Saiyan - Design and Implementation of a Low-power Demodulator for LoRa Backscatter Systems

Explore the design and implementation of Saiyan, an ultra-low-power demodulator for LoRa backscatter systems, in this 15-minute conference talk from NSDI '22. Learn about the challenges of long-range backscatter communication and how Saiyan addresses them by enabling feedback signal demodulation, packet re-transmission, rate adaptation, and channel hopping. Discover the key observations, frequency-amplitude transformation techniques, and use of Surface Acoustic Wave (SAW) filters that contribute to Saiyan's improved demodulation sensitivity and range. Examine the high-level circuit schematic, implementation details, and performance metrics, including demodulation range, throughput, power consumption, and system cost. Gain insights into how Saiyan achieves a 3.5-5x gain in demodulation range compared to state-of-the-art systems while consuming only 93.2 μW of power.

Intro
Backscatter Provides Ubiquitous Wireless Connectivity
LoRa Backscatter Primer
Challenge on Packet Delivery
Existing Works for Downlink Demodulation
How to demodulate LoRa Symbols?
Saiyan: a Low-power Demodulator
Key Observation
Frequency-amplitude Transformation
Surface Acoustic Wave (SAW) Filter
Demodulation Sensitivity of Vanilla Saiyan
Improving the Demodulation Sensitivity
Cyclic-frequency Shifting
High-level Circuit Schematic
Implementation
Demodulation Range
Throughput
Power Consumption & System Cost
Take Away
Conclusion