it f i rfids tinterference in rfid systemwinner.ajou.ac.kr/publication/data/invited/20070425.pdf ·...

I t f i RFID S tI t f i RFID S tInterference in RFID SystemInterference in RFID System

April 25, 2007April 25, 2007

JaeJae--Hyun KimHyun Kim

WWireless ireless IInformation anformation aNNd d NNetwork etwork EEngineering ngineering RResearch Lab. esearch Lab. ff g gg gSchool of Electrical Engineering School of Electrical Engineering

Ajou University, KoreaAjou University, Koreaj y,j y,

ContentsContents

Interference in RFIDTagTag--toto--tag interference tag interference ReaderReader--toto--tag interferencetag interferenceReaderReader--toto--reader interferencereader interference

Anti collision algorithms in RFID systemAnti-collision algorithms in RFID systemMultiMulti--tag antitag anti--collision algorithmscollision algorithms

AutoID Class 0/1ISO 18000-6 Type A/BISO 18000-6 Type C

EPCglobal Class 1 Gen 2MultiMulti--reader antireader anti--collision algorithmscollision algorithms

FDMA – Gen 2LBT(CSMA) - ETSI EN 302 208 standardLBT(CSMA) ETSI EN 302 208 standard

ConclusionReference

Jae-Hyun Kim2

Interference in RFID

Jae-Hyun Kim3

Interference in RFIDInterference in RFID

Tag-to-tag interference [1]

Occur when multiple tags respond to the same reader simultaneouslyOccur when multiple tags respond to the same reader simultaneouslyOccur when multiple tags respond to the same reader simultaneouslyOccur when multiple tags respond to the same reader simultaneouslyCan be avoided only by having each tag respond at different timesNeed to the multi-tag anti-collision algorithm to resolve this interference.

Jae-Hyun Kim4 Tag-to-tag interference


Reader-to-tag interference [1]

Occur when a tag is in the interrogation zone of multiple readers and moreOccur when a tag is in the interrogation zone of multiple readers and moreOccur when a tag is in the interrogation zone of multiple readers and more Occur when a tag is in the interrogation zone of multiple readers and more than one reader transmits simultaneously.than one reader transmits simultaneously.

Can be avoided only by having neighboring readers operate at different times or different frequenciesdifferent frequencies.Need to the multi-reader anti-collision algorithm to resolve this interference.

R1 Read Range

T1T2

g

R1

T3

R1

R2 Read Range

Reader

Tag

Jae-Hyun Kim5 Reader-to-tag interference


Reader-to-reader interference [1]

Occur because of the interfering signal from neighboring readersOccur because of the interfering signal from neighboring readersOccur because of the interfering signal from neighboring readersOccur because of the interfering signal from neighboring readersCan be avoided only by having neighboring readers operate at different times or different frequency.Need to the multi-reader anti-collision algorithm to resolve this interferenceNeed to the multi-reader anti-collision algorithm to resolve this interference.

R2 Interference Range

R2 Read RangeR1 Read Range

R1 R2

T1

T2

T1ReaderTag

Jae-Hyun Kim6 Reader-to-reader interference

Anti-collision algorithm in Standards

Jae-Hyun Kim7

MultiMulti--tag Antitag Anti--collision Algorithms collision Algorithms in Standardsin Standards

Arbitration Air Interface(R->T / T->R)

EPC Data rate(R->T / T->R)

Security( ) ( )

AutoID Class 0

Bit-by-bit Binary Tree

Pulse Width Mod./FSK

64/96b40/80 kbps /40/80 kbps

24-bit kill

AutoID Class 1

Binary treeusing 8 bin slots

Pulse Width Mod. / Pulse Interval AM 64/96b

70.18 kbps/140.35 kbps

8-bit kill

ISO 18000-6TYPE A

Framed Slotted

Pulse interval ASK / FM0

notdefined

33 kbps /40 kbps

None

ISO 18000-6TYPE B

Probabilistic Binary tree

Manchester-ASK / FM0

notdefined

8/40 kbps /40 kbps

None

ISO 18000-6TYPE C(Gen 2)

ProbabilisticSlotted

Pulse interval ASK /Miller, FM0

96/496b40 kbps /640 kbps

32-bit kill,Access

Jae-Hyun Kim8

(Gen 2)

Multi-tag Anti-collision Algorithms

Jae-Hyun Kim9

MultiMulti--tag Antitag Anti--collision Algorithmscollision Algorithms

Bit-by-bit Binary Tree [2]

AutoID Class 0AutoID Class 0AutoID Class 0AutoID Class 0

Binary Tree using Bin Slot [3]

AutoID Class 1AutoID Class 1AutoID Class 1AutoID Class 1

Framed Slotted ALOHA [4]

ISO 18000ISO 18000--6 TYPE A6 TYPE A

Deterministic Binary Tree [4]

ISO 18000ISO 18000--6 TYPE B6 TYPE B

Probabilistic Slotted ALOHA [5]

ISO 18000ISO 18000--6 Type C6 Type CEPCglobal Gen 2 protocol

Jae-Hyun Kim10

AutoID Class 0

Jae-Hyun Kim11

AutoID Class 0 Features (UHF)AutoID Class 0 Features (UHF)

