Improving Requirements in Model-Based Systems Engineering Through Multi-layer Goal Models

Model-driven methods are increasingly being adopted in many industrial sectors to support the design and development of software intensive systems. Many available model-based system engineering methods support progressive levels of functional decomposition, enabling to reason at different levels of granularity. In contrast, requirements modelling tends to stay quite monolithic in nature despite the ability to provide different forms of refinement and traceability. This work analyses how to better structure requirements across multiple levels in the scope of goal-oriented requirements engineering to provide better support for decomposition and analysis of inner subcomponents or the outer system of systems. We introduce the explicit notion of system and show how to integrate it in the widely used KAOS and i* frameworks. Our extension is prototyped on available tools and validated on two complementary case studies of a meeting scheduler and a smart city.