A typical wireless sensor network performs only one
action: sensing the environment. The need for smart interaction
with the environment has led to the emergence of Wireless Sensor
and Actor Networks (WSANs), where a group of sensors, actors
and the sink linked by wireless medium perform distributed
sensing and acting tasks.
In WSANs, it is important that the actors act only to the appropriate level when the event occurs in order to perform the desired action on the evironment. In this context, we identify the problem of mutual exclusion, which is the need to act only once for any particular location and command. We define three flavors for mutual exclusion and show the undesirable consequences of not providing mutual exclusion. In this context, we discuss the design of centralized and distributed approaches required to address this problem efficiently. Through a preliminary set of simulations we study the performance of the proposed solution and two basic strategies.