Enabling Cross-Band Backscatter Communication With Twaltz

Frequency switching is a fundamental capability for wireless communication systems. However, this capability is significantly constrained in backscatter systems. The difficulty is to generate tunable high-frequency modulation signals on a backscatter tag at an acceptable power budget. In this paper, we present Twaltz, a new design paradigm for backscatter communication that enables frequency switching across large frequency bands. By exploiting a low-power semiconductor device, i.e., tunnel diode, and carefully addressing its physical features, Twaltz generates oscillation signals up to 1.2 GHz while maintaining micro-watt level power consumption. Twaltz further facilitates on-tag oscillation signal stabilization and programmable oscillation frequency tuning. We prototype Twaltz on a PCB board, demonstrating its efficiency in cross-band communication for LoRa backscatter, and verifying its performance in concurrent transmission, channel hopping, and data transmission.