Route in Mobile WSN and Get Self-Deployment for Free

International audienceWe consider a system composed of a set of mobile sensors, disseminated in a region of interest, which mobility is controlled (as opposed to mobility imposed by the entity on which they are embedded). A routing protocol, in this context, enables any point of the region to be reached. In this paper, we present Grasp, a GReedy stateless Routing Protocol for mobile wireless sensor networks (WSN). The strength of Grasp, beyond its simplicity, is that routing enables a free and close to optimal self-deployment of sensors over a given region. Grasp transparently copes with dynamic changes of the region of interest. In addition, Grasp is independent from the underlying communication model. Grasp ensures (i) that routing is always possible in a mobile WSN irrespective of the number of sensors and (ii) above a given number of sensors in a considered zone, the protocol eventually ensures that routing does no longer require sensors to move, thus providing self-deployment. In one dimension, Grasp converges to a full connected-coverage of the region with the minimum required number of sensors in a finite number of steps, ensuring an optimal deployment. In two dimensions, sensors reach autonomously a stable full coverage following geometrical patterns. This requires only 1.5 the optimal number of sensors to cover a region. A theoretical analysis of convergence proves these properties in one and two dimensions. Some simulation results matching the analysis are also presented