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1
A
SUMMER TRAINING REPORT
ON
BASIC GSM CONCEPT AND 3G EVOLUTION
Submitted as a requirement for the parial fulfillment of
Bachelors Degree from
Rajasthan Techinal University, Kota
Session 2010-2011
Submitted to: Submitted by:
Mr. manoj gupta Lokesh Kumar Garg
HOD of college Final year, ECE
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Preface
Summer training is the essential organ of healthy technical carrer.
The B.TECH course summer training helps a student in getting
acquinted with the manner in which his knowledge is being
practically used outside his institute and this is normally different
from what he has learnt from books. Hence, when the student
switches from the process of learning to that of implementing his
knowledge, he finds an abrupt change.
The need of training arises for doing things yourself, understanding
its way. Practical exposure for doing things make a person
conversant to the techicalities involved in any job. To overcome the
problem of profit and growth through the soundest utilization of
human capacities effective recruitment and selection process in first
step. If it is not done well no amount of training, supervision or
incentive make for it. In view of such benefits, impairing of
vocational training has been made as an integral part of any
academic structure.
In third year of B.TECH in Electronics and Communication my training
has been at IDEA CELLULAR LIMITED, JAIPUR. In this training I had a
knowledge about BASICGSM CONCEPT AND 3G EVOLUTION.
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Acknowledgement
Before I get into thick of the things I would like to add a few heartfelt
for the people who were part of my training in numerous ways,
people who gave unending support right from the stage the training
was conceived.
In the beginning of the report I want to give my thanks to Mr. Ritesh
Saraswat (Head of Department-Electronics and Communication) for
all his encouragement and appreciations that I have received from
him.
I am thankful to all the faculty members because in the supervision,suggestions and guidance of them I gain all the knowledge
experience. I give my thanks to Mrs. Hareeta Malani (Lect. ICT), Mrs.
Sarita Chauhan (Lect. ICT) and to Mr. Anurag Jagetia (TPO).
It gives me imense pleasure to acknlowledge my humble, sincere
gratitude to training incharge. I am indebted to all my elders and
friends for inspiring me to have my training with immense
dedication.
Lokesh kumar Garg
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Contents
1.Company profile.............................................................6
1.1 Location.........................................................................6
1.2 Profile............................................................................6
1.3 Boardof directors...........................................................7
1.4 Registered Office............................................................7
1.5 Corporate Office.............................................................7
1.6 Website..........................................................................8
2. Introduction.....................................................................9
2.1 Switching Systems..................................................................9
2.2 GSM Concept..............................................................................9
2.3 3G Evolution..............................................................................10
3.Switching Systems.............................................................11
3.1 MSC...........................................................................................12
3.2 VLR.............................................................................................14
3.3 MSC/VLR implementation.........................................................15
3.4 GMSC.........................................................................................17
3.5 GMSC implementation..............................................................17
3.6 HLR............................................................................................17
3.7 HLR implementation.................................................................18
3.8 Authentication Centre (AUC)....................................................18
3.9 AUC implementation................................................................18
3.10 Equipment Identity Register..................................................18
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3.11 Duplex Communication........................................................19
3.12 Radio Communication..........................................................20
4. Base Station System.........................................................25
4.1 Introduction...........................................................................25
4.2 BSC and Transcoder Controller..............................................26
5. Wireless concepts and Logical Channels.............................28
5.1 Frequency..............................................................................28
5.2 Channels................................................................................29
5.3 Modulation Method..............................................................30
5.4 Logical Channels....................................................................30
6. 3G Evolution....................................................................33
6.1 Introduction...........................................................................33
6.1.1 HSCSD.................................................................................34
6.1.2 GPRS...................................................................................34
6.1.3 EDGE..................................................................................35
6.2 The 3G of Mobile systems.....................................................36
6.2.1 Services...............................................................................36
6.2.2 Migration............................................................................37
7. Introduction to UMTS.....................................................39
7.1 UMTS Network Structure......................................................39
8. References.....................................................................40
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Chapter-1
Company Profile
1.1 Location
Idea Cellular Limited
Sahakar Marg
Jaipur
1.2 Profile
Idea Cellular is a leading GSM mobile services operator in India with
67 million subscribers, under brand IDEA. It is a pan India integrated
GSM operator covering the entire telephony landscape of the
country, and has NLD and ILD operations. A frontrunner in
introducing revolutionary tariff plans, IDEA Cellular has the
distinction of offering the most customer friendly and competitive
Pre Paid offerings, for the first time in India, in an increasingly
segmented market. From basic voice & Short Message Service (SMS)
services to high-end value added & GPRS services such as Blackberry,
Datacard, Mobile TV, Games etc - IDEA is seen as an innovative,
customer focused brand.
