A Counter-Based RFID Anti-Collision Protocol Using Parallel Splitting

1. A Counter-Based RFID Anti-Collision Protocol Using Parallel Splitting Ming-Kuei Yeh and Jehn-Ruey Jiang Department of Computer Science and Information Engineering National Central University

2. Outline • Introduction • Anti-collision protocols • Proposed protocol • Evaluation • Conclusion

3. Outline • Introduction • Anti-collision protocols • Proposed protocol • Evaluation • Conclusion • Introduction

4. Introduction RFID system • RFID (Radio Frequency IDentification) system • Reader • Tag (Transponder) • Application

5. Introduction Application

6. Introduction Interrogation zone Tag 1 Tag 3 reader Interrogation zone Tag 2

7. Introduction Tag-to-tag interference tag reader Interrogation zone Tag collision problem: collision occurs when multiple tags respond to the same reader simultaneously

8. Outline • Introduction • Anti-collision protocols • Proposed protocol • Evaluation • Conclusion • Anti-collision protocols

9. Anti-collision protocols category • Anti-collision protocols • For solving the tag collision problem • Two classes • ALOHA based • Tree based • deterministic tree-based • probabilistic counter-based

10. Tag10 Tag9 Tag8 Collision ! Tag7 Tag6 Tag5 Tag4 Collision ! Tag3 Tag2 Tag1 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 Anti-collision protocols ALOHA based S: time slot An example of slotted ALOHA protocol

11. Anti-collision protocols Tree based 0 1 0 1 1 0 1 0 1 0 1 0 Tag1 Tag2 Tag3 Tag4 Tag5 Tag6 ID:0010 An example of bit-by-bit tree protocol

12. Anti-collision protocols Counter based C = 0 C= counter C = 0 C = 0 C =3 C =4 C = 0 C = 0 C =2 C =3 C = 0 C = 0 C = 0 C =1 C = 0 C =1 C =2 C = 0 C =2 C = 0 C = 0 C = 0 C = 0 C = 0 C =1 C =0 C = 0 C =1 Tag1 Tag1 An example of a counter-based protocol: ISO/IEC18000-6B

13. Outline • Introduction • Anti-collision protocols • Proposed protocol • Simulation • Conclusion • Proposed protocol

14. Proposed protocol • Parallel Splitting (PS) forRFID Tag Anti-Collision • Counter based anti-collision protocol • Using two schemes • Parallel Splitting • Adaptive Identification-Tree Height Adjustment

15. Proposed protocol Parallel Splitting C = 0 C =0 C = 0 C = 0 C =1 C = 0 C =1 C =0 C =1 C = 0 C = 0 C = 2 C =1 C =3 C =0 C =1 C =2 C =3 Just left-shift their counters one bit and add one or zero randomly to the counters. C =1 C =3 C =5 C =7 C =0 C =2 C =4 C =6 Tag1 C =5 C =7 C =10 C =12 C =0 C =2 C =6 C =8 C =9 C =11 C =13 C =1 C =3 C =4 C =14 C= counter

16. Proposed protocol Adaptive Identification-Tree Height Adjustment • Why do we need to adjust the • identification-tree height? • May not be so lucky to split the tags perfectly(to be a full tree)

17. Proposed protocol Adaptive Identification-Tree Height Adjustment (cont’) • Analyzing the ratio of the numbers of • leaf nodes that including zero tag, one tag • and multiple tags p(S): the probability that there are S tags residing at a leaf node N:The number of tags in the interrogation zone L:The number of leaf nodes; ;

18. Proposed protocol Adaptive Identification-Tree Height Adjustment (cont’)

19. Proposed protocol Adaptive Identification-Tree Height Adjustment (cont’)

20. Proposed protocol Adaptive Identification-Tree Height Adjustment (cont’)

21. Proposed protocol Adaptive Identification-Tree Height Adjustment (cont’)

22. Proposed protocol Adaptive Identification-Tree Height Adjustment (cont’) Let the expected numbers of leaf nodes containing none, one and multiple tags be e(0), e(1) and e(m), respectively.

23. Proposed protocol Adaptive Identification-Tree Height Adjustment (cont’) It is reasonable to assume L>>1 and N>>1, and to take L–1as L, and N–1, N–2 as N. We have

24. Proposed protocol Adaptive Identification-Tree Height Adjustment (cont’) • Analyzing the ratio of the numbers of • leaf nodes that including zero tag, one tag • and multiple tags • The result of analysis Rule1 Rule2 L :The number of leaf nodes N:The number of tags in the interrogation zone

25. Proposed protocol Adaptive Identification-Tree Height Adjustment (cont’) • The Actions of Adjustment • Rule 1: If N0 > 2*N1 and N1 > 3.4*Nm, • ＝＞all unidentified tags right-shift their counters one bit to divide L by 2. • Rule 2: If 2*N0 < N1 and 1.7*N1 < Nm • ＝＞ all unidentified tags left-shift their counters one bit to multiply L by 2, and subsequently add one or zero randomly to the counters.

26. Proposed protocol Two Phases of PS Protocol • In phase I • All tags are split in parallel until the first tag is identified successfully. • In phase II • Tags are identified one by one according to • The normal identification procedure of ISO/IEC 18000-6B protocol. • The reader applies Rule1 or Rule2for adjusting the number of leaf nodes to approach the actual number N of tags (N is unknown) • In phase II

27. Outline • Introduction • Anti-collision protocols • Proposed protocol • Evaluation • Conclusion • Evaluation

28. Evaluation • The simulations are programmed in Java language • Each simulation is performed 1,000 times and then calculates the average value

29. Evaluation -The relation between the height of the identification tree and the number of iterations needed An iteration is defined as a reader sends a command and tags perform corresponding actions N is the number of tags in the interrogation zone is the “perfect” height of the identification-tree The comparison of the number of iterations for 1,025~2,025 tags.

30. Evaluation-the number of iterations The comparison of the number of iterations between ISO18000-6B and the PS protocol for 512~2,012 tags.

31. Evaluation-System Efficiency System efficiency is defined as the ratio of the number N of tags to the number S of slots (iterations) required to identify all the tags The comparison of PS, query tree (QT), ISO/IEC 18000-6B, and frame slotted ALOHA protocols in terms of system efficiency for 100~1,000 tags

32. Outline • Introduction • Anti-collision protocols • Proposed protocol • Evaluation • Conclusion • Conclusion

33. Conclusion • We have proposed a newcounter based anti-collision protocol (PS) for RFID systems • Two schemes are used in this protocol • parallel splitting • adaptive identification-tree height adjustment • PS has better performance than ISO-18000 6B

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