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HoR: The house of requirements

Submitted by agonzalez on Wed, 09/24/2008 - 14:34
Overview of the solution: 

Model-based methodology for requirements engineering based on the House of Quality, for knowing the interrelationship among requirements.

Co-Design Challenges Addressed: 

The HoR methodology allows the developers and testers:

  • to define and classify the requirements,
  • to know the traceability of the requirements,
  • to have a model of interrelation of requirement in cases of codesign of hardware and software, that permits to know the implications among requirements of changing one of them.
  • to have a method to show the clients the implication of changing requirements along the design process.
Additional Information: 

The following picture shows the house of requirements and its five important components:

House of Requirements Methodology

  1. HARDWARE Requirements
    This box collects all the hardware requirements. In case of a big amount of them, the requirements could be grouped.
  2. SOFTWARE/FIRMWARE Requirements
    This box collects all the software/firmware requirements. In case of a big amount of them, the requirements could be grouped.
  3. Correlation matrix of HW req.
    This triangle represents the relation between each hardware requirement.
  4. Correlation matrix of SW//FW req.
    This triangle represents the relation between each software/firmware requirement.
  5. Interrelationship matrix
    This is the main component of the method and the main difference with other methodologies for requirements engineering because this component allows considering the interrelation between hardware and software/firmware requirements, something essential in the codesign processes.

The HoR method involves all the people in the development team and in the testing equipment. It is very important the participation of all of them from the very beginning of the codesign process, with the aim of having the more complex information about the system/product and its development process.

The steps to follow are:

  1. To list all the requirements to have into account for designing and developing the new product.
  2. To classify the requirements between hardware or software/firmware requirements.
  3. To put the hardware requirements into the HARDWARE requirements box.
  4. To establish the relation among hardware requirements in the Correlation matrix of HW req. For each cell, the question is asked: Does improving one hardware requirement cause a deterioration or improvement in the other hardware requirement? Where the answer is a deterioration, put a “-” into the cell and where improving one requirement automatically leads to an improvement in the other requirement, the symbol is a “+”.
  5. To put the software/firmware requirements into the SOFTWARE/FIRMWARE requirements box.
  6. To establish the relation among hardware requirements in the Correlation matrix of SW/FW req. For each cell, the question is asked: Does improving one software/firmware requirement cause a deterioration or improvement in the other software/firmware requirement? Where the answer is a deterioration, put a “-” into the cell and where improving one requirement automatically leads to an improvement in the other requirement, the symbol is a “+”.
  7. Finally, to determine the relation between each hardware and each software/firmware requirements. Each combination of hardware and software/firmware is considered in turn by the team, answering the question: How influences the variation of a requirement in the other? The level of interdependency is weighted usually on a four point scale (strong, moderate, weak or nothing) and a symbol representing this level of interrelationship is entered into the cell.