ZeroScatter-LoRa: Microcontrollers Are RFIDs

ZeroScatter-LoRa is an all-digital and zero-added component technique for Long Range (LoRa) backscatter communication using commodity Microcontroller Units (MCUs).Instead of using traditional Radio Frequency (RF) switches for impedance modulation, it utilizes existing digital peripheral pins of ultra-low-power MCUs, such as Inter-IC Sound (I2S), Serial Peripheral Interface (SPI), or Inter-Integrated Circuit (I2C), to produce LoRa chirp signals using logic-level changes. We show backward compatibility of ZeroScatter-LoRa with commercial LoRa Wide Area Network (LoRaWAN) gateways in multipath rich indoor environments with an average power consumption of 9.8 µA. The results show that the monostatic configuration using Universal Software Radio Peripheral (USRP) in full duplex mode has an achievable range of 2.5 m, and the bistatic configuration using a single-tone generator at a distance of 2m has valid packet reception more than 20 m. The technique is applicable to billions of existing MCUs using high-speed digital interfaces. The long range that is achieved using MCU pins for backscatter communication also suggests that security risks maybe present in existing digital systems if digital I/O lines are not electromagnetically shielded from outside signals.