1. DEPARTMENT OF ELECTRICAL AND INFORMATION ENGINEERING
FACULTY OF ENGINEERING
UNIVERSITY OF RUHUNA
INDUSTRIAL TRAINING REPORT SUBMITTED IN PARTIAL FULFILMENT
OF THE DEGREE OF BACHELOR OF SCIENCE IN ENGINEERING
ON 27th APRIL 2016
DIALOG AXIATA (PVT) LTD
736/2, EASTERN PROVIENCE REGION,
BUDDANGALA ROAD, AMPARA
(04.01.2016 to 27.03.2016)
GANGASUTHAN (EG/2013/2194)
2. i
Preface
This documentation presents the information about the industrial training that I acquired
for the period of 12 weeks from 4th of January 2016 to 27th of March 2016 at Dialog
Axiata PLC.
The first chapter of this report demonstrates a brief introduction to Dialog Axiata PLC.
Including history of Dialog Axiata PLC, vision and mission of Dialog Axiata PLC,
present performance of Dialog Axiata PLC and organizational structure of Dialog
Axiata PLC.
Second chapter describes the technical training experience that I got from the Dialog
Axiata PLC. The chapter is further subdivided into five parts. Those are GSM Network,
WCDMA Network, LTE Network, Transmission and Operation division, Transmission
Techniques, Microwave Communication and Optical Fiber Transmission. These are
obtained from Transmission division and Operation division. Technical and theoretical
information are described under each sub headings.
Third chapter gives the experience on management side, the administrative and office
practices and safety procedures.
Fourth chapter summarizes the training experience and it has conclusion of the training
program from Dialog Axiata PLC adopted by the EEC and NAITA.
GANGASUTHAN.M.
EG/2013/2194
Department of Electrical and Information Engineering
Faculty of engineering
University of Ruhuna.
3. ii
ACKNOWLEDGEMENT
I would like to take this opportunity to record my grateful acknowledgement to all the
people who helped me to success my Industrial Training. First of all I offer my sincere
gratitude to the Industrial Training Unit of Engineering Education Centre of Faculty of
Engineering University of Ruhuna, for giving the opportunity to finish my Industrial
Training period in Dialog Axiata PLC.
I would like to give my special thanks to the Coordinator of the Engineering Education
Center for give me this opportunity to get knowledge about the industry and
experiences. I must also thank Dr. G.S.H.K.K.Gunawikrama, Head of the Department
of Electrical and Information Engineering in Faculty of Engineering, University of
Ruhuna for his valuable support and advice to make this a success.
I must be grateful to the National Apprentice & Industrial Training Authority (NAITA)
for providing Industrial Training opportunities for undergraduates of University of
Ruhuna. My special thanks should be delivered to the Regional IN-Charge of Dialog
Axiata PLC Eastern Mr.Raheem .M Ismail, Engineers & Assistant Engineers.
Finally I would like to thank all the Engineers, technical officers, electricians and all the
officers of the organization for their allocation for sharing their knowledge and
experiences with us, guiding ourselves for a proper training. And also I give my sincere
gratitude to my friends for supporting me to complete my training period with great
achievement & success.
Gangasuthan .M
EG/2013/2194
Department of Electrical and Information Engineering,
Faculty of Engineering,
University of Ruhuna.
4. iii
Table of Contents
Chapter One
Introduction.....................................................................................................................4
1.1 History of Dialog Axiata PLC ..................................................................................4
1.2 Vision of Dialog Axiata PLC ...................................................................................5
1.3 Mission of Dialog Axiata PLC .................................................................................5
1.4 Present Performance .................................................................................................6
1.5 2G and 3G coverage .................................................................................................7
1.5 Organizational Structure...........................................................................................8
Chapter Two
2.0 Training Experiences-Technical...............................................................................9
2.1 GSM (2G) Network ................................................................................................10
2.1.1 Introduction to GSM ........................................................................................10
2.1.3 GSM Network Components.............................................................................11
2.1.3.1 Mobile Station (MS)..................................................................................12
2.1.3.2 Base Station Subsystem (BSS)..................................................................12
2.1.3.3 Network Switching Subsystem (NSS).......................................................13
2.1.3.4 Operation and Support Subsystem (OSS) .................................................14
2.1.4 GSM Channel...................................................................................................14
2.1.4.1 GSM Control Channel...............................................................................15
2.2 WCDMA (3G) Network .........................................................................................18
2.2.1 Introduction to WCDMA.................................................................................18
2.2.2 Security of WCDMA .......................................................................................19
2.3 LTE (4G) Network .................................................................................................20
2.3.1 Introduction to 4G............................................................................................20
2.3.2 4G FDD AND TDD.........................................................................................20
5. iv
2.3.2.1 Frequency Division Duplex (FDD)...........................................................21
2.4 Transmission and Operations Division...................................................................22
2.4.1 Base Transceiver Station (BTS).......................................................................22
2.4.1.1 Sector antennas..........................................................................................22
2.4.1.2 Microwave Antenna ..................................................................................23
2.4.1.3 Outdoor Unit (ODU) .................................................................................26
2.4.1.4 Indoor Unit (IDU)......................................................................................30
2.4.1.5 Cards..........................................................................................................31
2.4.1.6 Cell splitting ..............................................................................................32
2.4.2 Towers..............................................................................................................34
2.4.2.1 Green Field Tower.....................................................................................34
2.4.2.2 Self-support Tower(SS/ GBT – Single Support/ Ground Based Tower(40m-
SS,50m-SS,60m-SS,70m-SS,80m-SS,120m-SS,170m-SS)).................................35
2.4.2.3 Monopole Tower (RTMP Roof Top Mono Pole (RT+6m, RT+9m) GBMP
–Ground Based Mono Pole (30m-GBMP))...........................................................35
2.4.2.4 Guyed Mast Tower (60m-GM,80m-GM,120m-GM,170m-GM)..............36
2.4.2.5 Roof-Top Tower........................................................................................36
2.5 Transmission Technique.........................................................................................37
2.5.1 TDM.................................................................................................................37
2.5.2 TDM-PDH .......................................................................................................37
2.5.3 SDH VS PDH ..................................................................................................38
2.5.4 Ethernet (IP).....................................................................................................39
2.5.4.1 Category of Ethernet Cables......................................................................39
2.5.4.2 RJ-45 Connector........................................................................................40
2.5.4.3 Making Ethernet Cables ............................................................................43
2.6 Microwave Transmission........................................................................................44
2.6.1 Microwave Introduction...................................................................................44
2.6.2 Microwave Propagation...................................................................................45
6. v
2.6.3 Fading Problem................................................................................................45
2.6.3.1 Reflection ..................................................................................................45
2.6.3.2 Refraction..................................................................................................46
2.6.3.3 Diffraction .................................................................................................47
2.6.3.4 Scattering...................................................................................................47
2.6.3.5 Absorption.................................................................................................48
2.6.4 Protection Mode...............................................................................................49
2.6.4.1 Protection Configurations..........................................................................49
2.7 Optical Fiber Transmission.....................................................................................50
2.7.1 Introduction to Optical Fiber Communication.................................................50
2.7.2 How Optical Fiber works.................................................................................50
2.7.3 Optical Fiber Cables.........................................................................................50
2.7.3.1 Single mode fiber ......................................................................................51
2.7.3.2 Multi-mode fiber .......................................................................................51
2.7.4 Advantages of Optical Fiber ............................................................................52
2.7.5 Disadvantages of Optical Fiber........................................................................53
