A Self-Adaptive Sleep/Wake-up Scheduling Approach for Wireless Sensor Networks - Supplementary Material

On-demand wake-up approaches typically require two channels: a data channel and a wake-up channel for waking nodes when needed. This allows for the immediate transmission of a signal on the wake-up channel, if a packet transmission is needed on the data channel. Thus, the wake-up latency can be reduced. The drawback is the additional cost for the second radio. In [2], Gu and Stankovic present a power management scheme, where nodes are woken up only when they need to be. In their scheme, energy consumption can be significantly reduced, but a special hardware component, a radio-triggered circuit, is required to wake up a node. The radio-triggered circuit is powered by the radio signals themselves. It is powered off when there is no suitable radio signals and starts working when suitable radio signals arrive. Miller and Vaidya [3] propose a power management protocol to reduce sensor network energy consumption using an additional wakeup radio. Unlike other studies, where a wakeup radio has to wake up a node’s entire neighbourhood, their protocol enables a radio to selectively wake up some of a node’s neighbours. The selection of the neighbours is based on the frequency with which each neighbour previously engaged in communication. They also give equations to find the optimal wake-up interval to minimise energy consumption.