In wireless sensor networks (WSNs), batteries are unlikely to be replaced or recharged once they get depleted, because of costs and feasibility. In a typical application, sensor nodes should be accessible and able to respond within a defined period of time, especially in real-time applications. However, the idle listening of the radio wastes most of the energy since the radio transceiver is constantly active. On the other hand, putting it into sleep state disconnects the node from the network. To cope with such a challenge, an ultra-low-power radio receiver referred to as a wake-up receiver (WuRx) handles the idle listening while keeping the main radio completely off. A WuRx consumes much less power than the main transceiver and triggers an interrupt only when a packet with a user-defined address is received. Embedding such a device enables better event-triggered applications where real-time behavior is required and a longer lifetime is mandatory. The proposed WuRx features practical sensitivity and includes the minimum number of active components in order to remain within the power budget. In this paper, an ultra-low-power WuRx with a power of 7.5 µW and a sensitivity of −60 dBm is developed. The decoding process of 16 bit of a wake-up packet (WuPt) takes less than 15 ms.

A novel wake-up receiver for wireless sensor networks is introduced. It operates with a modified medium access protocol (MAC), allowing low-energy consumption and practical latency. The ultra-low-power wake-up receiver operates with enhanced duty-cycled listening. The analysis of energy models of the duty-cycle-based communication is presented. All the WuRx blocks are studied to obey the duty-cycle operation. For a mean interval time for the data exchange cycle between a transmitter and a receiver over $1.7$ $\mathrm{s}$ and a 64-bit wake-up packet detection latency of 32 ms, the average power consumption of the wake-up receiver (WuRx) reaches down to 3 μ $\mathrm{W}$ . It also features scalable addressing of more than 512 bit at a data rate of 128 $\mathrm{k}$ $\mathrm{bit}$ / $\mathrm{s}$ ⁻¹. At a wake-up packet error rate of ${10}^{-2}$ , the detection sensitivity reaches a minimum of $-90$ $\mathrm{dBm}$ . The combination of the MAC protocol and the WuRx eases the adoption of different kinds of wireless sensor networks. In low traffic communication, the WuRx dramatically saves more energy than that of a network that is implementing conventional duty-cycling. In this work, a prototype was realized to evaluate the intended performance.