IDEA offers affordable and world-class mobile services to varied
segments of mobile users. Be it high end users, or low-end, price
sensitive consumers - IDEA's tariff plans are designed to suit
everyones pocket.
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1.3 Board of Directors
y Mr. Kumar Mangalam Birla Chairman
y Mrs. Rajashree Birla Non-Executive Director
y Dr. Rakesh Jain Non-Executive Director
y Mr. Biswajit A. Subramanian Non-Executive Director
y Mr. Juan Villalonga Navarro Non-Executive Director
y Mr. Arun Thiagarajan Independent Director
y Mr. Gian Prakash Gupta Independent Director
y Mr. Mohan Gyani Independent Director
y Ms. Tarjani Vakil Independent Director
y Mr. R.C. Bhargava Independent Director
y Mr. P. Murari Independent Director
y Mr. Sanjeev Aga Managing Director
y Dr. Shridhir Sariputta Hansa Wijayasuriya Alternate Director to
Mr. JuanVillalonga Navarro
1.4 Registered Office
Suman Tower,
Plot No. 18, Sector 11,
Gandhinagar 382 011
Gujarat
1.5 Corporate Office
Windsor, 5th Floor,
Off CST Road,
Near Vidya Nagari, Kalina,
Santacruz (East),Mumbai
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1.6 Website
http://www.ideacellular.com
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Chapter -2
Introduction
2.1 Switching systems
The switching system is responsible for call processing and
subscriber related functions. It includes following the following
parts:-
1. Mobile services Switching Centre (MSC)
2. Home Location Register (HLR)
3. Visitor Location Register (VLR)
4. Authentication Centre (AUC)
5. Equipment Identity Register (EIR)
2.2 GSM concept
GSM stands for Global Standards for Mobile Communications. The
GSM is divided into two basic components:-
1. Switching systems
2. Base station subsystem
The switching system is responsible for call processing and
subscriber related functions and the BSS is responsible for radio
related functions.
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There are two parts of BSS:
Base Station Controller
Base Transceiver Station
2.3 3G Evolution
3G network is todays the most growing technology in the
mobile network. There is a specific term related with the 3G network
i.e. UMTS (Universal Mobile Telecommunication System). The 3G
UMTS is mostly based on the GSM technical solutions due to two
reasons. Firstly, the GSM as technology dominates the market, and
secondly, investment made to GSM must be utilized as much as
possible.
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Chapter-3
Switching systems
The following picture illustrates the Switching system in
Ericssons GSM systems.
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3.1MSC
MSC stands for Mobile Switching Centre. It is the primary node
in a GSM network. It is the node which controls calls both to
MS (Mobile Stations) and from MS. The primary function of the
MSC the following:-
y Switching and call routing: a MSC controls call set-up,
supervision and release and may interact with other
nodes to successfully establish a call. This includes routingof calls from MS to other networks such as a PSTN.
y Charging: an MSC contains functions for charging mobile
calls and information about the particular charge rates to
apply to a call at any given time or for a given destination.
