Figure 1. Examples of complex systems in defence

  Figure 2. Integrated Air Defence Network - A system of systems

 ABSTRACT

The transformation of the Singapore Armed Forces into a fully networked force operating with network-centric systems of systems is a strategic imperative for the Third Generation Singapore Armed Forces (3G SAF). Systems architecting has been identified as one of the effective means to coherently realise system of systems capabilities. The successful application of this strategic competency will enable us to realise our potential and create an even more capable 3G SAF.

This paper presents a working understanding of Systems Architecting (SA), a seven-step SA methodology and the architectural framework currently adopted by DSTA's Directorate of Masterplanning and System Architecting. It also highlights some of the well-known heuristics and principles in systems architecting.

Tan Yang How
Dr Yeoh Lean Weng
Pang Chung Khiang
Sim Kok Wah

INTRODUCTION

"The transformation of the SAF to exploit rapidly emerging technologies and concepts is a strategic imperative for the 3G SAF. These will lead to changes in organisation, less demand for conventional platforms, more demand for less visible technologies like information systems, precision weapons, electronic warfare systems, unmanned platform technologies, and a new type of soldier who is trained to exploit these capabilities." Minister for Defence Teo Chee Hean said this in Parliament in March 2004 when he introduced Transformation and the Third Generation Singapore Armed Forces (3G SAF).
Systems Architecting was identified as one of the effective means that will facilitate this new thrust of Transformation and help realise our capabilities in building a system of systems. Within DSTA, the Directorate of Masterplanning and Systems Architecting (DMSA) has been formed to spearhead the build-up of this strategic system competency and work with the SAF to create and build a system of complex systems.

WHAT IS SYSTEMS ARCHITECTURE?

Systems architecture is a structure comprising key entities or components, interconnections and interactions (Hastings, 2005). In other words, it provides the structure or skeleton of the system, as well as the principles, rules and guidelines governing the system design, creation and evolution. It also provides the broad framework, system level constraints as well as relationship for the sub-structures and modules of the system. It determines the options available for future development.

Systems architecture is essential for order, effectiveness and efficiency. It typically shapes systems behaviour and may provide clues on possible emergent behaviour. It is also a useful tool to address systems attributes such as complexity, flexibility, interoperability, modularity, robustness, vulnerability, scalability, sustainability and impact on the environment (physical, political, social, etc). Varying the systems architecture allows one to address alternate forms that the system can take. Ideally, the architecture should be enduring and robust for a long time so that it can absorb future developments.
Systems architecture is different from a design concept, which describes an engineering system in terms of abstract concept that involves symbolic attributes and possibly also relations among design components. A design concept is an outline or an illustration whereas systems architecture goes further and provides a structure of conceptualisation, description, or design of the system, its components, their interfaces and relationships with internal and external entities, as they evolve over time.

WHAT IS A SYSTEM OF SYSTEMS?

Generally, a system can be defined as a set of different elements so connected or related that it performs a unique function that cannot be achieved by the individual component elements alone. Incomplete or erroneous integration of the component elements will result in the system becoming incapable of performing its required functions. A system can be described as simple or complex, small or large in scale. Our focus on systems architecting for the transformation of the 3G SAF is naturally on the complex systems.

A complex system comprises many mutually interacting and interwoven (complex) parts or entities which, either by design or function or both, are difficult to understand and verify.

The complex relationships among the component parts or entities may also evolve over time or in accordance with system states. The interfaces between the component elements are mainly software-driven. Any incomplete or erroneous integration of these component elements will trigger the complex system to malfunction in varying degrees. Figure 1 shows examples of defence systems that are considered complex.

The integrated air defence network as illustrated in Figure 2 is a good example of a system of systems (SoS) comprising advanced jet fighters, early warning aircraft, either standalone or platform mounted advanced radars and surface-to-air missile systems, anti-aircraft artillery and Command and Control (C2) network. The loss of any part or component of the SoS may degrade the performance or capabilities of the whole SoS. An SoS typically exhibits five principal characteristics (Maier, 1996):