Cooperation Helps Power Saving

In Wireless Sensor Networks (WSN), energy efficiency is crucial to achieving satisfactory network lifetime. The most commonly used and may be the only efficient method to reduce the energy consumption significantly is to turn off the radios most of the time, except when it has to participate in data communication. The key challenge is to operate the radio at a low duty cycle but still ensure the delay is relatively low. Various power-saving Medium-Access control (MAC) protocols have been proposed along this thread. However, most of such protocols focus on a point-to-point communication setting, in which a node will drop a overheard packet if it is not the destination.