ieee 1220: for practical systems engineering

3
92 Computer STANDARDS P rimarily targeting product- oriented systems such as air- planes and information sys- tems, IEEE Std 1220-2005, IEEE Standard for Applica- tion and Management of the Systems Engineering Process, “defines the inter- disciplinary tasks that are required throughout a system’s life cycle to trans- form stakeholder needs, requirements, and constraints into a system solution.” IEEE 1220 enjoys global application in industry, government, and academic systems engineering efforts and has not changed substantially since its trial issue in 1995. This formal revision of IEEE Std 1220-1998 facilitates the applica- tion of IEEE 1220’s detailed process and practices with the broad system life-cycle process set offered in Inter- national Organization for Standard- ization/International Electrotechnical Commission (ISO/IEC) 15288. In late 2002, the IEEE Computer Society initiated alignment of IEEE Std 1220-1998 with ISO/IEC 15288: 2002, Systems Engineering—System Life Cycle Processes, as a part of an effort to harmonize the collections of the Computer Society’s Software and Systems Engineering Standards Com- mittee (S2ESC) with those of JTC1/ SC7, the corresponding ISO/IEC committee responsible for developing software and systems engineering standards. Completion of the multiphase IEEE 1220-ISO/IEC 15288 harmonization project depends on the current JTC1/SC7 effort to reconcile ISO/IEC 15288 and ISO/IEC 12207, Software Life Cycle Processes. The S2ESC-sponsored adoption of IEEE Std 15288-2004, Adoption of ISO/IEC 15288:2002 Systems Engineering—System Life Cycle Pro- cesses, presents another harmonization achievement. Combined, IEEE 1220 and IEEE Std 15288-2004 provide detailed technical and management process practices that can be applied to produce a balanced, well-engineered system solution for a product offering. They also supply foundational pro- cesses and support for staged life-cycle model definition from system concept through disposal. Both standards are intended for use with lower-tier soft- ware standards such as ISO/IEC 12207 or the IEEE/EIA 12207 series. STANDARD FUNDAMENTALS Clause 1 of IEEE 1220 describes the standard’s scope, purpose, and orga- nization. It sets the context for use and outlines the fundamental elements, relationships, and structure that com- prise a system. An exemplar system breakdown structure is used to explain key concepts in the “IEEE 1220 System Structural Concepts” sidebar. In support, Annex A describes systems engineering’s role in the enterprise. Clauses 2 and 3 list references and explain basic terms and acronyms used in the standard. Clause 4 defines general require- ments for developing a total system solution. This includes enterprise poli- cies and procedures, plans, schedules, development strategies, and the use of models and prototypes. It also covers documentation and project support mechanisms, such as specification trees, integrated teaming, technical reviews, and quality management. Clause 4 requires establishment of a shared repository to capture evolv- ing technical and management infor- mation in an integrated data package for life-cycle process support. Annex B adds a systems engineering man- agement plan template and guidelines. Clause 5 threads Clause 6 systems engineering process (SEP) provisions with the general requirements of Clause 4 across a typical system life cycle, which consists of the develop- ment stages of systems definition and subsystem definition, and the opera- tions stages of production and support. The clause describes work products and activities associated with refining system, subsystem, and component levels in the development stages and with deficiency correction and prod- uct evolution in the operations stages. It also addresses activities and phas- ing for the simultaneous engineering of life-cycle processes. IEEE 1220: For Practical Systems Engineering Teresa Doran IEEE 1220 guides enterprises or projects to a well-engineered solution for product-oriented systems.

Upload: t

Post on 22-Sep-2016

290 views

Category:

Documents


2 download

TRANSCRIPT

Page 1: IEEE 1220: for practical systems engineering

92 Computer

S T A N D A R D S

P rimarily targeting product-oriented systems such as air-planes and information sys-tems, IEEE Std 1220-2005,IEEE Standard for Applica-

tion and Management of the SystemsEngineering Process, “defines the inter-disciplinary tasks that are requiredthroughout a system’s life cycle to trans-form stakeholder needs, requirements,and constraints into a system solution.”

IEEE 1220 enjoys global applicationin industry, government, and academicsystems engineering efforts and has notchanged substantially since its trial issuein 1995. This formal revision of IEEEStd 1220-1998 facilitates the applica-tion of IEEE 1220’s detailed processand practices with the broad systemlife-cycle process set offered in Inter-national Organization for Standard-ization/International ElectrotechnicalCommission (ISO/IEC) 15288.

In late 2002, the IEEE ComputerSociety initiated alignment of IEEE Std 1220-1998 with ISO/IEC 15288:2002, Systems Engineering—System

Life Cycle Processes, as a part of aneffort to harmonize the collections ofthe Computer Society’s Software andSystems Engineering Standards Com-mittee (S2ESC) with those of JTC1/SC7, the corresponding ISO/IEC committee responsible for developingsoftware and systems engineeringstandards.