Operating frequency range860860--960 MHz960 MHz860860 960 MHz960 MHz

Air interface RR-->T : AM pulse width modulation>T : AM pulse width modulationTT-->R : Passive Backscatter : FSK>R : Passive Backscatter : FSK

Data rate (North America)RR-->T : 40/80 kbps>T : 40/80 kbpsRR T : 40/80 kbpsT : 40/80 kbpsTT-->R : 40/80 kbps>R : 40/80 kbps

Collision arbitrationBitBit--byby--bit binary treebit binary tree

Security2424--bit killbit kill2424 bit killbit kill

Tag read speed1000 tags/sec1000 tags/sec

Jae-Hyun Kim12

BitBit--byby--bit Binary Treebit Binary Tree

Basic operation

TAG READER TAG READERTAGREADERTAGREADERREADER

REPLY X(0) REPLY

STATE

X(0)REPLYCMDREPLYX(0)CMD

X X 001 X

TAG1(001)

STATE

0

X

0 1

X 001 X

TAG3(100)

TAG2(011) 0 1 0

1 1

Jae-Hyun Kim13

AutoID Class 1

Jae-Hyun Kim14

AutoID Class 1 Features (UHF)AutoID Class 1 Features (UHF)

Operating frequency range :860860--960 MHz960 MHz860860 960 MHz960 MHz

Air interface RR-->T : AM pulse width modulation>T : AM pulse width modulationTT-->R : Passive Backscatter : Pulse interval AM>R : Passive Backscatter : Pulse interval AM

Data rate (North America)RR-->T : 70.18 kbps>T : 70.18 kbpsRR T : 70.18 kbpsT : 70.18 kbpsTT-->R : 140.35 kbps>R : 140.35 kbps

Collision arbitrationBinary Tree using 8 BinBinary Tree using 8 Bin--slotslot

Security88--bit killbit kill88 bit killbit kill

Tag read speedNot specifiedNot specified

Jae-Hyun Kim15

Binary Tree using 8 BinBinary Tree using 8 Bin--slotslot

Basic operationCan select specific tags for identificationCan select specific tags for identificationCan select specific tags for identificationCan select specific tags for identificationUse 8 bin slots (3 bit info.) to singulate the tagsUse 8 bin slots (3 bit info.) to singulate the tags

Reader TAG

COMMAND

REQ.Bin 0(000)

Bin 1(001)

Bin2(010)

Bin 3(011)

Bin 4(100)

Bin 5(101)

Bin 6(110)

Bin 7(111)

POINTERLENGTHVALUE

STATUS

PingID0000 00000000 0100

1010IDLE IDLE SUCC IDLE IDLE SUCC IDLE IDLE

PingID0000 00000000 01111010010

IDLE SUCC COLL IDLE IDLE IDLE IDLE IDLE

ScrollID0000 00000000 01111010001

STATUS

TAG 1

TAG 2(1010001110101010) 00111010

01010100 10100101

(1010001110101010)

IDLE IDLE SUCC IDLE IDLE SUCC IDLE IDLEIDLE SUCC COLL IDLE IDLE IDLE IDLE IDLE

(1010001110101010)TAG 1 sends ITM ( Full ID )

(1010001110101010)(1010001110101010)

TAG 3(1010010101001010)

(1010010010011010)

01010100

0100100101001101

10100101(1010010101001010)

(1010010010011010)

(1010010101001010)

(1010010010011010)

(1010010101001010)

(1010010010011010)

(1010010101001010)

(1010010010011010)

Jae-Hyun Kim16


0 1 1 0 0 1 1 1Tag 1 1 0 0 0 00

Basic operation

………………

………………

0 1 1 0 0 1 1 1Tag_1 1 0 0 0 0

0 1 1 1 0 1 0 1Tag_2 1 1 0 0 0

0

0

………………0 1 1 1 0 1 1 1Tag_3 0 1 0 0 00

0 0 0[LEN] = 1

Bin000

Bin111

Bin110

Bin101

Bin100

Bin011

Bin010

Bin001

0 00PingID [LEN]=1,[VALUE]=0 01

00 0 0[LEN] = 4 0 01 1

S llID [LEN] 7 [VALUE] 0011001

PingID [LEN]=4,[VALUE]=0011

ScrollID [LEN]=7,[VALUE]=0011001

00 0 0[LEN] = 4 0 0 1 1PingID [LEN]=7,[VALUE]=0011101

ScrollID [LEN]=10,[VALUE]=0011101011

Jae-Hyun Kim17 ScrollID [LEN]=10,[VALUE]=0011101110


Tree structure of EPC Class 1 system

Jae-Hyun Kim1818

Proposed AntiProposed Anti--collision Algorithmcollision Algorithm

Fast Anti-collision Algorithm in EPC Class 1 UHFAjou Univ. proposedAjou Univ. proposedAjou Univ. proposedAjou Univ. proposedEnhance the performance of the algorithm defined in AutoID Class 1Enhance the performance of the algorithm defined in AutoID Class 1Basic concept of the proposed algorithmsBasic concept of the proposed algorithms

B i S i f i f h l ID b i d f hBy using Sequence information of whole ID obtained from the tag By using ScrollAllID command Reduce the number of PingID commands

By using a proposed tree search algorithmBy using a proposed tree-search algorithmReduce the number of unnecessary procedures

0

0 0 1 0 0 1 …… X 0 X X 0

(N-1) bits

X ……0

0 1

PingID ( [PTR]=N-1, [LEN]=1,[VALUE]=0)0 1 0 1 0 1 0 1

0 1 0 1

Jae-Hyun Kim19 [6] H. S. Choi and J. H. Kim, "Anti-collision algorithm using Bin slot in RFID System," in Proc. IEEE

TENCON '05, Melbourne, Australia, Nov. 21-24, 2005, p.71.

