Contents I. Introduction
A WSN [1] is a network compounded by small embedded systems that gather information from its sensor, make a set of computations and communicate via wireless links with other nodes. These nodes can be deployed in many environments and each environment has its own needs. For example, in hostile ones WSN need to be secure and trustworthy, while in unattended environments they need to be autonomous and self-sufficient. Due to these reasons the complexity of sensors may vary significantly, from small computation power with low energy consumption to large nodes with complex systems used in military environments. But in most cases nodes are designed as simple as possible to minimize production costs and reduce power consumption.
