A New Index for SoS Reliability-Viability

A System of Systems (SoS) is a special complex system. On the one hand, there is no well-defined requirement boundary in SoS, leading to the absence of a fixed reliability block diagram model. On the other, the self-organization feature of SoS enables it to maintain its ability by dynamically adjusting itself in case of partial failure, thus making the evaluation of the failures of a SoS as a whole more complex. Traditional reliability evaluation techniques may not be adequate at the SoS level. A new index for the evaluation of the ability of SoS to fulfill its missions and tasks, "viability",- is proposed on the basis of an analysis of the differences between SoS and systems, and deficiencies in the application of traditional reliability theories to SoS. In addition, the methods and focuses of SoS viability evaluation are introduced in terms of the functional and structural viability of SoS, thereby providing references regarding methods for evaluating the ability of SoS to fulfill its missions and tasks.