On the Reliability Analysis of Systems and SoS: The RAMSAS Method and Related Extensions

The paper aims at contributing to fill the lack of methods specifically conceived for addressing the analysis and verification of non-functional requirements. In particular, the attention is focused on system reliability which is a key requirement to satisfy especially for mission critical systems where system failures could cause even human losses. To this end, the paper presents the up-to-date version of RAMSAS, a recently proposed model-based method for the reliability analysis of systems through simulation. The present version of RAMSAS is the result of an intensive experimentation phase in several application domains (avionics, automotive, satellite) which allowed improving the effectiveness of the method especially in the modeling of both the intended and dysfunctional system behavior. Moreover, the paper discusses the specific issues that arise when moving from the reliability analysis of Systems to that of Systems of Systems (SoSs) and propose a possible extension of the RAMSAS method (called RAMSoS) able to address the identified issues and thus to support the reliability analysis of SoSs through simulation.