We propose a 2x2 requirement chart enabling effective identification of items in ConOps, a standard provided by IEEE, and establish a methodology how to use it. The main focus of our proposal is to obtain requirements necessary for constructing ConOps without any bias from realization methods and adopted techniques. By properly constructing ConOps through our chart, we are able to focus on the study period in systems engineering, and as a result to reduce the costs in operation period. We developed two identical enterprise systems, each using a different method, and compared the cost in the operation period of each result. The first method, without creating ConOps in the study period, goes through systems architecture development and systems design based on initial requirements provided by the customers, then moves on to implementation period (case 1). The other method creates ConOps using our 2x2 requirement chart, then processes the rest in the same way as case 1 (case 2). Through this experiment, we verified the effectiveness of the proposed requirement chart.

This paper proposes a 2x2 requirement chart based on a requirement model for a service system. The model was developed to attention on critical issues and retains the essence of the requirement types. Therefore, we can use it as a template for requirement design. On the other hand, the chart is efficient to identify the items in ConOps (Concept of OPerationS), a standard provided by IEEE. The main purpose of the chart is to execute the requirement development process sufficiently, which is in the Concept Stage within the service lifecycle, without increasing the cost. Utilizing this chart also reduces the extra costs of the Development Stage caused by errors that are extremely difficult to estimate during the planning phase. High quality service system won't have cost overrun problem in any phase. We established two identical enterprise service systems each using different cases and compared their development costs. The first case is to proceed with systems architecture development and systems designing based on the initial requirements provided by sponsors and then move on to the Development Stage. The second case is to use the 2x2 requirements chart that we have proposed to develop ConOps in the same stage.