Date Added: Nov 2012
In Wireless Sensor Networks (WSNs) duty cycling has been an imperative choice to reduce idle listening but it introduces sleep delay. Thus, the conventional WSN MAC protocols are bound by the energy-latency trade-off. To break through the trade-off, the authors propose a radio wave sensor called RF watchdog that is dedicated to sense the presence of a RF signal. The distinctive feature of their design is that the RF watchdog can provide the same sensitivity but with two orders of magnitude less energy than the underlying RF module. With RF watchdog a sensor node no longer requires duty cycling. Instead, it can maintain a sleep state until its RF watchdog detects a communication signal.