2.7.6 Fiber Connectors..............................................................................................53
2.7.7 SFP (Small Form Factor Pluggable) ................................................................54
2.8 PAT Test and Drive Test ........................................................................................55
2.8.1 Preliminary Acceptance Test (PAT)................................................................55
2.8.2 Drive Test.........................................................................................................56
Chapter Three
Training experiences management ...............................................................................58
3.1 Administrative and office practices ........................................................................58
3.2 SECURITY AND SAFETY ...................................................................................58
9. 2
Figure 2. 29 : RJ45 ............................................................... 42
Figure 2. 30 : CRIMPER TOOL............................................................................................. 43
Figure 2. 31 : MICROWAVE COMMUNICATION............................................................. 44
Figure 2. 32 : REFELECTION ON EART............................................................................. 46
Figure 2. 33 : REFLECTION ON BUILDING AND AIR LINE PATH ............................... 46
Figure 2. 34 : REFRACTION................................................................................................. 46
Figure 2. 35 : DIFFRACTION ............................................................................................... 47
Figure 2. 36 : SCATTERING................................................................................................. 48
Figure 2. 37 : HOT STAND BY............................................................................................. 49
Figure 2. 38 : SPACE DIVERSITY ....................................................................................... 49
Figure 2. 39 : PACE DIVERSITY ......................................................................................... 49
Figure 2. 40 : SINGLE MODE FIBER .................................................................................. 51
Figure 2. 41 : MULTI-MODE FIBER.................................................................................... 52
Figure 2. 42 : DIFFERENT WITH MULTI-MODE AND SINGLE MODE FIBER............ 52
Figure 2. 43 : CROSS SECTION OF FIBER CABLE........................................................... 52
Figure 2. 44 : LC CONNECTOR ........................................................................................... 53
Figure 2. 45 : FC CONNECTOR ........................................................................................... 53
Figure 2. 46 : SC CONNECTOR ........................................................................................... 54
Figure 2. 47 : ST CONNECTOR............................................................................................ 54
Figure 2. 48 : SFP ................................................................................................................... 55
Figure 2. 49 : PAT DIAGRAM ............................................................................................. 55
Figure 2. 50 : SAMPLE DRIVE TEST BY NEMO OUTDOOR .......................................... 57
Figure 2. 51 : DETAILE ABOUT THE DRIVE TEST BY NEMO OUTDOOR.................. 57
10. 3
Table of Tables
Table 2. 1 : GSM FREQUENCY BAND ............................................................................... 15
Table 2. 2 : CATEGORY OF ETHERNET............................................................................ 40
Table 2. 3 : T568B STANDARD ........................................................................................... 41
Table 2. 4 : T568A STANDARD ........................................................................................... 41
11. 4
Chapter One
Introduction
1.1 History of Dialog Axiata PLC
Dialog Axiata PLC was established on 27th
of August 1993 as a mobile telecommunication
provider. Dialog was incorporated in 1993 as MTN Networks Private Limited with 90% of
equity through Telekom Malaysia Berhad (TM) and 10% by Capital Maharaja being the local
promoters to the investment. Telekom Malaysia (TM) is Majority owned by the Government
of Malaysia, and is the incumbent and dominant fixed line telecom operator in Malaysia. At
the time of setup, MTN was the 4th entry to the Sri Lankan Mobile market which already had
3 established operators.
In 1995 just after 2 years of incorporation MTN Networks began its commercial operations
under the brand name Dialog GSM by rolling out the first digital network in South Asia using
GSM technology hence offering a superior service compared to analogue networks at the time.
Committed to delivering a world class quality service to its subscribers MTN obtained ISO
9002 certification in 1998 and ISO 9001 in 2001. The company has the distinction on both
occasions, of being the first telecommunications operator in South Asia to obtain certification
at 9002 and 9001 levels respectively.
Year 2001 saw the launch of Dialog Internet thus starting ISP operations by launching GPRS
and MMS services based on existing 2G infrastructure and becoming the first GPRS and MMS
operator in South Asia.
In 2002 MTN Networks announced the launch of satellite mobile telephony services under the
brand DialogSAT the newest pioneering extension to its state-of-the-art service portfolio.
DialogSAT with a groundbreaking partnership with Thuraya satellite mobile telephony
services enables GSM roaming where compatible satellite handset can use the Thuraya
services where Dialog GSM service is not available which includes territorial waters and 99
countries across 3 continents (Europe, North Africa, Middle East and Central Asia).
In 2004 surpassing a milestone Dialog GSM was able to attain 1 million subscriber base and
to commission its 500th 2G base station. In celebration Dialog GSM removed incoming call
12. 5
charges within the network thus increasing the affordability and encouraging mobile
telephony.
1.2 Vision of Dialog Axiata PLC
To be the undisputed leader in the provision of multi-sensory connectivity resulting always,
in the empowerment and enrichment of Sri Lankan lives and enterprises.
1.3 Mission of Dialog Axiata PLC
To lead in the provision of technology enabled connectivity touching multiple human sensors
and faculties, through committed adherence to customer-driven, responsive and flexible
business processes, and through the delivery of quality service and leading edge technology
unparalleled by any other, spurred by an empowered set of dedicated individuals who are
driven by an irrepressible desire to work as one towards a common goal in the truest sense of
the team spirit
Figure 1. 1 : Logo
13. 6
1.4 Present Performance
Dialog is the largest Mobile Service Provider in Sri Lanka. The network offers a variety of
services and currently operates GSM, GPRS, EDGE, UMTS, WCDMA, HSPA, HSPA+, DC-
HSPA+, FD-LTE and TD-LTE network utilizing 2G, 2.5G, 2.75G, 3G, 3.5G, 3.75G and 4G
technologies. It covers most of Sri Lanka with its GSM network. Dialog offers both prepaid and
postpaid mobile services, along with mobile broadband services using the 3.5G network and
postpaid mobile services, along with mobile broadband services using the 4G network. Dialog
offers a variety of value added services such as Ticket booking, WAP, MMS, Closed User Group
services, Mobile banking, e-channeling, Directories, Menu based services (OTA) which are
updated to the SIM card, EZ cash, Ideamart Apps (Powered by Google Apps), Live scores of
cricket matches and International Roaming facilities in over 180 countries while including
special services such as the Voice Notification messages which alert a person on roaming status
and other features such as Call Home and SMS Roaming. Ideamart customers can create their
own apps and in Ideabiz customers can get and give business ideas.
Figure 1. 2 : LOGO OF IDEAMART AND IDEABIZ
16. 9
Chapter Two
2.0 Training Experiences-Technical
I was assigned to Dialog Engineering Access network planning Division during 03months
training period. I was trained 12 weeks at Transmission Project Division. During these periods
I had good experience on the respective field with the help of the Engineers, Engineering
Executive and Technical officers at Dialog. They were really friendly and they taught us what
they knew. They let us use the manuals and other resources which were given for their uses.
Even there were some presentations held for the trainees on technical matters.
I got several opportunity to take part in field works for many sides such as Batticaloa, Ampara,
Baddulla and Monaragala. Then I went to many BTS (Base Transceiver Station) sites to both
roof top and ground based mono-pole towers with the technical officers. To,
Check faults and alarms
Cleaning maintenance of BTS cabinet
Adding new IDU (Indoor Unit)
Replacing IDU
Changing the configurations of the sites
Dropping E1 channels
Replacing microwave links with Fiber links
Check the quality of mobile radio coverage
Adding sites to NMS (Network Management System)
Testing parameters of the site like power consumption and data rate.
Replacing Indoor and Outdoor repeaters.
Drive test Ect.
During these visits I had done on experience with creating E1 cables, RJ45 cables and
configuration of the devices, using the tools like crimpers, power meters etc. we were given
transportation facilities by Dialog for all of these visits.
Although whole 03 months I was assigned to Transmission division I could learn something
related to other divisions such as NOC (Network operating center), Transmission Planning,
RNO (Radio network operation).
17. 10
During this whole training period I experienced lot of activities and theoretical background. I
will try to demonstrate some of them under the following subheadings
2.1 GSM (2G) Network
2.1.1 Introduction to GSM
Global System for Mobile (GSM) is a second generation cellular standard developed
to cater voice services and data delivery using digital modulation.
Tele Services: Includes mobile phones, emergency calling etc.
Data Services: Includes SMS, fax, voicemail, electronic mail.
Supplementary Services: Incoming & Outgoing calls, call forwarding, call hold, call
waiting, conference, etc.
GSM Network is divided into four systems.
Mobile Station (MS)
Base Station System (BSS)
Network Switching System (NSS)
Operation Support Subsystem (OSS)
2G Data Transmission Capacity:
With GPRS (General Packet Radio Service), you have a theoretical transfer
speed of max. 50 kbit/s (40 kbit/s in practice).
