A report that is close to the field of Telecommunication and gives the basic idea on various technology used in this field.

1. ALTTC BSNL Training Report
A Report Submitted
in the Partial Fulfillment of the Requirements
for the Degree of
B.Tech
in
Electronics and Communication Engineering
by
Sonal Bansal
1133231023
Under the Guidance of
Mr. S.K. Gupta
ELECTRONICS AND COMMUNICATION DEPARTMENT
MAHARAJA AGARSAIN INSTITUTE OF TECHNOLOGY,
GHAZIABAD – 245304, INDIA
June, 2014

2. UNDERTAKING
I declare that the work presented in this report ti-
tled “ALTTC BSNL Training Report”, submitted to
the Electronics and Communication Engineering De-
partment, Maharaja Agarsain Institute of Technology,
Ghaziabad, for the award of the B.Tech degree in
Electronics and Communication Engineering, is my original
work. I have not plagiarized or submitted the same work for
the award of any other degree. In case this undertaking is
found incorrect, I accept that my degree may be unconditionally
withdrawn.
June, 2014
Ghaziabad
(Sonal Bansal)
ii

3. CERTIFICATE
Certified that the work contained in the report titled “ALTTC
BSNL Training Report”, by Sonal Bansal, Registration Number
1133231023 has been carried out under my supervision and that this
work has not been submitted elsewhere for a degree.
June, 2014
(Mr. S.K. Gupta)
ALTTC BSNL, Ghaziabad
iii

4. Acknowledgment
It would not have been possible to write this report without the help and support of
almighty God and kind people around me, to only some of whom it is possible to give
particular mention here.
Above all, I am truly indebted and thankful to my parents and my family for their
personal support and great patience at all times. My family has given me their unequivocal
support throughout, as always, for which my mere expression of thanks does not suffice.
This report would not have been possible without the help, support and patience of
my training incharge, Mr. S.K. Gupta. His advice and unsurpassed knowledge has been
invaluable, for which I am extremely grateful. I was privileged to experience a sustained
enthusiastic involved interest from his side.
I would like to acknowledge the academic and technical support of ALTTC BSNL,
Ghaziabad and its staff. I am thankful for their valuable support and guidance.
Last, but not the least, I would like to thanks everyone who has contributed for the
successful completion of my training.
- Sonal Bansal
iv

5. Contents
Acknowledgment iv
1 Introduction 1
1.1 Voice Signal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Switching System Fundamentals . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Trunking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Call Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.5 A Typical Telephone Exchange-OCB-283 . . . . . . . . . . . . . . . . . 3
2 Corporate Network 4
2.1 Security of Corporate Network . . . . . . . . . . . . . . . . . . . . . . . 5
3 Signalling In Telecommunications 7
3.1 ISDN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Signalling System Number 7 . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Pulse Code Modulation Principle 9
4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2 Basic requirements for PCM system: . . . . . . . . . . . . . . . . . . . . 10
v

6. 5 Dense Wavelength Division Multiplexing 13
5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2 Challenges of Today’s Telecommunication Network . . . . . . . . . . . . 14
5.3 Optical Fiber Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3.1 Optical Fiber Transmission . . . . . . . . . . . . . . . . . . . . . 14
5.3.2 Classification of Optical Fiber . . . . . . . . . . . . . . . . . . . 15
5.3.3 Optical Fiber in the DWDM . . . . . . . . . . . . . . . . . . . . 15
5.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6 GSM Architecture and Technology 17
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1.1 Mobile Station . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.1.2 The Base Station Subsystem . . . . . . . . . . . . . . . . . . . . 19
6.2 The Network and Switching Subsystem . . . . . . . . . . . . . . . . . . 19
6.2.1 The Mobile services Switching Center (MSC) . . . . . . . . . . . 19
6.2.2 The Gateway Mobile services Switching Center (GMSC) . . . . . 19
6.2.3 Home Location Register (HLR) . . . . . . . . . . . . . . . . . . 20
6.2.4 Visitor Location Register (VLR) . . . . . . . . . . . . . . . . . . 20
6.2.5 The Authentication Center (AuC) . . . . . . . . . . . . . . . . . 20
6.2.6 The Equipment Identity Register (EIR) . . . . . . . . . . . . . . 20
7 Base Transceiver Station 21
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8 Introduction oF 3G Communication 23
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8.2 Architecture Model of 3G Network . . . . . . . . . . . . . . . . . . . . . 24
9 CDMA Technology 25
9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.2 Advantage of CDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9.3 Disadvantage of CDMA . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9.4 Difference between CDMA and GSM . . . . . . . . . . . . . . . . . . . 26
vi

