Data propagation in wireless sensor networks is usually performed as a multihop process. To deliver a single mes- sage, the resources of many sensor nodes are used and a lot of energy is spent. Recently, a novel approach is catching momentum because of important applications; that of hav- ing a mobile sink move inside the network area and collect the data with low energy cost. Here we extend this line of research by proposing and evaluating three new protocols.

Our protocols are novel in a) investigating the impact of having many mobile sinks b) in weak models with restricted mobility, proposing and evaluating a mix of static and mo- bile sinks and c) proposing a distributed protocol that tends to equally spread the sinks in the network to further improve performance. Our protocols are simple, based on random- ization and assume locally obtainable information. We per- form an extensive evaluation via simulation; our findings demonstrate that our solutions scale very well with respect to the number of sinks and significantly reduce energy con- sumption and delivery delay.