Proposed antiProposed anti--collision algorithmcollision algorithm

Number of Ping ID commands ( )Conventional algorithmConventional algorithm

totalI

Conventional algorithmConventional algorithm

17 1 1 11k k k

L L Lm r r r

total k

r n r n L r nI mr r n r n r nr

−∞ ⎛ ⎞− − − − −⎛ ⎞ ⎛ ⎞ ⎛ ⎞⎜ ⎟= + − − ⋅⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎜ ⎟⎝ ⎠ ⎝ ⎠ ⎝ ⎠∑∑∑

2 0 0L k n r r n r n r nr= = = ⎜ ⎟− − −⎝ ⎠ ⎝ ⎠ ⎝ ⎠⎝ ⎠

∑∑∑

1k

mr

>where,

Proposed algorithmProposed algorithm

1 1 11 1 11k km m

r rk r m rI I I− −

−∞ ∞ ⎛ ⎞− −⎛ ⎞ ⎛ ⎞⎜ ⎟⎜ ⎟ ⎜ ⎟∑ ∑0 10 1

1kto ta l k k

k k

I I I rr r rr −

= =

⎛ ⎞ ⎛ ⎞⎜ ⎟= = + × − − ⋅⎜ ⎟ ⎜ ⎟⎜ ⎟⎝ ⎠ ⎝ ⎠⎝ ⎠

∑ ∑

1 1k

m> , I0 = 1 (Number of first reader command)where,

1kr − , I0 1 (Number of first reader command),

Jae-Hyun Kim20

Simulation and analysis results (1/4)Simulation and analysis results (1/4)

Number of PingID command vs. Number of used tagsRandom tag IDRandom tag IDRandom tag IDRandom tag ID

600 Conventional EPC CLASS 1(analysis)Conventional EPC CLASS 1(simulation)

500

mm

and

Conventional EPC CLASS 1(simulation)Proposed algorithm(analysis)Proposed algorithm(simulation)Proposed algorithm using ScrollAllID(analysis)Proposed algorithm using ScrollAllID(simulation)

300

400

Pin

gID

com

200

300

umbe

r of P

100The

n

Jae-Hyun Kim21 20 40 60 80 100 120 140 160 180 200

0The number of used tags


Tag identification time vs. Number of used tagsRandom tag IDRandom tag IDRandom tag IDRandom tag ID

1 8

2 Conventional EPC CLASS 1(analysis)Conventional EPC CLASS 1(simulation)

1 4

1.6

1.8

sec)

Proposed algorithm(analysis)Proposed algorithm(simulation)Proposed algorithm using ScrollAllID(analysis)Proposed algorithm using ScrollAllID(simulation)

1

1.2

1.4

atio

n tim

e(s

태그의개수가 200개일때최대 130%성능향상

0.6

0.8

1

g id

entif

ica

0.2

0.4

Tag

Jae-Hyun Kim22 20 40 60 80 100 120 140 160 180 200

0 The number of used tags


Number of PingID command vs. Number of used tagsSequential tag IDSequential tag IDSequential tag IDSequential tag ID

2500 Conventional EPC CLASS 1Proposed algorithm

2000

mm

and

p gProposed algorithm using ScrollAllID

50

1500

Pin

gID

com

35

40

45

50

1000

num

ber o

f P

15

20

25

30

500 The

n

20 40 60 80 100 120 140 160 180 2005

10

Jae-Hyun Kim23 20 40 60 80 100 120 140 160 180 200

0 The number of used tags


Tag identification time vs. Number of used tagsSequential tag IDSequential tag IDSequential tag IDSequential tag ID

6 Conventional EPC CLASS 1Proposed algorithm

5

sec)

Proposed algorithm using ScrollAllID

3

4

atio

n tim

e(

0.65

0.7

0.75태그의개수가 200개일때최대 146%성능향상

2

ag id

entif

ica

0.45

0.5

0.55

0.6

1

Ta

100 120 140 160 180 2000.35

0.4

Jae-Hyun Kim24 20 40 60 80 100 120 140 160 180 200

0The number of used tags

Proposed antiProposed anti--collision Algorithm 2collision Algorithm 2

High-speed Tag Anti-collision AlgorithmAjou Univ. proposedAjou Univ. proposedAjou Univ. proposedAjou Univ. proposedEnhance the performance of the antiEnhance the performance of the anti--collision algorithm used in the collision algorithm used in the conventional system (Alien Technolog Corporation, ALRconventional system (Alien Technolog Corporation, ALR--9780)9780)

Bin slot (response) -> ScrollIDBin slot (response) ScrollID2 transmissions of commands(ScrollID/PingID) to confirm after successful identification

Basic concept of the proposed algorithmsBasic concept of the proposed algorithmsBy using collision information in a bin slot

No collision -> ScrollID command Collision -> PingID command

By reducing transmissions of confirmation commandsBecause of repeated operations of RFID readerBecause of repeated operations of RFID reader

An example of PingID replies with 3 tags: [LEN]=1, [VALUE]=0

Jae-Hyun Kim2525 [7]이충희, 김재현, "RFID 시스템에서의고속충돌방지알고리즘," in Proc. 한국통신학회추계학술대회, 인천,

p.82, 2006년 11월.

