Optimal System's Complexity, An Architecture Perspective

Systems Complexity is driven by more connectivity among constituents and increased environmental uncertainties. Modularity is a system's mechanism to manage complexity in the presence of environmental heterogeneities. Here, a general design decision framework for modularity and fractionation in complex systems is presented. This framework incorporates spatial and temporal heterogeneity of the environment, adaptability of the system and costs associated with modularity. It is argued that as the space-time heterogeneity of the environment increases, higher levels of modularity are needed. To determine the optimal level of complexity in a modular design, a four-level modularity pyramid is introduced. This pyramid takes into account functional and physical dimensions of modularity and allows for resource sharing to enables dynamic modularity. Moving up from each level is quantified by an M+ operation that calculates the net value of increased modularity for each sub-system.