University of Southern California
Center for Systems and Software Engineering
IFCnSSCM-23
Realistic Software Cost Estimation for F6
Fractionated Space Systems
A. Winsor Brown, Ramin Moazeni
{AWBrown, Moazeni}@CSSE.USC.edu
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
Center for Systems and Software Engineering
Goals of Presentation
Context
 DARPA’s System F6: Future Fast, Flexible, Fractionated, FreeFlying Spacecraft united by Information eXchange
 Incremental Commitment Models (ICMs)
 Constructive Incremental Commitment Cost Model
[AKA Constructive Integrated Cost Model] (COINCOMO) & Tool
Software Cost Estimation Approaches for an F6
Conclusions
 ICMs provide frameworks for estimation
 Lower effort, but longer schedule
 Significantly lower overall risks (system and software)
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Context: F6
Future Fast, Flexible, Fractionated, Free-Flying Spacecraft
united by Information eXchange
(Courtesy Dr. Owen Brown’s Briefing for BAA)
• Microsat-like modules
• Intra-module connectivity
– Wireless data
– Wireless power transfer
• Inter-module connectivity
– Wireless data
• Robust, secure, selfforming wireless network
• Resource sharing across
modules
– Computation, etc.
• Cluster Orbits
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Context: ICMs
For Systems/Acquisitions, including
 Directed Systems of Systems
 Systems
For Software Subsystems
 Parallels to Rational Unified Process (RUP)
 Differences from Systems
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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ICM LC Processes for Systems (Hw, Sw & Pw)
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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ICM Activity Categories and Level of Effort
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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RUP/MBASE Application Development Model1
I
R
R
L
C
O
L
C
A
C
C
D
I
O
C
P
R
R
1 (efforts not to scale)
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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ICM-Sw/RUP Activity/Process Model
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Why Multiple Build Software Systems
Simplest: Early Functionality in the hands of ALL users
 Architecture/Core plus some functionality
 Implies Full Qualification/Acceptance Sw Testing each software
build so systems can go into Integration & Test earlier
Increasingly Complex Systems
 Multiple, diverse "platforms"
 Different "foci" of functionality (in each build)
 Network Centric Systems Operation
 Evolution/federation of legacy systems
 System of Systems by design
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Possible Overlapping Software Development Spirals
IFCnSSCM-23 – Realistic Software Cost Estimation for F6
Traditional Deliver And Enhance
University of Southern California
Center for Systems and Software Engineering
Overlaps Across Software Builds
Inception Elaboration Construction Transition
Inception Elaboration Construction Transition
Evolve During Transition [After Sw IOC]
Inception
Elaboration
Construction Transition
Inception Elaboration Construction Transition
Evolve After Architecture Complete
Inception Elaboration with Evol. Req.
Construction
Transition
Incept. Elaboration Construction Transition
I. Elab. Construction Transition
...
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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ICM Showing Multi-Build Software in a System
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ICM Showing Multi-Build Software in DSOS (N layers)
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MBASE/RUP/ICM-Sw Concurrent Activities
I
R
R
L
C
O
L
C
A
C
C
D
I
O
C
COCOMO II
Estimation Covers
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P
R
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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COCOMO II with COPSEMO (for I&T)
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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COPSEMO: Phased Schedule and Effort Dist.
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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COINCOMO – 1
COCOMO + COPSEMO
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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COINCOMO Direction – 1b
COCOMO + COPSEMO:
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COINCOMO – 2
Multiple Build Capability from COINCOMO 2.0
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Multi-Build COCOMO II
COINCOMO Sums Across Builds For Est.
New
Build x
Build x+2
Build x+1
Build x
Carried
Modify
Build x
Carried
New,
Reused and
COTS
New
Build x+1
New,
Reused and
COTS
Box size notional for effort.
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Modify
Build x+1
Carried
etc.