Proposed antiProposed anti--collision Algorithm 2collision Algorithm 2

Performance matricsNumber of command transmissionsNumber of command transmissionsNumber of command transmissionsNumber of command transmissionsTag identification timeTag identification timeNumber of tag identifications per secondNumber of tag identifications per second

⎡ ⎤

Conventional algorithm Proposed algorithm

1 1 12 2

1

1 1 12 12

k km mr rk

k k

r m rIS rr r rr

− −−

−

⎡ ⎤− −⎛ ⎞ ⎛ ⎞⎢ ⎥= × − + ⋅⎜ ⎟ ⎜ ⎟⎢ ⎥⎝ ⎠ ⎝ ⎠⎣ ⎦

1 1 11 1 1k km m

−⎡ ⎤⎛ ⎞ ⎛ ⎞

1 12

1

1 122

kmrk

k k

m rIS rr rr

−−

−

⎡ ⎤−⎛ ⎞⎢ ⎥= × ⋅⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦

m m⎡ ⎤1 1

2

2 2

1

121

1 1 12 12

1 1

k k

k

r rkk k

mrk

r m rIP rr r rr

m r

− −

−

−

−

⎡ ⎤− −⎛ ⎞ ⎛ ⎞⎢ ⎥= × − − ⋅⎜ ⎟ ⎜ ⎟⎢ ⎥⎝ ⎠ ⎝ ⎠⎣ ⎦

⎡ ⎤−⎛ ⎞⎢ ⎥

1 1 12 2

1

1 1 12 12

k km mr rk

k k

r m rIP rr r rr

− −−

−

⎡ ⎤− −⎛ ⎞ ⎛ ⎞⎢ ⎥= × − − ⋅⎜ ⎟ ⎜ ⎟⎢ ⎥⎝ ⎠ ⎝ ⎠⎣ ⎦

212

1 122

rkk

m rrr rr

−−

⎛ ⎞⎢ ⎥+ × ⋅⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦

ISk : number of ScrollID transmissions with [LEN]=1+3k m : total number of tags

Jae-Hyun Kim26IPk : number of PingID transmissions with [LEN]=1+3k r : number of bin slot = 8

Simulation and analysis result (1/4)Simulation and analysis result (1/4)

Number of ScrollID transmissions vs. Number of tags

1200

1400.

Conventional(Sim., Rand. ID)Conventional(Sim., Seq. ID)Conventional(Anal., Rand. ID)

1000

1200

smis

sion

Proposed(Sim., Rand. ID)Proposed(Sim., Seq. ID)Proposed(Anal., Rand. ID)

600

800

ollID

Tra

ns

200

400

ber o

f Scr

o

00 50 100 150 200 250 300 350 400 450 500

Num

b

Jae-Hyun Kim2727

Number of Tags


Number of command transmissions vs. Number of tags

3000on

.Conventional(Sim., Rand. ID)Conventional(Sim., Seq. ID)Conventional(Anal., Rand. ID)Proposed(Sim Rand ID)

2000

2500

rans

mis

sio Proposed(Sim., Rand. ID)

Proposed(Sim., Seq. ID)Proposed(Anal., Rand. ID)

1500

mm

and

Tr

500

1000

ber o

f Com

00 50 100 150 200 250 300 350 400 450 500

f

Num

b

Jae-Hyun Kim2828

Number of Tags


Tag identification time vs. Number of tags

9

10 Conventional(Sim., Rand. ID)Conventional(Sim., Seq. ID)Conventional(Anal., Rand. ID)P d(Si R d ID)

7

8

e (s

ec) .

Proposed(Sim., Rand. ID)Proposed(Sim., Seq. ID)Proposed(Anal., Rand. ID)

4

5

6

atio

n Ti

me

2

3

g Id

entif

ica

0

1

0 50 100 150 200 250 300 350 400 450 500

Tag

Jae-Hyun Kim2929

Number of Tags


Identification rate vs. Number of tags

120

140.

100

120ta

gs/s

ec)

60

80

ion

Rat

e (t

20

40

dent

ifica

ti Conventional(Sim., Rand. ID)Conventional(Sim., Seq. ID)Conventional(Anal., Rand. ID)Proposed(Sim., Rand. ID)Proposed(Sim., Seq. ID)

00 50 100 150 200 250 300 350 400 450 500

Tag

Id Proposed(Sim., Seq. ID)Proposed(Anal., Rand. ID)

Jae-Hyun Kim3030

Number of Tags

ISO 18000-6 TYPE A

Jae-Hyun Kim31

ISO 18000ISO 18000--6 Type A Features (UHF)6 Type A Features (UHF)

Operating frequency range860860--960 MHz960 MHz860860 960 MHz960 MHz

Air interfaceRR-->T : Pulse interval ASK>T : Pulse interval ASKTT-->R : Passive backscatter : Bi>R : Passive backscatter : Bi--phase Space AMphase Space AM

Data rate (North America)RR-->T : 33kbps>T : 33kbpsRR T : 33kbpsT : 33kbpsTT-->R : 40kbps>R : 40kbps

Collision arbitrationFramed slotted ALOHAFramed slotted ALOHA

SecurityNoneNoneNoneNone

Tag read speed100 tags/sec100 tags/sec

Jae-Hyun Kim32

Probabilistic Slotted ALOHAProbabilistic Slotted ALOHA

Basic operation

2nd REQSlot4Slot3Slot2Slot11st REQREADER

TAG1(1011)

STATE IDLE1011 COLL 0101

1011

TAG2(1010)

TAG1(1011)

1010

1011

1010

TAG4(0101)

TAG3(0011) 0011

0101

0011

TAG4(0101)

Frame size = 4

0101Frame size = ?