With EDGE (Enhanced Data Rates for GSM Evolution), you have a
theoretical transfer speed of max. 1 Mbit/s (500 kbit/s in practice).
2.5G (GPRS).
2.75 (EDGE).
18. 11
2.1.2 GSM Architecture
2.1.3 GSM Network Components
Mobile Station (MS)
Mobile Equipment (ME)
Subscriber Identity Module (SIM)
Base Station Subsystem (BSS)
Base Transceiver Station (BTS)
Base Station Controller (BSC)
Network Switching Subsystem(NSS)
Mobile Switching Center (MSC)
Home Location Register (HLR)
Visitor Location Register (VLR)
Authentication Center (AUC)
Equipment Identity Register (EIR)
Gate way Mobile Services Switching Center (GMSC)
Operation and Support Subsystem (OSS)
Figure 2. 1 : GSM ARCHITECTURE
19. 12
2.1.3.1 Mobile Station (MS)
The Mobile Station (MS) consists of the physical equipment used by a PLMN
subscriber to connect to the network.
The mobile station consists of:
Mobile Equipment (ME)
Subscriber Identity Module (SIM)
2.1.3.1.1 Mobile Equipment (ME)
ME includes radio transceiver, digital signal processors and subscriber identity
module (SIM).
User interface.
Antenna, usually located inside the phone.
Control circuitry.
Voice encoding and Transmission.
Monitoring power and signal quality of surrounding cells for optimum handover.
2.1.3.1.2 Subscriber Identity Module (SIM)
A small smart card, Allows user to send and receive calls and receive other
subscribed services. It contains a micro-controller and storage.
Holds encryption codes needed to identify the subscriber.
Holds Subscriber IMSI number for authentication.
Holds Subscriber’s own information (telephone directory), Accounting information,
and emergency medical information.
Holds Third party applications (banking etc.)
Can be moved from phone to phone.
2.1.3.2 Base Station Subsystem (BSS)
All radio related functions are performed that are required to complete the
connection between MS and the network.
Consists of BTS, BSC
20. 13
2.1.3.2.1 Base Transceiver Station (BTS)
Handle the radio interface to the MS.
BTS is not an intelligent equipment. It is control by a particular BSC.
2.1.3.2.2 Base Station Controller (BSC)
Provides all the control functions and physical links MSC and BTS.
Handover.
Cell configuration data.
Control of RF power level in BTS.
A group of BSCs are controlled by a MSC.
2.1.3.3 Network Switching Subsystem (NSS)
It is responsible for performing call processing and subscriber related functions.
Including following functional units.
2.1.3.3.1 Mobile Switching Center (MSC)
Performing the telephony switching functions for the mobile network.
It controls calls to and from other telephony and data systems.
Such As PSTN (Public Switched Telephone Network).
ISDN (Integrated Services Digital Network)
PLMN (Public Land Mobile Network)
Private network
Other network
Mobility management.
Billing information.
2.1.3.3.2 Home Location Register (HLR)
It is a database which stores permanent data about subscriber.
Such as subscriber’s profile, location information, active status.
Subscriber supplementary services. (e.g. GPRS, MMS, roaming)
Stores and manage all mobile subscriber.
21. 14
2.1.3.3.3 Visitor Location Register (VLR)
VLR is a database that contains temporary information about subscriber.
2.1.3.3.4 Authentication Center (AUC)
The task of the AUC is give the access (authentication) the network to the
authorized subscribers who are attempting to use the network. If there isn’t an
AUC there is no way to block another operator’s subscriber. AUC consists of a
database which is connected to the HLR. So that it AUC provides authentication
parameters and other important parameters (Security Codes) to the protection of
the network of the Company.
2.1.3.3.5 Equipment Identity Register (EIR)
EIR is a database which is containing mobile equipment identify information.
EIR helps to block calls from defective, unauthorized and stolen MS.
2.1.3.3.6 Gate way Mobile Services Switching Center (GMSC)
It is a node used to connect two network.
2.1.3.4 Operation and Support Subsystem (OSS)
The OSS or operation support subsystem is an element within the overall GSM network
architecture that is connected to components of the NSS and the BSC. It is used to control
and monitor the overall GSM network and it is also used to control the traffic load of the
BSS.
2.1.4 GSM Channel
Physical Channel: Each timeslot on a carrier is referred to asa physical channel Physical
channels are used to transmit speech, data or signaling information.
Logical Channel: The other channel type is logical channels. These logical channels are
mapped in to physical channels. Variety of information is transmitted between the MS
and BTS. Different types of logical channels:
Traffic channel
Control Channel
22. 15
GSM Access Scheme and Channel Structure
GSM uses FDMA and TDMA to transmit voice and data.
The uplink channel between the cell phone and the BTS uses FDMA and a specific
frequency band.
The downlink channel between the BTS and the cell phone uses a different frequency
band and the TDMA technique.
There is sufficient frequency separation between the uplink freq. band and the
downlink freq. band to avoid interference.
Each uplink and downlink frequency bands is further split up as Control Channel
(used to set up and manage calls) and Traffic Channel. (used to carry voice)
Uplink and downlink take place in different time slots using TDMA.
Uplink and downlink channels have a bandwidth of 25 MHz
These channels are further split up in a 124 carrier frequencies (1 control channels and
the rest as traffic channels); each carrier frequency is spaced 200 kHz apart to avoid
interference.
These carrier frequencies are further divided by time using TDMA and each time slot
lasts for 0.577 ms.
GSM Frequency Uplink/BTS Downlink/BTS
Band Transmit Receive
900 MHz 935-960 MHz 890-915 MHz
1800 MHz 1805-1880 MHz 1710-1785 MHz
1900 MHz 1850-1910 MHz
1930-
1990 MHz
Table 2. 1 : GSM FREQUENCY BAND
2.1.4.1 GSM Control Channel
Control Channel is used to communicate management data (setting up calls, location)
between BTS and the cell phone within a GSM cell.
Control Channel is used to communicate management data (setting up calls, location)
between BTS and the cell phone within a GSM cell.
23. 16
Only data is exchanged through the control channel. (no voice)
A specific frequency from the frequency band allocated to a cell and a specific time
slot are allocated for the control channel; a single control channel for a cell.
GSM control channels can have the following types:
Broadcast channel.
Common control channel.
Dedicated control channel.
2.1.4.1.1 Broadcast Channel
The broadcast channels (BCH) carry only downlink information and are responsible mainly
for synchronization and frequency correction. This is the only channel type enabling point-to-
multipoint communications in which short messages are simultaneously transmitted to several
mobiles.
It is composed from
Broadcast Control Channel (BCCH) – General information, cell-specific; e.g. local
area code, network operator, access parameters, list of neighboring cells, etc. The
MS receives signals via the BCCH from many BTSs within the same network
and/or different networks.
Frequency Correction Channel (FCCH) – Downlink only; correction of MS
frequencies; transmission of frequency standard to MS; it is also used for
synchronization of an acquisition by providing the boundaries between timeslots
and the position of the first time slot of a TDMA frame.
Synchronization Channel (SCH) –Downlink only; follows the FCCH and frame
synchronization (TDMA frame number) and identification of base station. The
valid reception of one SCH burst will provide the MS with all the information
needed to synchronize with a BTS.
2.1.4.1.2 Common Control Channels
A group of uplink and downlink channels between the MS card and the BTS. These channels
are used to convey information from the network to MSs and provide access to the network.
It is composed of:
Paging Channel (PCH) – Downlink only; the BTS uses this channel to inform the
cell phone about an incoming call; the cell phone periodically monitors this
channel.
24. 17
Random Access Channel (RACH) – is an uplink channel used by the cell phone
to initiate a call; the cell phone uses this channel only when required; if 2 phones
try to access the RACH at the same time, they cause interference and will wait a
random time before they try again; once a cell phone correctly accesses the RACH,
BTS send an acknowledgement.
Access Grant Channel (AGCH) – Downlink only; BTS allocates a TCH or
SDCCH to the MS, thus allowing the MS access to the network.
2.1.4.1.3 Dedicated Control Channel
Responsible for e.g. roaming, handovers, encryption, etc. The DCCHs include the following
channels:
It is comprised from:
Standalone Dedicated Control Channel (SDCCH) – used along with SACCH to
send and receive messages; relays signaling information during call setup before
a traffic channel (TCH) is allocated.
Slow Associated Control Channel (SACCH) – Transmits continuous
measurement reports (e.g. field strengths) in parallel to operation of a TCH or
SDCCH; needed, e.g. for handover decisions; always allocated to TCH or
SDCCH; needed for "non-urgent" procedures, e.g. for radio measurement data,
power control (downlink only), timing advance, etc.; always used in parallel to a
TCH or SDCCH.
Fast Associated Control Channel (FACCH) – used to transmit unscheduled
urgent messages; FACCH is faster than SACCH as it can carry 50 messages per
second, while SACCH and carry only 4.
2.1.4.1.4 GSM Traffic Channel
It is used to carry voice data. There are 2 types of Traffic Channels.
Full rate traffic channel (TCH/F) :
TCH/F allows one time slot per frame for the communication channel
between user and the communication system.
Half rate traffic channel (TCH/H) :
TCH/H allows one time slot per two frames for the communication channel
between user and the communication system.
25. 18
Figure 2. 2 : GSM LOGICAL CHANNEL
2.2 WCDMA (3G) Network
2.2.1 Introduction to WCDMA
3G is the third generation of mobile telecommunications technology. This is based on a set of
standards used for mobile devices and mobile telecommunications use services and networks
that comply with the International Mobile Telecommunications specifications by the
International Telecommunication Union. 3G finds application in wireless voice telephony,
mobile Internet access, fixed wireless Internet access, video calls and mobile TV.
3G telecommunication networks support services that provide an information transfer rate of
at least 200 kbit/s. Later 3G releases, often denoted 3.5G and 3.75G, also provide mobile
broadband access of several Mbit/s to smartphones and mobile modems in laptop computers.
This ensures it can be applied to wireless voice telephony, mobile Internet access, fixed
wireless Internet access, video calls and mobile TV technologies.
A new generation of cellular standards has appeared approximately every tenth year since 1G
systems were introduced in 1981/1982. Each generation is characterized by new frequency
bands, higher data rates and non–backward-compatible transmission technology. The first 3G
networks were introduced in 1998 and fourth generation "4G" networks in 2008.
26. 19
The following standards are typically branded 3G:
The UMTS (Universal Mobile Telecommunications Service) system, first offered in
2001, standardized by 3GPP, used primarily in Europe, Japan, China (however with a
different radio interface) and other regions predominated by GSM (Global Systems for
Mobile) 2G system infrastructure. The cell phones are typically UMTS and GSM
hybrids. Several radio interfaces are offered, sharing the same infrastructure:
The original and most widespread radio interface is called W-CDMA (Cell
Division Mobile Access).
The TD-SCDMA radio interface was commercialized in 2009 and is only
offered in China.
The latest UMTS release, HSPA+, can provide peak data rates up to 56 Mbit/s
in the downlink in theory (28 Mbit/s in existing services) and 22 Mbit/s in the
uplink.
The CDMA2000 system, first offered in 2002, standardized by 3GPP2, used
especially in North America and South Korea, sharing infrastructure with the
IS-95 2G standard. The cell phones are typically CDMA2000 and IS-95
hybrids. The latest release EVDO Rev B offers peak rates of 14.7 Mbit/s
downstream.
2.2.2 Security of WCDMA
3G networks offer greater security than their 2G predecessors. By allowing the UE (User
Equipment) to authenticate the network it is attaching to, the user can be sure the network is
the intended one and not an impersonator. 3G networks use the KASUMI block cipher instead
of the older A5/1 stream cipher. However, a number of serious weaknesses in the KASUMI
cipher have been identified.
In addition to the 3G network infrastructure security, end-to-end security is offered when
application frameworks such as IMS are accessed, although this is not strictly a 3G property.
27. 20
2.3 LTE (4G) Network
2.3.1 Introduction to 4G
4G is the fourth generation of mobile telecommunications technology, succeeding 3G. A 4G
system must provide capabilities defined by ITU in IMT Advanced. Potential and current
applications include amended mobile web access, IP telephony, gaming services, high-
definition mobile TV, video conferencing, 3D television, and cloud computing.
Two 4G candidate systems are commercially deployed: the Mobile WiMAX standard, and the
first-release Long Term Evolution (LTE) standard (in Oslo, Norway, and Stockholm, Sweden
since 2009). It has however been debated if these first-release versions should be considered
to be 4G or not, as discussed in the technical definition section below.
In the United States, Sprint has deployed Mobile WiMAX networks since 2008, while
MetroPCS became the first operator to offer LTE service in 2010. USB wireless modems were
among the first devices able to access these networks, with WiMAX smartphones becoming
available during 2010, and LTE smartphones arriving in 2011. 3G and 4G equipment made
for other continents are not always compatible because of different frequency bands. Mobile
WiMAX is not available for the European market as of April 2012.
2.3.2 4G FDD AND TDD
Figure 2. 3 : FDD and TDD METHOD
28. 21
2.3.2.1 Frequency Division Duplex (FDD)
FDD requires two separate communications channels. In networking, there are two cables.
Full-duplex Ethernet uses two twisted pairs inside the CAT5 cable for simultaneous send and
receive operations.
Wireless systems need two separate frequency bands or channels (Figure). A sufficient amount
of guard band separates the two bands so the transmitter and receiver don’t interfere with one
another. Good filtering or duplexers and possibly shielding are a must to ensure the transmitter
does not desensitize the adjacent receiver.
FDD requires two symmetrical segments of spectrum for the uplink and downlink channel
2.3.2.2 Time Division Duplex (TDD)
TDD uses a single frequency band for both transmit and receive. Then it shares that band by
assigning alternating time slots to transmit and receive operations (Figure2.0.0). The
information to be transmitted—whether it’s voice, video, or computer data—is in serial binary
format. Each time slot may be 1 byte long or could be a frame of multiple bytes.
Figure 2. 5 : TDD METHODS
Figure 2. 4 : FDD METHODS
29. 22
2.4 Transmission and Operations Division
2.4.1 Base Transceiver Station (BTS)
A base transceiver station (BTS) is a piece of equipment that facilitates wireless
communication between user equipment (UE) and a network. UEs are devices like mobile
phones (handsets), WLL phones, and computers with wireless Internet connectivity.
BTS connects MS with the BSC of the network. In BTS, there are sector antennas and MW
antennas to transmit and receive signals with the MS and another connection by means of a
micro wave link or fiber link to connect with the network. Figure 2.3 shows the basic
components of a BTS site.
2.4.1.1 Sector antennas
These are antennas which are used for transmitting and receiving 2G, 3G and 4G signals with
the MS. These are may be one or two or three or four on a telecommunication tower. Most
commonly, Dialog uses three sector antennas. In some special cases, they use the other number
of sector antennas. These sector antennas can be categorized as
Single band antenna (only 900 MHz or 1800 MHz or 2100 MHz)
Dual band antenna (any of two)
Tri band antenna (900 MHz, 1800 MHz and 2100 MHz)
In general the angle between two sector antennas is 120 degrees if they are serving for an area
where the population has been spread with no significant variations over the region. But according
to the geographical considerations tilting angle and azimuth angle can be changed.
Figure 2. 6 : BASE TRANSCEIVER STATION
30. 23
When sector antennas are installed the first sector is placed to the north side and named as
‘A’ if it is for 2G (900 MHz). The second sector which is placed 120 clockwise to the first
one is named as ‘B’. And the last one is named as ‘C’.
For 2G (1800 MHz) the sectors are named as ‘P’, ‘Q’, and ‘R’. For 3G, the sectors are named
as ‘W’, ‘X’ and ‘Y’. And for 4G the sectors are named as ‘G’, ‘H’, and ‘I’.
2.4.1.2 Microwave Antenna
This is also called as drum antenna as its physical shape is like a drum. For microwave
communication there should be two microwave antennas at both ends of the link. They should
have line of sight (LOS). The area where the signal is spread is called lobes. There are two
lobes in an antenna.
The main lobe contains the highest energy. As the power consumption should be kept in a
lower level, main lobe of one antenna should collapse with the other antenna. The process of
collapsing is called alignment.
The antenna is used to directionally radiate the microwave power emitted by the transmitter
ODU and transmit the microwave power received to the receiver ODU. Commonly used
microwave antenna includes parabolic antenna and cassegrainian antenna. The diameter of the
Figure 2. 7 : SECTOR ANTENNA
31. 24
microwave antenna includes 0.3, 0.6, 1.2, 1.8, 2.0, 2.4, 3.0, 3.2m. There are many types of
antennas. Antenna of different diameters has different specifications for different frequencies.
Below Figure shows the Microwave Antenna:
2.4.1.2.1Antenna Alignment
Figure 2. 8 : MICROWAVE ANTENNA
Figure 2. 9 : MICROWAVE ANTENNA ANTENNA
32. 25
2.4.1.2.2 Microwave Antenna Radiation patterns
2.4.1.2.3 Polarization
The polarization defines the way of movement of the wave. Point- to- point microwave paths
can be either vertically or horizontally polarized. The vertical polarization is used as default
since it’s less sensitive to rain.
The polarization must be identical in one hop. Both of the antennas should be in same
polarity.
Figure 2. 10 : SIDE VIEWOF MWANTENNA RADIATION
Figure 2. 11 : : VERTICAL AND HORIZONTAL POLARIZATION
33. 26
2.4.1.3 Outdoor Unit (ODU)
2.4.1.3.1 ODU Function
ODU supports all bands (6 /7/8/11/13/15/18/23/26/28/32/ 38 GHz). It is mainly used to
implement the frequency conversion and amplification of signals. The specific functions are
as follows:
In the transmit direction, ODU performs up conversion and amplification for analog
IF signal received from IDU (300-450 MHz) for several times and converts it to RF
signal at a specific frequency. Then it forwards the RF signal to the antenna. (to GHz
ranges)
In the receive direction, ODU performs down conversion and amplification for RF
signal received from the antenna for several times and converts it to analog IF signal
at a specific frequency. Then it sends the IF signal to the IDU.
Provides the control channel to IDU, being controlled and managed by IDU.
Provides ATPC function.
Provides various alarm and performance messages.
Provides the detection of ODU transmitting power and RSSI.
Supports the detection of ODU temperature.
Supports the query of ODU equipment information.
Figure 2. 12 : OUT DOOR UNIT
34. 27
2.4.1.3.2 ODU Working Principle
Signal processing in transmit direction, the multiplexing unit separates the input signal of the
IDU into IF service transmit signal and power supply signal. The ODU converts the IF service
transmit signal into RF transmit signal by performing the up conversion, filtering and
amplification of the IF service transmit signal. The amplified RF transmit signal is sent to the
antenna via the separating & filtering unit.
Signal processing in receive direction, the separating & filtering unit separates the antenna
signal to get the RF input signal. The ODU converts the RF signal into IF service receive signal
by performing the down conversion, filtering and amplification of the RF signal. Then the IF
service receive signal is sent to the multiplexing unit. The multiplexing unit forwards the IF
service receive signal to the IDU through the IF cable.
Figure 2. 13 : BLOCK DIAGRAM OF ODU
35. 28
2.4.1.3.3 ODU Interface
Depending of ODU mount on MW antenna there are two types
1. Direct Mount
2. Separate Mount
Figure 2. 14 : ODU INTERFACE
Figure 2. 15 : DIRECT MOUNT
36. 29
ODU does not need an external power supply for the process. Power is taken from same IF
cable. Another important thing is the protection mode. When designing a site they decide
whether to use 1+0 protection or 1+1 protection or 2+0 XPIC or 2+2 XPIC.
1 + 0 protection: This is where no alternative devices are present. There is only
one ODU. This is used when the risk of device being malfunctioning is low.
1 + 1 protection: At this type an alternative or standby device is present ready
to bypass the load if the main device fails. This kind of protection is used in
most of the sites.
2 + 0 XPIC: It is used when dual polarized antenna is present. No any
alternative or standby ODU. One ODU is used for vertical polarization and
another ODU is for horizontal polarization.
2 + 2 XPIC: It is also used when dual polarized antenna is present. But there
are two alternative or standby ODUs for each horizontal and vertical
polarization ODUs.
Figure 2. 16 : SEPARATE MOUNT
37. 30
2.4.1.4 Indoor Unit (IDU)
An IDU, or In-Door Unit, is a telecommunication device that is used in mobile communication
and Internet service to receive and decode transmissions. An IDU is responsible for receiving
the mobile communication signals transmitted by service provider and decoding them in order
to mobile communication or Internet access.
There are two types of Indoor Units (IDU) which are using either PDH (Plesiochronous digital
hierarchy) or SDH (Synchronies digital hierarchy) hierarchies. IDUs using PDH hierarchy
consist of two parts, a modem and a multiplexer. Both modulation and demodulation are done
by the modem. IF cable is connected to the modem. Electrical cables which carry E1s are
coming out from the IDU. IDUs using SDH hierarchy only have a modem. Separate
multiplexer have to be used for the E1 dropping. Connection between IDU and multiplexer is
done via fibers due to the higher data rate.
IDU consist,
Multiplexing modem Unit (MMU): It deals with all the multiplexing and modulating
activities.
Traffic Unit (TRU): Main functions of the TRU are regenerate the signaling signal,
Terminate the signaling signal, Transmit the signaling signal to the MMU, Receive the
signaling signal from MMU.
Access Module Magazine (AMM): It acts as a housing magazine for both the modem
unit and traffic unit.
Switch Multiplexer Unit (SMU): The SMU acts as multiplexing and De multiplexing
switch and control the 1+1 protection system.
DC Distribution Unit (DDU): This unit is used for the primary DC power distribution.
Fan Unit: In order to minimize the heat generated, a cooling method has to be provided.
38. 31
2.4.1.5 Cards
In BTS cabinet lot of cards are used for several purposes. Some of those names are given
below
PM Power Module
RPUA Radio Power Unit A
RCUA Radio Core Cross Unit A
RMUB Radio Modem Unit B
RMUC Radio Modem Unit C
RTUA Radio Traffic Unit A
Figure 2. 17 : BTS CABINET
39. 32
RFA Radio Fan Unit
RTUME/RTUMO Radio Traffic Unit
GTMU GSM Transmission Management Unit
WMPT WCDMA Main Processing and Transmission Unit
WBBP WCDMA Base Band Processing Unit
LMPT LTE Main Processing and Transmission Unit
UMPT Universal Main Processing and Transmission unit
LBBP LTE Base Band Processing Unit
UPEU Universal Power and Environment Unit
UEIU Universal Environment Interface unit
UELP Universal E1/T1 Lightning Protection Unit
UFLP Universal FE/GE Lightning Protection Unit
UTRP Universal Transmission Processing Unit
2.4.1.6 Cell splitting
Cell splitting is the process of dividing the radio coverage of a cell site in a wireless
telephone system into two more new cell sites. Cell splitting may be performed to provide
additional capacity within the region of the original cell site.
Figure 2. 18 : CELL SPLITTING
40. 33
This diagram shows the process of cell splitting that is used to expand the capacity (number of
channels) of a mobile communication system. In this example, the radio coverage area of large
cells sites are split by adjusting the power level and using reduced antenna height to cover a
reduced area. Reducing the radio coverage area of a cell site by changing the RF boundaries
of a cell site has the same effect as placing cells farther apart, and allows new cell sites to be
added.
Advantages of cell splitting:
Because cells are smaller, system capacity increases. Also, less power used by
mobiles and base stations.
Disadvantages:
Handoffs become more common. To prevent handoffs and dropped calls, umbrella
cells are needed for high speed traffic.
Figure 2. 19 : GRAPHICAL DIAGRAM OF CELL SPLITTING
41. 34
2.4.2 Towers
In the GSM communication, we use GSM signal to connect with mobile station (MS) and
microwave signal is used for interconnection towers. Normally GSM towers are made
Steel. Because antennas which are mount top of the tower are heavy weight. Therefore the
towers should be well-set. Then we can see various kinds of towers in the telecommunication
field. Normally low height towers are used for urban areas and very height towers are used for
remote areas.
Classified by body structure.
Self-support tower.
Guyed mast tower.
Monopole.
Pole.
Classified by number of legs.
Three leg tower.
Four leg tower.
Classified by tower location.
Roof top tower.
Green field tower.
2.4.2.1 Green Field Tower
Also referred to as a self-support tower, the green field tower affords the greatest flexibility
and is often used in heavy loading conditions. It is typically three sided or four sided.
Figure 2. 20 : GREEN FIELD TOWER
42. 35
2.4.2.2 Self-support Tower (SS/ GBT – Single Support/ Ground Based Tower(40m-
SS,50m-SS,60m-SS,70m-SS,80m-SS,120m-SS,170m-SS))
2.4.2.3 Monopole
Tower (RTMP Roof Top Mono Pole (RT+6m, RT+9m) GBMP –Ground Based Mono Pole
(30m-GBMP))
Figure 2. 21 : SELF-SUPPORT TOWER
Figure 2. 22 : MONOPOLE TOWER
43. 36
2.4.2.4 Guyed Mast Tower (60m-GM,80m-GM,120m-GM,170m-GM)
A
guyed master tower is a tower
structure which consists of a free-
standing basement, in most cases of concrete or of lattice steel with a guyed mast on the top.
The anchor basements of the guyed mast can be on the top of the tower or on the ground.
2.4.2.5 Roof-Top Tower
Rooftop towers are contain low height. Because these
towers are set up on the building.
Therefore Rooftop tower are set up for the urban areas.
Figure 2. 23 : GUYED MASTER TOWER
Figure 2. 24 : ROOF-TOP TOWER
44. 37
2.5 Transmission Technique
2.5.1 TDM
Time-division multiplexing (TDM) is a method of transmitting and receiving independent
signals over a common signal path by means of synchronized switches at each end of the
transmission line so that each signal appears on the line only a fraction of time in an alternating
pattern. In TDM, incoming signals are divided into equal fixed-length time slots. After
multiplexing, these signals are transmitted over a shared medium and reassembled into their
original format after de-multiplexing. Time slot selection is directly proportional to overall
system efficiency.
Time division multiplexing (TDM) is also known as a digital circuit switched.
2.5.2 TDM-PDH
Plesiochronous digital hierarchy (PDH) is a technology used in telecommunications
networks to transport large quantities of data over digital transport equipment such as
fiber optic and microwave radio systems.
"Plesiochronous" is the word that describes operations that are almost, but not quite,
in synchronization - in other words, almost synchronous.
The E1/T1 carriers are the first level of multiplexing in PDH.
Figure 2. 25 : HIERARCHY OF PDH
45. 38
Multiplex levels,
1. 2.048 Mbit/s
2. 8.448 Mbit/s
3. 34.368 Mbit/s
4. 139.264 Mbit/s
2.5.3 SDH VS PDH
PDH
The data rate is controlled by a clock in the equipment generating the data. The rate is
allowed to vary by ±50 ppm of 2.048 kbit/s (according to ITU-T recommendation).
This means that different data streams can (and probably do) run at slightly different
rates to one another.
Used in 2Mb, 8Mb, 34Mb and 140 Mb systems only.
No world standard on digital format (three incompatible regional standards - European,
North American and Japanese).
No world standard for optical interfaces. Networking is impossible at the optical level.
SDH
Figure 2. 26 : PDH LEVELS AND BIT RATES
46. 39
Synchronous digital hierarchy (SDH) and synchronous optical network (SONET) refer
to a group of fiber-optic transmission rates that can transport digital signals with
different capacities. Overview. This tutorial discusses synchronous transmission
standards in world public telecommunications networks.
Used in STM-1 (155.52Mbps), STM-4(622.08Mbps), STM-16 (2.5Gbps) and STM-
64 (10Gbps) transmission systems.
World standard on digital format (three incompatible regional standards - European,
North American and Japanese).
World standard for optical interfaces. Networking is possible at the optical level.
2.5.4 Ethernet (IP)
Ethernet is a family of computer networking technologies commonly used in local area
networks (LANs) and metropolitan area networks (MANs). It was commercially
introduced in 1980 and first standardized in 1983 as IEEE 802.3, and has since been
refined to support higher bit rates and longer link distances.
Higher level network protocols like Internet Protocol (IP) use Ethernet as their
transmission medium.
Data travels over Ethernet inside protocol units called frames.
Ethernet evolved to include higher bandwidth, improved media access control
methods, and different physical media. The coaxial cable was replaced with point-to-
point links connected by Ethernet repeaters or switches.
2.5.4.1 Category of Ethernet Cables
The Ethernet standard is well established. It is used in a variety of different environments and
accordingly there is a variety of different types of cable over which it operates.
It is possible not only for Ethernet to operate at different speeds, but there are different varieties
of cable that can be used within the same speed category. In order to ensure that Ethernet
operates correctly, the types of cable, their electrical conditions and the maximum lengths over
which they may operate are specified.
47. 40
Category Cable Type Max. Data
Transmission
Speed(Mbps)
Max.
Bandwidth
(MHz)
Category 3 UTP 10 16
Category 5 UTP 10/100 100
Category 5e UTP 1000 100
Category 6 UTP or STP 1000 250
Category 6a STP 10,000 500
Category 7 SSTP 10,000 600
Table 2. 2 : CATEGORY OF ETHERNET
Ethernet ports accept cables with RJ-45 connectors.
2.5.4.2 RJ-45 Connector
RJ45 is a standard type of connector for network cables.
RJ45 connectors are most commonly seen with Ethernet cables and networks.
RJ45 conductor data cable contains 4 pairs of wires each consists of a solid colored
wire and a strip of the same color.
There are two wiring standards for RJ45 wiring.
Pin number designations.
There are pin number designations for each color in T-568A and T-568B
Figure 2. 27: RJ-45 CONNECTOR
48. 41
Table 2. 3 : T568B STANDARD
Table 2. 4 : T568A STANDARD
T-568 B
Pin Color Pin Name
1 Orange/White TX+
2 Orange TX-
3 Green/White RX+
4 Blue Not Used
5 Blue/W hite Not Used
6 Green RX-
7 Brown/White Not Used
8 Brown Not Used
T-568 A
Pin Color Pin Name
1 Green/White RX+
2 Green RX-
3 Orange/White TX+
4 Blue Not Used
5 Blue/White Not Used
6 Orange TX-
7 Brown/White Not Used
8 Brown Not Used
49. 42
To create a straight-through cable, we’ll have to use either T-568A or T-568B on
both ends of the cable.
To create a cross-over cable, we'll wire T-568A on one end and T-568B on the other
end of the cable.
The straight-through cables are used when connecting Data Terminating Equipment
(DTE) to Data Communications Equipment (DCE), such as computers and routers to
modems (gateways) or hubs (Ethernet Switches).
The cross-over cables are used when connecting DTE to DTE, or DCE to DCE
equipment; such as computer to computer, computer to router; or gateway to hub
connections.
The DTE equipment terminates the signal, while DCE equipment do not.
Figure 2. 28: WIRING STANDARD OF BOTH T568A AND T568B
Figure 2. 29 : RJ45 CONNECTION
50. 43
2.5.4.3 Making Ethernet Cables
Cut into the plastic sheath about 1 inch from the end of the cut cable. The crimping
tool has a razor blade that will do the trick with practice.
Unwind and pair the similar colors.
Pinch the wires between your fingers and straighten them out as shown. The color
order is important to get correct.
Use scissors to make a straight cut across the wires 1/2 inch from the cut sleeve to the
end of the wires.
Push the wires into the connector.
Carefully place the connector into the Ethernet crimper and cinch down on the
handles tightly.
The copper splicing tabs on the connector will pierce into each of the eight wires.
There is also a locking tab that holds the plastic sleeve in place for a tight
compression fit.
Figure 2. 30 : CRIMPER TOOL
51. 44
2.6 Microwave Transmission
2.6.1 Microwave Introduction
"Microwaves" is the range of radio frequencies between about 1 GHz (one gigahertz,
or one billion oscillations per second) and about 300 GHz. For comparision, television
transmissions normally occupy frequencies below the microwave region, from about
50 MHz to 600 MHz (one Megahertz is one million oscillations per second, one GHz
is 1,000 MHz). Cellular telephones operate in two bands, one from about 800 to 900
MHz and another around 1.8 to 1.95 GHz.
We can define “Microwaves” are electromagnetic radiations in the frequency range
300MHz to 300 GHz and wave length of 1mm to 1m.
Generally for telecommunication 3GHz-30GHz range is needed.
Microwaves are widely used for point-to-point communications.
Microwave communication is the transmission of signals by sending microwaves,
either directly or via satellite. The receivers for microwave signals are usually disc-
shaped antennae from a foot to a few feet across and are often seen installed in any
locations.
Figure 2. 31 : MICROWAVE COMMUNICATION
52. 45
2.6.2 Microwave Propagation
Various phenomena associated with propagation, such as multipath fading and
interference affect microwave radio performance.
LOS - line of sight is the most important characteristic of Microwave link.
Any obstacle in the LOS makes the link unavailable.
The signal propagating in free space is attenuated and its energy is diffused to space,
this is called Free Space loss.
FSL depends on frequency and distance of the path falls under the formula.
Lfs = 92.45 + 20 log (dist * freq).
2.6.3 Fading Problem
Following major phenomenon affect MW Link
Reflection
Refraction
Diffraction
Scattering
Absorption
2.6.3.1 Reflection
Reflection is one of the major factors that affect MW link on lakes or smooth surface
Ex: water body.
Reflected Wave can have different phase and amplitude as compared to original wave.
Thus, this causes fading of signal at receiver and this fading is called Multi Path Fading.
To overcome this problem, we either adjust antenna heights at two ends to avoid
major source of reflection or to reduce its intensity.
53. 46
2.6.3.2 Refraction
Theory says that MW / electromagnetic waves travel in a straight line and they do so
in vacuum. But when it comes to atmosphere it undergoes the effect of refraction.
Density in atmosphere is not uniform. It varies from one place to another. As we all
know that light ray bends towards or away from normal as it moves from higher
density medium to lower or vice versa.
Figure 2. 32 : REFELECTION ON EART
Figure 2. 33 : REFLECTION ON BUILDING AND AIR LINE PATH
Figure 2. 34 : REFRACTION
54. 47
2.6.3.3 Diffraction
The Microwave signals and Radio signals may also undergo diffraction. It is found that
when signals encounter an obstacle they tend to travel around them. This can mean that
a signal may be received from a transmitter even though it may be "shaded" by a large
object between them. This is particularly noticeable on some long wave broadcast
transmissions.
2.6.3.4 Scattering
Scattering happens when an RF signal strikes an uneven surface (for example by
irregularities in the propagation medium, particles, or in the interface between two media)
causing the signal to be scattered. The resulting signals are less significant than the
original signal.
Scattering = Multiple Reflections
Figure 2. 35 : DIFFRACTION
55. 48
.
2.6.3.5 Absorption
Above 10 GHz, absorption in atmosphere becomes dominant. Rain droplets become
comparable to wavelength. Humidity or gas can affect as well. This absorption can be
2 dB/Km or can be as high as 3 dB/Km in case of rain. Vertical polarization is less
sensitive to the rain.
Figure 2. 36 : SCATTERING
56. 49
2.6.4 Protection Mode
2.6.4.1 Protection Configurations
Several protection and diversity configuration are available
Hot Stand-By (HSB)
Space Diversity (SD)
Frequency Diversity (FD)
Figure 2. 37 : HOT STAND BY
Figure 2. 38 : SPACE DIVERSITY
Figure 2. 39 : PACE DIVERSITY
57. 50
2.7 Optical Fiber Transmission
2.7.1 Introduction to Optical Fiber Communication
Fiber-optic communication is a method of transmitting information from one place
to another by sending pulses of light through an optical fiber. The light forms
an electromagnetic carrier wave that is modulated to carry information.
The process of communicating using fiber-optics involves the following basic steps:
Creating the optical signal involving the use of a transmitter, relaying the signal
along the fiber, ensuring that the signal does not become too distorted or weak,
receiving the optical signal, and converting it into an electrical signal.
The frequency of Light at 1014 to 1015 Hz.
2.7.2 How Optical Fiber works
The concepts of reflection and refraction are important in the design of Optical Fiber
and has a key part in how Optical Fibers Works.
The law of reflection states that a beam of light striking a flat surface would be
reflected at the same angle. That would also mean the angle of incidence is also
equivalent to the angle of reflection.
Light travels along a fiber cable by a process called “Total Internal Reflection”, this is
made possible by using two types of glass which have different refractive indexes.
The inner core has a high refractive index and the outer cladding has a low refractive index.
2.7.3 Optical Fiber Cables
An optical fiber cable is a cable containing one or more optical fibers that are used to carry
light. The optical fiber elements are typically individually coated with plastic layers and
contained in a protective tube suitable for the environment where the cable will be deployed.
Basically there are two types of fiber
1. Single mode fiber.
2. Multi-mode fiber.
58. 51
2.7.3.1 Single mode fiber
Single mode Fiber Cables are the best choice for transmitting data over long distances.
They are usually used for connections over large areas and it has a higher bandwidth
than multimode cables to deliver up to twice the throughput.
Single mode fiber is used for both interbuilding and intrabuilding backbone cable. Single
mode fiber will deliver data rates up to 10 Gbps with a bandwidth of 20 GHz. Its operating
wavelengths are 1310 nm and 1550 nm.
Single mode fiber's primary uses are full motion video and any applications requiring
extremely high bandwidth.
2.7.3.2 Multi-mode fiber
Multi-mode optical fiber is a type of optical fiber mostly used for communication over
short distances, such as within a building or on a campus. Typical multimode links
have data rates of 10 Mbit/s to 10 Gbit/s over link lengths of up to 600 meters (2000
feet).
They are typically used for data and audio/visual applications in local-area networks
and connections within buildings so they are used for voice, data, security, and video
systems.
Figure 2. 40 : SINGLE MODE FIBER
59. 52
2.7.4 Advantages of Optical Fiber
Immunity to Electromagnetic Interference.
High Channel Capacity; much wider bandwidth (10 GHz).
Data Security.
Non Conductive Cables.
Eliminating Spark Hazards.
Ease of Installation.
High Bandwidth over Long Distances.
Light Weight.
Thinner.
Figure 2. 41 : MULTI-MODE FIBER
Figure 2. 42 : DIFFERENT WITH MULTI-MODE AND SINGLE
MODE FIBER
Figure 2. 43 : CROSS SECTION OF FIBER CABLE
60. 53
2.7.5 Disadvantages of Optical Fiber
High investment cost.
Need for more expensive optical transmitters and receivers.
More difficult and expensive to splice than wires.
More expensive to repair/maintain.
2.7.6 Fiber Connectors
There are several types of fiber connectors. The following types of fiber connectors are mostly
used in telecommunication.
Lucent Connector (LC Connector).
Ferrule Connector. (FC Connector)
Figure 2. 44 : LC CONNECTOR
Figure 2. 45 : FC CONNECTOR
61. 54
Subscriber Connector. (SC Connector)
Straight Tip Connectors. (ST Connector)
2.7.7 SFP (Small Form Factor Pluggable)
The small form-factor pluggable (SFP) is a compact, hot-pluggable transceiver used for
both telecommunication and data communications applications. The form factor and
electrical interface are specified by a multi-source agreement (MSA). It interfaces a network
device motherboard (for a switch, router, media converter or similar device) to a fiber
optic or copper networking cable.
Figure 2. 46 : SC CONNECTOR
Figure 2. 47 : ST CONNECTOR
62. 55
2.8 PAT Test and Drive Test
2.8.1 Preliminary Acceptance Test (PAT)
Site installations are done by external subcontractors. Before accepting that by Dialog it should
be checked for the proper installation. This is called as Preliminary Acceptance Test. Several
checkups are done to ensure proper installation like,
Proper functionality of alarms.
