System Tao Li (University of Florida, US) Shigang Chen (University of Florida, US) Yibei Ling (Telcordia Technologies, US)

  2. Outline • Introduction • System Model • Missing-tag Detection Protocols • Simulation Results • Conclusion Identifying the Missing Tags in a Large RFID System

  3. Introduction • RFID (radio-frequency identification) • Used in: • Warehouse management • Object tracking • Inventory control • Australia Goats Identifying the Missing Tags in a Large RFID System

  4. Introduction • Other topics: • Tag-collection problem • Tag-estimation problem • This paper studies missing-tag problem. • Few research papers has investigated this problem before. Identifying the Missing Tags in a Large RFID System

  5. Introduction • The most important thing is to minimize the detection time. • Two guidelines to achieve time efficiency: • Reduce radio collision • Report presence by each transmitting a bit instead of a whole tag duel. Identifying the Missing Tags in a Large RFID System

  6. Outline • Introduction • System Model • Missing-tag Detection Protocols • Simulation Results • Related Work • Conclusion Identifying the Missing Tags in a Large RFID System

  7. Problem and Assumption • A large RFID system of N tags. • Each tag carries a unique ID. • Each tag can perform certain computations and communicating with the RFID reader wirelessly. • RFID reader has access to database that stores the ID of the tags. Identifying the Missing Tags in a Large RFID System

  8. Time Slots • Empty slot, singleton slot, collision slot. • ttag for tag slot, tl for long-response slot, ts for short-response slot. ts <tl<ttag. • ts = 0.4ms,tl= 0.8ms,ttag = 2.4ms Identifying the Missing Tags in a Large RFID System

  9. Outline • Introduction • System Model • Missing-tag Detection Protocols • Simulation Results • Conclusion Identifying the Missing Tags in a Large RFID System

  10. Baseline Protocol • Because RFID reader has access to database, no need to read directly from tags. • For each tag: • Broadcast the tag ID: ttag • Wait to receive short response: ts • Total executing time: N(ttag+ts) Identifying the Missing Tags in a Large RFID System

  11. Two-Phase Protocol (TPP) • Reduce the number of tag IDs transmit. • Two phase: • Frame phase • Polling phase Identifying the Missing Tags in a Large RFID System

  12. ID ID ID H(id, r) H(id, r) H(id, r) Frame 0 to f-1 Frame Phase of TPP • RFID reader transmit <r, f> • r is a random number, f is the frame size • pseudo-randomly mapped H(id, r) -> [0, f-1] Identifying the Missing Tags in a Large RFID System

  13. Frame Phase of TPP • Hash function H(id, r): • String of 200 random bits stored in the tag • Return a certain number of bits after the rth bit in the ring. • If necessary, the number of bits can be larger than 200. Identifying the Missing Tags in a Large RFID System

  14. ID1 ID2 ID3 ID4 Frame 0 to f-1 Polling Phase of TPP • Perform the baseline protocol on the tags that are mapped to the collision slots in the frame. Identifying the Missing Tags in a Large RFID System

  15. Time Efficiency of TPP • Set the value of the protocol parameter f. • The executing time of TPP is T1. • The number of tags mapped to the collision slots is N1. Identifying the Missing Tags in a Large RFID System

  16. Time Efficiency of TPP Identifying the Missing Tags in a Large RFID System

  17. Time Efficiency of TPP • When N = 50,000, the optimal frame size is f = 104,028, and the minimum execution time of TPP is 95.04 seconds. Identifying the Missing Tags in a Large RFID System

  18. Two-Phase Protocol with Tag Removal (TPP/TR) • In TPP, two tags mapped to a collision slot, we have to broadcast both tags. • The information in the collision slot is totally unused. • Remove tags from collision slot to make it a singleton slot. Identifying the Missing Tags in a Large RFID System

  19. Two-Phase Protocol with Tag Removal (TPP/TR) • Tow Phase: • Polling Phase (with tag removal) • Frame Phase • For each k-collision slot, randomly removes k-1 tags to turn the slot a singleton. Identifying the Missing Tags in a Large RFID System