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y Service provisioning:supplementary services are provided
and managed by a MSC.
y Communication with HLR: the primary occasion on which
an MSC and HLR communicate is during the set up of a
call to an MS, when the HLR requests some routing
information from the MSC. In addition, the SMS service is
handled by MSCs.
y Communication with HLR: the primary occasion on which
an MSC and HLR communicate is during the set-up of a
call to an MS, when the HLR requests some routing
information from the MSC.
y Communication with VLR: associated with each MSC is a
VLR, with which it communicates for subscription
information, especially during call set-up and release.
y Control of connected BSCs: as the BSS (Base Station
Subsystem) acts as the interface between the MSs and
the SS, the MSC has the function of controlling the
primary BSS node i.e. the BSC. Each MSC may control
many BSCs depending on the volume of traffic in a
particular MSC service area. An MSC may communicate
with its BSCs during: for example, call set-up and
handovers between two BSCs.
y Direct access to Internet services: traditionally, an MSC
accessed the Internet nodes of the PSTN. However, this
function enables an MSC to communicate directly with
internet nodes, thus reducing call set-up time.
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3.2 VLR
VLR stands for Visitor Location Register. The role of a VLR in a
GSM network is to act as a temporary storage location for
subscription information for MSs which are within a particular
MSC service area. Thus, there is one VLR for each MSC service
area. This means that the MSC does not have to contact the
HLR (which may be located in another country) every time the
subscriber uses a service or changes its status.
The following occurs when MSs move into a new service area:
y The VLR checks its database to determine whether or not
it has a record for the MS.
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y When the VLR finds no record for the MS, it sends a
request to the subscribers HLR for a copy of the MSs
subscription.
y The HLR passes the information to the VLR and updates
its location information for the subscriber.
y The VLR stores its subscription information for the MS,
including the latest location and status.
3.3 MSC/VLR implementation
In Ericssons GSM systems, the MSC and VLR are integrated in
the AXE based node. The MSC-VLR interface is completely
internal within the AXE, but each is treated as a distinct and
separate function.
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3.4 GMSC
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y It stands for Gateway Mobile Switching Centre.
y Gateway functionality enables an MSC to interrogate HLR
in order to route a mobile terminating call. It is not used
in calls from MSs to any terminal other than another MS.
3.5 GMSC implementation
Any MSC in the mobile network can function as a gateway by
integration of the appropriate software and definition of HLR
interrogation information. In effect it then becomes a
GMSC/VLR.
In Ericssons GSM systems, gateway functions are provided
within the subsystems MSC. The only additional hardware
required is the hardware to interface the signalling link to the
HLR.
3.6 HLR
HLR stands for Home Location Register. The HLR is a centralised
network database that stores and manages all mobile
subscriptions belonging to a specific operator. It acts as a
permanent store for a persons subscription information until
that subscription is cancelled. The information stored includes:
y Subscriber identity(i.e. IMSI, MSISDN)
y Subscriber supplementary services
y Subscriber location information(i.e. MSC service area)
y Subscriber authentication information
3.7 HLR implementation
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The HLR can be implemented in the same network as the
MSC/VLR (i.e. MSC/VLR/HLR) or as a stand-alone database. An
MSC/VLR/HLR node is a suitable solution for a small start-up
GSM network as it saves hardware and signalling load on the
links between MSC/VLR and HLR.
3.8 Authentication Centre(AUC)
The Authentication Centre is a function to authenticate each
SIM card that attempts to connect to the GSM core network
(typically when the phone is powered on). Once the
authentication is successful, the HLR is allowed to manage the
SIM and services. An encryption key is also generated that is
used to encrypt all the wireless communications (voice, SMS
etc) between the mobile phone and the GSM core network. If
the authentication fails, then no service is possible from that
particular combination of the SIM card and mobile phone.
3.9 AUC implementation
There is a separate hardware of this in the switching systems.
3.10 Equipment Identity Register(EIR)
The EIR keeps a list of mobile phones (identified by their IMEI)
which are to be banned from the network or monitored. This is
designed to allow tracking of stolen mobile phones. In theory
all data about the stolen mobile phones should be distributedto all EIRs in the world through a Central EIR. However, there
are some countries where this is not in operation. The EIR data
does not have to change in real time, which means that this
function can be less distributed than the function of the HLR.
The EIR is a database that contains information about the
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identity of the mobile equipment that prevents calls from
stolen, unauthorized or defective mobile stations.