New
Build x+2
New,
Reused and
COTS
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Multiple Subsystems Overlapping Builds
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Outline
Context
Software Cost Estimation Approach for an F6
Conclusions
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Software Cost Estimation Approach for an F6
Hypothesized (builds, capabilities and SLOC/build)
 Common Operating Environment
 Service Based Architecture Middleware
 Common Services
 Small satellites
 Power Generation
 Space-Ground (S/G) Communication
 Micro satellites
 A Sensor Payload
 A Radar Payload
 An Actuator Payload
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Software Capabilities of F6 Modules
Module
COE
Build SLOC Software Capabilities
1
30K Communication, Minimal Information
Assurance, Minimal Operating
System (OS) abstraction, Initial
System Services
2
40K Minimal Analysis Services, Minimal
Data Store Services, Software
Support Services, More Information
Assurance, More OS Abstraction
3
30K Complete Information Assurance,
Complete OS abstraction, Complete
Analysis Services
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Software Capabilities of F6 Modules
Module
Power;
S/G
Comm.;
and
Payloads
Sensor
and
Radar.
Build SLOC Software Capabilities
1
5K
Initial prototype with Executable
Architecture and possibly minimal
functionality
2
15K Expand or replace initial prototype
with more capabilities, more
functionality, and bug fixes in carried
code
3
15K Complete Functionality, and bug
fixes in carried code
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Software Capabilities of F6 Modules
Module
Build SLOC Software Capabilities
1
10K Initial prototype with Executable
Architecture and possibly minimal
functionality
2
20K Expand or replace initial prototype
Payload
with more capabilities, more
Actuator
functionality, and bug fixes in carried
code
3
20K Complete Functionality, and bug
fixes in carried code
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Software Cost Estimation Approach for an F6
Using the COINCOMO 2.0 tool
 COCOMO model as a base2: estimated the software Effort (PM)
and Schedule (M) for each module
 COPSEMO model to separate the man power loading across
Elaboration and Construction phases
 COPSEMO model to add additional effort and schedule for
Inception and Transition phases
Used a spreadsheet to combine efforts AFTER aligning
the beginning of Elaboration with the end of Construction
Used COINCOMO for a monolithic equivalent
2 COCOMO calculates effort and schedule for the Elaboration and Construction phases of a build with new code and code carried
forward from the previous build treated as re-used code with very favorable re-use parameters.
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COINCOMO’s Component = COCOMO Project
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COINCOMO’s COPSEMO for Single Component
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COINCOMO naming conventions
COINCOMO Systems, Sub-Systems and Components
 System is conceptual aggregator of Sub-Systems
 Sub-System is aggregator for (software) Components
 Component = COCOMO Project
 Sub-Component = COCOMO Module
A CSV output of COINCOMO facilitates “aggregation”
using a spreadsheet
 Schedule after anchor point alignment
 Effort per phase per build after anchor point alignment
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Generated Spreadsheet with Totals
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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More Realistic Estimates
First run used all nominal driver settings
Second run used more realistic Drivers settings
 SF:
 PREC = Low
 FLEX = LOW
 RESL = VH (required: Architecting Sweet-spot
 TEAM = 50% H to VH (required by a DSOS)
 PMAT = VH (CMM Level 5 organizations)
 EAFs:
 RELY = VH
 APEX H (SubSystems)
 CPLX = 50% H to VH
 APEX N (COE)
 REUSE = VH
 PLEX ?? (we used L)
 ACAP = ?? (we used H)  LTEX = 50% H to VH
 PCAP = ?? (we used H)  SITE = XH (1st Sys.)
 PCON = ?? (we used H)  SITE = N-XH (subseq.)
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More Realistic Estimates (cont.)
Generated second run taking advantage of COINCOMO’s
DataBase centricity:
 Replicated all elements of system(s): subsystems &
components
 Renamed systems (only): subsystems & components
unchanged
 Changed driver settings in one component;
copied to other instances (builds) of same component

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Outline
Context
Software Cost Estimation Approach for an F6
Conclusions
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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PM & M of the Fractionated Modules
Total Fractionated Software Development Effort and Schedule spread over
three builds
Build 1
Incept. Elab. Const. Trans.