  20. ID1 ID2 ID3 ID4 Frame 0 to f-1 Tag Removal • ID3 is removed, it will be broadcast in polling phase. • ID4 will be checked in frame phase. Identifying the Missing Tags in a Large RFID System

  21. Time Efficiency of TPP/TR • Set the value of the protocol parameter f. • The executing time of TPP/TR is T2. • The number of removal tags is N2. Identifying the Missing Tags in a Large RFID System

  22. Time Efficiency of TPP/TR Identifying the Missing Tags in a Large RFID System

  23. Time Efficiency of TPP/TR • When N = 50,000, the optimal frame size is f = 75,479. Identifying the Missing Tags in a Large RFID System

  24. Three-Phase Protocol with Collision Sensitive Tag Removal (TPP/CSTR) • When f is reasonably large, most collision slot are 2-collision slots. • Long response is needed. • The situation of the two tags response: • Empty: both are missing • Singleton: one is missing, check later • Collision: neither is missing. Identifying the Missing Tags in a Large RFID System

  25. Three-Phase Protocol with Collision Sensitive Tag Removal (TPP/CSTR) • Three Phase: • Polling Phase 1 (with tag removal) • Frame Phase • Polling Phase 2 • For each k-collision slot with k>2, randomly removes k-2 tags to turn the slot 2-collision. Identifying the Missing Tags in a Large RFID System

  26. ID5 ID1 ID2 ID3 ID4 Frame 0 to f-1 Tag Removal • ID3 is removed, it will be broadcast in polling phase 1. • ID4 and ID5 will be checked in frame phase and polling phase 2. Identifying the Missing Tags in a Large RFID System

  27. Time Efficiency of TPP/CSTR • Set the value of the protocol parameter f. • The executing time of TPP/TR is T3. • The number of removal tags is N3. • The number of tags broadcast in polling phase 2. Identifying the Missing Tags in a Large RFID System

  28. Time Efficiency of TPP/CSTR Identifying the Missing Tags in a Large RFID System

  29. Time Efficiency of TPP/CSTR • When N = 50,000, the optimal frame size is f = 38466. Identifying the Missing Tags in a Large RFID System

  30. Iterative ID-free protocol (IIP) • Transmitting tag IDs is an expensive operation. • IIP remove all the polling phase, it iteratively performs the frame phase. Identifying the Missing Tags in a Large RFID System

  31. Frame Phase in IIP • Transmitting a pre-frame vector: • ‘0’ for empty and singleton, ‘1’ for collision • A tag in a collision slot decide with 50% probability to not participate in the current frame. • Using H’(id,r). Identifying the Missing Tags in a Large RFID System

  32. Frame Phase in IIP • Transmitting a post-frame vector: • ‘0’ for empty and collision, ‘1’ for singleton • A tag in a singleton slot will not participate in the further execution. • Pre-frame or post-frame will be divide into segments of 96 bits (length of ID), and transmit in ttag. Identifying the Missing Tags in a Large RFID System

  33. Time Efficiency of IIP • Set the value of the protocol parameter f. • The executing time for a frame size of f of IIP is T4. • The expected number of tags whose presence will be verified by the frame is N’. • N* tags not confirm. Identifying the Missing Tags in a Large RFID System

  34. Time Efficiency of IIP Identifying the Missing Tags in a Large RFID System

  35. Time Efficiency of IIP • The average time for verifying the presence of one tag is Identifying the Missing Tags in a Large RFID System

  36. Time Efficiency of IIP • The optimal value the load factor is 1.516. Identifying the Missing Tags in a Large RFID System

  37. Outline • Introduction • System Model • Missing-tag Detection Protocols • Simulation Results • Conclusion Identifying the Missing Tags in a Large RFID System

  38. Simulation Results Identifying the Missing Tags in a Large RFID System

  39. Simulation Results Identifying the Missing Tags in a Large RFID System

  40. Outline • Introduction • System Model • Missing-tag Detection Protocols • Simulation Results • Conclusion Identifying the Missing Tags in a Large RFID System

  41. Conclusion • Monitoring the set of tags in a large RFID system and identifying the missing ones. • Proposing five missing-tag detection protocols with increasing time efficiencies. Identifying the Missing Tags in a Large RFID System

More Related