Energy-Efficient Sensing Data Delivery for Low Power Environmental Sensors

Sensor networks are becoming extensively used to effectively and autonomously monitor our environment, where examples include environmental and habitat monitoring, structural health monitoring and condition-based equipment maintenance, and disaster management and emergency response. One of the popular and primary mechanisms for achieving low energy consumption in energy-constrained wireless sensor networks (WSNs) is duty cycling where each node periodically alternates the states of awake and dormant, motivated by the fact that a non-negligible portion of energy is consumed when in the idle listening state. In this chapter, under the framework of duty cycling, we survey the four key components for energy-efficient delivery of sensing data: (i) medium access control (MAC), (ii) routing, (iii) wake-up scheduling, and (iv) time synchronization. These four components are often coupled in many cases, where they have to be collaboratively optimized for better energy efficiency in operating WSNs. We survey the recent advances in those four components and conclude with the discussion of the future directions in this area.