3.11 Duplex Communication
Simplex is communication in a one-way direction, such as AM
and FM broadcast to one or multiple receivers.Half duplex is
communication in a two-way direction. However, only one person
may talk at a time, since half duplex uses only one frequency. Duplex
is communication in a two-way direction on two frequencies. One
frequency is used to talk and the other one to listen. This is the
modern way of cellular communication.
There are two common ways to realise duplex transmission:
y Frequency Division Duplex(FDD)
In this case, frequency resources are allocated to the mobile
communication system. Some of the frequency bands are
allocated to uplink communication only, while other frequency
bands are used for downlink communication.
y Time Division Duplex(TDD)In this case, one carrier frequency band is used for uplink and
downlink communication. The transmission is organised in
time frames. In each time frame, time resources are used for
downlink transmission.
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FDD and TDD
3.12 Radio communication
There are two basic formats used in the radio communication:
analogue and digital. The commercially available analogue
format has been used since 1900, while the commercially
available digital format was introduced in 1900.
There are four basic air interface technologies used for
communication:
y Frequency Division Multiple Access (FDMA)
y Space Division Multiple Access (SDMA)
y Time Division Multiple Access (TDMA)
y Code Division Multiple Access (CDMA)
Frequency Division Multiple Access (FDMA)
The main logic behind the FDMA technology is the frequency range is
broken down into unique bandwidths and distributed to the users.
FDMA is used in cellular communications. One frequency to speak on
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and one to listen on; thus we have duplex communications. That way
multiple users can operate in a particular frequency spectrum.
FDMA
Space Division MultipleA
ccess (SDMA
)
The main idea behind SDMA is that the same frequency can be used
multiple times in the same geographical region. The geographical
region is break into smaller areas called cell. Each cell would use a
frequency different than those of its nearest neighbours to prevent
any interface.
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SDMA
Time Division Multiple Access (TDMA)
The idea behind TDMA is dividing the frequency into multipletime slices so that multiple users can access the same
frequency at the same time.
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TDMA
Code Division Multiple Access (CDMA)
In CDMA systems, several transmissions via the radio interface
take place simultaneously on the same frequency bandwidth.
The user data is combined at the transmitters side with a code,
then transmitted. In air, all transmissionget mixed. At the
receivers side, the same code is used as in the transmitters
side. The code helps the receiver to filter the the user
information of the transmitter from the incoming mixture of all
transmissions on the same frequency band and same time.
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CDMA
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Chapter-4
Base Station System
4.1 Introduction
The Base Station System (BSS) is responsible for all the radio-
related functions in the system, such as:
y Radio communication with the mobile units
y Handover of calls in progress between cellsy Management of all radio network resoures and cell
configuration data.Ericssons BSS consists of three components:
y Base Sation Controller (BSC): the BSC is the central
node within a BSS and co-ordinates the actions of
TRCs and RBSs.
y Transcoder Controller (TRC): the TRC provides the
BSS with rate adaption capabilites. This is necessarybecause the rate used over the air interface and that
used by MSC/VLR are different 33.8 kbits/s and 64
kbits/s respectively. A device, which performs the
adaption is called a transcoder.
y Radio Base Station (RBS): an RBS acts as the
interface between MSs and the network, by
providing radio coverage functions from their
antennae.
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BSS in Ericsson GSM systems
4.2 Base Station Controller and Transcoder
Controller
The Ericsson BSC product family consists of a combined
BSC/TRC and a remote BSC (without transcoders). The
transcoders are pooled, meaning they can be allocated on
demand Full rate, Half rate, Enhanced Full rate, AMR(Adaptive
Multi Rate) full rate or AMR half rate.
The two main available for implementing the TRC and BSC in
Ericssons BSS:
y BSC/TRC: a combined BSC andTRC on the same AXE. This
is suitable for medium and high capacity applications, e.g.
urban and suburban area networks. The node can handle
up to 1,020 transceivers (TRXs). 15 remote BSCs can be
supported from one BSC/TRC.
y Stand-alone BSC and stand-alone TRC: the stand-alone
BSC (without transcoders) is optimized for low and
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medium capacityapplications and is a complement to the
BSC/TRC, especially in rural and suburban areas. The
stand-alone TRC is located at the MSC/VLR to increase
transmission efficiency. A stand-alone TRC can support 16
remote BSCs.
