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System Design and Development

Definition: System design is the process of defining the components, modules, interfaces, and data for a system to satisfy specified requirements. System development is the process of creating or altering systems, along with the processes, practices, models, and methodologies used to develop them.

Keywords: contractor, design, design review, development, evaluation, requirements, specifications, strawman, traceability, validation, verification

Context

Core activities in system design and development include developing system-level technical requirements and top-level system designs and assessing the design's ability to meet the system requirements.

System-level technical requirements describe the users' needs, and provide information for the finished system to meet legal restrictions, adhere to regulations, and interoperate or integrate effectively with other systems. The system-level technical requirements are used by the government to acquire a capability, system, or product to meet a user need. They are used as part of a procurement contract solicitation or prototyping/experimentation effort and by the product vendors as their design criteria. The decisions made when defining system-level technical requirements can affect the number of potential solutions, the technical maturity of the potential solutions, system cost, system evolution, and development time and phasing.

System-level technical requirements are a critical precursor to and foundation of system design and development. A top-level system design is generally under the stewardship of the government team and represents the government team's independent projection of the way a system could be implemented to meet requirements with acceptable risk. The primary reason for developing a top-level system design is to provide a technical foundation for planning the program. It is the government's de facto technical approach to meeting the customer's needs. A top-level system design developed early in an acquisition program can be used to assess system feasibility and provide some assurance that the implemented design will satisfy system requirements. Done early in a program, a government design effort can be a powerful basis for developing fact-based government projections of cost, schedule, performance, and risk and provide the foundation for subsequent contractor design efforts.

Requirements traceability is a critical activity during the design, development, and deployment of capability that starts with the translation of the users' operational needs into technical requirements and extends throughout the entire system life cycle. It is a technique to develop a meaningful assessment of whether the solution delivered fulfills the operational need. Traceability is also the foundation for the change process within a project or program. Without the ability to trace requirements from end to end, the impact of changes cannot be effectively evaluated. In addition, change should be evaluated in the context of the end-to-end impact on other requirements and overall performance (e.g., see the Enterprise Engineering section). This bi-directional flow of requirements must be managed carefully throughout a project/program and be accompanied by a well-managed requirements baseline.

The articles in this topic highlight important elements of system design and development. The article Develop System-Level Technical Requirements provides guidance on selecting the right level of detail in writing technical requirements, highlights common challenges in achieving stakeholder agreement on requirements, suggests ways to handle them, and provides a checklist to help ensure that all bases have been covered in developing the system-level requirements. The article Develop Top-Level System Design provides guidance on early design efforts. The article is written from the perspective of an in-house government design activity, but many of the best practices and lessons learned can be used to shape, guide, and monitor contractor design efforts. The article Assess the Design's Ability to Meet the System Requirements provides guidance in establishing and accomplishing traceability, the importance of two-way traceability (both up and down), the need to have testing in mind when beginning traceability efforts, and the value of engaging with the operational user. It describes the technique of using a requirements traceability matrix to manage the specific traceability and verification from user need to requirements to design and development modules to test cases and measures/metrics for success. 

MITRE SE Roles & Expectations: The MITRE systems engineer (SE) is expected to have a sound understanding of what a system requirement is intended to convey, what constitutes a good system requirement, how to identify a poorly written requirements statement, and what constitutes a good set of systems requirements. MITRE SEs are expected to be able to transform business/mission and operational needs into system requirements. Typically MITRE systems engineers lead the government acquisition program office effort to develop these requirements or are heavily involved in it. Collectively the descriptions and constraints comprising the system-level technical requirements are one of the most important products that MITRE can develop for the customer.

MITRE SEs are expected to help lead the government effort to create realistic top-level designs and associated risk mitigation activities so that planning will be based on a realistic foundation. Cost, schedule, and performance projections based on the top-level system design can be instrumental in mitigating and managing program risks. MITRE SEs are expected to be able to evaluate and influence the contractor's design and development effort, including making independent performance assessments and leading design review teams. In some programs, contractors will have primary responsibility for the top-level design with MITRE systems engineers providing guidance and verification of their efforts. In other programs, the government will develop a top-level design as part of its early systems engineering activities. Often MITRE will have a lead role or substantial responsibility for developing the government's top-level system design.

MITRE SEs are expected to understand the importance of system design in meeting the government's mission and goals. They are expected to be able to review and influence the contractor's preliminary design so that it meets the overall business or mission objectives of the sponsor, customer, and user. MITRE SEs are expected to be able to recommend changes to the contractor's design activities, artifacts, and deliverables to address performance shortfalls and advise the sponsor or customer if a performance shortfall would result in a capability that supports mission requirements, whether or not the design meets technical requirements. MITRE SEs are expected to be thought leaders in influencing decisions made in government design review teams and to appropriately involve specialty engineering.

For related information, see the following SE Guide topic areas: Concept Development, Requirements Engineering, and System Architecture.

References

1. Wikipedia contributors, "Systems Design," Wikipedia, The Free Encyclopedia, accessed December 4, 2009.
2. Wikipedia contributors, "Systems Development Life Cycle," Wikipedia, The Free Encyclopedia, accessed December 4, 2009.