1. Ways of Benchmarking the UHF RFID Systems
Damon Tsang
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

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
Tag
External Interface
Antenna
Computer
Software
Reader
2018/12/27
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
2018/12/27
CSL--A Chung Nam Company

4. Scenario 1 – Read/Write Tags in An Assembly Line
Antenna
Read coverage
50 trials – Fail to read all tags
Rec
EPC ID
RSSI 1 EA
-47 17 EA
-48 18
Missing 19 20
Tags
3 tags gone
missing
Outcomes:
Shorter the antenna, narrower the reading range
Only 17 tags are read due to out of range
Conditions:
Be able to read all 20 tags at the height of 0.75m
Read with 1 antenna
Output power at 28dBm
Cont…
2018/12/27
CSL--A Chung Nam Company

5. Scenario 2 – Read/Write Tags in An Assembly Line
50 trials – Fail to read all tags
Antenna
Read coverage
Wider read range
Rec
EPC ID
RSSI 1 EA
-47 16 EA
-45 17 EA
-48 18 EA
-38  19
Missing 20
-58 
Tags
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
Outcomes:
Higher the antenna, wider the reading coverage
Be able to read more tags
Only 19 tags are read due to the insufficient power
Cont…
2018/12/27
CSL--A Chung Nam Company

6. Scenario 3 – Read/Write Tags in An Assembly Line
50 trials – Cross read occurs
Output Power 28dBm -> 30dBm
Rec
EPC ID
RSSI 1 EA
-55    19 EA
-47    20 EA
-50    21
-65    22 EA
-68   
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…
2018/12/27
CSL--A Chung Nam Company

7. Scenario 4 – Read/Write Tags in An Assembly Line
Set RSSI to -60 dBm 19 EA
-47    20 EA
-50    21
-65    22 EA
-68   
50 trials – Perfect result!
EPC ID
RSSI 1 EA
-53   19 EA
-48   20 EA
-50   
Solutions:
Power increases from 28dBm to 30dBm
Change the value of the RSSI
Filter the unwanted tags < -60dBm
2018/12/27
CSL--A Chung Nam Company

8. Scenario 5 – Double Gate Door Benchmarking
Forklift trucks are
in queue waiting
Database Checklist
Rec
EPC ID
RSSI 1 EA
-38 2 EA
-47
Association 38 EA
-45 39 EA
-47 40 EA
-52
Out
Conditions:
Be able to read all 40 tags
4 antennas with output power at 32.5dBm each
Outcomes:
40 tags are successful read against the backend database
Cont…
2018/12/27
CSL--A Chung Nam Company

9. Scenario 6 – Double Gate Door Benchmarking
Database Checklist
Forklift trucks are
in queue waiting
Rec
EPC ID
RSSI 1 EA
-38 2 EA
-47 38
Missing 39 EA
-48  40 EA
-52
Association
Go back & proceed again due to missing tags
Outcomes:
1 tag is missing after checking against the backend database
Conditions:
Be able to read all 40 tags
4 antennas with output power at 32.5dBm each
Solutions:
Go back and pass the gate door again until all tags are read
Cont…
2018/12/27
CSL--A Chung Nam Company

10. Scenario 7 – Double Gate Door Benchmarking
Forklift trucks are
in queue waiting
Database Checklist
Association 38 EA
-68 39 EA
Missing 40 EA
-52  
Database Checklist
Association
Rec
EPC ID
RSSI 1 EA
-38 39 EA
-38 40 EA
-52
Conditions:
Be able to read all 40 tags when passing thru 2 doors
8 antennas with output power at 32.5dBm each
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
Cont…
2018/12/27
CSL--A Chung Nam Company

11. Scenario 8 – Double Gate Door Benchmarking
Forklift trucks are
in a queue waiting
Database Checklist 38 EA
Missing 39 EA
-35    40 EA
-52   
Cross referencing
Database Checklist 38 EA
-48    39 EA
-38    40 EA
Missing
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
Conditions:
Be able to read all 40 tags when passing thru 2 doors
8 antennas with output power at 32.5dBm each
Cont…
2018/12/27
CSL--A Chung Nam Company

12. CSL--A Chung Nam Company
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
2018/12/27
CSL--A Chung Nam Company

13. CSL--A Chung Nam Company
Thank You!!
Contact:
2018/12/27
CSL--A Chung Nam Company