TRC utilization and transmission rates in BSS
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Chapter-5
Wireless concepts and Logical Channels
5.1 Frequency
The following table summarizes the frequency-related specifications
each of the GSM systems. The terms used in the table are explained
in the remainder of this section.
An MS communicates with a BTS by transmitting or receiving radio
waves, which consist of electromagnetic energy. The frequency of a
radio wave is the number of times the wave oscillates per second.
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5.2 Channels
A channel is afrequency or set of frequencies which can be allocated
for the transmission, and the receipt, of information.
Communication channels of any form can be one of the following
types:
A simplex channel such as a FM radio station, uses a single frequency
in a single direction only. A duplex channel, such as that used during
a mobile call, uses two frequencies: one to the MS and one from the
MS. The direction from the MS to the network is referred to as
uplink. The direction from the network to the MS is referred to as
downlink.
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Uplink and downlink on a radio channel
5.3 Modulation Method
The modulation technique used in GSM is Gaussian Minimum Shift
Keying (GMSK) and is a form of phase modulation. This gives a bit
rate of 1.3 bits/s per Hz.
5.4 Logical Channels
All information to and from an MS must be formatted correctly, so
that the receiving device can understand the meaning of different
bits in the message.
The relationship between bursts and logical channels is shown in the
figure below.
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Logical channels and bursts
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Chapter-6
3G Evolution
6.1 Introduction
GSM has evolved to become a 3G network through several
steps to make a soft evolution. GSM is optimized for speech
and not for data and originally it only provides 9.6 kbits/s over
the air interface.
The most important steps involved in the evolution of GSM to
increase the data transfer rate are:
y High Speed Circuit Switched Data (HSCSD)
y General Packet Radio Service (GPRS)
y Enhanced Data for the GSM Evolution (EDGE)
The Evolution of GSM to 3G
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6.1.1 HSCSD
High Speed Circuit Switched Data (HSCSD) makes it possible to
use several timeslots simultaneously in circuit switched mode.
Today upto 4 timeslots can be used at the same time.
Furthermore, the maximum data rate in one of the timeslots is
increased from 9.6 kbit/s to 14.4kbit/s with the new coding
scheme. It is preferable for real time services (voice/video).
6.1.2 GPRS
The general trend in data applications is the generation of
increasingly bursty data streams. To support data streams with
higher bit rates a greater bandwidth is needed. Although
HSCSD does well on bandwidth by combining multiple
channels, it wastes scarce radio resources due to its circuit
switched nature. It therefore became necessary to introduce
packet switching in GSM networks in order to provide an
attractive bearer service for users wanting fast, efficient and
cheap access to the Internet and/or corporate intranet.
Extending GSM networks to support packet switching services
is therefore critical for operators wanting to position
themselves in the 3G telecom market.
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The GPRS architecture
GPRS is a bearer service realized by the introduction of twonew logical nodes in an existing GSM system: the SGSN (Serving
GPRS Support Node) and the GGSN (Gateway GPRS Support
Node). A new unit is introduced into existing BSCs called the
Packet Control Unit (PCU). The PCU consists of both hardware
and software with a central and regional processor.
6.1.3 EDGE
Operators deploying GSM/GPRS system have two paths from
which to choose. With the addition of EDGE to a GPRS network,
operators can introduce EGPRS (Enhanced GPRS) that offers
speed upto 384 kbit/s. EDGE stands for Enhanced Data rates for
Global Evolution, is an improved versions of GPRS and a logical
cost-effective step toward third-generation (3G) technology.
The implementation of GDGE in Ericsson GSM networks creates
minor changes in the network.
