MAS.S61: Emerging Wireless & Mobile...
Transcript of MAS.S61: Emerging Wireless & Mobile...
![Page 1: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/1.jpg)
MAS.S61: Emerging Wireless & Mobile Technologies
Lecture 4: Low-power communica2on, RFID
![Page 2: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/2.jpg)
RFID (Radio Frequency IDentification)
Access Control
Security Sensitive Applications
Long-Range Payment Systems
Tracking & Localization
Inventory control
![Page 3: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/3.jpg)
RFID (Radio Frequency IDentification)
Access Control
Security Sensitive Applications
Long-Range Payment Systems
Tracking & Localization
Inventory control
> 100 Billion in the world
![Page 4: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/4.jpg)
Reply to wireless reader with a unique identifier
RFID: cheap battery-free stickers
Basic Principle of Operation
Reader
![Page 5: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/5.jpg)
• WWII: Aircraft IFF Transponder – Identify Friend or Foe, Transmitter-
Responder
• 1945: “The Thing” or “The Great Seal Bug” - “Gift” given by the Soviets to American
ambassador
• 1980s: development of E-Toll transponders
• 2004: Auto-ID lab at MIT led to the birth of modern battery-free RFIDs - Goal: supply chain chain optimization - Paper: “Towards the 5 cent tag”
History of RFIDs
![Page 6: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/6.jpg)
Types of RFIDs
Power consumption
Frequency Range
LF (120-150kHz)
HF (13.56MHz)
UHF (~900MHz)
short range (few cm)
long range (few m)
Range of Operation
“need to tap”
Where do these fall?
![Page 7: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/7.jpg)
Types of RFIDsFrequency
Range
Passive (battery-free)
Semi-Passive or Semi-Active
Active (with battery)
LF (120-150kHz)
HF (13.56MHz)
UHF (~900MHz)
Other less common versions: 2.4GHz, UWB (3-10GHz), etc.
Power consumption
Costfew cents 10s to 100s
of $
the vast majority of
RFIDs
![Page 8: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/8.jpg)
In The Rest of This Lecture..
• LF/HF: Power-up / Communicate
• UHF: Power-up / Communicate
• Medium Access control
![Page 9: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/9.jpg)
How does an RFID power up?
UHF (~900MHz)
Inductive Coupling Radiative
Harvests Energy from Reader’s Signal
Magnetic (Near Field)
Electromagnetic (Far Field)
Coil Antenna
LF (120-150kHz)
HF (13.56MHz)
![Page 10: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/10.jpg)
Inductive Coupling
![Page 11: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/11.jpg)
Inductive Coupling• Magnetic field also induced in the reverse direction • By modulating its impedance, the tag can communicate bits that
are sensed due to the mutual coupling
• Where else is this used?
![Page 12: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/12.jpg)
How does the receiver decode?
• Training sequence is sent at the beginning is used
• How does it know whether the high or the low is zero or one?
• Any other type of Near filed operation?
![Page 13: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/13.jpg)
In The Rest of This Lecture..
• LF/HF: Power-up / Communicate
• UHF: Power-up / Communicate
• Medium Access control
![Page 14: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/14.jpg)
Backscatter Communication
‘1’
‘0’
• A flashlight emits a beam of light
• The light is reflected by the mirror
• The intensity of the reflected beam can be associated with a logical “0” or “1”
![Page 15: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/15.jpg)
Backscatter Communication
![Page 16: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/16.jpg)
Reader shines an RF signal on nearby RFIDs
Tag reflects the reader’s signal using ON-OFF keying
Backscatter Communication
![Page 17: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/17.jpg)
Power Harvester
Switch Controller
Switch “Off”
Power Harvester
Switch Controller
Switch “On”
Uplink Communication
Antenna Switch
![Page 18: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/18.jpg)
Backscatter Schematic Implementation Overview
![Page 19: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/19.jpg)
Demodulation/Harvesting
Hardware
![Page 20: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/20.jpg)
Demodulation
Hardware: Demodulator
![Page 21: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/21.jpg)
Power Harvester
Hardware: Power Harvester
![Page 22: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/22.jpg)
Voltage Rectification
Aside: Voltage RectificationAside: Voltage Rectification
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.
Voltage-multiplying rectifiers
Half-wave rectifier
Diodes
Diode
![Page 23: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/23.jpg)
Voltage Rectification
![Page 24: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/24.jpg)
Power Harvester
Hardware: Power Harvester
![Page 25: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/25.jpg)
Hardware: Demodulator
Demodulation
![Page 26: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/26.jpg)
Hardware: Demodulator
Demodulation
![Page 27: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/27.jpg)
Hardware: DemodulatorSchmitt Trigger
Schmitt Trigger
Demodulation
![Page 28: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/28.jpg)
In The Rest of This Lecture..
• LF/HF: Power-up / Communicate
• UHF: Power-up / Communicate
• Medium Access control
![Page 29: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/29.jpg)
MAC
Single receiver, many transmitters
E.g., Satellite system, wireless
Receiver
Transmitter Transmitter Transmitter
![Page 30: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/30.jpg)
MAC (EPC-Gen 2)
Slotted Aloha: – Reader allocates Q time slots and transmits a query at the
beginning of each time slot – Each tag picks a random slot and transmits a 16-bit random
number – In each slot:
• RN16 decoded ! Reader ACKs ! Tags transmits 96-bit ID • Collision ! Reader moves on to next slot • No reply ! Reader moves on to next slot
Reader
Tag
![Page 31: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/31.jpg)
Inefficient: – If reader allocates large number of slots ! Too many empty
slots – If reader allocates small number of slots ! Too many collisions
Reader
Tag
MAC (EPC-Gen 2)
![Page 32: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/32.jpg)
• Probability that a tag transmits in a given slot:
• Probability that any tag transmits in a given slot without collision:
• To maximize E, set:
• p=1/N => K=N
Minimizing Collisions• N RFID Tags & K Time slots• Each tag picks a slot uniformly at random to transmit in• Let’s assume the reader knows the number of tags N; how
should it set K?
![Page 33: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/33.jpg)
• Probability that a tag transmits in a given slot:
• Probability that any tag transmits in a given slot without collision:
• p=1/N => K=N
Minimizing Collisions• N RFID Tags & K Time slots• Each tag picks a slot uniformly at random to transmit in• Let’s assume the reader knows the number of tags N; how
should it set K?
![Page 34: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/34.jpg)
EPC Gen2 – MAC
Inefficient: – If reader allocates large number of slots ! Too many empty slots – If reader allocates small number of slots ! Too many collisions – If reader knows number of tags = N ! Allocate K=N slots ! 37%
efficiency
Reader
Tag
Significant work on “spanning trees”, efficient scanning, decoding with collisions, etc.
![Page 35: MAS.S61: Emerging Wireless & Mobile Technologiesfadel/courses/MAS.S61/materials/lec4-slides-2020.pdf(Near Field) Electromagnetic (Far Field) Coil Antenna LF (120-150kHz) HF (13.56MHz)](https://reader033.fdocuments.us/reader033/viewer/2022060914/60a8182d600f4b35bf7c2e34/html5/thumbnails/35.jpg)
In This Lecture..
• LF/HF: Power-up / Communicate
• UHF: Power-up / Communicate
• Medium Access control