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Risk Identification and Analysis of Communication Project
Based on Fault Tree: The Case of the Telecom IVR Project BAI Xu
School of information Engineering,
Wuhan University of Technology, Wuhan, 430070, P.R.China
Tel:086-13397162758 Email:wuhantracy@gmail.com
Abstract—Aiming at the characteristics of communication projects such as the circumstance being complex
and affecting factors being numerous, a risk identification method has been put forward based on the fault
tree analysis and has combined work breakdown structure(WBS) with structure of risk analysis. With the
introduction of WBS-FTS, the coupling judgment has been carried out on the work breakdown structure
and risk resource breakdown structure of the telecom IVR project and the corresponding risk factors and
risk events have been stated. Then the logic connection among each factor has been set up according to
fault tree and the upper layer and the lower layer have been connected with logic gate, and thus come to the
main fault tree of IVR communication project. On this basis, the sensitivity analysis on risk factors has
been conducted and corresponding preventive measures have been put forward.
Keywords—communication project; fault tree analysis; risk identification; sensitivity analysis
0 INTRODUCTION
With arrival of the era marked with the integration of
data and information, telecom value-added services are
also entering the real golden age, and "to enter the field of
value-added services" has become a unique landscape.
The IVR (Interactive Voice Response) is a new hotspot
and benefit growth point within the field of telecom
value-added services. IVR communications project is a
complicated system as well as a reciprocal chiasma
interrelated entirety, involving the combination of new
technologies and original business, but also including the
impact of market conditions and other aspects. Therefore,
IVR project is a risk project and it is necessary to identify
and analyze the risk events as well as taking appropriate
preventive measures to avoid accidents.
At present, domestic and international research on the
risk of IVR project is still in its infancy, and the risk
identification methods mainly include case analysis,
factor analysis, SWOT analysis, brainstorming, Delphi
method, etc. However, these methods have their own
advantages and effects for the identification of risk, but
not fixed for the identification of risk. The absolutely
effective method should be chosen flexibly according to
project characteristics and considered comprehensively,
thus risk analysis can be conducted quickly and
efficiently. Therefore, in this thesis, the WBS method will
be used to give system decomposition of the IVR
communication engineering work structure and risk
source, and couple to the relevant risk factors and events.
Then establish the IVR communication engineering fault
tree with the logic gate according to the logic connection,
and on this basis determine the key risk factors and put
forward preventive measures through sensitivity analysis.
I. FAULT TREE ANALYSIS
Fault Tree Analysis (FTA) is a technology suitable for
the reliability and safety analysis of large and complex
system. With the application of mathematical logic
methods, FTA take the most undesired event of the
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system as the top event of the fault tree, and then look for
the trigger event, the direct and indirect causes leading to
the event gradually level by level as well as analyzing the
logical relationships between the causes of each event.
Consequently the various compound modes and the
occurrence probability of the causes leading to the system
failure are determined, and corresponding measures are
taken to improve the system reliability.
The characteristics of fault tree analysis are intuitive,
intelligible, clear and logical, and qualitative analysis can
be made as well as quantitative analysis. Not only the
relationships of failures inside the system are reflected,
but also reflect the influence of the external factors of the
system (environmental factors, human errors, etc.) The
process of fault tree analysis is an in-depth understanding
process of the system, which requires the researchers to
grasp the internal relations of the system and to ascertain
the impact way and degree of the underlying factors
having on the failures, So that the problems can be
analyzed and solved in the analysis process to improve
the system reliability. The analysis steps are listed below:
Table 2-1 The basic steps of FTA
the basic
analysis steps Specific contents
Learn more about the system state and
various parameters, and draw the flow chart
or lay-out diagram.
Collect incident cases, conduct accident
statistics, and envisage the possible accidents
in the given system.
Give comprehensive analysis on the accident
investigated to find out the consequences
which are more likely to occur and may lead
to serious consequence as the top event
According to lessons learned and accident
cases, solve the accident probability
(frequency) as a target value to control the
incident by statistical analysis.
