Chapter 9: Systems architecting: Principles (pt. 1) ISE 443 / ETM 543 Fall 2013

Architecting a large-scale complex system is the centerpiece of systems engineering 2 443/543– 9 Recall, from chapter 2, the essential elements of systems architecture: RRequirements MMission engineering RRequirements analysis/allocation FFunctional analysis/allocation AArchitectural design/synthesis SSystem analysis LLife-cycle costing RRisk analysis OOther system/subsystem considerations FFormulation of a preferred system architecture

What is a system architecture? NASA defines an architecture as: How functions are grouped together and interact with each other. Applies to the mission and to both inter- and intra-system, segment, element, and subsystem. Mission design is viewed in terms of 3 early phases 1. The conceptual design process: Prephase A 2. The mission analysis process: Phase A “The purpose of the Phase A study is to refine the mission and systems(s) requirements, determine a baseline mission configuration and system architecture, identify risks and risk mitigation strategies, identify the “best” candidates, and select one.” 3. The definition process: Phase B 3 443/543– 9

The DoD provides 3 different views of system architecture  The operational architecture view is a description of the tasks and activities, operational elements, and information flows  The systems architecture view is a description, including graphics, of systems and interconnections  The technical architecture view is the minimal set of rules governing the arrangement, interaction, and interdependence of system parts or elements, whose purpose is to ensure that a conformant system satisfies a specified set of requirements And provides 6 steps for building an architecture  See page /543– 9

The IEEE definition is simple... A structure of components, their relationships, and the principles and guidelines governing their design and evolution over time We can define the process of system architecture using elements 3-10 of the 30 elements of SE (refer back to – ):  Requirements analysis/allocation (element 3)  Functional analysis/decomposition (element 4)  Architecture design/synthesis (element 5)  Alternatives analysis/evaluation (element 6)  Technical performance measurement (element 7)  Life-cycle costing (element 8)  Risk analysis (element 9)  Concurrent engineering (element 10) 5 443/543– 9

Your turn... Select one of the systems architectures illustrated in the chapter  Identify the functional decomposition; that is, state “function xxx is decomposed into the following subfunctions....”  Identify the characteristics of a functional decomposition as illustrated in this example 6 443/543– 9

Characteristics of functional decomposition Physical facilities at the top level, decomposed to functions and/or other physical facilities External systems/functions differentiated from internal systems/functions Use of subsections to group common elements of the system – layering of the elements to represent multiple elements of the same type Functions/subfunctions connected by arrows indicating direction of information flow Coding of different types of connections (data types) 7 443/543– 9

Your turn (again)... Look at problem 9.3 on page 301 As a group, agree on the major functions of a personal computer system Begin the functional decomposition The complete architecture is due on Tuesday, October 29.  This is to be an INDIVIDUAL assignment.  You may (but you are not required to) use the work you did in the group as a starting point, but the final architecture should be your own work.  The final product must be a graphical representation /543– 9