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Transcript of Airtel Report
BHARTI AIRTEL LIMITED
GSM-Global System for Mobile Communication Architecture, Functionality and Management
Submitted by- VAZIR
TERII, KURUKSHETRA
30/08/2010
GSM-Global System for Mobile Communication 2
PREFACE
This record is concerned about my industrial training during the Summer Vacations after
2nd year. In course of B.Tech (Electronics And Communications Engineering) from
Tecnology Education And Research Integrated Institute,Kurukshetra , it is required
to undergo a practical training. Main objective of the training is to acquire knowledge
and attitude of practical nature which can be learned in industrial environment.
We have taken our Practical training at BHARTI AIRTEL LTD, Gurgaon. During this
training, I learnt many new things about the industry and the current requirements of
companies. This training proved to be a milestone in my knowledge of present industry
scenario and a practical know
how of the technology that is
used in present communication
techniques. It developed an
awareness of general
workplace, behavior and
interpersonal skills.
BHARTI AIRTEL LIMITED
GSM-Global System for Mobile Communication 3
CERTIFICATE
This is to certify that this “ TRAINING DOCUMENT ON GSM ARCHTECTURE,
FUNCTIONALITES & MANAGEMENT” is the bonafide work of “Vazir ” who
carried out his industrial training under my supervision.
Mr. Jaswant Rawat
Zonal Team Manager
Bharti Airtel Ltd
Gurgaon
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GSM-Global System for Mobile Communication 4
ACKNOWLEDGEMENT
Every endeavor, I understand takes an indomitable urge, perseverance and proper
guidance especially when it is most needed. Internally motivated to undertake some
appreciable work as a part of curriculum of bachelor’s degree, I undertook this project.
Unsure though but with a hope and then I was introduced to the project work to be
completed. Initially, I had hardly thought of the kind of work I was going to do.
I would like to take this opportunity to thank and show my gratitude to the stalwarts of
this esteemed organization. I would like to thank our project guide Mr. Jaswant Rawat sir
for his excellent guidance and time to time support. In addition I would like to thank Mr.
Aditya Choudhary sir and Mr. Sikander sir of the operation and maintenance Department
of MSC location for their continuous support and encouragement throughout the project
work.
Last but not the least; I would like to acknowledge all the people who are nevertheless
involved in the project directly or indirectly made it a success.
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GSM-Global System for Mobile Communication 5
Table of Contents
Index Page No.
Chapter 1: Introduction to Bharti Airtel Ltd. 8
Chapter 2: Introduction to GSM:
GSM history 10
Services provided by GSM 11
GSM specifications 11
Mobile subscriber identities in GSM 12
Chapter 3: GSM Evolution
Cellular network generations 14
Various technologies for data transmission 16
1. Edge
2. GPRS
Chapter 4: Hardware technicalities of GSM
Architecture of GSM 18
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GSM-Global System for Mobile Communication 6
GSM telecommunication services 20
Chapter 5: Antenna and Transmission
Important features of a tower 31
Radio resource management 33
1. Uplink frequency
2. Downlink frequency
Tower mounted amplifier 34
Transmission topologies 35
Chapter 7: Call flow
Multiple access scheme 36
1. FDMA
2. TDMA
Channel structure 37
Call origination and termination 40
Handover 42
Chapter 8: NSS 47
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Chapter 9: BSS
BTS 55
BSC 57
TRAU 57
Hardware 58
Chapter 10: MS 62
Chapter 11: Operations and Maintenance
OMT 65
OSS 65
MapInfo professional 66
Ericsson Win foil 66
Chapter 12: Project management 67
CONCLUSION 70
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Chapter 1
Introduction to Bharati Airtel LTd .
As we spread wings to expand our capabilities and explore new horizons, the fundamental focus remains unchanged: seek out the best technology in the world and put it at the service of pure ultimate user: our customer.”
- Sunil Bharti Mittal
Airtel comes to you from Bharti Airtel Limited, one of Asia’s leading integrated telecom services providers with operations in India, Sri Lanka and Bangladesh. Bharti Airtel since its inception has been at the forefront of technology and has pioneered several innovations in the telecom sector.
