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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
Interference in RFIDInterference in RFID
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
Interference in RFIDInterference in RFID
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
Binary Tree using 8 BinBinary Tree using 8 Bin--slotslot
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
Binary Tree using 8 BinBinary Tree using 8 Bin--slotslot
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
Simulation and analysis results (2/4)Simulation and analysis results (2/4)
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
Simulation and analysis results (3/4)Simulation and analysis results (3/4)
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
Simulation and analysis results (4/4)Simulation and analysis results (4/4)
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
Simulation and analysis result (2/4)Simulation and analysis result (2/4)
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
Simulation and analysis result (3/4)Simulation and analysis result (3/4)
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
Simulation and analysis result (4/4)Simulation and analysis result (4/4)
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.
Proposed antiProposed anti--collision algorithmcollision algorithm
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.
Proposed antiProposed anti--collision algorithmcollision algorithm
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
Proposed antiProposed anti--collision algorithmcollision algorithm
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
Proposed antiProposed anti--collision algorithmcollision algorithm
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
Proposed antiProposed anti--collision algorithmcollision algorithm
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→∞ −
Proposed antiProposed anti--collision algorithmcollision algorithm
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
Proposed antiProposed anti--collision algorithmcollision algorithm
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=
Proposed antiProposed anti--collision algorithmcollision algorithm
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
Jae-Hyun Kim44
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)
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
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 :
1) SC=0 : Tag sends RN16
2) SC<>0 : No reply
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Probabilistic SlottedProbabilistic Slotted
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)
Identification time vs. number of tags
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
Simulation Results(3/5)Simulation Results(3/5)
Identification time vs. 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
Simulation Results(4/5)Simulation Results(4/5)
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
Simulation Results(5/5)Simulation Results(5/5)
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
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Multi-reader Anti-collision Algorithms
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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
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