Correct VSWR level of feeders. ( ≤1.4 )
Correct receiving and transmitting power.
Proper grounding of the site.
Tilt, height and azimuth of sector antennas as planning division said.
Proper labeling of cables.
Figure 2. 48 : SFP
Figure 2. 49 : PAT DIAGRAM
63. 56
2.8.2 Drive Test
Drive testing is a method of measuring and assessing the coverage, capacity
and Quality of Service (QoS) of a mobile radio network.
The technique consists of using a motor vehicle containing mobile radio network air
interface measurement equipment that can detect and record a wide variety of the
physical and virtual parameters of mobile cellular service in a given geographical area.
To verify that new sides are performing as expected.
Also drive test is done for customer complaints and optimizations are done according
to the result.
To drive test we can use any Outdoor tool in Dialog we used “NEMO Outdoor”.
The data set collected during drive testing field measurements can include information
such as
Signal intensity.
Signal quality.
Service level statistics.
Call statistics.
QOS information.
Hand over information.
Neighboring cell information.
GPS location coordinates.
Dropped calls.
Block calls.
Interference.
RX signal reduction.
64. 57
Figure 2. 50 : SAMPLE DRIVE TEST BY NEMO OUTDOOR
Figure 2. 51 : DETAILE ABOUT THE DRIVE TEST BY
NEMO OUTDOOR
65. 58
Chapter Three
Training experiences management
3.1 Administrative and office practices
I was assigned to train at Dialog Engineering Division in Ampara. It has well organized
schedule for everyone who works at Dialog Engineering Division.
Each one who works at Dialog always try put their maximum effort to develop the company
to a good high level and every time they concern about their company reputation. Total office
environment is fully neat full. Every telecommunication equipment is properly named and
placed at proper places. The 5-s is highly used to maintain the neatness of the company.
The working environment is joyful and very friendly. There were no big distinction between
Engineers, Engineering Executive, Technical officers and other staff. In this environment,
there are no masters but only leaders who lead work by example. Managers don’t have to force
people to do this and that, instead they only have to point out what has to be done and they
perform it as of something of their own. And to work punctually and active lot of facilities are
also provided.
In every division, they are taking meetings weekly in order to get fresh ideas from their
workers to level up their tasks. Staff meetings also held from two weeks to integrate ideas with
all the divisional members.
3.2 SECURITY AND SAFETY
During the training period at Dialog Engineering Division we had to follow some safety
precautions for ensure proper safety for our own protection. Engineers, Engineering
Executive and Technical officers always advised us how to prevent from such an accident.
Some of procedures are given below
Required warning signs (e.g. Danger stack gas, danger high voltage) must be
properly posted.
Trained and qualified person should be allowed to install or replace equipment.
Do not work alone if potentially hazardous conditions exist.
Use authorized equipment to perform maintenance work.
Do not perform any action that creates a potential hazard to people or makes
equipment unsafe.
66. 59
Chapter Four
4.1 SUMMARY
The industrial training period is very useful for our future, because it provides us to how to
work with others as a professional engineer. It provides us a better idea to select our future
carrier path and to identify our weak points. Also we can identify to succeed in the industry
what are the areas we have to improve.
So, I gained a lot of technical experiences about Telecommunication Industry. I also got a
chance to familiar with the management processes of them as well. During this period I got
the chance to participate several workshops those are conducted specially for Trainees by the
Engineers who are working at the Division.
During this time I was able to learn how the things that I learnt in the lecture room are
practically applied. At the Dialog I was able to join with engineer’s work. During my training
I was familiar to that software Such as Map Info.
At the first day of the training period, I was assigned to the Access Network Planning section
which takes care of all the future planning’s regarding the Access Network. All my 12 weeks
were dedicated to Access Network Planning section and I got lots of practical experiences
during that time. At this time I was familiar to transmission equipment.
4.2 CONCLUSION
It was a great opportunity for me to obtain the training at Dialog Company because it is the
most popular mobile telecommunication operator in Sri Lanka.
Dialog Axiata PLC is a widely spread mobile partner in Sri Lanka. One can argue that it
is the most popular and used service provider in communication field in Sri Lanka. I
selected Dialog as my first training location under the field of telecommunication and to
acquire good knowledge of the field. 3 months at Dialog was a good experience in
getting a good knowledge on telecommunication. But the time was not enough to take it
to a sound position. The reason behind that is the attention was taken by 6 months
industrial training students over 3 months training. Any way than working more on new
technical stuffs, I was able to gather much of theoretical background. It would have much
67. 60
better if every trainee got the same attention from the working staff inspire of their
institute.
When talking about the industrial training for the degree programme it is a vital aspect
in building a good engineer to the competitive society. It may uphold the attitudes
towards the industry and will help to use the skills and knowledge with the practical
work. As this is my 1st industrial training I got to know how the communication skills,
groups work and other social aspects got more attention along with the educational or
theoretical knowledge. When leaving outstations we had to manage our selves and those
life experiences added huge value to my training. So this training is a very important in
bringing up a good engineer.
In that period I got the opportunity to work with executive staff such as Regional Manager,
Engineers and Engineering Executive. All of them gave me to good support to success my
industrial training.
Finally I conclude that I was able to success my training at the Dialog Axiata PLC. I must
appreciate NAITA and University training division for their help to make my industrial
training success.
68. 61
References
Official Dialog Axiata PLC. website, 15.05.2015, www.dailog.lk
Michel Mouly and Marie-Bernadette Pautet, 1992, “The GSM system for
mobile communications”
Ericsson, Huawei and ZTE instrument manuals
GSM traffic channels, 18.05.2015, http://www.rfwireless-
world.com/Terminology/GSM-traffic-channel-TCH-FS-HS.html
Cellular Technology, 21.05.2014,
http://www.radioelectronics.com/info/cellulartelecomms/
http://www.wirelesscommunication.nl
http://www.pcmag.com/encyclopedia/term
DOC 0085 (e) - 01.06.2011/01 - Mikron SA Agno - RAN
69. I
Abbreviations
AUC Authentication Center
BSC Base Station Controller
BSS Base Station System
BTS Base Transceiver System
EIR Equipment Identity Register
GMSC Gateway MSC
MSC Mobile services Switching Center
HLR Home Location Register
NMC Network Management System
OSS Operation and Support system
UE User Equipment
MS Mobile Station
NSS Network Switching System
VLR Visitor Location Register
OMC Operation and Maintenance Center
2G 2nd Generation
3G 3rd Generation
4G 4th Generation
IP Internet Protocol
IF Intermediate Frequency
DCE Data Communication Equipment
DTE Data Terminating Equipment
CDMA Code Division Multiple Access
GPRS General Packet Radio Service
GPS Global Positioning System
GSM Global System for Mobile Communication
MMS Multi-media Message Service
INOC Intelligent Network Operation Centre
PDH Plesiochronous Digital Hierarchy
QOS Quality of Service
PM Power Module
70. II
RPUA Radio Power Unit-A
RCUA Radio Core Cross Unit-A
RMUB Radio Modem Unit-B
RMUC Radio Modem Unit-C
RTUA Radio Traffic Unit-A
RTUB Radio Traffic Unit-B
RFA Radio Fan Unit
GTMU GSM Transmission Management Unit
LMPT LTE Main Processing and Transmission Unit
UMPT Universal Main Processing and Transmission unit
UEIU Universal Environment Interface unit
UELP Universal E1/T1 Lightning Protection Unit
WMPT WCDMA Main Processing and Transmission unit
LBBP LTE Base Band Processing Unit
UPEU Universal Power and Environment Unit
UFLP Universal FE/GE Lightning Protection Unit
UTRP Universal Transmission Processing Unit
WBBP WCDMA Base Band Processing Unit
RNC Radio Network Controller
ODU Out Door Unit
IDU In Door Unit
SDH Synchronous Digital Hierarchy
SIM Subscriber Identity Module
SMS Short Message Service
TDM Time Division Multiple
TRX Transmit Receiving Equipment
WCDMA Wideband Code Division Multiple Access