The company is structured into four strategic business units - Mobile, Telemedia, Enterprise and Digital TV. The mobile business offers services in India, Sri Lanka and Bangladesh. The Telemedia business provides broadband, IPTV and telephone services in 89 Indian cities. The Digital TV business provides Direct-to-Home TV services across India. The Enterprise business provides end-to-end telecom solutions to corporate customers and national and international long distance services to telcos.
Bharti Airtel formally known as bharti –tele-venture ltd.(BTVL), is an Indian company offering telecommunication service in 18 countries. it is the largest cellular service provider in India with more than 135 million subscription as may 2010. Bharti airtel is world largest single country mobile operator and fifth largest telecom operator in the world in terms of subscriber base. it also offers fixed line service and broadband service internet access (dsl )in over 89 cities India. it offers it telecom service under the Airtel brand and is headed by Sunil Bharti Mittal. it also act as carrier for national and international long distance communication service. The company has submarine cable landing station at Chennai which connects the submarine cables connecting Chennai and Singapore.
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GSM-Global System for Mobile Communication 9
It is known for being the first mobile phone in the world to outsource everything except marketing and sales .Its network (base station microwave link etc is maintain by ericsson and nokia Siemens network,business is supported by IBM and transmission power by another company. Ericsson agreed for first time to be paid by the minute for installation maintenance of their equipment rather than being paid up front this unable the company to provide pan India phone call rates of Rs 1per minute (us$0.02 minute).
The company is structured in four strategic business units.
Mobile Telemedia Enterprise Digital TV
The mobile business offer service in 18 countries across the Indian subcontinent and Africa. Telemedia business provides broadband IPTV and telephone services in 89 Indian cites .The digital TV business provides direct to home TV service across India. The enterprise business provide end to end telecom solution to corporate customer and national and international long distance service to tellcos..
Globally Bharti Airtel is the 3rd largest in the country mobile operator by subscriber base behind china mobile and china Unicom .in India has 24.6% share of the wireless service market followed by 17.7% for reliance communication and 17.4% for Vodafone essar. In January 2010 company announced that Manoj Kohli ,joint managing director and current chief executive officer of Indian officer of India and south Asian operation will became the Sanjay Kapoor will replace Manoj Kohli and will be the CEO effective from 1 April 2010.
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Chapter 2
Introduction to GSM
2.1 GSM HISTORY
During the early 1980s, analog cellular telephone systems were experiencing rapid growth in Europe, particularly in Scandinavia and the United Kingdom, but also in France and Germany. Each country developed its own system, which was incompatible with everyone else's in equipment and operation. This was an undesirable situation, because not only was the mobile equipment limited to operation within national boundaries, which in a unified Europe were increasingly unimportant, but there was also a very limited market for each type of equipment, so economies of scale and the subsequent savings could not be realized.
The Europeans realized this early on, and in 1982 the Conference of European Posts and Telegraphs (CEPT) formed a study group called the Groupe Spécial Mobile (GSM) to study and develop a pan-European public land mobile system. The proposed system had to meet certain criteria:
* Good subjective speech quality* Low terminal and service cost* Support for international roaming* Ability to support handheld terminals* Support for range of new services and facilities* Spectral efficiency* ISDN compatibility
2.2 Services provided by GSM
From the beginning, the planners of GSM wanted ISDN compatibility in terms of the services offered and the control signalling used. However, radio transmission limitations,
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in terms of bandwidth and cost, do not allow the standard ISDN B-channel bit rate of 64 kbps to be practically achieved
Using the ITU telecommunication services can be divided into bearer services, teleservices, and supplementary services. The most basic teleservice supported by GSM is telephony. As with all other communications, speech is digitally encoded and transmitted through the GSM network as a digital stream. similar to that of 911) A variety of data services is offered. GSM users can send and receive data, at rates up to 9600 bps, to users on POTS (Plain Old Telephone Service), ISDN, Packet Switched Public Data Networks, and Circuit Switched Public Data Networks using a variety of access methods and protocols, such as X.25 or X.32. SinceGSM is a digital network, a modem is not required between the user and GSM network, although an audio modem is required inside the GSM network to interwork with POTS.
