a counter-based rfid anti-collision protocol using parallel splitting

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Adaptive Computing and Networking Laboratory

WASN 2009

A Counter-Based RFID Anti-Collision Protocol

Using Parallel Splitting

Ming-Kuei Yeh and Jehn-Ruey JiangDepartment of Computer Science and Information Engineering

National Central University

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WASN 2009

Outline

• Introduction• Anti-collision protocols• Proposed protocol • Evaluation• Conclusion

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WASN 2009

Outline


• Introduction

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Introduction RFID system

• RFID (Radio Frequency IDentification) system

Reader

Tag (Transponder)

Application

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Introduction Application

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Tag 1

reader

Tag 2

Tag 3

Interrogation zone

Introduction Interrogation zone

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Interrogation zone

tag

Tag collision problem: collision occurs when multiple tags respond to the same reader simultaneously

reader

Introduction Tag-to-tag interference

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Outline


• Anti-collision protocols

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Anti-collision protocols category

• Anti-collision protocolsFor solving the tag collision problem

Two classes• ALOHA based • Tree based

– deterministic tree-based

– probabilistic counter-based

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S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15

Tag1

Tag2

Tag3

Tag4

Tag5

Tag6

Tag7

Tag8

Tag9

Tag10

Collision !

Collision !

S: time slotAn example of slotted ALOHA protocol

Anti-collision protocols ALOHA based

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0 1

0

0

0

1

1

11

1

0

0

Tag1 Tag2 Tag3 Tag4 Tag5 Tag6

An example of bit-by-bit tree protocol

Anti-collision protocols Tree based

ID:0010

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WASN 2009C = 0C= counter

Anti-collision protocols Counter based

C = 0 C =1C = 0 C =2

C = 0 C =1

C = 0

C = 0 C =4

C =3

C =2

C = 0 C =1

Tag1

C = 0

C = 0

C = 0

C = 0

C =3

C =2

C =1

C = 0 C =0

Tag1

C = 0

C = 0

C = 0

C = 0

An example of a counter-based protocol: ISO/IEC18000-6B

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WASN 2009

Outline

• Introduction• Anti-collision protocols• Proposed protocol • Simulation• Conclusion

• Proposed protocol

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Proposed protocol

• Parallel Splitting (PS) forRFID Tag Anti-Collision

Counter based anti-collision protocol

Using two schemes• Parallel Splitting

• Adaptive Identification-Tree Height Adjustment

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C= counter

C = 0

Proposed protocol Parallel Splitting

C = 0 C =1

C = 0

C =1

C = 0 C =1

C = 0

C = 0

C = 2 C =3

C =0

C =0

C =0

C =0

C =1

C =1 C =2 C =3

C =1 C =2 C =3 C =4 C =5 C =6 C =7

C =0 C =1 C =2 C =3 C =4 C =5 C =6 C =7 C =8 C =9 C =10 C =11 C =12 C =13 C =14

Tag1

Just left-shift their counters one bit and add one or zero randomly to the counters.

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WASN 2009• 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)

Proposed protocol Adaptive Identification-Tree Height Adjustment

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• 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 nodeN: The number of tags in the interrogation zoneL: The number of leaf nodes; ;

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

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Let the expected numbers of leaf nodes containing none, one and multiple tags be e(0), e(1) and e(m), respectively.

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It is reasonable to assume L>>1 and N>>1, and to take L–1 as L, and N–1, N–2 as N. We have

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• Analyzing the ratio of the numbers of

leaf nodes that including zero tag, one tag

and multiple tags• The result of analysis

L : The number of leaf nodes N : The number of tags in the interrogation zone

Rule1

Rule2


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WASN 2009• 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.


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• In phase IAll tags are split in parallel until the first tag is identified successfully.

• In phase IITags are identified one by one according to

The normal identification procedure of ISO/IEC 18000-6B protocol.

The reader applies Rule1 or Rule2 for adjusting the number of leaf nodes to approach the actual number N of tags (N is unknown)

• In phase II

Proposed protocol Two Phases of PS Protocol

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Outline


• Evaluation

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Evaluation

• The simulations are programmed

in Java language• Each simulation is performed 1,000 times

and then calculates the average value

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Evaluation

The comparison of the number of iterations for 1,025~2,025 tags.

-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

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Evaluation-the number of iterations

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

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Evaluation-System Efficiency

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

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

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WASN 2009

Outline

• Introduction• Anti-collision protocols• Proposed protocol • Evaluation• Conclusion• Conclusion

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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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WASN 2009

Thanks for Your Listening!

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a counter-based rfid anti-collision protocol using parallel splitting

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