1.Familiar with
the system
↓
2. Investigate
the accident
↓
3.Determine
the top event
↓
4.Determine
the target value
↓
5. Investigate
Investigate all the accident-related cause
events and various factors.
Find out the direct cause accident step by
step from the top event, until get the desired
depth of analysis, and draw the fault tree
according to the logic.
Simplify fault tree in the structure ,and
determine the structure importance degree of
basic events
Determine the occurrence probability of all
incidents, mark on the fault tree, and find the
occurrence probability of the top event
(accident).
Compare and discuss the maintenance
system and non-maintenance system.
Compare the former and calculate top event
probability of the latter.
the cause
accident
↓
6. Draw the
fault tree
↓
7.Analyze
↓
8.Accident
probability
↓
9.Compare
↓
10.Analyze In the analysis, keep flexible according to
the particular issue. If the fault tree is large,
we can make use of computer.
As a logical causality diagram, the fault tree diagram
displays the system status (top event) in accordance with
the component unit status (basic events). The systematic
fault tree logic model formed by Boolean logic gates
(such as "and", "or") describes how the combination of
the equipment failure and human error lead to the top
event.
II. THE RISK IDENTIFICATION AND ANALYSIS OF IVR
COMMUNICATION PROJECT
A. The risk factor identification of IVR communication
project
The risk identification of telecom has made use of the
existing achievements such as the telecom IVR project
flow chart (Figure1), the project requirements
specification and the project development plan. Based on
the Work Breakdown Structure (WBS) table and the
schedule plan of the project development plan, the project
team members can consider the risk factors in accordance
with the different stages and each unit in the project work
breakdown structure diagram, thus forming the project
risk identification list.
According to the project risk identification feature of
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all-the-people-involvement and in reference to the Delphi
method, the risk identification is conducted based on the
preliminary risk classification standard and risk lists by
the experienced employees from the telecom subsidiary
design institute, the project center director of the IVR, the
network infrastructure department, the information
transfer department, the system software control
department , the international liaison department and
other related sectors, and in this basis a formal risk list
document is formed (table 3-1). Through the staff's view
of risk identification, calculate the average, and "average"
means the average number of days delayed. In addition,
the optimistic value, pessimistic value and the most
probable value of the risk occurring probability from the
staff are converted into a risk occurrence "probability"
with the three point method.
Project approval risk
B. construct the WBS-FTA diagram of telecom IVR
project
From the development process of telecom IVR project,
the main factors that have led to the failure of the project
exist in almost every phase and the number of factors is
pretty large, so the work breakdown structure (WBS) of
the IVR project and the FTA analysis combined to
evaluate the risk of the telecom IVR project. Firstly,
adjust Table 3-1 by classifying the delayed days of
several stages caused by a risk to the first place where the
risk appears, and the adjusted table is shown as Table 3-2.
Secondly, the fault tree diagram of the telecom IVR
project constructed in accordance with the basic principle
of fault tree and the work breakdown and development
risk factors of the telecom IVR project development is
shown as Figure 2.
Combine table 2 (data derives from survey) and the
characteristics of telecom IVR project with the fault tree,
and give collation and calculation to the data, then it
comes to the probability and weight of the risk source
of telecom IVR project (the basic events on fault tree),
shown in table 3-2. Weight is calculated as:
FIGURE 1 THE TELECOM IVR PROJECT PROCEDURES AND RISK
IDENTIFICATION
TABLE 3-1 THE TELECOM IVR PROJECT RISK LIST AND RISK
IDENTIFICATION
Risk factor’s impact on project
schedule(unit:day) R
is
k
Risk factor Pha
se 1
Pha
se 2
Pha
se 3
Pha
se 4
ave
rag
e
pro
babi
lity
%
1Overall solution
design
1.
1
Network
arrangement 3 2 2 2 2.25 20
Market forecasting Phase 1:Overall
solution design Design risk
Phase2:Network
arrangement
Phase 3:
Equipment
Network adjustment
Equipment introduction
Material supply risk
Base station location
Base station negotiation
Phase4:The
installation and
debugging of
Personnel risk
Management risk
Project phase flow Risk factors of the project
The total process of the project
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1.
