Contents I. Introduction
With the emerging development of the Internet of Things (IoT), smart sensors and wireless sensor networks (WSN) are widely used, such as the human health monitoring system with wearable sensors [1] and the complex environment monitoring system with fixed or mobile sensors [2]. Sensing, data processing, and communication are three essential domains in WSN, where data communication occupies the majority power consumption [3]. Due to the market requirement and potential applications of internet-connected things [4], a lot of modern low power communication protocols, devices and components have been occurred and promote the development of smart wireless sensor networks [5], [6]. In each intelligent wireless sensor, communication distance, operation frequency and power consumption are significant specifications. In traditional wireless sensors, long communication distance can be achieved by adopting high-performance transceiver but with several milli-watt power consumption [7], which shortens the sensors lifetime because of the limited power capacity and volume of the battery. To solve the power consumption issue, the duty-cycled transceiver is a direct technique, but it suffers from the long communication latency, it cannot be used in the inactive nodes. Event-driven wake-up receiver (Wu-Rx) is a viable technique to scale down the standby current [8], [9] and further the average current to meet the system power requirement. Accordingly, the wake-up receiver based sensor node is shown in Fig.1. The always-on wake-up receiver monitors the ambient event with low power consumption and enables the main transceiver with partly enabled power supply, digital signal processing, memory, and sensors with small latency to be waken-up if active communication is required.
Wake-up receiver based on sensor node in WSN application.
