A Distributed Connectivity Restoration Algorithm in Wireless Sensor and Actor Networks

There has been an increased interest in applications of wireless sensor and actor networks (WSANs) in recent years. In such applications, a set of mobile actor nodes are deployed in addition to sensors in order to collect sensors' data and perform specific tasks in response to detected events/objects. In most scenarios actors have to respond collectively which requires an inter-actor coordination. Therefore, maintaining a connected inter-actor network is crucial to the effectiveness of WSANs. However, WSANs often operate unattended in harsh environments where actors can easily fail or get damaged. Due to such failures an actor will be unable to communicate with its neighbors which may lead to partitioning the inter-actor network. In this paper we present DARA; a Distributed Actor Recovery Algorithm, which opts to efficiently restore the connectivity of the inter-actor network that has been affected by the failure of an actor. The idea is to identify the least set of actors that should be repositioned in order to establish connectivity among disjoint network partitions. DARA strives to localize the scope of the recovery process and minimize the movement overhead imposed on the involved actors. The effectiveness of DARA is validated through simulation experiments.

I. INTRODUCTION

Wireless sensor and actor networks (WSANs) have attracted lots of interest in recent years. WSANs can increase the effectiveness of numerous applications such as homeland security, battlefield reconnaissance, space exploration, search and rescue, etc. A typical WSAN consists of a larger set of miniaturized sensor nodes reporting their data to significantly fewer actor (actuator) nodes [1]. Sensors probe their surroundings and report their findings to one or multiple of actors, which process the collected sensor reports and respond to emerging events of interest. An actor's response would depend on its capabilities, which varies based on the application and the expected role the actor plays. For example, an actor can deactivate a landmine, extinguish a fire and rescue a trapped survivor. It is worth noting that a heterogeneous set of actors may be employed and assigned complementary roles.