Wake-Up Receiver Based Routing Protocols in Internet of Things: A Survey

We are currently living in the era of the Internet of Things (IoT) where numerous smart objects are surrounding us and reporting various information about our environment. The main challenge of these IoT devices is energy consumption since the lifetime of each device is tightly related to its limited battery capacity. For this reason, it is beneficial to keep the IoT nodes in sleeping mode and to wake them up only when they are required. Wake-up-based wireless sensors present nowadays a leading technology that shapes well this requirement. However, despite their important impact on extending the network lifetime, these sensors present a real obstacle for IoT routing protocols. Effectively, routing in IoT networks should be time efficient, whereas these sensors require additional time to wake up and to be prepared for data reception and forwarding. In this paper, we give a general overview of the wake-up-based sensors and detail the most important challenges facing these sensors in the scope of the routing protocols. We also survey and propose a taxonomy of the most important and recent routing protocols that have used these sensors.