The emerging field of wireless sensor networks combines sensing, computation, and communication into a single tiny device. Through advanced mesh networking protocols, these devices form a sea of connectivity that uses any possible communication path by hopping data from one node to another in search of its destination. While the capabilities of any single device are minimal, the collection of hundreds of sensors offers major new technological possibilities. Examples of usage scenarios for these devices are real-time tracking and security monitoring, issues that will be studied in this thesis. ...