A Passive Crystal-Less Tag Demonstrating Battery-Free GSM-CW/5G-NR Downlink and BLE-to-BLE/BLE-to-WiFi/WiFi-to-WiFi Multi-Channel-Hopping Uplink with Smartphones

The ubiquitous deployment of IoT applications requires low-power and low-cost wireless connectivity compatible with commodity hardware such as smartphones. Traditional IoT devices using WiFi, BLE, LTE, or 5G-NR dissipate at least mW-level power from batteries or wall power [1]–[6], which limits their lifespan or increases the hardware cost. In comparison, passive IoT tags based on backscatter communication can be compatible with existing ecosystem [7]–[15], which offer much lower hardware cost and longer life time. However, most of existing passive tags need either an incident continuous-waveform (CW) [7]–[9] or an additional codeword decoder [11]–[13], increasing the infrastructure overhead. To achieve seamless interconnection with widely-deployed hardware, both the power and data links of the passive tags should be compatible with commodity devices (such as smartphones).