Braidio: An Integrated Active-Passive Radio for Mobile Devices with - - PowerPoint PPT Presentation

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Braidio: An Integrated Active-Passive Radio for Mobile Devices with - - PowerPoint PPT Presentation

Apr 16, 2023 501 likes •817 views

Braidio: An Integrated Active-Passive Radio for Mobile Devices with Asymmetric Energy Budgets Pan Hu , Pengyu Zhang, Mohammad Rostami, Deepak Ganesan University of Massachusetts Amherst 1 CICS@UMass Amherst Variability in battery capacity 100

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CICS@UMass Amherst

Braidio: An Integrated Active-Passive Radio for Mobile Devices with Asymmetric Energy Budgets

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Pan Hu, Pengyu Zhang, Mohammad Rostami, Deepak Ganesan University of Massachusetts Amherst

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CICS@UMass Amherst

0.1 1 10 100

Battery Capacity/Wh

Three orders of magnitude variation in battery capacity

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Variability in battery capacity

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CICS@UMass Amherst

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Asymmetric battery lifetime

Devices with smaller batteries deplete far ahead

  • f those with larger batteries

10% 90%

50mW 50mW Sensor Data

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CICS@UMass Amherst

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Symmetric power consumption

TX RX

55~60mW 59~67mW TX/RX 0.82~1.0

TX RX

21~30mW 19mW TX/RX 1.1~1.6

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Can we design a power proportional radio?

Can we create a radio which consumes power proportional to battery size?

90% 90%

0.1mW 50mW Sensor Data

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Diversity of radio architectures

WiFi/ Bluetooth

Backscatter: Low power transmitter

Passive: Low power receiver RFID Tag AM receiver Active: Symmetric Radio

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Diversity of radio architectures

WiFi/ Bluetooth

Backscatter: Low power transmitter

Passive: Low power receiver RFID Tag AM receiver Active: Symmetric Radio

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CICS@UMass Amherst

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Symmetric active radio architecture

Active TX Active RX

Baseband Mixer Amplifier Antenna Baseband 2.4GHz Carrier Mixer Amplifier Antenna 2.4GHz Carrier

Similar power consumption at TX and RX

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Diversity of radio architectures

WiFi/ Bluetooth

Backscatter: Low power transmitter

Passive: Low power receiver RFID Tag AM receiver Active: Symmetric Radio

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Backscatter radio architecture

Backscatter transmitter

Antenna

Baseband

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Backscatter radio architecture

Backscatter receiver Backscatter transmitter

Baseband 2.4GHz Carrier Mixer Amplifier Antenna 1 Antenna 2 Antenna

Baseband

Much less power at TX but reduced range

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Diversity of radio architectures

WiFi/ Bluetooth

Backscatter: Low power transmitter

Passive: Low power receiver RFID Tag AM receiver Active: Symmetric Radio

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Passive radio architecture

Active TX Passive RX

Baseband Diode Antenna Baseband 2.4GHz Carrier Mixer Amplifier Antenna

Much less power at RX but reduced range

Capacitor Resistor

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CICS@UMass Amherst

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Power consumption of radios

Can we take advantage of these architectures?

Radio type TX RX TX/RX Active 20mW 20mW 1 Backscatter 20mW 0.02mW 1000:1 Passive 0.02mW 20mW 1:1000

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CICS@UMass Amherst

Any ratio in between 1:1000 to 1000:1

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Architecture of radios

TX Power

RX power

TX/RX=1000:1 TX/RX=1:1000 TX/RX=1:1

Radio type TX/RX Active 1 Backscatter 1000:1 Passive 1:1000

Achievable region Available radio

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Challenges in combining three modes

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Different types of radios have different working ranges Backscatter RX consumes excessive power

00.225 0.45 0.675 0.9 1.125 BLE Bluetooth Receiver 1 Receiver 2 Power/W >5x gap Backscatter

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Why is a Backscatter reader power hungry?

Self-interference cancellation

Baseband 2.4GHz Carrier Mixer Amplifier Antenna 1 Antenna 2 Leakage

Σ

  • +
  • Est. of

interferenc e

Active IQ Receiver

In-phase Quadrature 1

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Reducing power of Backscatter reader

Passive receiver with SAW filter

Baseband Amplifier Diode Antenna Capacitor Resistor Filter

Antenna diversity

Antenna 1 Antenna 2 path 1 path 2

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Bradio Backscatter RX: Design Tradeoffs

Passive receiver with SAW filter Antenna diversity Reduced sensitivity Reduced robustness Reduced range

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Active radio as a safety net

What if the Braidio backscatter mode fails?

Active radio as safety net

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Challenge #2: different working ranges

TX Power RX power

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Challenge #2: different working ranges

TX Power RX power

Backscatter: 70% Passive: 30%

Braidio multiplexes across modes based on SNR of each link and battery levels to achieve desired power ratio.

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Implementation of Braidio

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Braidio: Achievable energy ratios

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Braidio: Operating distance

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Braidio: Performance gain over active radio

>300x improvement when fitness band transmits to laptop

Transmitter Receiver

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Conclusion

Active Backscatter Passive

Braidio: A novel power-proportional radio that can deal with asymmetric energy budgets on mobile devices.

Thank you

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Conclusion

Active Backscatter Passive

Braidio: A novel power-proportional radio that can deal with asymmetric energy budgets on mobile devices.

Thank you

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Backup

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Backup