7. References 28
vii

8. List of Figures
1 Corporate Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Frequency Division Multiplexing . . . . . . . . . . . . . . . . . . . . . . 10
3 Time Division Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . 10
4 Quantization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5 Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6 Optical Fiber Transmission . . . . . . . . . . . . . . . . . . . . . . . . . 15
7 Network of GSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8 Base Transceiver Station . . . . . . . . . . . . . . . . . . . . . . . . . . 21
9 Overview of BTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
10 Architecture of 3G Network[1] . . . . . . . . . . . . . . . . . . . . . . . 24
xiii

9. Chapter 1
Introduction
Telephone is a telecommunication device that is used to transmit and receive electroni-
cally or digitally encoded speech between two or more people conversing[1]. It is one of
the most common household appliances in the world today.
Telecommunication networks carry information signals among entities, which are ge-
graphically far apart. An entity may be a computer or human being, a teleprinter, a data
terminal and so on. The entities are involved in the process of information transfer that
may be in the form of a telephone conversation or a file transfer between two computers
or message transfer between two terminals etc.
With the rapidly growing traffic and untargeted growth of cyberspace, telecommuni-
cation becomes a fabric of our life. The future challenges are enormous as we anticipate
rapid growth in terms of new services and number of users. What comes with the chal-
lenge is a genuine need for more advanced methodology supporting analysis and design
of telecommuniction architectures. Telecommunication has envolved with a growth at an
explosive rate in the recent years and will undoubtedly continue to do so.
The communication switching system enables the universal connectivity. The univer-
sal connectivity is realized when any entity in one part of the world can communicate
1

10. with any other entity in another part of the world. In many ways telecommunication acts
as a substitute for the increasingly expensive physical transportation.
1.1 Voice Signal Characteristics
The range of frequencies used by a communication device determines the communication
channel, communicating devices, and bandwidth or information carrying capacity. The
most commonly used parameter that characterizes an telephone system, the frequencies it
passes are restricted to between 300 to 3400 Hz[2].
1.2 Switching System Fundamentals
Telecommunication switching systems generally perform three basics function:-
• They transmit signals over separate channels to convey the identify of the called
address, and ring the called station.
• They establish connections through a switching network for conversational use dur-
ing the entire call.
• They process the signal information to control and supervise the establishment and
disconnection of the switching network connection.
Switching techniques
Space and time division are the two basics techniques used in establishing connections:-
When an individual conductor path is established through a switch for the duration of
a call, the system is known as space division.
When the transmitted speech signals are sampled and the samples multiplexed in time
so that high-speed electronic devices may be used simultaneously by several calls, the
switch is known as time division.
2

11. 1.3 Trunking
In telecommunication systems, trunking is aggregation of multiple user circuits into a
single channel. The aggregation is achieved using some form of multiplexing[3].
1.4 Call Routing
Routing in the PSTN (public switched telephone network) is the process used to route
telephone calls across the PSTN. This process is the same whether the call is made be-
tween two phones in the same locality, or across two different continents. Thus the ob-
jective of routing is to establish a successful connection between any two exchanges in
the network. By selecting routes that meet the constraints set by the user traffic and the
network, routing determines which network resources should be used to transport which
user traffic[4].
1.5 A Typical Telephone Exchange-OCB-283
The Alcatel E10 system is located at the heart of the telecommunication networks con-
cerned. It is made up of three independent functional units:-
• Subscriber Access Subsystem
• Connection and Control
• Operation and Maintenance
3

