Systems engineering — Best practices

A system of systems (SoS) is an assembly of different systems, independent of each other at both managerial and operational levels. This means that they are potentially acquired and implemented independently of each other. Assembling them within a SoS provides capabilities to act, carry out missions and produce effects that none of them can do alone. It is these capabilities, missions and effects that the stakeholders involved in the design and implementation of a SoS are looking for. Such a combination also optimizes the overall value of the systems, in particular by avoiding the development of a costly ad hoc system, providing the desired capabilities and effects, but for rare missions, generating a very high cost of use.

Operational, contractual, budgetary and legal dimensions interact closely with technical ones. Compared with "traditional" systems engineering, this requires greater consideration of all dimensions, technical and non-technical, and forces greater integration of program management and systems engineering.

Examples of systems of systems, which clearly highlight these points, include: air traffic for long-haul flights, multimodal transport on the scale of a community of municipalities, electrical grids (generation, transmission, distribution of electrical energy) on the scale of several countries, the banking system, response to terrorist threats...

The article begins by presenting the key issues and concepts of systems of systems. In particular, the notions of independence, scalable configuration, connectivity, diversity and maximum value chain are defined. Next, the article sets out the various dimensions, both technical and non-technical, of SoS that need to be mastered, often grouped together under the two Anglo-Saxon acronyms DOTMLPFI (doctrine, organization, training, materiel, leadership, personnel, facilities, information) and PESTEL (political, economic, social, technological, environmental, legal), the different activities to be carried out according to these dimensions, as well as the legal and contractual impacts on program management and system engineering activities. Finally, the specific program management and system engineering activities to be carried out at the SoS level are presented, along with recurring activities adapted to the SoS level. In particular, the modeling of operational scenarios and the definition of functional chains are described, enabling the systems contributing to the desired capability to be designated and their interfaces designed.