This comprehensive text shows the effectiveness of using mobile sinks in obtaining potential energy savings for the sensors in wireless sensor networks. The entire sensor network is divided into two layers: the resource-constrained sensor nodes constituting the lower layer and a mobile ad hoc network of resource-rich sinks forming the upper layer. Each sink is responsible for monitoring and data collection from a particular cluster of sensors. A sink moves to the vicinity of the sensor nodes - in a cluster - to collect data and exchanges the collected data with peer mobile sinks. The data can...