A REACH-Mote: A Range Extending Passive Wake-up Wireless Sensor Node

A wireless sensor network that employs passive radio wake-up of the sensor nodes can reduce the energy cost for unnecessary idle listening and communication overhead, extending the network lifetime. A passive wake-up radio is powered by the electromagnetic waves transmitted by a wake-up transmitter rather than a battery on the sensor node. However, this method of powering the wake-up radio results in a short wake-up range, which limits the performance of a passive wake-up radio sensor network. In this paper, we describe our design of a passive wake-up radio sensor node, called REACH2-Mote, using a high efficiency energy harvesting module and a very low power wake-up circuit to achieve an extended wake-up range. We implemented REACH2-Mote in hardware and performed field tests to characterize its performance. The experimental results show that the REACH2-Mote can achieve a wake-up range of 44 ft. We also modeled the REACH2-Mote and evaluated its performance through simulations, comparing its performance with that of another passive wake-up radio approach, an active wake-up radio approach, and a conventional duty cycling approach. The simulation results show that the REACH2-Mote can significantly extend the network lifetime, while achieving high packet delivery rate and low latency.