Simulation is imagining … Testbed is sore reality.
WSN Testbeds PrinciplesAs iterated throughout this book, WSNs are large-scale distributed embedded systems incorporating small, limited energy, and resource constrained sensor nodes communicating over wireless media. Because of their massively distributed nature, the design, implementation and evaluation of sensor network applications, middleware and communication protocols are difficult tasks. The first design steps can often be made with the help of simulations; however, they frequently force the designer to make non-realistic assumptions about traffic, failure patterns and topologies. The coming after steps of implementation, and evaluation of application performance, as well as assessment of error resilience, and other nonfunctional properties, require the use of real hardware, realistic environments and realistic experimental setups.Practically, real experiments with distributed systems like WSNs become very cumbersome if the number of nodes exceeds a few dozens. In fact, all the phases of the experiment are almost infeasible without a targeted, specialized support, specifically: