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BROADBAND CONNECTIVITY USING OPTICAL 
ACCESS FOR THE EASTERN PROVINCE OF
SRI LANKA
Ms.B.Alakurajah
(108005J)
UBRARY
UNIVERSITY 0? MORATUWA, SRI LANKA 
MORATUWA
Thesis Submitted in Partial Fulfillment of the Requirement for the Degree Master of
Science Cxj h
Department of Electronics and Telecommunication Engineering
University of Moratuwa 
Sri Lanka
/OS 9^/6August 2014
J
University of Moratuwa
108946
108946
Declaration
I declare that this is my own work and this theses does not incorporate without 
acknowledgement any material previously submitted for a Degree or Diploma in any 
other University or institute of higher learning and to the best of my knowledge and 
belief it does not contain any material previously published or written by another 
person except where the acknowledgement is made in the text.
Also, I hereby grant to University of Moratuwa the non-exclusive right to reproduce 
and distribute my thesis, in whole or part in print, electronic or other medium. I retain 
the right to use this content in whole or part in future works (such as articles or 
books)
Date:Signature:
The above candidate has carried out research for the Masters under my supervision.
Date:Signature of the supervisor:
#ofi!
i
Abstract
In Sri Lanka the widely used wired technology for broadband access is Asymmetric Digital 
Subscriber Line (ADSL). Fiber access is available in the Western Province with limited 
usage such as for business purposes. The Eastern Province is the focus for this research 
because it is one of the affected areas during the last two decades of war and therefore has 
limited facilities for the people living in that part of the country. The development work in 
the Eastern Province is in progress at present and it also includes facilities for broadband 
access.
ADSL broadband usage within Eastern Province is available but limited to city areas only. 
This work focuses on a system to implement Fiber to the Home (FTTH) for the Eastern 
Province and thus provide efficient broadband access for its people. The available Fiber 
Access technologies are analyzed and the most suitable one is selected for implementation. 
The thesis proposes a network based on Passive Optical Network (PON) technology to be 
employed with Gigabit PON (GPON) in order to provide FTTH to a wider area of the 
Eastern Province. The GPON technology includes Coarse Wavelength Division Multiplexing 
(CWDM) with Time Division Multiple Access (TDMA); known as Hybrid PON.
For the selected four cities Optical Line Terminal (OLT) locations are identified and Ring 
topology access is used with Remote Nodes which can be expandable when customer 
number increased.
A cost estimate using the current equipment prices and the payback of the capital are 
calculated and presented in the thesis. The performance of the proposed network is analyzed 
which includes the Link Power Budget and the Bit Error Rate (BER). The performance 
analysis shows that the proposed Optical Access Network using GPON is feasible for 
implementation in the Eastern Province.
ii
Acknowledgements
I am deeply indebted to my supervisor Eng. A.T.L.K. Samarasinghe, who proposed the topic 
for my research and guided me and supervised me throughout the period of my research 
work. He met me regularly and spent long hours to help me and to be in the right direction 
until the completion of the work. Without him this thesis would not have been a reality. Prof. 
(Mrs.) I.J. Dayawansa also contributed to several discussions I had with my supervisor. She 
also gave valuable advise whenever I needed. She was almost a second supervisor to me. I 
offer a big ‘Thank You’ to her.
I wish to gratefully acknowledge the useful contributions towards this research work, by 
Dr.Ruwan Weerasuriya, Senior Lecturer of the Department.
Several Engineering and other members of Sri Lanka Telecom were a great support for me in 
collecting the necessary data for the project. I offer my sincere thanks to them all. I also wish 
to place on record my thanks to the officers of Survey Department and Eastern Province 
Kachcherry whose contribution were very valuable for the project.
Prof.Kapila Gunasekare, Vice Chancellor, UNIVOTEC encouraged me to go for higher 
studies and approved the necessary leave to register for this M.Sc. degree. I am very grateful 
to him. Without ‘leave of absence’ from my work place, the UNIVOTEC, I would not have 
been able to undertake and complete this work.
I wish to convey my heartfelt gratitude to anyone who gave me a hand in some way to make 
this research success.