12. Chapter 2
Corporate Network
A corporate network is a closed and private computer network that affords secure commu-
nication between geographically dispersed LANs of an enterprise. These point to point
connection have delivered through leased lines.
A corporate network is also defined as a group of computers, connected together in a
building or in a particular area, which are all owned by the same company[1].
4

13. Figure 1: Corporate Network
2.1 Security of Corporate Network
Protect PC workstations over your network with Corporate Network Security. This net-
work based password protected security software lets you impose access restrictions to all
your PC workstations you have in your corporate network to stop users from tampering
with them. The workstations are controlled from a single administrator’s computer from
5

14. almost everywhere you have access to the TCP/IP- based network or Internet.
Corporate Network Security’s features
• Complete bullet-proof protection of the remote computers you have on your net-
work.
• Executable patches can be easily uploaded to all your remote computers and exe-
cyted remotely.
• You do not need to physically visit your workstations when you need to change
security settings or install patches.
6

15. Chapter 3
Signalling In Telecommunications
The term signaling, when used in telephony, refers to the exchange of control information
associated with the establishment of a telephone call on a telecommunications circuit. An
example of this control information is the digits dialed by the caller, the caller’s billing
number, and other call-related information.
When the signalling is performed on the same circuit that ultimately carry the conver-
sation of the call, it is termed Channel Associated Signalling (CCS).
In contrast, SS7 signalling is termed Common Channel Signalling (CCS) in that the
path and facility used by the signalling is separate and distinct from the telecommunica-
tions channels that will ultimately carry the telephone conversation.
In the PSTN one channel of a communication link is typically used for the sole pur-
pose of carrying signaling for establishment and tear down of telephone calls. The re-
maining channels are used entirely for the transmission of voice data. In most cases, a
single 64Kbits/s channel is sufficient to handle the call setup and call clear-down traffic
numerous voice and data channels.
CCS offers the following advantage over CAS, in the context of the PSTN:-
• Faster call setup
7

16. • No falsify interference between signaling tones by network and speech frequency.
• No security issues related to the use of in-band signalling with CAS.
• CCS allows the transfer of additional information along with the signalling traffic
providing features such as caller ID.
The most common CCS signaling method in use today are Integrated Services Digital
Network (ISDN) and Signalling System 7 (SS7).
3.1 ISDN
ISDN signaling is used primarily on trunks connecting enduser Private Branch Exchange
(PBX) system to a central office.
3.2 Signalling System Number 7
SS7 is a set of telephony signaling protocols which are used to set up most of the world’s
public switched telephone network telephone calls. The main purpose is to set up and tear
down telephone calls. Other uses include number translation, prepaid billing mechanisms,
short message service (SMS), and a variety of other mass market services[5].
8

17. Chapter 4
Pulse Code Modulation Principle
4.1 Overview
Pulse-code modulation (PCM) is a method used to digitally represent sampled analog
signals. It is the standard form of digital audio in computers, Compact Discs, digital
telephony and other digital audio applications. In a PCM stream, the amplitude of the
analog signal is sampled regularly at uniform intervals, and each sample is quantized to
the nearest value within a range of digital steps[3].
Multiplexing techniques: There are basically two types of multiplexing techniques:-
1). Frequency Division Multiplexing
2). Time Division Multiplexing
1). FDM principle- Frequency Division Multiplexing (FDM) is inherently an analog
technology. FDM achieves the combining of several signals into one medium by sending
signals in several distinct frequency ranges over a single medium[6]. In the figure it is
clear that how three different signals are tnransmiting over a single medium.
9

18. Figure 2: Frequency Division Multiplexing
2). TDM principle- Basically, Time Division Multiplexing involves nothing more than
sharing a transmission medium by a number of circuits in time domain by establishing a
sequence of time slots during which individual channels (circuits) during which individual
channels are transmitted. Thus the entire bandwidth is periodically available to each
channel[7].
Figure 3: Time Division Multiplexing
4.2 Basic requirements for PCM system:
• Filtering
• Sampling
• Quantization
• Encoding
• Line coding
10