2
Excessive
design of
equipment
subscriptions
2 — — — 0.50 20
1.
3
Low level of the
clients’
technicians
1 — — 3 1.00 30
1.
4
The frequent
extra demands
made by clients
1 2 1 1 1.25 40
1.
5
The strategic
objective of the
clients being
unclear.
1 — — — 0.25 10
2 Network
arrangement
2.
1
Central
apparatus room
dissatisfies the
design
requirements
— 2 — — 0.50 30
2.
2
The poor quality
of
communications
circuits
— 3 2 1 1.50 30
2.
3
Network
adjustment
affects the users’
use.
— 2 — — 0.50 50
2.
4
The adjustment
of network
coverage area
— 2 1 — 0.75 40
3 Equipment
installation
3.
1
Inappropriate
Device picking
for its
unfamiliarity to
the manufacture
— — 3 1 1.00 40
3.
2
The negotiation
risk of
base-station
installation
brought by
market
competition
— — 3 — 0.75 30
3.
3
the delay of the
equipment
materials supply
— — 2 1 0.75 50
4
The installation
and debugging
of software
system
4.
1
Cross-departme
nt coordination 1 1 1 1 1.00 20
4.
2
The rework
modification of
the project
— — — 6 1.50 20
4.
3
Slow market
reaction of the
project
1 — — — 0.25 30
TABLE 3-2 THE TELECOM IVR PROJECT RISK ADJUSTMENT TABLE
Risk factor’s impact on
project schedule(unit:day)
ris
k
nu
mb
er
Risk factor
P
h
a
se
1
Ph
ase
2
Ph
ase
3
Ph
ase
4
av
er
ag
e
p
r
o
b
a
bi
li
ty
%
1 Overall
solution design
M1
1.1 Inaccurate
network
capacity survey
X0
9 — — — 2.
25
2
0
1.2 Excessive
design of
equipment
subscriptions
X1
2 — — — 0.
50
2
0
1.3 Low level of
the clients’
technicians X2
4 — — — 1.
00
3
0
1.4 The frequent
extra demands
made by clients
X3
5 — — — 1.
25
4
0
1.5 The strategic
objective of the
clients being
unclear. X4
1 — — — 0.
25
1
0
1.6 Cross-departm
ent
coordination
X5
4 — — — 1.
00
2
0
1.7 Slow market
reaction of the
project X6
1 — — — 0.
25
3
0
2 Network
arrangement
M2
2.1 Central
Apparatus
Room
dissatisfies the
design
requirements.
X7
— 2 — — 0.
50
3
0
2.2 The poor
quality of
communication
s circuits X8
— 6 — — 1.
50
3
0
2.3 Network
adjustment
affects the
users’ use. X9
— 2 — — 0.
50
5
0
2.4 The adjustment
of network
coverage area
X10
— 3 — — 0.
75
4
0
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3 Equipment
installation
M3
3.1 Inappropriate
Device picking
for its
unfamiliarity to
the
manufacture
X11
— — 4 — 1.
00
4
0
3.2 The
negotiation risk
of base-station
installation
brought by
market
competition
X12
— — 3 — 0.
75
3
0
3.3 the delay of the
equipment
materials
supply X13
— — 3 — 0.
75
5
0
4 The installation
and debugging
of software
system M4
4.1 The rework
modification of
the project
X14
— — — 6 1.
50
2
0
FIGURE 2 THE TELECOM IVR PROJECT FAULT TREE
:the delayed days caused by risk factor i of the
project
: the delayed days caused by all the risk factors
of the project
TABLE 3-3 THE PROBABILITY AND WEIGHT OF THE BASIC EVENT IN THE
TELECOM IVR PROJECT PROCEDURES AND RISK
Basic event Probability q Weight w
X0 0.20 0.163636
X1 0.20 0.036364
X2 0.30 0.072727
X3 0.40 0.090909
X4 0.10 0.018182
X5 0.20 0.072727
X6 0.30 0.018182
X7 0.30 0.036364
X8 0.30 0.109091
X9 0.50 0.036364
X10 0.40 0.054545
X11 0.40 0.072727
X12 0.30 0.054545
X13 0.50 0.054545
X14 0.20 0.109091
C. The risk analysis on the telecom IVR project based
on Fault tree
According to the analysis on the telecom IVR project
fault tree, the minimal cut set of the telecom IVR project
can be obtained, and then through the analysis of
probability and weight M1, M2, M3, M4, T are
calculated(shown in Table 3-4.