2.3 GSM SPECIFICATIONS:
Bandwidth—the range of a channel's limits; the broader the bandwidth, the faster data can be sent
Bits per second (bps)—a single on-off pulse of data; eight bits are equivalent to one byte
Frequency—the number of cycles per unit of time; frequency is measured in hertz (Hz)
Megahertz (MHz)—1,000,000 hertz (cycles per second) Milliseconds (ms)—one-thousandth of a second Watt (W)—a measure of power of a transmitter
2.4 MOBILE SUBSCRIBER IDENTITIES IN GSM
International Mobile Subscriber Identity (IMSI)
An IMSI is assigned to each authorized GSM user. It consists of a mobile country code
(MCC), mobile network code (MNC) (to identify the PLMN), and a PLMN unique
mobile subscriber identification number (MSIN). The IMSI is the only absolute identity
that a subscriber has within the GSM system. The IMSI consists of the MCC followed by
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GSM-Global System for Mobile Communication 12
the MNC and MSIN and shall not exceed 15 digits. It is used in the case of system-
internal signalling transactions in order to identify a subscriber..
Temporary Mobile Subscriber Identity (TMSI)
ATMSI is a MSC-VLR specific alias that is designed to maintain user
confidentiality. It is assigned only after successful subscriber authentication. The
correlation of a TMSI to an IMSI only occurs during a mobile subscriber’s initial
transaction with an MSC (e.g.: location updating). Under certain condition (such
as traffic system disruption and malfunctioning of the system), the MSC can
direct individual TMSIs to provide the MSC with their IMSI.
Mobile Station ISDN Number
The MS international number must be dialled after the international prefix in
order to obtain a mobile subscriber in another country. The MSISDN numbers is
composed of the country code (CC) followed by the National Destination Code
(NDC), Subscriber Number (SN), which shall not exceed 15 digits. Here too the
first two digits of the SN identify the HLR where the mobile subscriber is
administrated.
The Mobile Station Roaming Number (MSRN)
The MSRN is allocated to the MS. The MSRN is there for every mobile
terminated call. It is assigned upon demand by the HLR on a per-call basis.
International Mobile Equipment Identity
The IMEI is the unique identity of the equipment used by a subscriber by each
PLMN and is used to determine authorized (white), unauthorized (black), and
black marketed (gray) GSM hardware. In conjunction with the IMSI, it is used to
ensure that only authorized users are granted access to the system.
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Location Area Identity
Each Location Area within the PLMN has an associated internationally-unique
identifier (LAI). The LAI is broadcast regularly by BTSs on the Broadcast
Control Channel (BCCH), thus uniquely identifying each cell with an associated
LA.
Cell Identifier
The CI an identifier assigned to each cell within a network. However, the CI is
only unique within a specific Location Area. When combined with the
internationally unique LAI for its associated LA, the Cell Global Identity (CGI) is
produced which is also internationally unique.
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Chapter 3
GSM EVOLUTION
3.1 CELLULAR NETWORK GENERATIONS
1G
Analogue services are referred here.
For voice only, didn’t provide for sms or other data services.
Circuit switching.
Insecure air interface.
2G
Widespread introduction in1990s
Digital services are referred here.
Provided internet access & improved voice quality.
Secure air interface.
2 technologies GSM & CDMA are defined here.
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2.5G/3G
Packet switching rather than circuit switching
EDGE provides data rates 3 times greater than GSM/GPRS.
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3.2 VARIOUS TECHNOLOGIES FOR DATA TRANSMISSION
The Wireless Evolution is achieved through the GSM family of wireless
technology platforms - today's GSM, GPRS, EDGE.
It is the basis of a powerful family of platforms for the future - providing a direct link into
next generation solutions including GPRS (General Packet Radio Services) EDGE
(Enhanced Data for GSM Evolution) .
3.2.1 EDGE
EDGE (or Enhanced Data Rates for Global Evolution) is a 3G technology that delivers
broadband-like data speeds to mobile devices. It allows consumers to connect to the
Internet and send and receive data, including digital images, web pages and photographs,
three times faster than possible with an ordinary GSM/GPRS network. EDGE enables
GSM operators to offer higher-speed mobile-data access, serve more mobile-data
customers, and free up GSM network capacity to accommodate additional voice traffic.
The technology EDGE has been designed to increase GPRS on-air data rates 2.5 to 3
times while meeting essentially the same bandwidth occupancy as the original 0.3-GMSK
signals. EDGE technology also enables each base station transceiver to carry more voice
and/or data traffic.
needed for a site depend on the amount of traffic that is expected to be handled by the site
as well as the site configuration.
3.2.2 GPRS
General Packet Radio Service (GPRS) enabled networks offer 'always-on', higher
capacity, Internet-based content and packet-based data services. This enables services
such as color Internet browsing, e-mail on the move, powerful visual communications,
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GSM-Global System for Mobile Communication 17
multimedia messages and location-based services. GPRS is used to implement high-
speed data transmission between the MS and some other party. GPRS utilizes multiple
BTSs in the same BSS. The MS sends different packets to different BTSs, which are
reconstructed at the SGSN. This enables the MS to use a higher transmission speed than
one transmission channel can handle. GPRS facilitates several new applications that have
not previously been available over GSM networks due to the limitations in speed of
Circuit Switched Data (9.6 kbps) and message length of the Short Message Service (160
characters). GPRS will fully enable the Internet applications you are used to on your
desktop from web browsing to chat over the mobile network
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Chapter 4
Hardware technicalities of GSM network
4.1 Architecture of the GSM network
A GSM network is composed of several functional entities, whose functions and interfaces are specified. Figure 1 shows the layout of a generic GSM network. The GSM network can be divided into three broad parts. The Mobile Station is carried by the subscriber. The Base Station Subsystem controls the radio link with the Mobile Station. The Network Subsystem, the main part of which is the Mobile services Switching Center (MSC), performs the switching of calls between the mobile users, and between mobile and fixed network users. operation . The Mobile Station and the Base Station Subsystem communicate across the Um interface, also known as the air interface or radio link. The Base Station Subsystem communicates with the Mobile services Switching Center across the A interface.
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The GSM network architecture as defined in the GSM specifications can be grouped into four main areas:
Mobile station (MS) Base-station subsystem (BSS)
Network and Switching Subsystem (NSS)
Operation and Support Subsystem (OSS).
GSM ARCHITECTURE
MS BSS NSS OSS
MT SIM
BSC BTS TRAU RR
MSC HLR VLR EIR AUC GMSC
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4.2 GSM TELECOMMUNICATION SERVICES
The ETSI Standards define the telecommunication services. With D900/D1800 the GSM
telecommunication services offered to the GSM subscriber are subdivided as follows:
Bearer services (for data only)
Tele-services (for voice and data)
Supplementary services
Bearer services and tele-services are also called basic telecommunication services. The
use of GSM telecommunication services is subject to subscription. A basic subscription
permits participation in those GSM telecommunication services that are generally
available. If a GSM subscriber roams out of the entitled area there is no possibility of
establishing communication (roaming not allowed), except the use of the tele-service
emergency call.
4.2.1 Bearer Services
Bearer services are telecommunication services providing the capability of transmission
of signals between access points. The bearer services describe what the network can offer
(e.g. speech, data and fax).
The bearer services are pure transport services for data. Some of the transmission modes
and rates already used in modern data networks are implemented; others are planned. The
following, already implemented, bearer services provide unrestricted information transfer
between the reference points in the mobile stations.
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Data CDA (circuit duplex asynchronous) + basic PAD (packet assembler
Dissembler) access.
Data CDS (circuit duplex synchronous)
PAD CDA (dedicated PAD access)
Alternate speech/data CDA (circuit duplex asynchronous)
Speech followed by data CDA (circuit duplex asynchronous)
Data compression on the GSM radio interface
4.2.2 Teleservices
Teleservices are telecommunication services including terminal equipment functions,
which provide communication between users according to protocols established by
agreement between network operators. The teleservices are user end-to-end services (e.g.
emergency call and short message service).
Tele-services use both low layer and high layer functions for the control of
communication from terminal to terminal. The following tele-services have already been
realized:
Telephony
Emergency call
Short message service (SMS)
Short message cell broadcast
Automatic facsimile (group 3)
Alternative speech and facsimile (group 3)
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4.2.3 Supplementary Services
Supplementary Services modify or supplement a basic telecommunication service.
