Telecommunication Report on Systems Engineering in Telecomm

This report examines the application of systems engineering principles within telecommunication networks. It explores concepts such as reliability, availability, maintainability, and safety, providing mathematical models for analyzing system performance, including parallel systems and digital microwave radio systems. The report also delves into real-world applications, such as the National Broadband Network (NBN) technology in Australia, and discusses factors influencing coverage area and traffic-carrying capacity of telephone exchanges. Through calculations and analyses, the report offers insights into optimizing network design and performance, providing a comprehensive overview of key considerations in telecommunication systems engineering. The report also covers the impact of technology on the economy.

Running Head: Telecommunication Report 1
Telecommunication Report
Name
Institution
Professor
Course
Date

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Introduction
In the assignment, we shall discuss the fundamental systems engineering principles and their
application in telecommunication systems. There are many components and circuits that
constitute to any telecommunication network [1], [3]. A network is composed of
interconnections of systems, subsystems, circuits and electrical components which function to
deliver the desired task [1], [2], [3]. Just like in social systems, humans continually fail while
they increasingly seek to improve their lives and environment in which they live [1]. Similarly,
these networks or systems are subject to failure [1]. Their availability and reliability can vary
anytime depending on technical issues or expiry of their expected life [2], [3]. The following are
some of the basic concepts applied in engineering systems.
Reliability
A system’s reliability is defined as its freedom from failure of subsystem equipment or a
component while keeping a specific performance [1], [2]. Hence it is the measure of its
trustworthiness or dependability in accomplishing a given task with a specific period. Engineers
are always keen on a system’s reliability [1]. If not properly monitored and maintained [1], a
system can fail leading to enormous losses [1], [2]. Risk assessment and reliability analysis
activities are complementary and are designed to ensure that a system’s performance is
quantifiable as expected as well as not posing potential risks to its users, operators and the
environment [1].
Availability

2
1
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It is defined as the system’s ability to perform its desired function at a specified time or over a
given period of time under the combined aspects of its maintainability, reliability and
maintenance support [2].
Maintainability
This refers to the capability of a system’s to perform its required functions under certain
conditions when maintenance is performed [1], [2]. Maintainability is deemed as the principal
factor determining the availability of the system [2].
Safety
This is the freedom of a system from all the conditions that can pose death, occupational illness,
and injury, loss of property or damage to property [2].
Dependability
This refers to the general term applied to describe the reliability, maintainability and availability
performance as well as maintenance support performance [2].
The following part concerns application of mathematical model to real life telecommunication
systems. Systems can either be in series, parallel or combination of both.
Question 1: Reliability of a Parallel System
Consider the system shown in Figure 1, which is a model of an active redundant generator at a
main exchange of Telecommunication Company.

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Input
Figure 1: Active redundant generator pair
a) Assume that the reliability of each subsystem (or component) i has the reliability of Ri.
Calculate the reliability of the overall system RS as a function of Ri.
Solution: take i=1, 2, 3...
The overall reliability of the system is written as:
Rs(t) = P(T>t =1-P(T≤t)
= 1-P(T1≤t, T2≤t) = 1-P(T1≤t) x P(T2≤t) = 1- (1-R1(t)) x (1-R2(t))
= 1-[1-R1(t)-R2(t) + R1(t).R2(t)]
= R1(t) + R2(t) – R1(t)R2(t)
Note that the above equation assumes that the two components are working and depends
on each other.
b) If the reliability of component i at time t is Ri(t)=e-λit, what is the reliability function of
the overall system at time t?
Solution:
The overall reliability for the function becomes;
Output

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Rs(t) = e-λ1t + e-λ2t - e-(λ1+ λ2) t
c) Evaluate the mean time to failure (MTTF) of the overall system as a function of λi using
the reliability function in part (b).
The expected time to failure of a parallel system or MTTF can be obtained by integrating
the reliability function.
MTTF = ∫
0
∝
R (t) dt = ∫
0
∝
[ e−λ 1t +e−λ 2 t−e− ( λ1+ λ 2 ) ]t dt
= 1
λ 1 + 1
λ 2 - 1
λ 1+ λ 2
d) Calculate the failure rate of the overall system with exponential reliability. Hint use
binomial distribution.
Solution:
The failure rate function for the system is;
F(t) = Q(t) = 1- e-λ(t-β)
Thus the reliability function for the exponential distribution is;
R(t) = 1- Q(t) = 1 - ∫
0
t −β
f ( t ) dt
R(t) = 1- ∫
0
t −β
λe−λt dt = e− λ ( t−β )
e) What is the mean time before failure (MTBF) of the above system?
Solution:
MTBF = ∫
0
∝
R s(t )dt = ∫
0
∝
[e−λ 1t +e−λ 2 t−e− ( λ1+ λ 2 ) ]t dt
MTBF = [ e−λ 1 t ]∨+[e−λ 2 t] – [ e− ( λ 1+λ 2 ) ] Limits of the Integral is 0 and ∞

Terminal A Terminal B
A1
A2
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Therefore, MTBF = = 1
λ 1 + 1
λ 2 - 1
λ 1+ λ 2
Taking λ1 = λ2 = λ, the overall equation becomes 1.5 λ
Question 2 Digital Microwave Radio System
a) Calculate the overall system availability
Solution:
System availability, A = Mean time between failure (MTBF) / Total mean down time
A = 100000 / (100000 + 2) = 0.99998 or 99.998%
Considering the parallel pair configuration, the overall system availability becomes:
0.99999 + 0.99998 – (0.99999 x 0.99998) = 0.9999999 or 99.99999%
b) Draw the reliability diagram of the system
c) How would you increase the availability of the system required by the bank?

