This paper describes a two-step process to infer specific technical constraints and parameters needed for a reliable mission-specific design of wireless sensor networks (WSN). As the first step, we propose a new requirement catalog helping end-users to formulate a complete and consistent specification of WSN mission requirements. Its generality allows the unambiguous characterization of a wide spectrum of applications from the end-user's perspective. As the second step, we introduce a methodology to deduce fine grained technical specifications from the general requirements. The proposed automatic graph-based requirement expansion approach translates the content of the catalog and additional requirements to specific technical terms, which provide the basis for an application-specific WSN design. A real-world use case – a new WSN application in the area of critical infrastructure protection – demonstrates the applicability of the presented approach.