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Ways of Benchmarking the UHF RFID Systems
第一屆中國無線射頻識別基準測試發展論壇 暨 備忘協議簽訂儀式March 1, 2008
Damon Tsang
112/05/01 CSL--A Chung Nam Company 2
A Typical UHF RFID System• Main components contain:
– Reader– Antennas– Tags– Computer software for controlling the reader to read from and
write to tags
IC
Tag Antenna
TagTag
External Interface
Antenna
Computer Computer SoftwareSoftware
ReaderReader
112/05/01 CSL--A Chung Nam Company 3
Common Problems found in UHF RFID Systems
• Missing Tags - Out of read coverage- Insufficient output power
• Cross Reads- Reflection- Over power
112/05/01 CSL--A Chung Nam Company 4
Scenario 1 – Read/Write Tags in An Assembly Line
Conditions:1. Be able to read all 20 tags at the
height of 0.75m2. Read with 1 antenna 3. Output power at 28dBm
Rec EPC ID RSSI
1 00000000000EA00000000001 -47
Outcomes:• Shorter the antenna, narrower
the reading range• Only 17 tags are read due to
out of range
Antenna Read coverage
3 tags gone missing
Cont…
Tags
50 trials – Fail to read all tags
17 00000000000EA00000000017 -48
18 Missing
19 Missing
20 Missing
112/05/01 CSL--A Chung Nam Company 5
Scenario 2 – Read/Write Tags in An Assembly Line
16 00000000000EA00000000016 -45
17 00000000000EA00000000017 -48
18 00000000000EA00000000018 -38
19 Missing
20 00000000000EA00000000018 -58
Conditions:• Increase the height to 1m to cover wide
read range• Be able to read all 20 tags • Read with 1 antenna • Output power at 28dBm
Rec EPC ID RSSI
1 00000000000EA00000000001 -47
Outcomes:• Higher the antenna, wider the
reading coverage• Be able to read more tags• Only 19 tags are read due to
the insufficient power
Antenna Read coverage
Wider read range
Cont…
Tags
50 trials – Fail to read all tags
112/05/01 CSL--A Chung Nam Company 6
Scenario 3 – Read/Write Tags in An Assembly Line
Output Power 28dBm -> 30dBm
19 00000000000EA00000000019 -47
20 00000000000EA00000000088 -50
21 00000000000EA00000000088 -65
22 00000000000EA00000000098 -68
Rec EPC ID RSSI
1 00000000000EA00000000001 -55
Conditions:• Increase the height to 1m to cover wider
read range• Increase the output power to 30dBm• Be able to read all 20 tags • Read with 1 antenna• Avoid cross reading of tags
Outcomes:• Higher the antenna, wider the
reading coverage• More output power to radiate the
tags• Be able to read all tags• 2 more unwanted tags are read
due to an increase of output power (cross read occurs)
Cont…
50 trials – Cross read occurs
112/05/01 CSL--A Chung Nam Company 7
Scenario 4 – Read/Write Tags in An Assembly Line
19 00000000000EA00000000019 -48
20 00000000000EA00000000020 -50
EPC ID RSSI
1 00000000000EA00000000001 -53
• Power increases from 28dBm to 30dBm• Change the value of the RSSI• Filter the unwanted tags < -60dBm
19 00000000000EA00000000019 -47
20 00000000000EA00000000088 -50
21 00000000000EA00000000088 -65
22 00000000000EA00000000098 -68
50 trials – Perfect result!
Solutions:
Set RSSI to -60 dBm
112/05/01 CSL--A Chung Nam Company 8
Scenario 5 – Double Gate Door Benchmarking
Conditions:• Be able to read all 40 tags• 4 antennas with output
power at 32.5dBm each
38 00000000000EA00000000038 -45
39 00000000000EA00000000039 -47
40 00000000000EA00000000040 -52
Rec EPC ID RSSI
1 00000000000EA00000000001 -38
2 00000000000EA00000000002 -47
Outcomes:• 40 tags are successful read again
st the backend database
Database ChecklistForklift trucks arein queue waiting
Out
Association
Cont…
112/05/01 CSL--A Chung Nam Company 9
Scenario 6 – Double Gate Door Benchmarking
38 Missing
39 00000000000EA00000000039 -48
40 00000000000EA00000000040 -52
Rec EPC ID RSSI
1 00000000000EA00000000001 -38
2 00000000000EA00000000002 -47
Outcomes:• 1 tag is missing after checking
against the backend database
Database Checklist
Association
Go back & proceed again due to missing tags
Solutions:• Go back and pass the gate door
again until all tags are read Cont…
Forklift trucks arein queue waiting
Conditions:• Be able to read all 40 tags• 4 antennas with output
power at 32.5dBm each
112/05/01 CSL--A Chung Nam Company 10
Scenario 7 – Double Gate Door Benchmarking
38 00000000000EA00000000038 -68
39 00000000000EA00000000039 Missing
40 00000000000EA00000000040 -52
Database Checklist
Conditions:• Be able to read all 40 tags when
passing thru 2 doors• 8 antennas with output power at
32.5dBm each
39 00000000000EA00000000039 -38
40 00000000000EA00000000040 -52
Database Checklist
Rec EPC ID RSSI
1 00000000000EA00000000001 -38
Outcomes:• 1 tag is missing at the Door 1• 100% read is at the Door 2• Improve the chance of success of the
reading rate• Shorten the queuing time
Association
Association
Cont…
Forklift trucks arein queue waiting
112/05/01 CSL--A Chung Nam Company 11
Scenario 8 – Double Gate Door Benchmarking
38 00000000000EA00000000038 Missing
39 00000000000EA00000000039 -35
40 00000000000EA00000000040 -52
Database Checklist
38 00000000000EA00000000038 -48
39 00000000000EA00000000039 -38
40 00000000000EA00000000040 Missing
Database Checklist
Outcomes:• No identical missing tags read in 2 doors
assuming that 100% read rate is achieved – no missing tags occur
• Improve the chance of success of the reading rate
• Shorten the queuing time
Cross referencing
Cont…
Conditions:• Be able to read all 40 tags when
passing thru 2 doors• 8 antennas with output power at
32.5dBm each
Forklift trucks arein a queue waiting
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Summary• Benchmarking a RFID system in an
assembly line is based on the read coverage, output power, and RSSI to minimize missing tags and cross reads
• Benchmarking a RFID system using the double gate door system avoids missing tags, increases productivity, and reduces queuing time