Need to vary the Frame size for the number of tags

Jae-Hyun Kim33

y g

Related work on RFIDRelated work on RFID

Tag estimation schemes by VogtUsing lower boundUsing lower boundUsing lower boundUsing lower bound

Through the observation that a collision involves at least two different tags.

0 1 1( , , , ) 2lb k KL C C C C Cε = + ⋅

U i i i di tU i i i di t

L : Frame size, C0 : # of idle slots, C1 : # of successful slot, and Ck : # of collided slots

Using minimum distanceUsing minimum distanceThe distance between the read result n and the expected value vector to determine the value of for which the distance becomes minimal.

,0 0

,1 1min( )

L n

L nmd

L n

a cn a cε

⎡ ⎤⎛ ⎞ ⎛ ⎞⎢ ⎥⎜ ⎟ ⎜ ⎟= −⎢ ⎥⎜ ⎟ ⎜ ⎟⎢ ⎥⎜ ⎟ ⎜ ⎟

⎝ ⎠

, 1 11r n r

L nr

na L

r L L

−⎛ ⎞⎛ ⎞ ⎛ ⎞= −⎜ ⎟⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠⎝ ⎠

Where is the expected value of the number of slots with occupancy number r,L nra

,2

L nkca≥

⎢ ⎥⎜ ⎟ ⎜ ⎟⎝ ⎠⎢ ⎥⎝ ⎠⎣ ⎦

r L L⎝ ⎠ ⎝ ⎠⎝ ⎠

Jae-Hyun Kim34 [8] H. Vogt, ”Efficient Object Identification with Passive RFID tags, ” In International Conference on Pervasive

Computing, Zurich, 2002, pp. 98-113.


Dynamic Framed Slotted ALOHAAjou Univ. proposedAjou Univ. proposedAjou Univ. proposedAjou Univ. proposedEnhance the performance of the algorithm defined in ISO 18000Enhance the performance of the algorithm defined in ISO 18000--6 6 Type AType A

The problems of ISO 18000 6 type A protocolThe problems of ISO 18000-6 type A protocolPerformance will be degraded when :

The number of tags are either (even) more or less than the frame size.Need to dynamically vary the frame size for the number of tags.y y y g

No detailed methods in StandardsHow to estimate the number of tagsHow to dynamically allocate according to the number of estimated tags.

Basic concept of the proposed algorithmsBasic concept of the proposed algorithmsPropose Tag Estimation method (TEM)

Estimate the number of tags around the readerPropose Dynamic Slot Allocation method (DSAM)

Dynamically allocate the optimal frame size

Jae-Hyun Kim35

[9] J. R. Cha and J. H. Kim, "Dynamic Framed Slotted ALOHA Algorithm using Fast Tag Estimation method for RFID System," in Proc. CCNC2006, Las Vegas, USA, Jan. 8-10, 2006.

[10] J. R. Cha and J. H. Kim, "Novel Anti-collision Algorithms for Fast Object Identification in RFID system," in Proc. ICPADS2005, Fukuoka, Japan, Jul. 20-22, 2005, pp. 63-67.


Dynamic Framed Slotted ALOHA I (DFSA I)Tag estimation method I (TEM I)Tag estimation method I (TEM I)Tag estimation method I (TEM I)Tag estimation method I (TEM I)

Use the ratio of the collided slots for the frame size.Dynamic slot allocation method I (DSAM I)Dynamic slot allocation method I (DSAM I)

U h i i d l fUse the transmission delay of a tag.

Dynamic Framed Slotted ALOHA II (DFSA II)Dynamic Framed Slotted ALOHA II (DFSA II)Tag estimation method II (TEM II)Tag estimation method II (TEM II)

Use the collision rate when throughput of the system is maximum.Dynamic slot allocation method II (DSAM II)Dynamic slot allocation method II (DSAM II)

Use throughput of the system.

Jae-Hyun Kim36


TEM ICollision ratioCollision ratioCollision ratioCollision ratio

Ratio the number of slots where collision occurs for the frame size.

11 1 1 .

