3. Needs Answers
Asset management
Logistics
Retail
The
Entertainment
Internet of
Things
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 3
Healthcare
…
…
Pictures taken fromhttps://www.flickr.com/ Pictures fromtheir websites
4. RFID-MIMO Prototype
based on GnuRadio
• Theoretical Fundamentals
• Goal
• SWOT
• Implementation
• Results
• Conclusions
5. Theoretical Fundamentals
EPC Gen 2 Standard
Pictures taken from the mentioned Standard
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 5
6. Theoretical Fundamentals
EPC Query Process
Reader Tag
QUERY
RN16
ACK
PC EPC CRC-16
QREP
1.
2.
3.
4.
5.
PR
PT
FS
PT
FS
PR: Preamble of Reader
PT: Preamble of Tag
FS: Frame-Sync
RN16: 16-Bit Random Number
Diversity combining techniques:
Selection Combining (SC)
Maximal Ratio Combining (MRC)
푠퐶 =
푁푟
푖=1
∗/휎푖
푠푅푋,푖 − 푆푎,푖 ℎ푖
Equal Gain Combining (EGC)
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 9
2
7. Goal
This thesis discusses the possibility of setting up a prototyping MIMO RFID
testbed based on USRP devices and GNU radio implementation for UHF
RFID systems.
The performance improvements will be compared to existing commercial
and USRP single antenna solutions.
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 10
8. Weaknesses Strengths
• My lack of experience
• Limited: time, access to
the laboratory
• Start-up
• My interest in the topic
• Erasmus scolarship
• Guidance of my tutor
• Selection of GnuRadio
• MIMO prototype
• Speed on technological
advances
• Competitiveness
• Cut in research
• Legislation behind technology
• Control, surveillance
• GnuRadio: free & open-source
• The Comprehensive GNU Radio
Archive Network, Internet
• High demand frombusiness and
institutions.
• Several fields of application
Threats Opportunities
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 11
9. Implementation
Set up the laptop: Ubuntu, UHD, GnuRadio
Gen2 RFID Listener fromCGRAN
USRP to_mag MF A Reader CR Tag sink
to_mag: complex-to-magnitude
MF: Matched Filter
A: Amplifier
Reader: Reader-Monitor-cmd-gate
CR: Clock Recovery
Tag: Tag-Monitor
Two phases:
1. Working with a single antenna
2. Implement a Diversity CombiningTechnique (DCT)
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 12
10. Implementation (1)
Setting important parameters: BLF, DR, Miller (M), RTcal, TRcal
Command DR M TRext Sel Session Target Q CRC
# of bits 4 1 2 1 2 2 1 4 5
description 1000 0: DR=8
1: DR=64/3
00: M=1
01: M=2
10: M=4
11: M=8
0: No pilot
tone
1: Use pilot
tone
00: All
01: All
10: ~SL
11:SL
00: S0
01: S1
10: S2
11: S3
0: A
1: B
0-15 CRC-5
푅푇푐푎푙 = 0푙푒푛푔푡ℎ + 1푙푒푛푔푡ℎ = 40 + 80 = 120
1.1 푅푇푐푎푙 ≤ 푇푅푐푎푙 ≤ 3 푅푇푐푎푙
132 ≤ 푇푅푐푎푙 ≤ 360
퐵퐿퐹 =
퐷푅
푇푅푐푎푙
= 320 푘퐻푧
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 13
11. Implementation (1)
tag_log.out empty
RN16? -> d_rn16
1
1. Picture taken from Google
2
2. Picture taken from EPC-RFID INFO
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 14
12. Implementation (2)
USRP to_mag
Selection Combining
MF A Reader CR Tag sink
USRP to_mag
SC
Rx
Rx2
푠퐶
to_mag MF A
Maximal Ratio Combining
Reader CR Tag sink
MRC
to_mag MF A
Reader CR Tag sink
Rx
Rx2
USRP
USRP
Reader -> tag
Preamble found
푠퐶
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 15
14. Results: Performance achieved for the RFID Listener
100
80
60
40
20
0
Rx2
0 10 20 30 40 50 60
%
Distance (cm)
100
80
60
40
20
0
SC
0 10 20 30 40 50 60
%
Distance (cm)
90
80
70
60
50
40
30
20
10
Listener-Success Ratio
Rx
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 17
L - SR
CRC Error Ratio
CRC Miss Ratio
0
0 10 20 30 40 50 60
%
Distance (cm)
Rx
Rx2
SC
100
80
60
40
20
0
0 10 20 30 40 50 60
%
Distance (cm)
15. Conclusions
Idea
▪ Slow hunch: incubation
▪ Space: laboratory
▪ Environment
Achievements:
▪ Adapt the project fromCGRAN
▪ Design and create a new block
using a tool of GnuRadio
▪ Implement a DCT: SC
Propose a possible
implementation for MRC
Keep working on this project
Pictures taken fromhttps://www.flickr.com/
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 18
16. I appreciate you listening
Thank you
and feel free to ask
RFID-MIMO Prototype based on GnuRadio Amelia Jiménez Sánchez 19
Notes de l'éditeur
Selecting the antenna with the strongest signal, this is known as selection combining (SC).
In maximum ratio combining (MRC), the branch signals are weighted and combined so as to yield in the highest instantaneous SNR possible with any linear combining technique. Nr: total number of receive antennas. Sigma_i: noise power at antenna i. h_i: channel coefficient -> corresponds to the two-way reader-to-tag-to-reader channel.
MRC requires the knowledge of the channel coefficients and the noise power, channel estimation is required.
In equal gain combining (EGC) all of the weights have the same magnitude but an opposite phase to that of the signal in the respective branch.
However, MRC or EGC diversity techniques require important modification in commercial readers.
Absorb state -> T1: period of time between a reader command and the tag response
Reflect state -> during the period of the first bit of the preamble of the tag response
If all receive branches are decoupled from the transmitter by separated antennas, equal noise power can be expected, and thus it can be omitted.