Measuring the Requirements Allocation Capacity within a System of Systems

1. Measuring the Requirements Allocation Capacity within a System of Systems David Flanigan The Johns Hopkins University Applied Physics Laboratory Dr Peggy Brouse George Mason University August 21, 2014

2. Outline Objective Literature Review Steps in the SoS Requirements Allocation Process Case Study Next Steps 2

3. Objective During initial development of a System of Systems (SoS), many SoS do not have authority over the systems and need to work with developers and stakeholders to identify and allocate requirements to the system level Traditional Systems Engineering techniques do not have the ability to allocate SoS requirements and determine if this they are satisfactory or not A process and series of metrics are offered to develop SoS requirements allocation

4. Literature Review We examine existing requirements allocation processes for any methods / metrics applicabile to SoS: Multi-attribute optimization process (Sutton) Decomposition of top-level requirements (Kusiak and Qin) Martin et al. studies three Requirements Engineering (RE) process models: Linear incremental model (Kotonya & Sommerville) Purely linear model (Macaulay) Iterative and cyclical model (Loucopoulos and Karakostas) Interaction matrix to identify system – system interactions (Fry and DeLaurenitis) We are motivated to develop a SoS requirements allocation method since there is currently no process to ensure this SoS allocation is successfully conducted 4

5. SoS Requirements Allocation Process Define the SoS problem space and scope Inventory existing system objectives and requirements Allocate SoS requirements to system requirements Assess the SoS requirements allocation

6. Case Study An illustrative case study involving a US Navy Carrier Strike Group (CSG) will conduct Surface Warfare (SUW), e.g. identifying and engaging hostile surface platforms Enterprise Command and Control Requirements and Common Architecture on US Navy Surface Combatants, Naval Postgraduate School, NPS-SE-09-003, June 2009.

7. Step 1: Define the SoS problem space and scope Our SoS scope Limited to a US Carrier Strike Group – with only the organic platforms and not external systems (e.g. satellites, joint forces, other systems) Enterprise Command and Control Requirements and Common Architecture on US Navy Surface Combatants, Naval Postgraduate School, NPS-SE-09-003, June 2009.

8. Step 2: Inventory existing system objectives and requirements O'Rourke, R. "Unmanned Vehicles for US Naval Forces: Background and Issues for Congress". DTIC Document , 2005. US Navy. 2011. "Destroyers - DDG." Last modified 31 January 2011. http://www.navy.mil/navydata/fact_display.asp?cid=4200&tid=900&ct=4. US Navy. 2009. "F/A-18 Hornet strike fighter." Last modified 26 May 2009. http://www.navy.mil/navydata/fact_display.asp?cid=1100&tid=1200&ct=1. For our example, we look at three specific systems and their missions from various sources

9. Step 3: Allocate SoS requirements to system requirements Step 3a: Decompose SoS objective to SoS phases Step 3b: Identify frequency of use of each SoS phase Step 3c: Catalog the system-system interfaces within each SoS phase

10. Step 3a: Decompose SoS objective to SoS phases • For our example, we focus on one SoS mission • Surface Warfare (SuW) mission: the detection, tracking, and engagement of hostile surface platforms • We use the SuW kill chain to functionally describe the mission in six distinct phases: find, fix, track, target, engage, and assess • We leverage an example from NPS that describes a generic SuW kill chain and develop an activity diagram to map to our specific systems

11. Step 3a: Decompose SoS objective to SoS phases For this example, we derive the given SUW kill chain and convert into a SoS activity diagram that contains SoS phases and intra/inter-phase interfaces Enterprise Command and Control Requirements and Common Architecture on US Navy Surface Combatants, Naval Postgraduate School, NPS-SE-09-003, June 2009.

12. Step 3b: Identify frequency of use of each SoS phase For this example, we can solve the frequency based on simple assumptions and a 4-hour air wing event time constraint; future work would develop a full-scale discrete event simulation to calculate percentages

13. Step 3c: Catalog the system-system interfaces within each SoS phase • Identify the system-system interactions within each SoS phase transition • Extending Fry and DeLaurentis’ research on adjacency matrices to define SoS interactions • We must look at each SoS phase since there may be different systems interacting and differing levels of effort Fry, D. N., and D. A. DeLaurentis. "Measuring Net-Centricity". Paper presented at System of Systems Engineering (SoSE), 2011 6th International Conference on. IEEE, 27-30 June. 264-269.

14. Step 4: Assess the SoS requirements allocation Our calculations are intuitive: for a mission that heavily relies on the find/fix phase to search out a target (this often happens in SuW missions to detect and identify a single ship in a large body of water) • Total Network Capacity Requirements • Using our series of adjacency matrices, calculate the amount of network capacity that each system would require for the SoS mission • System contribution throughout the SoS • Since we know the frequency of each SoS phase and the number of activities that are used within each phase, we can calculate the contribution of each system within the entire SoS mission • The airborne platforms have the greatest network usage and contribute most to the SoS mission, which helps to identify & allocate system-level requirements

15. Next Steps • Add multiple missions for the SoS to simultaneously execute • Identify where adding more missions would compete and adversely affect other missions • Where does the over-allocation of particular systems occur? • Quantify the reallocation process of system contributions to SoS requirements • What happens to different SoS configurations? (e.g. have a more ship-centric activity flow)

16. Questions