Identifying the component subsystems of a product

System decompositions, or models, separate an overall architecture into component subsystems with progressively greater degrees of detail. With functional and logical models, you can illustrate and analyze solutions that meet the requirements of the product.

Each model is captured as a structured network of subsystems.

• A functional model illustrates a set of functions that the product should deliver.
  • Because requirements and functions are closely related, a functional architecture is a means of exploring, expanding, and deriving requirements.
  • At a given level, the functional design derives requirements at the next lower level of detail.
  • The derived requirements reveal a corresponding subset of functions for that level.
  • The functional model ties requirements to logical solutions.
• A logical model illustrates a proposed solution for implementing the requirements and functions.
  • During this analysis, logical models for several alternative solutions can be compared.
  • Typically, the accepted solution is implemented in both hardware and software, and that implementation is modeled later in the detailed design phase.