Critical issues in energy-constrained sensor networks: synchronization, scheduling, and acquisition

Energy-constrained wireless sensor networks have conflicting requirements between the need to communicate, and the desire to avoid idle listening and thus save energy. Beneath this simple observation lies a complex design space that encompasses all layers of the radio through application. Broad design principles include the desire to exploit resources external to the network, such as beacons and (perhaps mobile) access points that do not have strong energy constraints. We consider synchronization, scheduled communications rendezvous, and packet acquisition. Synchronization accuracy worsens with prediction interval, saves energy by enabling scheduling, but costs energy to maintain. Acquisition is probabilistic due to noise, fading, and synchronization error, with operating points defining energy-performance tradeoffs.