In order to fulfil the research objectives put forth in §1.4, an appropriate research methodology was established. This methodology is described in this section.
Since there are numerous complexities surrounding a GBAD system, it is important to under- stand the required level of modelling fidelity in order to achieve the stated objectives, prior to proceeding with the detailed work. The various levels of model fidelity used in an air-defense environment may be represented by the pyramid in Figure 1.3. Recognising the position of a system designer within this hierarchy is critical to understand the level of system fidelity that is required during the evaluation and design of the system [100].
The campaign models at the top of the pyramid typically includes many of end-users to test the system over a period of days, weeks or even months [100]. Consequently, these models are highly aggregated and are therefore limited to identifying the effect of individual systems on the performance of the larger system. The two middle layers — force-level and unit-system analysis — are able to illustrate the functioning of individual components of the larger air-defense system. The base of the pyramid (fundamental or engineering analysis), represents a higher level of detail for individual components of the system and thereby makes it attractive for a system-of-systems modelling approach.
Although the base layer provides the most detail regarding the system components and should therefore allow the system designer to obtain accurate results, this modelling approach requires extensive time and resources to effectively implement [100]. Furthermore, the scarcity of accu- rate, detailed information required in order to accurately model the different TEWA elements are typically classified and not available in the open literature. The approach followed in this
1.5. Research Methodology 7 Fundamental/ engineering Unit/systems analysis Force-level analysis Campaign analysis
Figure 1.3: Hierarchy of different analysis models [100].
thesis is a combination of the system and fundamental modelling approaches. Many detailed algorithmic models are implemented to represent the WSs and threats (fundamental), but in order to effectively analyse the performance of the system a more system perspective approach (unit or systems analysis) is employed.
In order to pursue the broad research aim put forth in§1.3, appropriate research methods have to be identified. The methodology has to be executed appropriately in order to achieve the detailed research objectives stated in §1.4. The research methodology adopted to achieve these objectives is described in the remainder of this section.
Objective I and all its sub-objectives is pursued by performing a literature survey. This entails identifying and analysing the most important literature related to TEWA systems in general. The majority of the detailed local research in this domain was done at the Stellenbosch TEWA Centre of Expertise. Unfortunately, detailed international research is often not available in the open literature.
The second objective also requires a literature survey related to HMIs used in a TEWA context and, consequently, qualitative methods are employed in order to derive suggestions for HMI display requirements. There exists a variety of research related to decision support in a military context [41, 113, 225]. As such, this type of research is more easily obtainable in the open literature than the core algorithms of TEWA systems.
Objective III entails developing a simulation model incorporating the majority of the TE and WA related algorithms developed at the Stellenbosch TEWA Centre of Expertise. Prior to starting software development, a suitable simulation environment is first identified. This objec- tive requires implementation in the form of computer code of the TE and WA so as to form a functioning TEWA system concept demonstrator which may be used for detailed performance evaluation.
Objective IV requires identifying limitations and conflicts present in the proposed TEWA al- gorithms. This objective is addressed by employing both qualitative methods and quantitative methods. The models developed at the Stellenbosch TEWA Centre of Expertise are compared to model formulations present in the open literature in order to qualitatively identify possible areas for improvement. Furthermore, the locally developed algorithms are tested by executing empirical experiments so as to qualitatively identify limitations and conflicts present between the algorithms. This objective is therefore, in effect, linked to Objective III. An evolutionary approach is followed to address Objective III — as limitations are identified through execution of Objective IV, mitigation strategies are implemented in the simulation environment, in turn,
addressing Objective III.
After developing a simulation model of a TEWA system and conducting a literature survey re- lated to the evaluation of complex systems, several performance metrics and a general framework is suggested for evaluating the performance of TEWA systems, thereby addressing Objective V. This framework is developed by qualitatively evaluating the available literature. Since detailed literature related to the performance evaluation of TEWA systems is scarce to non-existent, similar research is identified and residual capabilities are identified for the application to the performance evaluation of TEWA systems.
In order to demonstrate the functioning of the simulation model developed in pursuit of Objec- tives III–IV and the performance evaluation framework designed in puruit of Objective V — in effect addressing Objective VI — the various existing TEWA algorithms are tested within the context of a comprehensive worked hypothetical example. The algorithms are evaluated quan- titatively by visualising their results and calculating performance metrics, but also qualitatively by interpreting the results from a top-down perspective.
After having achieved all of the above objectives of §1.4, a critical review of the current state of TEWA DSSs is performed in order to determine desirable further work, in fulfilment of the last objective of§1.4.