Passive DSSS - Empowering the Downlink Communication for Backscatter Systems

Explore a 15-minute conference talk from USENIX NSDI '22 that introduces Passive DSSS, a novel approach to enhance downlink communication in backscatter systems. Learn how this technique addresses the asymmetry between uplink and downlink transmissions, improving signal-to-interference-plus-noise ratio (SINR) and extending the effective range of downlink communication. Discover the innovative solution to the challenge of DSSS signal demodulation on energy-constrained devices by shifting spreading code generation and synchronization to the gateway side. Examine the experimental results demonstrating a 16.5 dB improvement in downlink SINR and its practical implications for backscatter communication systems.

Intro
Downlink and Uplink are highly asymmetric
We propose Passive DSSS (Direct-Sequence Spread Spectrum)
Key challenge to achieve DSSS on the downlink
Basic idea of Passive DSSS
cannot demodulate existing DSSS signals
how to suppress interference from both channels
correlation calculation requires signal processing
Passive DSSS receiver design
Experimental setup
Evaluation - Performance and baseline
Evaluation - Interference Resistance
Evaluation Downlink Range