1

Number of collided slotsFrame size

n

ration

CL L

= = − − +−

⎛ ⎞ ⎛ ⎞⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠

Jae-Hyun Kim37


TEM I (con’t)Collision ratioCollision ratio

0.9

1L=8

L=16

L=32

Collision ratioCollision ratio

- An example -

0.7

0.8

L 32

L=64

L=128

L=192

Frame size = 320 slots

Collision ratio =0.46323

0.5

0.6

ollis

ion

Rat

io

L=256

L=320

L=512

Number of estimated tags = 400

0 2

0.3

0.4Co

L=640

0 100 200 300 400 500 600 700 800 900 10000

0.1

0.2

Jae-Hyun Kim38

0 100 200 300 400 500 600 700 800 900 1000Number of tags


TEM IICollision rateCollision rateCollision rateCollision rate

Prob. that there is the collision in a slot

1 P b h f i ID f ll= =rate

collCP

P P+1- Prob. that a tag transfers its ID successfully idle collP P+

Optimal collision rate for maximum throughputOptimal collision rate for maximum throughput

_ lim 0.41801

collopt rate

n

PC

P→∞= =

Jae-Hyun Kim39

1nsuccP→∞ −


TEM II (con’t)Number of tags related with collision in a slotNumber of tags related with collision in a slotNumber of tags related with collision in a slotNumber of tags related with collision in a slot

12 3922C

_

2.3922 .tags

opt rate

CC

==

Number of estimated tagsNumber of estimated tags

N b f ti t d t 2 3922 MNumber of estimated tags 2.3922 .collM= ×

Where, means the number of collided slots in a frame after a round.co llM

Jae-Hyun Kim40


DSAM IDetermine the frame size by selecting the valueDetermine the frame size by selecting the value LL whenwhen DD is minimumis minimumDetermine the frame size by selecting the value Determine the frame size by selecting the value LL when when DD is minimum.is minimum.

1 011

nd d LDdn dn −= =

⎛ ⎞−⎜ ⎟where n means the number of tags

Optimal Frame SizeOptimal Frame Size

1L⎜ ⎟

⎝ ⎠

DSAM IIDetermine the frame size by selecting the value Determine the frame size by selecting the value L L when when SS is maximum.is maximum.

optimalL n=

y gy g

1 2(1 ) ( 1) (1 ) 0n ndSn p n n p p

dp− −= − − − − =

Optimal Frame SizeOptimal Frame Size

p

L n

Jae-Hyun Kim41

optimalL n=


Identification time vs. number of tags

6Vogt-minVogt est18

20Slot-64Slot-128

4

5

e (s

ec)

Vogt-estDFSA IDFSA II

12

14

16

18

e (s

ec)

Slot 128Slot-256Vogt-min

2

3

tific

atio

n tim

e

8

10

12

tific

atio

n tim

e

1

2

Iden

t2

4

6

Iden

100 200 300 400 500 600 700 800 900 10000

Number of tags100 200 300 400 500 600 700 800 900 10000

Number of tags

Jae-Hyun Kim42

* DFSA I can identify 185 tags/sec.

ISO 18000-6 TYPE B

Jae-Hyun Kim43

ISO 18000ISO 18000--6 Type B Features (UHF)6 Type B Features (UHF)

Operating frequency range860860--960 MHz960 MHz

Air interfaceRR-->T : Manchester ASK>T : Manchester ASKTT-->R : Passive Backscatter : Bi>R : Passive Backscatter : Bi--phase Space AMphase Space AM

Data rate (North America)RR-->T : 10 or 40 kbps>T : 10 or 40 kbpsTT-->R : 40 kbps>R : 40 kbps

Collision arbitrationDeterministic Binary TreeDeterministic Binary Tree

SecurityNoneNone

Tag read speed 100 tags/sec100 tags/sec

Flexible selection maskingSelect specific tags for identificationSelect specific tags for identification

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Deterministic Binary TreeDeterministic Binary Tree

Basic operation

T3

0

1

0

T1 T2 T4

0 01 1 1 1

1

1 1 1 1

1 2 3 4 5 6 7 98 10 11 12Iterations

Coll Succ IdleColl Coll Coll Coll IdleSucc Succ Succ

Jae-Hyun Kim45

ISO 18000ISO 18000--6 TYPE B6 TYPE B

Performance AnalysisTo identifyTo identify nn tags 2 886tags 2 886nn 1 slots are needed1 slots are needed

3000

To identify To identify nn tags, 2.886tags, 2.886nn--1 slots are needed.1 slots are needed.For more details, refer toFor more details, refer to

2500

eded

1500

2000

r of s

lots

nee

500

1000

Num

ber

0 200 400 600 800 10000

Number of tags

Jae-Hyun Kim46 [11] J. L. Massey, "Collision resolution algorithms and random-access communications, " Univ.

California, Los Angeles, Tech. Rep. UCLAENG -8016, Apr. 1980.

ISO 18000-6 TYPE C(EPCglobal Gen 2)(EPCglobal Gen 2)

Jae-Hyun Kim47

EPC Gen2 FeaturesEPC Gen2 Features

Operating frequency860860--960 MHz960 MHz860860 960 MHz960 MHz

Air interfaceRR-->T : PIE ASK>T : PIE ASKTT-->R : FM0 or Miller>R : FM0 or Miller--modulated submodulated sub--carriercarrier

Data rate (North America)RR-->T : 26.7 to 128 kbps>T : 26.7 to 128 kbpsRR T : 26.7 to 128 kbpsT : 26.7 to 128 kbpsTT-->R : 40 to 640 kbps>R : 40 to 640 kbps

Collision arbitrationProbabilistic slottedProbabilistic slotted

Access control and privacy3232--bit kill and access passwordsbit kill and access passwords3232 bit kill and access passwordsbit kill and access passwords

Operating Channels50 channels supported for dense50 channels supported for dense--Interrogator operation.Interrogator operation.