Effort (PM) 13.76 54.94 173.94 27.47
Schedule(M) 2.01 6.21 10.58 2.01
Total Fractionated Sw Devel. E&S Build 2
Incept. Elab. Const. Trans.
Effort (PM)
32.92 131.66 416.90 65.83
Schedule(M)
2.37
7.31
12.44 2.37
Total Fractionated Sw Development Effort & Schedule
- Build 3
Incept. Elab. Const. Trans.
Effort (PM)
6.61
26.44 83.72 13.22
Schedule(M)
2.33
7.19 12.25 2.33
Cumulative Schedule(M)
21.17 28.48
Cumulative Total Fractionated Sw Development
Effort=
Build1= 270.11
Cumulative Schedule(M)
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40.92
43.29
917.42
1047.41
Build2= 647.31
Build3= 129.99
43.25 50.44 62.69 65.02
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Monolithic Counterpart
Also has three payloads of 50K SLOC:
Sensor, Radar and Actuator
A satellite bus might need 75K SLOC for
 Navigation and Control (N&C)
 Command and Telemetry (C&T) including s/g comm.
 Power Conditioning
 Fault Management & Recovery
 Thermal Management
Total of 225K SLOCs
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Monolithic Counterpart (cont.)
Effort and Schedule Estimates for a Single Build, Monolithic,
Conventional Satellite
Incept.
Effort (PM)
Schedule
(M)
Elab. Const. Trans.
Total
66.18 264.73 838.31 132.26
1301.48
4.04
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4.04
41.78
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Sw Cost Estimating Conclusions – 1
COCOMO II, or some other cost model,
Along with
COPSEMO, or its equivalent in some other cost model,
Had to be used for each build because
 Nobody has experience with developing software for an F6
 Traditional Cost Estimating Ratios (CERs) don't work without
sufficient data
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Sw Cost Estimating Conclusions – 2
Complications in parametric estimates for F6
 Differences between the teams producing the software
 Amounts of carried code and their reuse factors change with the
number of times the code is carried
(these factors influence what software cost estimators call
"Equivalent SLOC", or ESLOC, for the carried code which inturn impacts the effort and schedule)
When calculating the total schedule in a multi-build
approach, only the parts up to an overlap are counted.
 Total Efforts are additive
 Schedule is cumulative (at the longest subsystem build)
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Sw Cost Estimating Conclusions – 3
F6 Surprises (?)
 Total estimated software development effort of our example
fractionated system vs. the monolithic system:
 F6 with Incremental Builds: 1047 Person Months (PM)
 Monolithic satellite and single build: 1301 PM
 A 20% decrease in effort cost for the fractionated system
(which happens because the smaller pieces of the
fractionated approach are not as impacted by the
diseconomies of scale for the larger monolithic approach)
 Schedule
 The fractionated system would take about 65 months
 41 months for the monolithic system
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IFCnSSCM-23 – Realistic Software Cost Estimation for F6
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Sw Cost Estimating Conclusions – 4
Risks
 Lower risk of Multiple Build F6: not big bang
 With the multiple, overlapping builds: greater assurance that
more of the software will be fully functional by the planned
launch date.
 There are also clear systems' costs savings with the ability to
launch replacement parts without changes to the software
 Future savings with the fractionated system approach:
Lower penalties for enhanced functionalities launched
 Radically changing a sensor would probably take only take 38
calendar months & 188 PM of effort, assuming
 COE is reused without significant change
 Sensor code is completely re-written
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COINCOMO Conclusions
UI needs to be developed to assist in spawning estimates
Spreadsheet calculations were done in less than an hour
because csv file was properly organized.
Spreadsheet combination is probably best because of
multiple ways to do things
 Non-COE Components might start AgileArchitecting after
Elaboration/Foundation of System/COE
 Since Sub-Systems are not on the longest path, perhaps they
should be not start their next build until Transition is almost
complete
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