A Supplemental Zero-Energy Downlink Air-Interface Enabling 40-Year Battery Life in IoT Devices.

A zero-energy downlink air-interface (ZE-DL) that does not draw power from the device's battery is introduced. Information packets sent on the ZE-DL are preceded by a power-optimized preamble (POP) where the energy harvested from the POP is used by an ultra-low power receiver (ULP-RX) to decode the information packets. An approach for estimating the POP duration as a function of free-space path loss, the energy harvester efficiency and the ULP-RX power consumption is outlined. An IoT device architecture is proposed where the ZE-DL functions as a supplement to the 3GPP Uu air-interface. On-demand features are introduced into the 3GPP system using a broad class of wake-up signal (WUS) transmissions on the ZEDL. An analytical framework for estimating the network resource overhead associated with POP transmissions is developed. An energy model for the IoT device is developed and a pathway to 20, 40-year battery life for Uu uplink (UL) transaction cycles of 1, 5 days is demonstrated where the POP transmission related network overhead is limited to less than 6%.