Consequently, they cannot be offered to a customer as a stand-alone service. They must
be offered together or in association with a basic telecommunication service. The same
supplementary service may be applicable to a number of telecommunication services.
Most supplementary services are directly inherited from a fixed network, with minor
modifications (when needed) to adapt to mobility. Examples of supplementary services
are calling line identification and call waiting. Supplementary services extend beyond the
normal bearer services and teleservices (basic telecommunication services) and can be
subscribed to separately. In the following a supplementary service is called simply
service, in contrast to basic telecommunication service.
Number Identification Services
Calling line identification presentation (CLIP)
Calling line identification restriction (CLIR)
Call Offering Services
Call forwarding unconditional (CFU)
Call forwarding on mobile subscriber busy (CFB)
Call forwarding on no reply
Call forwarding on mobile subscriber not reachable
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Call Completion Services
Call hold
Call waiting (CW)
Multi-Party Service
Charging Services
Advice of charge (AOC)
Call Restriction Services
Barring of all outgoing calls (BAOC)
Barring of all outgoing international calls (BOIC)
Barring of all outgoing international calls except to home PLMN country
Barring of all incoming calls (BAIC)
Barring of all incoming calls when roaming outside home PLMN country
(BIC Roam)
Closed User Group (CUG)
Call rates are highly discounted with in a closed user group. Indian
Railways is the biggest closed user group in India. Its service provider is
Bharti.
ter 6
ANTENNA & TRANSMISSION
.
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GSM-Global System for Mobile Communication 24
CHAPTER - 6
6.1 IMPORTANT FEATURES OF A TOWER:
Polarization can be defined as the direction of the electrical field vector. Two
types of polarization are used:
For mobile communication – vertical polarization
For broadcast systems – horizontal polarization.
Beam width is generally the angular distance b/w the -3dB points of the antenna
pattern main lobe.
The Polarization mismatch b/w Rx and Tx antennas reduce the received signal
level.
Tower height is measured by the number of slots that are being used. All the slots
are equidistant, generally of 1.5 m.
Vertical antennas are having two types of tilts: electrical (for waveform
polarization) and mechanical (for dropping the signal at any desired angle) tilt.
The vertical height of the antenna can also be varied mechanically according to
the vertical antenna on the tower in front of this tower.
Vertical antennas are used for the latching the user mobile with the tower.
Antenna gain is the gain over an isotropic radiator in the direction of maximum
intensity (expressed in dB).
Tower is divided into 3 sectors of 120 degrees each & each of these sectors have a
hop and a vertical antenna installed on them.
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There are 2 types of towers: vertical and triangular towers. The triangular towers
need pole mounting for installation of any hop or vertical antenna.
The Hops control the network of Airtel through the E1s that travel in the
microwaves. The hops receive and transmit these microwaves.
The Hops are linked to the transmission rack in the site with the help of an RF cbl.
The angle of the Hop is put according to the next hop on the other tower. Both
these hops should have a perfect view of each other else there can be problems in
the network..
At the back of the hop there is a point for measuring the attenuation of the Hop.
We open it and we measure the voltage of the hop using a multimeter. The
voltage should be in the range of 2 to 2.5 V. The best possible voltage is 2.15 V.
Antenna gain = 20 log f + 20 log D; where f is frequency& D is diameter.
Antenna path loss = 20 log f + 20 log D; where f is frequency & D is length.
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6.2 RADIO RESOURCE MANAGEMENT:
In principle the GSM system can be implemented in any frequency band. However there are
several bands where GSM terminals are, or will shortly be available. Furthermore, GSM
terminals may incorporate one or more of the GSM frequency bands listed below to facilitate
roaming on a global basis.
Frequency Range
GSM900 880 - 915 MHz uplink and 935 - 960 MHz downlink
GSM1800 1710 - 1785 MHz uplink and 1805 - 1880 MHz downlink
Now there are 2 types of frequencies: uplink and downlink frequency.
Uplink frequency:
This is the frequency of the signal when it travels from Mobile to the BTS.
