| Wireless sensor networks (WSNs) have a wide variety of applications in civilian, medical and military applications. However, the nodes in such a network are limited to one type of action: sensing the environment . With increasing requirements for intelligent interaction with the environment, there is a need to not only perceive but also control the monitored environment. This has led to the emergence of a new class of networks, referred to as wireless sensor and actor networks (WSANs), capable of performing both sensing and acting tasks on the environment. The architecture for a WSAN comprises of three entities: (i) sensors, that monitor the environment and report the information to a central coordination entity, referred to as a sink (ii) actors, that operate on the environment based on the command issued by the sink, and (iii) a sink, that acts as a central coordination entity and sends queries and commands to sensors and actors respectively.;The evolution from WSNs, which can be thought of as performing only read operations, to WSANs, which can perform both read and write operations, introduces unique and new challenges that need to be addressed. The focus of this research is to investigate these unique problems that arise in the context of a WSAN environment, and design energy- and resource-efficient network protocols best suited to this environment. Specifically, in this research, we investigate problems from three different perspectives: (i) operation correctness, (ii) resource optimality, and (iii) operation performance. Addressing the problems on these three fronts provides the basis for effective operation of WSANs.;The introduction of acting task in WSANs, which can be viewed as a write operation, raises the need for write-specific mechanisms in WSANs in order to ensure correctness of operation. In this context, we address the problem pertaining to the ordered execution of queries and commands initiated by the sink, where the queries and commands are executed in the same order as issued by the sink. Also, since an acting task is more resource-intensive, only the desired set of actors need to execute a command for optimizing the overall resource consumption. In this context, we consider the problem pertaining to the determination of the minimal set of sensors and actors that fully covers the event occurrence region. To provide better operation performance, we consider the problem of the ideal rate of forwarding from sink-to-sensors (downstream) to minimize the local and global congestion in the network. This is necessary in order to ensure reliable and fast message delivery to the actors and sensors in the network.;The strategy adopted to achieve the research objective is (i) to first develop a distributed, energy-efficient approach to ensure ordered execution of the queries and commands among the sensors and actors in the event occurrence region, (ii) to determine the minimal set of sensors and actors that participates in an event region in order to minimize the resource consumption of the network, and (iii) to determine, in a distributed fashion, the ideal rate of forwarding for queries and commands to sensors and actors (from the sink). The protocols, when applied in unison, aid each other in developing an energy- and resource-efficient communication framework for addressing the problems unique to a WSAN environment. |
