Energy efficiency evaluation of wake-up radio based MAC protocol for wireless body area networks

In this paper, a generic wake-up radio (WUR) based medium access control (MAC) protocol (GWR-MAC) has been evaluated from the energy consumption point of view. GWR-MAC protocol's goal is to achieve energy efficiency by avoiding idle listening since the sensor nodes are awakened only when there is a need for communication. A successful wake-up signal (WUS) transmission and reception is needed to awaken the WUR enabled node(s) from the sleep mode which must be taken into account in the energy consumption evaluation. Success of wake-up process depends on the physical layer detection of the signal, and also on the collision probability of the wake-up signals if there can be multiple nodes that are transmitting the WUS approximately at the same time. The success probability of GWR-MAC wake-up process is analyzed in this work taking into account physical and MAC layer aspects when assuming that wake-up signals are transmitted using Aloha channel access method. WUS success probability derivation is incorporated to energy consumption model and results are obtained to compare the total energy consumption of WUR based network and duty-cycling based network. The results show that the WUR based networks can improve energy efficiency in comparison to conventional duty cycling approach when taking into account also the error probability of the wake-up process. Results show also that in which conditions the duty-cycling approach should be preferred instead of WUR approach.