A Long-Distance RF-Powered Sensor Node with Adaptive Power Management for IoT Applications

Abstract

We present a self-sustained battery-less multi-sensor platform with RF harvesting capability down to −17 dBm and implementing a standard DASH7 wireless communication interface. The node operates at distances up to 17 m from a 2 W UHF carrier. RF power transfer allows operation when common energy scavenging sources (e.g., sun, heat, etc.) are not available, while the DASH7 communication protocol makes it fully compatible with a standard IoT infrastructure. An optimized energy-harvesting module has been designed, including a rectifying antenna (rectenna) and an integrated nano-power DC/DC converter performing maximum-power-point-tracking (MPPT). A nonlinear/electromagnetic co-design procedure is adopted to design the rectenna, which is optimized to operate at ultra-low power levels. An ultra-low power microcontroller controls on-board sensors and wireless protocol, to adapt the power consumption to the available detected power by changing wake-up policies. As a result, adaptive behavior can be observed in the designed platform, to the extent that the transmission data rate is dynamically determined by RF power. Among the novel features of the system, we highlight the use of nano-power energy harvesting, the implementation of specific hardware/software wake-up policies, optimized algorithms for best sampling rate implementation, and adaptive behavior by the node based on the power received.

Micropower Design of an Energy Autonomous RF Tag for UWB Localization Applications

“…Modularity allows to easily upgrade single parts with newer versions. Unless we make the UHF interface of the tag compliant with EPC Gen 2 specification as in [12], even a 0.5 W ERP transmitted power is still suitable to supply the tag, regarded that a more efficient DC/DC converter is used as in [13]. The use of micro-power components and an energy-aware design have extended maximum activation range to the distances achievable with UHF RFID technology.…”

Dynamic Linked Data: A SPARQL Event Processing Architecture

“…Heterogeneous sensor data (e.g., soil moisture and temperature and humidity of some server control rooms) gathered by heterogeneous wireless sensor networks (e.g., DASH7 [70,71], LoRa (https://www.semtech.com/technology/lora/what-is-lora) and 6LowPan (https://tools.ietf.org/ html/rfc6282)) are sent over MQTT along with the temperatures of CPUs and hard disks of a set of servers. The application is an example of how raw data (i.e., the topic-value pairs provided by an MQTT broker) can be mapped into RDF triples.…”

Wake-Up Radio Impact in Self-Sustainability of Sensor and Actuator Wireless Nodes in Smart Home Applications

“…RF waves, despite being present in the environment (WiFi, GSM, etc. ), are not considered as they provide less energy than the other sources and not enough for the requirement of our application [18], even though recent prototypes for dedicated applications have been presented [19].…”