19. Filtering
Filters are used to limit the speech signal to the frequency band 300-3400 hz.
Sampling
In signal processing, sampling is the reduction of a continuous signal to a discrete signal.
A common example is the conversion of a sound wave (a continuous signal) to a sequence
of samples (a discrete time signal). A sample refers to a value or set of values at a point
in time and/or space. A sampler is a subsystem or operation that extracts samples from a
continuous signal.
Sampling theorem
If a band limited signal is sampled at regular intervals of time and at a rate equal to or
more than twice the highest signal frequency in the band, then the signal contains all the
information of the original signal, Or Fs is greter then 2fH where fH is the highest fre-
quency in the signal and Fs is the sampling frequency. Let us say that our voice signals are
band limited to 4khz and let the sampling frequency be 8 khz. Time period of sampling
Ts = 1 sec/8000 Or Ts= 125 micro seconds. In a 30 channel PCM system, Ts i.e. 125 mi-
croseconds are divided into 32 parts. That is 30 time slots are used for 30 speech signals,
one time slot for signaling of all the 30 channels and one time slot for synchronization
b/w transmitter and receiver. Time available per channel would be 3.9 microsec[3].
Quantization
Quantizing is a process of breaking down a continuous amplitude range into a finite num-
ber of amplitude values or steps. A sampled signal exists only at discrete times but its
amplitude is drawn from a continuous range of amplitudes of an analog signal. The fi-
nite no. of amplitude intervals is called the quantizing interval. Relation between Binary
Codes and No. of levels:- Because the quantized samples are coded in binary form, quan-
tization intervals will be in powers of 2. If we have a 4 bit code, then we can have 24=16
levels. Practical PCM systems use an 8 bit code with a first bit as sign bit. This means we
11

20. have 28= 256 levels. (128 levels in the positive direction and 128 levels in the negative
direction).
Figure 4: Quantization
Encoding
Conversion of quantized analog levels to binary signal is called encoding. To represent
256 steps, 8 level code is required.
Figure 5: Encoding
12

21. Chapter 5
Dense Wavelength Division
Multiplexing
DWDM is a fibre optic transmission technique that employs multiple light wavelengths
to transmit data in parallel through a single-fiber[1].
5.1 Overview
DWDM systems in enabling service providers to accommodate consumer demand for ever
increasing amounts of bandwidth. DWDM is a crucial components of optical networks hat
allows the transmission of a e-mail, video, multimedia, data and voice-carried in different
formats like Internet protocol (IP), over the optical layer.
Using DWDM, up to 80 (and theoretically more) separate wavelengths or channels
of data can be multiplexed into a lightstream transmitted on a single optical fiber. Each
channel carries a time division multiplexed (TDM) signal. In a system with each channel
carrying 2.5 Gbps (billion bits per second), up to 200 billion bits can be delivered a second
by the optical fiber. DWDM is also sometimes called wave division multiplexing (WDM).
13

22. Since each channel is demultiplexed at the end of the transmission back into the
original source, different data formats being transmitted at different data rates can be
transmitted together. Specifically, Internet (IP) data, Synchronous Optical Network data
(SONET), and asynchronous transfer mode (ATM) data can all be travelling at the same
time within the optical fiber[8].
5.2 Challenges of Today’s Telecommunication Network
To understand the importance of DWDM and optical networking, these capabilities must
be discussed in the context of the challenges faced by the telecommunications industry.
The forecasts of the amount of bandwidth capacity needed for networks were calculated
on the presumption that a given individual would only use network bandwidth six minutes
of each hour. In fact, today many people use the bandwidth equivalent of 180 minutes or
more each hour.
Therefore, an enormous amount of bandwidth capacity is required to provide the ser-
vices demanded by consumers. At the transmission speed of one Gbps.If one million
families decide they want to see video on Web sites and samples the new emerging video
application, then network transmission rates of terabits required.
5.3 Optical Fiber Layer
Optical Fiber is new medium, in which information (voice, Data or Video) is transmitted
through a glass or plastic fiber, in the form of light[9].
5.3.1 Optical Fiber Transmission
Optical fiber transmission can be understand by following diagram:-
14

