Bird-MAC: Energy-Efficient MAC for Quasi-Periodic IoT Applications by Avoiding Early Wake-up

Abstract

We propose a new MAC protocol for IoT applications, called Bird-MAC, which is highly energy efficient in the applications where IoT sensors report monitoring status in a quasi-periodic manner, as in structural health monitoring and static environmental monitoring. Two key design ideas of Bird-MAC are: (a) no need of early-wake-up of transmitters and (b) taking the right balance between synchronization and coordination costs. The idea (a) is possible by allowing a node (whether it is a transmitter or receiver) to wake up just with its given wake-up schedule, and letting a late bird (which wakes up later) notify its wake-up status to its corresponding early bird (which wakes up earlier), where the early bird just infrequently waits for the late bird's wake-up signal. The idea (b) is realized by designing Bird-MAC to be placed in a scheme between purely synchronous and asynchronous schemes. We provide a rigorous mathematical analysis that is used to choose the right protocol parameters of Bird-MAC. We demonstrate the performance of Bird-MAC through extensive simulations, and real experiments. The experiment on our testbed using a 26 node testbed at an underground parking lot of our office building to monitor its structural health shows that energy consumption is reduced by about up to 45 percent over existing sensor MAC protocols. We also confirm the applicability of Bird-MAC in a challenging and realistic scenario through the experiment on Yeongjong Grand Bridge in South Korea.