EDGE is an add on to the radio parts of GPRS, which means
GDGE requires GPRS and cannot work alone. EDGE increases
data transmission speeds upto 384 kbit/s or higher. The EDGE
standard has been defined for both circuit-switched and
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packet-switched traffic.Therefore, EDGE comprises both EGPRS
and ECSD (Enhanced Circuit-Switched Data).
6.2
The Third Generation of Mobile SystemsThe characteristic of third generation services is theinfrastructure capabilities to deliver several services in parallel
to each end user/terminal. This means subcribers to services
can carry on a voice conversation in parallel to accessing an
intranet or extranet to obtain important information or
participate in a video conferance and at the same time
exchange e-mails.
The general concepts for 3G systems are grouped under the
concept of the International Mobile Telecommunications 2000
(IMT-2000) system. This is complemented by development of
Universal Mobile Telecommunications Systems (UMTS) by ETSI.
UMTS aims to deliver wide-area/high-mobility data rates of 384
kbit/s and upto 2Mbps for local-area/low-mobility coverage.
To be able to support these bi rates, a new radio technology,
Wideband Code Division Multiple Access (WCDMA) is used.
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Mobile Multimedia Services
6.2.1 Services
Some basic planned 3G services include:
y Voice/high-quality audio
y High-speed data transmission
y E-postcard in combination with digital cameras
y Video conferencing and multimedia
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6.2.2Migration
The Migration of GSM to 3G
Going forward, GSM will continue to evolve to meet demands
for high-data through two complementary developments.
First, the existing MS-network interface has evolved to include
high bit rates for wide-area coverage, through HSCSD and
packet-switched data through GPRS that will provide
theoretical data rates upto 170 kbits/s.
Second, GSM will evolve to meet with 3G requirements by
offering data rates upto 384 kbit/s in all existing GSM
frequencies.
To reach this level of throughput, two air interfaces will co-
exist: the evolved GSM (TDMA) and the new UMTS interface
(WCDMA).
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Using dual-mode GSM/3G globel handsets with GSM providing
coverage and 3G delivering new functionality operators will be
able to fully leverage additional wideband services in their GSM
networks with full service transparency across the enormus
GSM worldwide presence.
The radio acess network will be a ditinct overlay network for
the two types of air interfaces. For the WCDMA radio access
network, some of the existing GSM concepts will be reused but
many principles and stuctures will be new. The core network
for WCDMA systems will be an evolution of todays GSM circuit
and packet switching networks. As a result the GMSC has
evolved to support circuit-switched accesses from the MS
towards either telecommunications-based networks.
Evolution of GSM to UMTS
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Chapter-7
Introduction to UMTS
7.1 UMTS Network Structure
The obvious lack of GSM systems is the bandwidth offered to
the end user. In the beginning the bandwidth offered to the
end user was reasonable, but as the technology developed, the
end user requirements increased. New services (such as
internet) became more common, so the bandwidth became
inadequate. This was the main reason for starting thespecification for the next generation cellular networks.The air
interface of the 3G should be generic, this means that the radio
part of the network should be even more functionally
separated than in the GSM. To clarify and specify this, the call
establishment related parts of the 3G network are expressed as
follows:
3G network principle diagram
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The multiple access method used between the User Equipment (UE)
and the RAN(Radio Access Network) is called Wideband Code
Division Multiple Access (WCDMA). The 3GPP is aiming to specify
open interfaces also within the RAN in order to guarantee
multivendor scenarios. Despite this, it is resonable to believe that
operators will not select a large number of suppliers for the RAN, nor
for the Core Network (CN) implementation.
In GSM, we use TDM (Time Division Multiplexing) as the transmission
method between the different network elements. For UMTS, ATM
(Asynchronous Transfer Mode) has been chosen as the transmission
method in the radio access network. The basic difference betweenTDM and ATM is that in TDM, we use timeslots for conveying
information between network elements. In ATM, on the other hand,
the data is transmitted in cells(packets) of fixed size across the
network.
3G network management layers
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References
1.en.wikipedia.org/wiki/GSM
2. www.tech-faq.com/gsm
3. en wikipedia.org/wiki/3G
4. www.mobilein.com/3G.htm