Downlink frequency:
This is the frequency of the signal when it travels from the BTS to the Mobile.
Uplink frequency: 890-915 MHz
Downlink frequency: 935-960 MHz
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The difference between the uplink and the downlink frequency is of 20 MHz.
The uplink frequency is less than the downlink frequency because the mobile has less
power because it works on battery. But in the case of downlink frequency, it is more
because we supply power continuously to the antenna (BTS).
We usually use 900 MHz (wavelength = .33 m) frequency band because we will have to
give less power for this. And because of the less frequency it will cover more and more
distance and less number of antennas will be required.
In the case of 1800 MHz (wavelength = .17 m) frequency band, if we use it then due to
the high frequency more power will be required and it will also travel a smaller distance.
So more antennas will be required and it will result to increase in the interference.
6.3 TOWER MOUNTED AMPLIFIER
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Tower mounted amplifier helps to give a boost to the uplink frequency so that it can properly reach the TRU in a good shape or manner.
6.4 TRANSMISSION TOPOLOGIES
1. Chain Topology: Linear approach to connect several BTS. Enhanced risk of service failure due to absence of protection path.
2. Ring Topology: Redundancy gives some protection if a link fails.SNCP protocol is used here.Main path and production path are there.
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3. Star Topology: Expensive as each BTS has its own link.one link feature always results in loss of BTS. Dependability upon single node. If central nod efails all connected nodes also fail.
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Chapter 7
CALL FLOW
7.1 MULTIPLE ACCESS SCHEME:
The multiple access scheme defines how different simultaneous communications,
between different mobile stations situated in different cells, share the GSM radio
spectrum. A mix of Frequency Division Multiple Access (FDMA) and Time Division
Multiple Access (TDMA), combined with frequency hopping, has been adopted as the
multiple access scheme for GSM.
FDMA and TDMA
Using FDMA, a frequency is assigned to a user. So the larger the number of users in a
FDMA system, the larger the number of available frequencies must be. The limited
available radio spectrum and the fact that a user will not free its assigned frequency until
he does not need it anymore, explain why the number of users in a FDMA system can be
"quickly" limited.
On the other hand, TDMA allows several users to share the same channel. Each of the
users, sharing the common channel, are assigned their own burst within a group of bursts
called a frame. Usually TDMA is used with a FDMA structure.
In GSM, a 25 MHz frequency band is divided, using a FDMA scheme, into 124 carrier
frequencies spaced one from each other by a 200 kHz frequency band. Normally a 25
MHz frequency band can provide 125 carrier frequencies but the first carrier frequency is
used as a guard band between GSM and other services working on lower frequencies.
Each carrier frequency is then divided in time using a TDMA scheme. This scheme splits
the radio channel, with a width of 200 kHz, into 8 bursts. A burst is the unit of time in a
TDMA system, and it lasts approximately 0.577 msec. A TDMA frame is formed with 8 BHARTI AIRTEL LIMITED
GSM-Global System for Mobile Communication 31
bursts and lasts, consequently, 4.615 msec. Each of the eight bursts, that form a TDMA
frame, are then assigned to a single user.
7.2 CHANNEL STRUCTURE
In GSM there are two types of channels:
The traffic channels used to transport speech and data information.
The control channels used for network management messages and some channel
maintenance tasks.
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Traffic channels (TCH)
Full-rate traffic channels (TCH/F) are defined using a group of 26 TDMA frames called a
26-Multiframe. The 26-Multiframe lasts consequently 120 Ms. In this 26-Multiframe
structure, the traffic channels for the downlink and uplink are separated by 3 bursts. As a
consequence, the mobiles will not need to transmit and receive at the same time that
simplifies considerably the electronics of the system.
The frames that form the 26-Multiframe structure have different functions:
24 frames are reserved to traffic.
1 frame is used for the Slow Associated Control Channel (SACCH).
The last frame is unused. This idle frame allows the mobile station to perform
other functions, such as measuring the signal strength of neighboring cells.
Half-rate traffic channels (TCH/H), which double the capacity of the system, are also
grouped in a 26-Multiframe but the internal structure is different. Here, speech coding is
done at around 7kbps instead of 13kbps.