23. Figure 6: Optical Fiber Transmission
5.3.2 Classification of Optical Fiber
Index Multi-mode Fiber
It contains a core in which the refractive index diminishes gradually from the center axis
out toward the cladding. The higher refractive index at the center makes the light rays
moving down the axis advance more slowly than those near the cladding. A digital pulse
suffers less dispersion.
Single-Mode Fiber
It has a narrow core (eight microns or less), and the index of refraction between the core[1]
and the cladding changes less than it does for multi-mode fibers. Light thus travels parallel
to the axis, creating little pulse dispersion. Telephone and cable television networks install
millions of kilometers of this fiber every year.
5.3.3 Optical Fiber in the DWDM
Single mode fibers are preferred for longer distance and higher bandwidth application
including DWDM.WDM is the practice of dividing the wavelength capacity of an optical
fiber into multiple channels in order to send more than one signal over the same fiber.
15

24. 5.4 Conclusion
Optical networking provides the backbone to support existing and emerging technologies
with almost limitless amounts of bandwidth capability. Such are as follow:-
• Speed: Fiber optic networks operate at high speeds - up into the gigabits.
• Bandwidth: large carrying capacity.
• Distance: Signals can be transmitted further without needing to be refreshed or
strengthened.
• Resistance: Greater resistance to electromagnetic noise such as radios, motors or
other nearby cables.
• Maintenance: Fiber optic cables costs much less to maintain.
16

25. Chapter 6
GSM Architecture and Technology
6.1 Introduction
The GSM technical specifications define the different entities that form the GSM net-
work by defining their functions and interface requirements[10]. The GSM network is
presented in figure:-
Figure 7: Network of GSM
17

26. A GSM network consists of several functional entities, whose functions and interfaces
are defined[1]. The GSM network can be divided into following broad parts:-
• The Mobile Station (MS)
• The Base Station Subsystem (BSS)
• The Network Switching Subsystem (NSS)
• The Operation Support Subsystem (OSS)
6.1.1 Mobile Station
A mobile station consists of two main elements:
The Terminal
There are different types of terminals distinguished principally by their power and appli-
cation:
• The fixed terminals are the ones installed in cars. Their max allowed output power
is 20 W.
• The GSM portable terminals can also be installed in vehicles. Their max allowed
output power is 8W. Hand-held terminals can emit up to 2W. The evolution of tech-
nologies allows decreasing the max allowed power to 0.8W.
The SIM
The SIM is a smart card that identifies the terminal. By inserting the SIM in the terminal,
user can have an access to all the subscribed services. The SIM card is protected by a
4 digit PIN (Personal Identification Number). In order to identify the subscriber to the
system, the SIM contains some parameters of the user such as its International Mobile
Subscriber Identity (IMSI).
18

27. 6.1.2 The Base Station Subsystem
The BSS connects the Mobile Station and the NSS. It is in charge of the transmission and
reception. The BSS can be divided into two parts:-
The Base Transceiver Station
The BTS corresponds to the transceivers and antennas used in each cell of the network.
The BTS is placed in the center of the cell. Each BTS has between one and sixteen
transceivers depending on the density of users in the cell.
The Base Station Controller
The BSC controls the group of BTS and manages their radio resources. A BSC is princi-
pally in charge of hand-overs, frequency hopping, exchange functions and control of the
radio frequency power levels of the BTS[11].
6.2 The Network and Switching Subsystem
Its main role is to manage the communications between the mobile users and other users,
such as mobile users, ISDN users, fixed telephony users etc. It also includes data bases
needed in other to store information about the subscribers and to manage their mobility.
The components of NSS are:-
6.2.1 The Mobile services Switching Center (MSC)
It is the central component of NSS. The MSC performs the switching functions of the
network. It also provides connection to the other network.
6.2.2 The Gateway Mobile services Switching Center (GMSC)
A gateway is a node interconnecting two networks. The GMSC is the interface between
mobile cellular network and the PSTN. It is in charge of routing calls from the fixed
19

