Use Case Maps and LOTOS for the prototyping and validation of a mobile group call system

SPEC-VALUE, a rigorous scenario-driven approach for the description and validation of complex system functionalities at the early stages of design, is presented. It is based on two notations. The first notation, called Use Case Maps (UCMs), is used to capture functional requirements. UCMs can help reasoning about system-wide functionalities at a high level of abstraction before a prototype is generated. The second notation is the formal specification language LOTOS. UCM scenarios are translated into LOTOS specifications, which animate UCMs with the help of tools. LOTOS-based techniques, especially specification-level testing, can be used to validate designs. It is shown how SPEC-VALUE can help to produce better-quality designs and standards and to improve human understanding with reduced time and costs. A real-life case study is provided: the Group Call service of the mobile data system General Packet Radio Services (GPRS).