Jae-Hyun Kim48

EPC Gen2 Features (con’t)EPC Gen2 Features (con’t)

Flexible logical layer1616--bit to 496bit to 496--bit electronic product code (EPC)bit electronic product code (EPC)Optional passwordOptional password--protected access controlprotected access controlOptional user memoryOptional user memory

Reliable operationReliable operationProbabilistic slotted antiProbabilistic slotted anti--collisioncollisionAdapt to rapidly changing tag populationsAdapt to rapidly changing tag populations

Q-Selection algorithmQ-Selection algorithmFlexible selection masking

Can select specific tags for identificationCan select specific tags for identification4 sessions s pported4 sessions supported

Jae-Hyun Kim49

Probabilistic SlottedProbabilistic Slotted

Basic operationReader Tag

Query (Q)

All tags choose SC ( = rand (0, 2^Q-1))Two possible outcomes :Two possible outcomes :

1) SC=0 : Tag sends RN16

Idle slot

Q R

2) SC<>0 : No reply

QueryRep

All tags decrease SC (SC=SC-1)Two possible outcomes :

1) SC=0 : Tag sends RN161) SC 0 : Tag sends RN16

2) SC<>0 : No replySuccessful slot

ACK(RN16)

My RN16 = rcvd RN16 ?Two possible outcomes :

1) Matching : Tag sends EPC

2) Not matching : No replySave EPC

Jae-Hyun Kim50 QueryRep

Save EPC

All tags decrease SC (SC=SC-1)


Basic operationReader Tag

Query (Q)

All tags choose SC ( = rand (0, 2^Q-1))Two possible outcomes :Two possible outcomes :


Collided slot

C 1 Q R

2) SC<>0 : No reply

Case 1 : QueryRep

All tags decrease SC (SC=SC-1)Two possible outcomes :

1) SC=0 : Tag sends RN161) SC 0 : Tag sends RN16

2) SC<>0 : No reply

Case 2 : QueryAdjust(UpDn)

Tags select their new slot counterTwo possible outcomes :


2) SC<>0 : No reply

Jae-Hyun Kim51


Q-Selection algorithm

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Enhanced QEnhanced Q--selection algorithmselection algorithm

Jae-Hyun Kim53

[국내특허]차재룡, 김재현, “RFID 시스템에서의무선태그인식방법"," 출원일 : 2007.1.23, 출원번호 : 제 10-2007-0006873호

Simulation Results (1/5)Simulation Results (1/5)

Simulation scenarios

시나리오 설 명 비 고

T1 충돌이발생하였을때Q er Adj st명령을전송함T1 충돌이발생하였을때QueryAdjust 명령을전송함

T2 충돌이발생하였을때QueryRep 명령을전송함

3S Q-selection 알고리즘에서사용되는 c값의범위를나타냄Ex : 3S - 3 steps (Q value : 1-5/6-10/11-15, c value : 0.5/0.3/0.1)

S Q-selection알고리즘에서Q값에따른 c값의범위를나타냄5S Q selection 알고리즘에서Q값에따른 c값의범위를나타냄Ex : 5S - 5 steps (Q value : 1-3/4-6/7-9/10-12/13-15, c value : 0.5/0.4/0.3/0.2/0.1)

ek링크에서의 BER 을나타냄

Ex : e0 – BER is 0 and e2 – BER is 10-20 2

F(f) Q-selection 알고리즘에서사용되는 c값이 f로고정(Fixed)되었음을의미함Ex : F(0.1) – c 값이 0.1로고정

Jae-Hyun Kim54 [12] J. R. Cha and J. H. Kim, "Performance evaluation of EPCglobal Gen 2 protocol in wireless

channel," in Proc. OPNETWORK 2006, Washington D.C, USA, Aug. 28 - Sep. 01, 2006.

Simulation Results(2/5)Simulation Results(2/5)


500

600T1-F(0.1)T1-F(0.2)T1-F(0.3)

400

me(

ms)

T1-F(0.4)T1-F(0.5)T2-F(0.1)T2-F(0.2)T2-F(0 3)

300

icat

ion

tim

T2 F(0.3)T2-F(0.4)T2-F(0.5)

100

200

Iden

tifi

0 50 100 150 200 250 3000

100

Jae-Hyun Kim55

0 50 100 150 200 250 300

Number of tags



500

600T1-3ST1-5ST2-3S

400

500

me(

ms)

T2 3ST2-5S

300

icat

ion

tim

100

200

Iden

tifi

0 50 100 150 200 250 3000

100

Jae-Hyun Kim56

0 50 100 150 200 250 300Number of tags


Identification rate vs. type of scenarios

580

600

540

560

ags/

sec)

480

500

520

tion

rate

(ta

440

460

480

Iden

tific

at

T1 3S T2 3S T1 F(0 1) T2 F(0 1)400

420

440

Jae-Hyun Kim57

T1_3S T2_3S T1_F(0.1) T2_F(0.1)Type of scenarios


Accuracy vs. number of tags (Considering BER)

100%

120%

fdf

60%

80%

100%y(%

)d

f

0%

20%

40%

Ac

cu

rac

0%

20 40 60 80 100 120 140 160 180 200

Nu mbe r o f t ags

T1_3_e0 T1_3_e2 T1_3_e3 T1_3_e4

T2_3_e0 T2_3_e2 T2_3_e3 T2_3_e4

Jae-Hyun Kim58

Multi-reader Anti-collision Algorithms

Jae-Hyun Kim59

MultiMulti--reader Antireader Anti--collision Algorithmscollision Algorithms

FDMA (Frequency Division Multiple Access)EPCglobal Gen 2 protocolEPCglobal Gen 2 protocolEPCglobal Gen 2 protocolEPCglobal Gen 2 protocol

A technique to allocate the reader’s transmission with different frequenciesA reader hops within its sub-channels every 0.4 sec.