28. network towards the GSM user. The GSMC is often implemented in the same machines
as the MSC.
6.2.3 Home Location Register (HLR)
The HLR is considered as a very important database to store information of the sub-
scribers belonging to the covering area of a MSC. It also stores the current location of
these subscribers and the services to which they have access. The location of subscribers
corresponds to the SS7 address of the Visitor Location Register(VLR) associated to the
terminal.
6.2.4 Visitor Location Register (VLR)
The VLR contains information from a subscribers HLR necessary in order to provide the
subscribed services to visiting users. When a subscriber enters the covering area of a new
MSC, the VLR associated to the MSC will request information about the new subscriber
to its corresponding HLR.
6.2.5 The Authentication Center (AuC)
The AuC register is used for security purpose. It provides parameters needed for authen-
tication and encryption functions. These parameters help to verify the users identity.
6.2.6 The Equipment Identity Register (EIR)
The EIR is also used for security purposes. It is a register containing information about the
mobile equipment. More particularly, it contains a list of all valid terminals. A terminal is
identified by its International Mobile Equipment Identity (IMEI). The EIR allows then to
forbid calls from stolen or unauthorized terminals (e.g. a terminal which does not respect
the specifications concerning the output RF power).
20

29. Chapter 7
Base Transceiver Station
7.1 Introduction
Figure 8: Base Transceiver Station
A base transceiver station (BTS) is a piece of equipment that facilitates wireless com-
munication between user equipment (UE) and a network. UEs are devices like mobile
phones (handsets), computers with wireless Internet connectivity. The network can be
that of any of the wireless communication technologies like GSM, CDMA, wireless lo-
cal loop,Wi-Fi, WiMAX or wide area network (WAN) technology. BTS is also referred
21

30. to as the radio base station (RBS), node B (in 3G Networks) or simply, the base station
(BS). For discussion of the LTE standard the abbreviation eNB for evolved node B is
widely used. Though the term BTS can be applicable to any of the wireless communi-
cation standards, it is generally associated with mobile communication technologies like
GSM and CDMA. In this regard, a BTS forms part of the base station subsystem (BSS)
developments for system management. It may also have equipment for encrypting and de-
crypting communications, spectrum filtering tools (band pass filters), etc. antennas may
also be considered as components of BTS in general sense as they facilitate the function-
ing of BTS. Typically a BTS will have several transceivers (TRXs) which allow it to serve
several different frequencies and different sectors of the cell (in the case of sectorised base
stations). A BTS is controlled by a parent base station controller via the base station con-
trol function (BCF). The BCF is implemented as a discrete unit or even incorporated in a
TRX in compact base stations. The BCF provides an operations and maintenance (OM)
connection to the network management system(NMS), and manages operational states of
each TRX, as well as software handling and alarm collection. The basic structure and
functions of the BTS remains the same regardless of the wireless technologies[12].
Figure 9: Overview of BTS
22

31. Chapter 8
Introduction oF 3G Communication
8.1 Introduction
3G is the next generation of wireless network technology; it is also known as UMTS
(Universal Mobile Telecommunication System) that provides high speed bandwidth (high
data transfer rates) to hand-held devices[13]. The high data transfer rates will allow 3G
networks to offer multimedia services combining voice and data. Specifically, 3G wireless
networks support the following maximum data transfer rates:-
• 2 M bits/second to stationary devices.
• 384 Kbits/second for slowly moving devices, such as a handset carried by a walking
user.
• 128 Kbits/second for fast moving devices, such as handset in moving vehicles.
UMTS is amalgamations of both packet are circuit switched technologies. It has si-
multaneously been designed to have the upgradeability features of earlier mobile systems
such as GSM and CDMA. In addition, it is expected that, IP multimedia will be and
integral part of thw UMTS standards.
23