Terminal
A
Terminal
B
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This system can be increased by minimizing the time required to recover from an outage
as well as minimizing any kind of a downtime. Moreover, the bank must continuously
assess the system’s availability and taking into consideration preventive and outage
measures to ensure the system stays online [2], [3].
d) The useful life of the equipment shown in Figure 2 is 15 years. Calculate the
reliability of the one radio terminal at the end of it life.
Figure 2: Microwave system
Solution:
Reliability of a component is given by, Ri(t)=e-λit
MTBF, m = 100000 hours = i/λ
Rearranging the equation, λ = 1/m
Therefore, Ri(t)=e-it/m
Time, t = 2 years = 365 x 24 x 2 = 17520
Substituting the values into the above equation, we have the reliability of the terminal as;
Ri(t) = 0.839289146

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Question 3 High Seed Connectivity
National Broadband Network technology is focused on delivering access to fast broadband
services throughout Australia [6], [5]. Australia’s broadband capabilities had been declining
compared to its international counterparts [5]. However, after many promises from the
government to invest in upgrading the internet connection in Australia; NBN installed less
expensive Fibre to the Node connection [5], [6]. Considering the fast speeds with which
technology is changing, FTTN is deemed as a network technology that would soon be obsolete
[5]. The fibre to the node technology has never been widely adopted as an option by the many
advanced nations in terms of network technology which Australia is looking up to [5], [6].
Additionally, in nations where the FTTN technology has been installed; the network operators
are shying away from the technology to more advanced broadband technologies like fibre to the
premises, FTTP [5]. Internet speeds have been shown to strongly correlate with a country’s GDP
growth [5], [6]. Therefore, installing newest technologies to both homes and business premises
will positively affect the economy of Australia [5].
Question 4 Functions of a Telecommunication Network
a) What limits the size of the coverage area of a telephone exchange?
The base station (BS) contains microwave radio equipment [4]. The base station has
comprises of trunks and data links connected to the mobile switching centres (MSC) [4]. The
number of base stations in a mobile network determines coverage area of a telephone
exchange [4]. There are always challenges associated with design of a system that can
adequately address the heterogeneous traffic, unpredictable variations in the channel and

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changing topology due to mobile nodes [4]. Such challenges determine the area of coverage
for a certain network system. Extending the adaptability of the physical layer enables more
effective use of the spectrum hence meeting the current environmental and network traffic
conditions [4]. It is also expensive maintaining existing network system. Therefore, by
adopting new technologies and equipment increases the quality of service and performance of
any network channel [4]. This increases the coverage area of a telephone exchange system.
b) What limits the traffic carrying capacity of a telephone exchange?
Older interexchange signaling systems are difficult or impossible to upgrade and therefore can
not accommodate more traffic [4]. Instead, newer forms of signaling are required to boast the
traffic carrying capacity of a telephone exchange [4]. Additionally, for a telecommunication
network to achieve its potential, it needs to accommodate several interacting control
mechanisms [4]. Such mechanisms include routing, queue scheduling, bandwidth allocation,
call admission control, input rate regulation, flow and congestion control, and buffer
management [4]. Implementation of network level control is essential in ensuring completion
of the optimum possible number of successful B-ISDN service calls [4].

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Reference List
Books
[1] A. Høyland and M. Rausand, System Reliability Theory. Hoboken: John Wiley & Sons, Inc.,
2009.
[2] K. Aggarwal and A. Keller, Reliability Engineering. Dordrecht: Springer Netherlands, 1993.
[3] J. Juang and Y. Huang, Intelligent technologies and engineering systems. New York, NY:
Springer, 2013.
[4] K. Venugopal, L. Patnaik and K. Venugopal, Wireless Networks and Computational
Intelligence: 6th International Conference on Information Processing, ICIP 2012, Bangalore,
India, August 10-12, 2012. Proceedings. .
Journals
[5] M. Gregg, "History in the Making: The NBN Rollout in Willunga, South Australia", Media
International Australia, vol. 143, no. 1, pp. 146-158, 2012.
[6 P. Gerrand, "TJA’s NBN policy panel: TJA quizzes Paul Budde, Joshua Gans, Mark Gregory
and Allan Horsley on the competing NBN policies in the 2013 Australian federal
election", Telecommunications Journal of Australia, vol. 63, no. 3, 2013.