Completion of the multiphase IEEE1220-ISO/IEC 15288 harmonizationproject depends on the currentJTC1/SC7 effort to reconcile ISO/IEC15288 and ISO/IEC 12207, SoftwareLife Cycle Processes.

The S2ESC-sponsored adoption ofIEEE Std 15288-2004, Adoption of ISO/IEC 15288:2002 SystemsEngineering—System Life Cycle Pro-cesses, presents another harmonizationachievement. Combined, IEEE 1220and IEEE Std 15288-2004 providedetailed technical and managementprocess practices that can be applied toproduce a balanced, well-engineeredsystem solution for a product offering.They also supply foundational pro-

cesses and support for staged life-cyclemodel definition from system conceptthrough disposal. Both standards areintended for use with lower-tier soft-ware standards such as ISO/IEC 12207or the IEEE/EIA 12207 series.

STANDARD FUNDAMENTALS Clause 1 of IEEE 1220 describes the

standard’s scope, purpose, and orga-nization. It sets the context for use andoutlines the fundamental elements,relationships, and structure that com-prise a system. An exemplar systembreakdown structure is used to explainkey concepts in the “IEEE 1220System Structural Concepts” sidebar.In support, Annex A describes systemsengineering’s role in the enterprise.

Clauses 2 and 3 list references andexplain basic terms and acronymsused in the standard.

Clause 4 defines general require-ments for developing a total systemsolution. This includes enterprise poli-cies and procedures, plans, schedules,development strategies, and the use ofmodels and prototypes. It also coversdocumentation and project supportmechanisms, such as specificationtrees, integrated teaming, technicalreviews, and quality management.

Clause 4 requires establishment ofa shared repository to capture evolv-ing technical and management infor-mation in an integrated data packagefor life-cycle process support. AnnexB adds a systems engineering man-agement plan template and guidelines.

Clause 5 threads Clause 6 systemsengineering process (SEP) provisionswith the general requirements ofClause 4 across a typical system lifecycle, which consists of the develop-ment stages of systems definition andsubsystem definition, and the opera-tions stages of production and support.

The clause describes work productsand activities associated with refiningsystem, subsystem, and componentlevels in the development stages andwith deficiency correction and prod-uct evolution in the operations stages.It also addresses activities and phas-ing for the simultaneous engineeringof life-cycle processes.

IEEE 1220: For Practical SystemsEngineering Teresa Doran

IEEE 1220 guides enterprises or

projects to a well-engineered solution

for product-oriented systems.

Page 2: IEEE 1220: for practical systems engineering

May 2006 93

architecture satisfies the validatedrequirements baseline. This processyields a verified physical architecture.

Systems analysis provides a tradestudy approach to support require-ments conflict resolution, functional

Clause 6 describes the SEP and itsassociated tasks, general process flows,and activities. It also recommends anapproach for tailoring an enterpriseversion of the SEP for a project.

SYSTEMS ENGINEERINGPROCESS

Figure 1 shows the SEP, whichdecomposes into eight subprocesses.

Requirements analysis establishessystem capabilities and product per-formance and defines the operationalenvironments, human and systeminterfaces, physical characteristics,and other constraints that impactdesign solutions. The project teamconducts various tradeoff and riskanalyses to identify and resolve con-flicts, ideally resulting in a require-ments baseline that balances anoperational view—how system prod-ucts serve the users; a functionalview—what the products do; and adesign view—design considerations.

Requirements validation evaluatesthis baseline to ensure that it adequatelyaddresses stakeholder expectations,enterprise and project constraints,external constraints, and system andlife-cycle support considerations. If not,the project team repeats requirementsanalysis and requirements validationuntil achieving a satisfactory validatedrequirements baseline.

Functional analysis refines the prob-lem statement for a system solution—as defined by the requirementsbaseline—and breaks down the sys-tem functions to lower levels to satisfysystem design elements. This processproduces a functional architecture.

Functional verification assessescompleteness in satisfying the vali-dated requirements baseline and yieldsa verified functional architecture.

Synthesis translates the verified func-tional architecture into a design archi-tecture. It derives a preferred solutionfrom a set of alternatives typically basedon associated costs, schedule, perfor-mance, and other risk implications.

Design verification assures traceabil-ity from the lowest level of the designarchitecture to the verified functionalarchitecture, and also that the design

decomposition, performance allo-cations, design selections, systemeffectiveness assessments, and riskmanagement.

Control tasks are performed tomanage and document SEP activities

IEEE 1220 System Structural Concepts

As Figure A shows, the IEEE 1220 building block breaks down into a sys-tem of products, their subsystems, and life-cycle processes that support theproducts. The figure further decomposes one subsystem into its elements,which can be viewed alternatively as another system, perhaps to be built by adifferent contractor.

