Radio-Triggered Wake-Up for Wireless Sensor Networks

Power management is an important technique to prolong the lifespan of sensor networks. Many power management protocols employ wake-up/sleep schedules, which are often complicated and inefficient. We present power management schemes that eliminate such wake-up periods unless the node indeed needs to wake up. This type of wake-up capability is enabled by a new radio-triggered hardware component inspired by the observation that the wake-up radio signal contains enough energy to trigger a wake-up process. We evaluate the potential power saving in terms of the lifespan of a sensor network application, using experimental data and SPICE circuit simulations. Comparing the result with always-on and rotation-based power management schemes, we find the radio-triggered scheme saves 98% of the energy used in the always-on scheme, and saves over 70% of the energy used in the rotation-based scheme. Consequently, the lifespan increases from 3.3 days (always-on) or 49.5 days (rotation-based) to 178 days (radio-triggered). Furthermore, a store-energy technique can extend operating distance from 10 feet to 22 feet, or even longer if longer latency is acceptable. Wake-up efficiency is evaluated in NS-2 simulations, which show that radio-triggered wake-up has fewer failures, shorter latency, and consistently larger sensing laxity than rotation based wake-up. We also present amplification and radio-triggered IDs which can further enhance performance.