Employing mobile elements for delay-constrained data gathering in WSNs.

In this paper, we present rendezvous-based data gathering protocols for wireless sensor networks employing multiple mobile elements. For satisfying timely delivery of sensory data to the base station, the mobile elements are forced to visit only an appropriate number of rendezvous nodes while the remaining sensor nodes send their data through multi-hop communication toward these nodes. The proposed techniques achieve prolonged network lifetime by (i) selecting as rendezvous nodes sensor nodes from energy rich network neighborhoods that are appropriately distributed across the network, especially in regions where increased energy consumption has been observed and (ii) building energy efficient routes for all sensor nodes of the network toward the trajectories of the mobile elements. We also conducted simulation tests which confirm the effectiveness of the proposed protocols.