32. 8.2 Architecture Model of 3G Network
Figure 10: Architecture of 3G Network[1]
24

33. Chapter 9
CDMA Technology
9.1 Introduction
Code division multiple access (CDMA) is a channel access method used by various radio
communication technologies. CDMA is an example of multiple access, which is where
several transmitters can send information simultaneously over a single communication
channel. This allows several users to share a band of frequencies. To permit this to be
achieved without undue interference between the users, CDMA employs spread spectrum
technology and a special coding scheme (where each transmitter is assigned a code).
CDMA is used as the access method in many mobile phone standards and WCDMA (the
3G standard used by GSM carriers), which are often referred to as simply CDMA.
The technology is used in ultra-high-frequency (UHF) cellular telephone systems in
the 800-MHz and 1.9-GHz bands. CDMA employs analog-to-digital conversion (ADC)
in combination with spread spectrum technology[14].
The original CDMA standard, also known as CDMA One and still common in cellular
telephones in the U.S., offers a transmission speed of only up to 14.4 Kbps in its single
channel form and up to 115 Kbps in an eight-channel form. CDMA2000 and Wideband
25

34. CDMA deliver data many times faster.
9.2 Advantage of CDMA
• Increased cellular communications security.
• Simultaneous conversations
• Increased efficiency, meaning that the carrier can serve more subscribers.
• Smaller phones
• Low power requirements and little cell-to-cell coordination needed by operators.
• Extended reach-beneficial to rural users situated far from cells.
9.3 Disadvantage of CDMA
• Due to its proprietary nature, all of CDMAs flaws are not known to the engineering
community.
• CDMA is relatively new, and the network is not as mature as GSM.
• CDMA cannot offer international roaming, a large GSM advantage.
9.4 Difference between CDMA and GSM
The GSM stands for global system for mobile communication and CDMA for code di-
vision multiple accesses. GSM is a form of multiplexing, which divides the available
bandwidth among the different channels. Most of the times the multiplexing used are
either TDM (Time Division Multiplexing) or FDM (Frequency Division Multiplexing).
On the other hand CDMA is a type of multiple access scheme (which means allotting the
given bandwidth to multiple users) and makes use of spread spectrum technique which
is essentially increasing the size of spectrum. In CDMA each user is provided a unique
26

35. code and all the conversations between 2 users are coded. This provides a greater level of
security to CDMA users then the GSM ones[15].
27

36. References
[1] “Hand out on ALT Vocational Training,” ferbury 2013-2014.
[2] “Voice fundamentals,” in http://www.uoverip.com/voice-fundamentals-human-
speech-frequency/, 2001.
[3] youtube http://www.youtube.com/watch?v=YJmUkNTBa8s.
[4] webopedia http://www.webopedia.com/TERM/R/routing.html.
[5] telecom.net http://telecom.tbi.net/history1.html#hierarchy.
[6] Harold P.E. Stern and Sanny A. Mahmound, “Communication System Analysis and
Design,” prentice Hall, 2006.
[7] Wikipedia http://en.wikipedia.org/wiki/Time-division_
multiplexing.
[8] searchtelecom http://searchtelecom.techtarget.com/
definition/dense-wavelength-division-multiplexing.
[9] craig Fredenrich http://computer.howstuffworks.com/
fiber-optic.htm.
[10] Wikipedia http://en.wikipedia.org/wiki/GSM.
28

37. [11] techopedia http://www.techopedia.com/definition/24191/
base-station-controller-bsc.
[12] techopedia http://www.techopedia.com/definition/2927/
base-transceiver-station-bts.
[13] “Draft summary minutes decisions and action from 3GPP Organizatiom Partners
Meeting, Tokyo,” in http://en.wikipedia.org/wiki/3GPP, vol. 6, October, 2001.
[14] Margaret Rouse http://searchtelecom.techtarget.com/
definition/CDMA.
[15] Sasche Sagan http://www.pcmag.com/article2/0,2817,2407896,
00.asp.
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