TABLE 3-4 THE QUANTITATIVE ANALYSIS ON THE TELECOM IVR
PROJECT
Basic
event
Probability
q
Weight w M T
X0 0.20 0.163636
X1 0.20 0.036364
X2 0.30 0.072727
X3 0.40 0.090909
X4 0.10 0.018182
X5 0.20 0.072727
X6 0.30 0.018182
M1=0.12
X7 0.30 0.036364
X8 0.30 0.109091
X9 0.50 0.036364
X10 0.40 0.054545
M2=0.08
X11 0.40 0.072727
X12 0.30 0.054545
X13 0.50 0.054545
M3=0.07
T=1.344×10-5
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X14 0.20 0.109091 M4=0.02
(4) The analysis of probability importance degree and
criticality importance degree
To get to know how much impact the change of basic
event’s(Xi) probability has brought on the top event(T)
further, it is expected to analyze the probability
importance degree of the basic events, the formula is as:
ig q
TiI
)(
Calculating Ig(0):
Ig(0)= w0*M1*M2*M3= 0.00001833 Calculating Ig(1)、Ig(2)、Ig(3)、Ig(4)、Ig
(5)、Ig(6)、Ig(7)、Ig(8)、Ig(9)、Ig(10)、Ig(11)、Ig(12)、Ig(13)、Ig(14)in sequence, shown as table 5-7。
The probability importance degree tells us materiality
level of the basic events on the top event, but it failed to
reflect on how to reduce the probability of the basic
events with a large probability. Hence it is expected to
calculate the criticality importance coefficient, which
measures the important standard of each basic event from
is the point of view of probability and sensitivity. The
formula is:
Lnq
LnTiCI g
)(
TABLE 3-5 THE PROBABILITY AND CRITICALITY IMPORTANCE DEGREE
OF THE TELECOM IVR PROJECT BASIC EVENTS
Basic event probability
importance degree
criticality importance
degree
X0 1.833×10-5 0.2727
X1 0.407×10-5 0.0606
X2 0.815×10-5 0.1818
X3 1.018×10-5 0.3030
X4 0.204×10-5 0.0151
X5 0.815×10-5 0.1212
X6 0.204×10-5 0.0455
X7 0.611×10-5 0.1363
X8 1.833×10-5 0.4090
X9 0.611×10-5 0.2273
X10 0.916×10-5 0.2727
X11 1.396×10-5 0.4156
X12 1.047×10-5 0.2338
X13 1.047×10-5 0.3896
X14 7.331×10-5 1.0909
D. The risk analysis result of telecom IVR project
(1)According to the fault tree of telecom IVR project,
there are a total of 84 minimal cut sets in IVR project,
which indicates that there are 84 ways leading to the
occurrence of the top event in the telecom IVR project.
The more the minimal cut sets are, the more dangerous
the system is, that is to say that the minimum cut set
reflects the risk level of the system.
(2)From the minimum path set of the telecom IVR
project fault tree, IVR project has a total of 4 minimal
path sets, which are the sufficient and necessary
conditions to ensure the top event not to occur. There are
84 minimal cut sets and 4 minimal path sets in the IVR
project fault tree, so it is more convenient to analyze the
minimal path set. For example, P4 = (X14) means X14
does not occur, and then the top event does not occur.
And during the analysis that P4 does not occur, the other
can be ignored. That is, if the rework succeeds after the
project ends, the telecom IVR project development can be
considered successful even if the Phase 1, Phase 2 and
Phase 3 are not going well.
