Requirement Management (RM) is essential for practicing System Engineering (SE)

Rafael Requirements Managements (RM) is being implemented for the last 20 years. Since 2011 we have changed the concept and methodology of RM with the aid of RM Tool.

On the previous concept – RM was used mainly to focus on how to satisfy customer requirements by defining system requirements for customer requirements.

The new concept concentrates on allocating and deriving any of the customer requirements to the relevant system or subsystems requirements according to the architecture presented in the System/

Subsystem Specification (SSS). The allocating and deriving process is accompanied by links from the SSS's requirements to the customer requirements. Thus we can prove that each Customer requirements is covered by SSS's system or subsystem requirements.

On the previous concept there was only an estimation of actual requirements coverage because of
the absence of hard links for analysis. Without the links we could not apply more than one level of hierarchy (each customer requirement has a system requirement), on the new concept there are a complex hierarchy between customer requirements and System requirements to a large number of derivative-sub-systems or even components. Now we may represent a tree of modules, each module has a requirement for a technological discipline, linked up along the tree to a customer requirement. As a result of the above it is possible to build the whole project's requirements from the root to the last leaf with the links network that enable us to prove requirements coverage of the whole tree requirements.

This is the real basis of RM with an ability to analyze the effect of wanted requirements changes as well as the unwanted changes and for maintaining the correctness of the whole requirements tree.

The consequence being of this concept is the implementation ability of linking the requirements to the verification and validation (V&V) matrix. That can be done to any System requirements in particular and any module's requirements in general. We use the links from the V&V to the module's requirements to show how the product is tested in all the tree levels in order to verify the requirements test coverage of any module's requirements instead of the traditional V&V matrix.

The main benefit of the new concept is accurate manageability of the whole project's requirement, and the ability to prove the relationship between the project's technological solutions to the customer's whishes. In other words, now we have new possibility to manage the engineering side of the project in addition to satisfying the customer's needs. The new concept allows us to check the integrity of the project's requirements modules tree (Technical Compliance) by analyzing the hierarchal links and generation of reports regarding coverage requirements and tests.

The second benefit of the new concept is the ability to manage, analyze and control changes in the requirements, and their impact on the systems.

These benefits justify the extra effort required to setup the requirements database while saving the production of numerous documents (requirement, tests and reports) by a simple act of producing them from the project's database.

There are benefits that are byproducts for saving SE efforts. It will be elaborate in the article. Our Methodology was built during the RM implementation process in Rafael since 2011 until 2014 (not included) and was adapted to projects needs. The Methodology is represented in details in this article including conclusions from RM implementation and Case Study.