Hi
TABLE OF CONTENTS
Declaration of the candidate and Supervisor 
Abstract
1
11
Acknowledgement 
Table of Contents 
List of figures 
List of Tables
111
IV
viii
xi
Abbreviations Xlll
Chapter 1: Introduction
1.1 Background
1.2. Objective of the Research
1.3. Literature Review
01
02
02
021.3.1. Definition of Broadband
1.3.2. Fixed Line Technologies (Wired Broadband)
1.3.3. Cable Modems
1.3.4. Broadband Power Line (BPL)
1.3.5. FTTC/FTTH/FTTB/FTTx
02
04
05
06
071.3.6. Wireless Technologies
1.3.7. Wi-Fi (wireless Fidelity) 08
091.3.8. WiMAX
Chapter 2: Broadband Quality Measurement 
2.1. Broadband Quality 11
2.1.1. Worldwide Broadband Quality Score Study 11
122.1.2. Broadband Quality Score 
2.2. ITU Indexes for worldwide ICT sector
2.2.1. The Digital Access Index (DAI)
2.2.2. The ICT Opportunity Index (ICT-OI)
19
19
19
iv
202.2.3. The Digital Opportunity Index (DOI)
2.2.4. ICT Development Index 20
Chapter 3: Optical Fiber Access Network
243.1.Technology
263.2. Passive Optical Networks (PONs)
283.3. PON Topologies
293.4. APON/BPON
303.5. GPON
303.6. EPON
313.7. WDM PON
313.8. Reason for GPON Selection
323.9. Signal Transmission in a PON
Chapter 4: Proposed Optical Access Network for the Eastern Province
4.1. Broadband in Sri Lanka
4.2. Eastern Province of Sri Lanka
4.3. Optical Access Network for the Eastern Province
4.4. CWDM Technology
4.5. Proposed four CWDM rings to cover the city areas
4.6. Selected Equipment and components
4.7. Cost Analysis
34
35
36
37
39
43
46
Chapter 5; Performance Analysis of the Proposed Access Network
5.1. Introduction
5.2. Design considerations
5.3. Link Power Budget
47
47
48
v
495.3.1. Power Budget of a PON
5.3.2. Typical Loss Values Selection 
5.4.Signal to Noise Ratio(SNR)
5.4.1. Electrical Signal Power Equation
5.4.2. Noise Power
5.4.3. The Q-Factor 
5.5. Considered Noise Effects
49
51
51
52
54
54
545.5.1. Shot Noise Effect
555.5.2. Thermal Noise Effect
565.5.3. Laser Intensity Noise
585.6. Bit Error Rate
585.6.1. BER calculation
635.7. Design Objective
5.7.1. SNR Analysis by varying PON length
5.7.2. SNR Analysis by varying Amplifier Gain
5.7.3. SNR Analysis by varying transmitted Power
5.7.4. SNR analysis for Different Wavelengths
64
66
67
68
695.8. Receiver Sensitivity
725.9. Dispersion in Fibers
5.9.1. Dispersion
5.9.2. Types of Dispersion
5.9.3. GVD calculation
5.9.4. Polarization Mode Dispersion
72
72
73
74
765.10. Analysis of Results
5.11. Discussion and Recommendations 79
795.11.1. Size of the Proposed CWDM Ring
vi
795.11.2. Cost Analysis
795.11.3. Link Power Budget
805.11.4. SNR Analysis
805.11.5. Uplink BER
81Conclusion
83References
vii
LIST OF FIGURES
Page
Figure 1.1 03Broadband fixed line access technology evolution
Figure 1.2 Cable Modem connection 04
Figure 1.3 Typical BPL connection 05
Figure 1.4 Typical Fiber Access Network 07
Figure 1.5 Wi-Fi Configuration 08
Figure 1.6 WiMAX Architecture 09
Figure 2.1 Broadband Quality Score in 2008 13
Broadband Quality Score in 2009 14Figure 2.2
Broadband Quality Divides in 2009 15Figure 2.3
Broadband Leadership (Top 20 in 2009) 16Figure 2.4
Broadband users/100 in Asia 2006 18Figure 2.5
IDI development stages 21Figure 2.6
FTTx Architecture 26Figure 3.1
PON Architecture 27Figure 3.2
viii
Figure 3.3 28PON Topologies
Figure 3.4 33Signal Transmission in a TDM/TDMA PON
Figure 4.1 34SLT Optical Core Network
Figure 4.2 36Eastern Province of Sri Lanka
Figure 4.3 37Hybrid PON
Figure 4.4 38Possible CDMA Wavelengths(ITU-T G.694.2)
Figure 4.5 Proposed Ring optical Access Network for the Kalmunai City 39
Proposed Ring optical Access Network for the Ampara City 40Figure 4.6
Proposed Ring optical Access Network for the Batticaloa City 40Figure 4.7
Proposed Ring optical Access Network for the Trincomalee City 41Figure 4.8
Eastern Province of Sri Lanka Proposed Optical Access Network 43Figure 4.9
OLT and ONU Devices and Connection 44Figure 4.10
48Link Power LossesFigure 5.1
Possibility of random noise at the threshold detection 59Figure 5.2
PDFs (Pi(y)dv,i = 0 or 1) for levels of ‘O’ and ‘1* v0 and vt in the 60 
presence of random (Gaussian) noise.