(3) The probability importance degree of telecom IVR
project is the most effective approach to prevent the
failure of the system development. According to the
probability importance degree, the sorting of the telecom
IVR basic event’s probability is as follows:
X14> X0 = X8> X11> X12 = X13> X3> X10> X2 =
X5> X7 = X9> X1> X4 = X6
This indicates that the event that rework modification
can not be completed affects the telecom IVR project
risks most, followed successively by the following events:
inaccurate network capacity survey, the poor quality of
communication circuits, inappropriate Device picking for
its unfamiliarity to the manufacture, the negotiation risk
of base-station installation brought by market competition,
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the delay of the equipment materials supply, the frequent
extra demands made by clients, the adjustment of network
coverage area, low level of the clients’ technicians,
cross-department coordination, central apparatus room
dissatisfies the design requirements, network adjustment
affects the users’ use, excessive design of equipment
subscriptions, the strategic objective of the clients being
unclear, slow market reaction of the project.
(4) The criticality importance degree of the telecom
IVR project reflects each basic event’s sensitivity to the
project risk, and the sorting is as follows:
X14> X11> X8> X13> X3> X0> X10> X9> X12> X2>
X7> X5> X1> X6> X4
According to the sorting, the project rework
modification is the most important for the IVR project.
Meanwhile, through the comparation of the criticality
importance degree and the probability importance degree,
it is concluded that the risk of the IVR project can be
greatly reduced by improving the following problems
substantially: if the IVR projects, Inappropriate Device
picking for its unfamiliarity to the manufacturer, poor
quality of communication circuits, the delay of the
equipment materials supply, the frequent extra demands
made by clients, the adjustment of network coverage area,
network adjustment affects the users’ use.
III. CONCLUSIONS
The implementation process of the IVR project is a
complex, one-off, open and complex system involving
many relations and variables, and the risk factors
affecting the system are numerous and anfractuous. At the
same time, the severity of consequence caused by
different risk factors is quite different, and there is great
uncertainty whether the project will achieve the desired
result. In this thesis, correlation analysis has been
conducted on the telecom IVR project with the fault tree
method, and the results indicate that: the core of the IVR
project management is risk management, the rework
modification of the project, equipment selection when
manufacturers do not thoroughly understand; the poor
quality of communication circuits, the delay of the
equipment materials supply, the frequent extra demands
made by clients, the adjustment of network coverage area,
network adjustment affects the users’ use, are the key risk
factors in the telecom IVR project that call for great
attention. Therefore system thinking of the risk
management in these areas needs to be strengthened and
corresponding preventive measures should be taken to
avoid the occurrence of the risks.
REFERENCES
[1] Lau, H, etc. Improved Moment-Estimation Formulas Using More Than Three Subjective Fractals [J]. Management Science, 1998 .
[2] Myung J. Maximum Entropy Aggregation of Expert Predictions [J].Management Science, 1996.
[3] Claudio Moraga, Chong fu Huang. A Fuzzy Risk Model and its Matrix Algorithm [J]. International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems, 2002 (10).
[4] Foreword. Financial Decision Models in A Dynamical Setting [J].Journal of Economic Dynamics & Control, 2004.
[5] Li Lin, Li Shucheng, Wang Daoping. Based on Risk-Analysis’ Estimating Method of Project’s Duration [J]. Systems Engineering, 2001 (5).
[6] Shen Guozhu. Fuzziness Analysis Method for Risk [J]. Systems Engineering and Electronics, 2000(10).
[7] Shi Xiaojun, Ren Zhi’an. A Study on the Risk Analysis of Project Investment: A Method of Influence Causal Reference Based on a Supporting Analytical Algorithm [J]. Systems Engineering-Theory & Practice, 2000 (3).
[8] Jia xiaoxia, Yang naiding. The Supporting Function of Project Management for the Profit of Risk Investment [J]. Scientific Management Research, 2003 (2).
[9] Xie Shengqiang, Zou Huiwen, Chen Demian. Study of the risk distribution and the optimal risk control management in venture- capital investing projects [J]. Journal of Anhui University, 2003(1).
[10] Zhang Yali, Yang Naiding. A Project Risk Management Process and Integration under the view of Knowledge Management [J]. Industrial Engineering and Management, 2006(6).
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978-1-935068-23-5 © 2010 SciRes.
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