A MAC-Protocol for Passive Wake-up Radios

Abstract

Energy efficiency remains a big challenge in wireless sensor networks and the internet of things (IoT) since sensor nodes have limited energy resources. Conventional duty-cycled medium access control (MAC) protocols reduce idle listening while incurring energy cost owing to periodic channel monitoring. Wake-up radio technology has emerged as a potential solution for on-demand node activation and reducing idle listening. In this paper, a passive wake-up radio MAC protocol is proposed for energy-constrained IoT sensor networks. Sensor nodes are awakened via radio frequency (RF) energy harvesting from received wake-up signals. To analyze packet transmissions and node energy consumption, a cross-layer analytical framework is created that incorporates physical layer wake-up processes and MAC layer communication behavior. Closed-form expressions are constructed for critical packet statistics such as wake-up calls, acknowledgements, and erroneous wake-up events, allowing for extensive study of protocol performance. The proposed protocol is evaluated using discrete-event simulation with different wake-up call durations and packet loss probabilities. Simulation results show that the proposed passive wake-up protocol consumes much less node energy than traditional duty-cycled and existing wake-up radio MAC methods while retaining acceptable communication delay and reliability. Simulation results show that, in comparison to conventional duty-cycled and benchmark wake-up radio MAC protocols, the proposed passive wake-up protocol reduces average node energy usage by more than 50% while maintaining acceptable packet reliability and delay. The operating lifetime of large-scale IoT deployments could be greatly extended by passive wake-up radio systems, according to these quantitative results.