The shaded boxes of the product hierarchy depict progressively subordinateelements within a system’s structure that typically result from the three majorlevels of system development—system definition, preliminary design, anddetailed design.

The unshaded boxes represent IEEE 1220’s eight functional life-cycleprocesses commonly required to support a product or element during its life-time. For example, an assembly might have components that must be devel-oped, tested, and manufactured prior to integration and incorporation into ahigher-level element. Each such process might require special personnel, facil-ities, hardware, software, procedures, and so on.

Once identified, a life-cycle process is treated as a system and evolves accord-ingly. By defining processes for downstream implementation, IEEE 1220 laysthe foundation for a product’s remaining life cycle.

Figure A. IEEE 1220 key system structural concepts—the building block, the product

hierarchy, and life-cycle processes that support the product hierarchy.

System

Subsystem

Product Product

SubsystemSubsystem Subsystem

Componentdesign

Subsystemdesign

Object Object Object

Componet(Processor)

Component(Hardware)

Component(COTS)

Component(Software)

Component(Cabinet)

DisposalTraining

SupportOperations

DistributionTest

ManufacturingDevelopment

Life-cycleprocesses

AssemblyAssembly Assembly Assembly

Subassembly

Subcomponent Subcomponent

IEEE 1220 Building Block

Systemdesign

Page 3: IEEE 1220: for practical systems engineering

94 Computer

S T A N D A R D S

and results. The project team moni-tors and controls data, configurations,interfaces, risks, and technical pro-gress with this process.

USING IEEE 1220 WITH ISO/IEC 15288

IEEE 1220 differs from ISO/IEC15288 in important ways with respectto both system structure and termi-nology. To help reconcile these differ-ences, Annex C offers ISO/IEC 15288definitions to explain overlappingterms and concepts.

ISO/IEC 15288 does not have struc-tural equivalents to the IEEE 1220system, subsystem, or building block.ISO/IEC 15288 breaks down a sys-tem-of-interest into discrete, imple-mentable parts, which allows it tocontain one or more further decom-posable systems or two system ele-ments. ISO/IEC 15288 definesenabling systems, which are equiva-lent to an IEEE 1220 system’s life-cycle processes, but they are externalto the system of interest.

In addition, while IEEE 1220 has asingle SEP with eight subprocesses

decomposed into tasks and activities,ISO/IEC 15288 has four process groupswith 25 system life-cycle processes.Each ISO/IEC 15288 process is definedby its purpose, outcomes used todemonstrate successful implementa-tion, and activities for implementationaccording to organizational policies andprocedures.

ISO/IEC 15288’s process set providesbroader coverage than IEEE 1220.Where IEEE 1220 lacks a processdescription, or has only a partial one,ISO/IEC 15288 processes provide agood reference base for supplementalprocess definitions. These processesinclude acquisition and supply, imple-mentation, integration, verification,transition, validation, operation, main-tenance and disposal, and enterpriseprocesses.

On the other hand, IEEE 1220’simplementation recommendations aretoo detailed to include at ISO/IEC15288’s process coverage level. IEEE1220 identifies specific work products,activities, and mechanisms—integrateddata package content, use of compo-nent detailed design reviews, build-to

baselines, and specification and draw-ing trees—during various levels of sys-tem development.

A nnex C describes how to success-fully use IEEE 1220 together withISO/IEC 15288, but there are still

gaps to bridge to fully harmonize thetwo standards. Although a “fast-track”ballot of IEEE Std 1220-2005 is cur-rently under way in JTC1, planningjoint committee activities to produce acoordinated IEEE-ISO/IEC version ofIEEE 1220 should allow for comple-tion of the ISO/IEC 15288:2002 revi-sion in late 2007. ■

Teresa “Terry” Doran, a systems andsoftware engineering process manage-ment consultant, is the revision editorand technical contact for IEEE 1220.Contact her at [email protected].

Editor: John Harauz, Jonic Systems Engineering, Inc., Willowdale, Ont., Canada; [email protected]

Control

Process outputs

Requirementstrade studies and

assessments

Functionaltrade studies and

assessments

Designtrade studies and

assessments

Systemanalysis

Design solution requirementsand alternatives

Design solution tradeoffsand impacts

Decomposition and requirementsallocation alternatives

Decomposition allocation tradeoffs and impacts

Requirement and constraint conflicts

Requirement tradeoffsand impacts

Requirementsanalysis

Requirementsvalidation

Functionalanalysis

Functionalverification

Synthesis

Designverificaton

Process inputs

Requirements baseline

Validated requirements baseline

Functional architecture

Verified functional architecture

Physical architecture

Verified physical architecture

Figure 1. IEEE 1220 systems engineering process. SEP decomposes into eight subprocesses with their associated tasks, general process

flows, and activities.