AmbientRider: Towards Infrastructure-Independent Ambient LoRa Backscatter

Abstract

The vision of ambient LoRa backscatter is to achieve long-range, pervasive connectivity by leveraging existing LoRa signals. However, requiring transmitter-side coordination limits widespread deployment because LoRa infrastructure needs to generate tag-specific traffic or allocate airtime and spectrum resources, thereby disrupting its primary services. We present AmbientRider, an infrastructure-independent LoRa backscatter system that operates over the signals without any transmitter-side coordination. Our key insight is that commodity LoRa chirps contain exploitable timing and phase structure that enables blind synchronization, channel adaptation, and interference cancellation, thereby supporting infrastructure-independent LoRa backscatter. We implement AmbientRider with off-the-shelf components and evaluate it over uncoordinated commercial LoRa transmitters. The system achieves up to 19.0 kbps throughput with the wake-up sensitivity of -24 dBm when uncooperative ambient gateways transmit across the entire 2.4 GHz ISM band with randomly varying spreading factors (SFs) and channels.