4.3.11. Requirements Analysis Process
4.3.11. Requirements Analysis Process
The Requirements Analysis process involves the decomposition of user needs (usually identified in operational terms at the system level during implementation of the Stakeholder Requirements Definition process; see DAG section 4.3.10 Stakeholder Requirements Definition Process) into clear, achievable, and verifiable high-level requirements. As the system design evolves, Requirements Analysis activities support allocation and derivation of requirements down to the system elements representing the lowest level of the design. The allocated requirements form the basis of contracting language and the system performance specification. The resultant system requirements are addressed at technical reviews and audits throughout the acquisition life cycle and in applicable program and systems engineering (SE) technical documentation.
The Requirements Analysis process objectives include:
- Define a capability that links the needs of the users to the system, system elements, and enabling system elements to be designed and developed
- Define a system that meets users’ operational mission requirements within specified cost and schedule constraints
- Provide insight into the interactions among various functions to achieve a set of balanced requirements based on user objectives
The Requirements Analysis process provides:
- Translation of user needs (usually stated in operational terms) to unambiguous, verifiable, and feasible system performance specification requirements
- Incorporation of design considerations including statutory and regulatory constraints (see DAG section 4.3.18. Design Considerations)
- Documented allocation of requirements from the system-level specification to the lowest-level system elements and enabling system elements
- Rationale for specification requirements and their decomposition / allocation
- A mechanism to support trade-off analyses between related requirements to provide maximized mission assurance within cost and schedule constraints
- A framework for accurate assessment of system performance throughout the life cycle
The process of defining, deriving, and refining requirements proceeds as follows:
- Analyze user requirements
- Translate user needs into basic functions
- Develop a quantifiable set of performance requirements by defining the functional boundaries of the system in terms of the behavior and properties to be provided
- Define each function that the system is required to perform
- Define implementation constraints (stakeholder requirements or solution limitations)
- Translate performance requirements into specific system technical design requirements and functions
The Requirements Analysis process is an iterative activity whereby system requirements are identified, refined, analyzed, and traded to remove deficiencies and minimize impacts of potential cost drivers to establish an agreed-to set of requirements coordinated with the appropriate stakeholders. Poorly written requirements can lead to significant problems in the areas of schedule, cost, or performance, and can thus increase program risk. A well-crafted set of functional/performance requirements can then be translated into design requirements for the total system over its life cycle and can allow stakeholders to assess system performance during execution of the Verification and Validation processes (see DAG sections 4.3.15. Verification Process and 4.3.16. Validation Process, respectively). Good requirements have the following attributes:
- Necessary
- Unique
- Unambiguous - clear and concise
- Complete
- Consistent
- Technically feasible/achievable/obtainable
- Traceable
- Measurable/quantifiable
- Verifiable (e.g., Testable)
- Able to be validated
- Operationally effective
- Singular
The Requirements Analysis process ensures that requirements derived from user-specified capability needs are analyzed, decomposed, and functionally detailed across the system design. Early development and definition of requirements using the attributes listed above reduces development time, enables achievement of cost and schedule objectives, and increases the quality of the final system. Requirements Analysis encompasses the definition and refinement of the system, system elements, enabling system elements, and associated functional and performance requirements. The development of the functional baseline is largely a product of the Requirements Analysis process. All requirements are placed under configuration control, tracked, and managed as described in the Requirements Management process and Configuration Management process (see DAG sections 4.3.5. Requirements Management Process and 4.3.7. Configuration Management Process, respectively).
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