Figure 5.3
ix
Figure 5.4 65SNR(dB) vs PON length(km)
Figure 5.5 66Maximum possible distance(km) vs. No.of Splits
Figure 5.6 67SNR(dB) vs Amplifier gain(dB)
Figure 5.7 SNR(dB) vs Transmitted Power(dBm) 68
Figure 5.8 SNR(dB) vs wavelengths(pm) 69
Figure 5.9 Pulse Broadening due to dispersion 72
Figure 5.10 DLAA vs.length 74
No PMD in a perfect fiber(top) & Real fiber with some 
asymmetries.(Bottom)
Figure 5.11 75
PMD parameter variation up to 60 km 76Figure 5.12
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LIST OF TABLES
Page
Table 1.1 DSL technologies 03
Table 1.2 Some available wireless Broadband Technologies 07
Table 1.3 Wi-Fi Technologies 09
Table 1.4 WiMAX Standards 10
Table 1.5 Some Available 3G Technologies 10
Table 2.1 Top /Changes in Broadband Quality Score (2008-2009) 16
Table 2.2 IDI Development Index for the top 20 Countries 23
Table 3.1 PON Standards 29
Table 4.1 Population Report-2009 35
Selected 8 wavelengths for up and down link 38Table 4.2
ADSL Customers in the city areas of Eastern Province 39Table 4.3
Proposed CWDM ring access length 41Table 4.4
Eastern Province Optical Access network Covered Areas 42Table 4.5
Eastern Province Optical Access ring Cost Estimate 45Table 4.6
Total cost and capital get back Period for each Ring 46Table 4.7
49PON classesTable 5.1
Table 5.2 OLT to RN Power budget 50
RN to ONU Power Budget 50Table 5.3
PON length vs. Noise variance for 64 splits 64Table 5.4
PON length vs. SNR for 64, 128, 256 and 512 splits 64Table 5.5
Maximum Possible PON length for each Splits 65Table 5.6
SNR values for different amplifier gain 66Table 5.7
xi
Table 5.8 67SNR values for different values of transmitted power
Table 5.9 69SNR values for different wavelengths
Table 5.10 70BER vs. Receiver Sensitivity
Table 5.11 BER vs. Receiver Sensitivity for different splits 71
Table 5.12 74DLAA values for different length
Table 5.13 Possible customer numbers with 128 splits 77
Table 5.14 Maximum receiver sensitivity for 15 km PON 78
Table 5.15 Selected design values for all splits 78
xii
LIST OF ABBREVIATIONS
Abbreviation Description
ADSL Asymmetric DSL
AGC Automatic Gain Control
AON Active Optical Network
ATM Asynchronous Transfer Mode
AWG Arrayed Waveguide Gratings
Bit Error RateBER
Clock-and-Data RecoveryCDR
Cable Modem Termination SystemCMTS
Central OfficeCO
Coarse Wavelength Division MultiplexingCWDM
Dynamic Bandwidth AllocationDBA
Distributed FiberDF
Distributed FeedbackDFB
Digital Subscriber LineDSL
xiii
DWDM Dense Wavelength Division Multiplexing
EDFA Erbium doped Fiber Amplifier
EPON Ethernet Passive Optical Network
FDD Frequency Division Duplex
FTTC Fiber to the curb
FTTH Fiber to the home
Four-Wave MixingFWM
General Encapsulation MethodGEM
Group -Velocity DispersionGVD
Bit Rate DSLHDSL
High High-Definition TelevisionHDTV
High Speed BroadbandHSBB
ICT Development IndexIDI
Institute of Electrical and Electronics EngineersIEEE
International Telecommunication 
Telecommunication standardization sector
Union-ITU-T
xiv
LMDS Local Multipoint Distribution Service
MAC Media Access Control
MMDS Multichannel Multipoint Distribution Service
MPCP Multiple-Point Control Protocol
O/E/O Optical/Electrical/Optical
ODN Optical Distribution Network
Orthogonal Frequency Division MultiplexingOFDM
Optical Line TerminalOLT
Optical Network TerminatorONT
Optical Network UnitONU
Point-to-PointP2P
Probability Distribution FunctionPDF
Polarization Mode DispersionPMD
Passive Optical NetworkPON
Quadrature Amplitude ModulationQAM
Quality of ServiceQoS
xv
QPSK Quadrature Phase Shift Keying
RMS Root Mean Square
RN Remote Node
SOA Semiconductor Optical Amplifier
SONET Synchronous Optical Network
TDD Time Division Duplex
Time-Division MultiplexingTDM
Very high Bit Rate DSLVDSL
Wireless FidelityWi-Fi
xvi