Channels for RFID (Korea)

Jae-Hyun Kim60

Channels for RFID (Korea)

[13] EPC™, Radio-Frequency Identity Protocols Class-1 Generation-2 UHF RFID Protocol for Communications at 860 MHz – 960 MHz Version 1.0.9, Jan., 2004.

MultiMulti--reader Antireader Anti--collision Algorithmscollision Algorithms

LBT (Listen Before Talk)ETSI EN 302 208 standardETSI EN 302 208 standardETSI EN 302 208 standardETSI EN 302 208 standardCSMA basedCSMA based

Sense the channel before transmission

If idle, then transmit the dataIf not idle, then sense the channel after random back-off time

Jae-Hyun Kim61

[14] ETSI EN 302 208-1 v1.1.1, Sep. 2004. CTAN:http//www.etsi.org

ConclusionConclusion

Anti-collision algorithms in passive RFID systemMultiMulti tag antitag anti collision algorithmscollision algorithmsMultiMulti--tag antitag anti--collision algorithmscollision algorithms

AutoID Class 0/1ISO 18000-6 Type A/BISO 18000-6 Type C

EPCglobal Class 1 Gen 2

MultiMulti--reader antireader anti--collision algorithmscollision algorithmsMultiMulti reader antireader anti collision algorithmscollision algorithmsFDMA or LBT

For reliable communications in passive RFID systemMore functional tags neededMore functional tags needed

Trade off for costSt h i d d f d d t i tiSt h i d d f d d t i tiStronger mechanisms needed for reader and tag communicationStronger mechanisms needed for reader and tag communication

Gen 3 ?Efficient Privacy & security solutionsEfficient Privacy & security solutions

Jae-Hyun Kim62

y yy y

ReferenceReference[1] S. Birari and S. Iyer,” PULSE : A MAC Protocol for RFID Networks,” USN’2005, Dec. 2005. [2] Auto-ID Center, Draft Protocol Specification for a Class 0 Radio Frequency Identification tag., 2003.[3] Auto-ID Center, Draft Protocol Specification for a Class 1 Radio Frequency Identification tag., 2003.[4] ISO/IEC 18000 6 : 2003(E) Part 6 : Parameters for air interface communications at 860 960 MHz Nov 26 2003[4] ISO/IEC 18000-6 : 2003(E), Part 6 : Parameters for air interface communications at 860-960 MHz, Nov. 26, 2003.[5] ISO/IEC 18000-6 : 2005(E), Part 6C : parameters for air interface communications at 860 MHz to 960 MHz, 2005.[6] H. S. Choi and J. H. Kim, "Anti-collision algorithm using Bin slot in RFID System," in Proc. IEEE TENCON '05,

Melbourne, Australia, Nov. 21-24, 2005, p.71.[7]이충희 김재현 "RFID시스템에서의고속충돌방지알고리즘 " in Proc 한국통신학회추계학술대회 인천 p 82[7]이충희, 김재현, RFID 시스템에서의고속충돌방지알고리즘, in Proc. 한국통신학회추계학술대회, 인천, p.82,

2006년 11월. [8] H. Vogt, ”Efficient Object Identification with Passive RFID tags, ” In International Conference on Pervasive

Computing, Zurich, 2002, pp. 98-113.[9] J. R. Cha and J. H. Kim, "Dynamic Framed Slotted ALOHA Algorithm using Fast Tag Estimation method for RFID [ ] , y g g g

System," in Proc. CCNC2006, Las Vegas, USA, Jan. 8-10, 2006.[10] J. R. Cha and J. H. Kim, "Novel Anti-collision Algorithms for Fast Object Identification in RFID system," in Proc.

ICPADS2005, Fukuoka, Japan, Jul. 20-22, 2005, pp. 63-67.[11] J. L. Massey, "Collision resolution algorithms and random-access communications, " Univ. California, Los Angeles,

Tech. Rep. UCLAENG -8016, Apr. 1980.

[12] J. R. Cha and J. H. Kim, "Performance evaluation of EPCglobal Gen 2 protocol in wireless channel," in Proc. OPNETWORK 2006, Washington D.C, USA, Aug. 28 - Sep. 01, 2006.

[13] EPC™, Radio-Frequency Identity Protocols Class-1 Generation-2 UHF RFID Protocol for Communications at 860 MHz [13] EPC , Radio Frequency Identity Protocols Class 1 Generation 2 UHF RFID Protocol for Communications at 860 MHz – 960 MHz Version 1.0.9, Jan., 2004.

[14] ETSI EN 302 208-1 v1.1.1, Sep. 2004. CTAN:http//www.etsi.org

Jae-Hyun Kim63

it f i rfids tinterference in rfid systemwinner.ajou.ac.kr/publication/data/invited/20070425.pdf ·...

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