Recent advances in micro electro-mechanical systems and VLSI lithography have enabled the miniaturization of sensors and controllers. Such minitiarization facilitates the deployment of large-scale wireless sensor networks (WSNs). However, the considerable cost of deploying and maintaining large-scale WSNs for experimental purposes makes simulation useful in developing dependable and portable WSN applications. SENS is a customizable sensor network simulator for WSN applications, consisting of interchangeable and extensible components for applications, network communication, and the physical environment. Multiple component implementations in SENS offer varying degrees of realism. Users can assemble application-specific environments; such environments are modeled in SENS by their different signal propagation characteristics. The same source code that is executed on simulated sensor nodes in SENS may also be deployed on actual sensor nodes; this enables application portability. Furthermor...