1. RFID Tag anti-Collision Protocols
Hamed Naeemaei

2. Problem Definition
T1
T2
R
T3

3. Existing Protocols for RFID Tag Anti collision
Tag multiple access / Anti Collision Method
Time Division
Multiple Access
Code Division
Multiple Access
Deterministic
Probability
Aloha Based
(Tree Based)
Dynamic Slotted Aloha
Accelerated Frame
Slotted Aloha
Tree Algorithm
Binary Tree
Search Algorithm
Dynamic Slot Allocation –
Tag Estimation Method
QT-Protocol
Spatial Division
Multiple Access
Gold Code
Twice Digital
Beam-Forming
Walsh Sequence
STDMA
Walsh Code +
Pseudo Random
Sequence
Generator
Beam Forming
And Reader
Power Control
Huffman
Sequence
Minimum
Distance
Constellation
I-Code
STAC
Polling
Bit-Slot
Contactless
Protocol
Frequency
Division Multiple
Access
FDMA Novel
With QAlgorithm

4. Existing Protocols for RFID Tag Anti collision

5. Other
A tree slotted ALOHA (TSA) is proposed in (Bonuccelli et
al. 2006),
hybrid tag anti-collision scheme (Shin et al. 2007)
…

6. Tree-based RFID protocols

7. Binary Tree
Dong-Her Shih 2006
1
2
3
4
5
6
7
8
9
10 11 12 13
C
C
E
C
T1 T3
C
T4
C
E
C
T2 T5

8. Query tree
Okkyeong Bang 2009

9. An Example
Tag
ID
Tag 1
000
Tag 2
010
Tag
Tag 3
Tag
Tag 4
1
Tag 5
Start
101
ID
Tag 1
Tag 2
Tag
Tag 1
0 1,2,3 1
00
ID
10
0
0
0
1
1,2
Tag
Tag 2
Tag
ID
Tag 1
0000
Tag 2
0010
Tag 3
0101
Tag 4
1100
Tag 5
1101
Tag
Tag 3
1
2
100
101
ID 4,5 1 Tag
0
Tag 4
0
Tag
E 1
4,5 5
1
0
Tag
Tag 4
ID
3 Tag 5
01
ID
Tag
ID
ID
0
Tag04
4
4,5
ID
00
01
E
1
5
Tag
Tag 4
ID

10. Problems

11. Aloha based protocols

12. BFSA

13. DFSA
After first broadcast determine three parameters:
1. Collision slots
2. Success slots
3. Empty slots
Then estimate unread tags:
If Collision slots> threshold then increase slots
Else : decrease slots

14. Problems

15. EDFSA

16. An Anti-collision Algorithm for Multi-Tag RFID
GENG Shu-qin, WU Wu-chen, HOU Li-gang and ZHANG Wang
If number of tags are large then
the tags can be grouped :

17. An Anti-collision Algorithm for Multi-Tag RFID
GENG Shu-qin, WU Wu-chen, HOU Li-gang and ZHANG Wang
Number of tags
Max Frame size
88-210
Frequency channels
64
P = 36%
210/64 = 3

18. An Anti-collision Algorithm for Multi-Tag RFID
GENG Shu-qin, WU Wu-chen, HOU Li-gang and ZHANG Wang

19. A Novel Anti-collision Protocol in Adaptive Framed Slotted Aloha about RFIDTags
Deng Zhongting, Wu Haifeng* , Liu Jing, Tan Yuan
SC = Slot number
RSC = Readable slot number
TSC = Tag slot number
frame length in a read cycle is set to the RSC’s value in the last cycle
Advantage : Reduce Time Of re-Identification
Disadvantage : Increase Number Of Computaion

20. A Novel Anti-collision Protocol in Adaptive Framed Slotted Aloha about RFIDTags
Deng Zhongting, Wu Haifeng* , Liu Jing, Tan Yuan
Algorithm 1. ADFA Reader Operation
1 Start
2 % Initialize L and RSC % L is frame length.
3 if RSC=NULL
4 L=N % N is set by user (frame size)
5 else
6 L=RSC (frame size = readable s n)
---------7 end if
8 RSC=0
------------9 do {
10 SC=0 % initialize SC
11 Transmit the command starting a frame
-----------------12 do {
13 Transmit the command starting a slot
14 Receive tag response and detect a
collision
15 if tag collision
16 f=collision
17 Transmit f
18 else if no tag response
19 f=idle
20 Transmit f
21 else only a tag response
22 Receive ID from tag and store it
23 RSC=RSC+1
24 f=successful
SC = Slot Counter
RSC = Readable slot number
frame length in a read cycle is set to
the RSC’s value in the last cycle
25 Transmit f with RSC
26 end if
27 SC=SC+1
28 }while SC<L ( end do line 12)
29 [E, S, C]=performCountSlot(L)
30 % Counts empty, successful and collision slots in
31 % a frame with L
32 L=2C
33 }while C>0 ( end do line 9)

21. A Novel Anti-collision Protocol in Adaptive Framed Slotted Aloha about RFIDTags
Deng Zhongting, Wu Haifeng* , Liu Jing, Tan Yuan
Algorithm 2. ADFA Tag Operation
1 Energized by reader
2 Enter Ready state
3 while state=Ready & Receive the
command starting a
4 frame with reader's L
5 do {
6 Enter Active state
7 if SSC=NULL or SSC>L or SSC<TSC
8 SSC=random number from 0 to L
9 End
10 TSC=0
11 while state=Active & Receive the
command
12 starting a slot
13 do {
14 if TSC=SSC
15 Transmit ID
16 Receive feedback f (with RSC) from
17 reader
18 if f= successful
19 SSC=RSC
20 Enter Quiet state
21 else
22 TSC=TSC+1
23 end
SC = Slot Counter
TSC = Tag slot Counter increase by one
SSC = Selected Slot Number
SSC<TSC means : the tag has not been
identified in last cycles
frame length in a read cycle is set to
the RSC’s value in the last cycle
24 else
25 TSC=TSC+1
26 end
27 }
28 Receive the command terminating this frame
29 form reader
30 if state=Active
31 Enter Ready state
32 end
33 }