Control channels:
1. Broadcast channels (BCH)
The BCH channels are used, by the base station, to provide the mobile station with the
sufficient information it needs to synchronize with the network. Three different types of
BCHs can be distinguished:
* The Broadcast Control Channel (BCCH), which gives to the mobile station the
parameters needed in order to identify and access the network.
* The Synchronization Channel (SCH), which gives to the mobile station the
training sequence needed in order to demodulate the information transmitted by
the base station.
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* The Frequency-Correction Channel (FCCH), which supplies the mobile station
with the frequency reference of the system in order to synchronize it with the
network.
2. Common Control Channels (CCCH)
The CCCH channels help to establish the calls from the mobile station or the network.
Three different types of CCCH can be defined:
* The Paging Channel (PCH). It is used to alert the mobile station of an incoming call.
* The Random Access Channel (RACH).It is used by the mobile station to request access
to the network
* The Access Grant Channel (AGCH) .It is used, by the base station, to inform the
mobile station about which channel it should use. This channel is the answer of a base
station to a RACH from the mobile station
3. Dedicated Control Channels (DCCH)
The DCCH channels are used for message exchange between several mobiles or a mobile
and the network. Two different types of DCCH can be defined:
*The Standalone Dedicated Control Channel (SDCCH). It is used in order to exchange
signaling information in the downlink and uplink directions.
*The Slow Associated Control Channel (SACCH). It is used for channel maintenance
and channel control.
*The Fast Associated Control Channels (FACCH) replace all or part of a traffic channel
when urgent signaling information must be transmitted. The FACCH channels carry the
same information as the SDCCH channels.
7.3 CALL ORIGINATION AND TERMINATION
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Call from Mobile Phone to PSTN:
When a mobile subscriber makes a call to a PSTN telephone subscriber, the following
sequence of events takes place:
1. The MSC/VLR receives the message of a call request.
2. The MSC/VLR checks if the mobile station is authorized to access the network. If
so, the mobile station is activated. If the mobile station is not authorized, service
will be denied.
3. MSC/VLR analyzes the number and initiates a call setup with the PSTN.
4. MSC/VLR asks the corresponding BSC to allocate a traffic channel (a radio
channel and a time slot).
5. The BSC allocates the traffic channel and passes the information to the mobile
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6. The called party answers the call and the conversation takes place.
7. The mobile station keeps on taking measurements of the radio channels in the
present cell and neighbouring cells and passes the information to the BSC. The
BSC decides if handover is required, if so, a new traffic channel is allocated to the
mobile station and the handover is performed. If handover is not required, the
mobile station continues to transmit in the same frequency.
Call from PSTN to Mobile Phone:
When a PSTN subscriber calls a mobile station, the sequence of events is as follows:
1. The Gateway MSC receives the call and queries the HLR for the information
needed to route the call to the serving MSC/VLR.
2. The GMSC routes the call to the MSC/VLR.
3. The MSC checks the VLR for the location area of the MS.
4. The MSC contacts the MS via the BSC through a broadcast message, that is,
through a paging request.
5. The MS responds to the page request.
6. The BSC allocates a traffic channel and sends a message to the MS to tune to the
channel. The MS generates a ringing signal and, after the subscriber answers, the
speech connection is established.
7. Handover, if required, takes place, as discussed in the earlier case.
The MS codes the speech at 13 Kbps for transmission over the radio channel in the given
time slot. The BSC converts (or transcodes) the speech to 64 Kbps and sends it over a
land link or radio link to the MSC. The MSC then forwards the speech data to the PSTN.
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In the reverse direction, the speech is received at 64 Kbps rate at the BSC and the BSC
does the transcoding to 13 Kbps for radio transmission.
7.4 HANDOVER
Handover Types
There are 4 different types of handovers in the GSM system, which involves transferring
a call between: Internal
Channels (time slots) Cells within the same BSS in the same cell.
External
Cells in different BSS. Cells under the control of different MSCs.
In a cellular network, the radio and fixed links required are not permanently allocated for
the duration of a call. Handover, or handoff as it is called in North America, is the
switching of an on-going call to a different channel or cell. The execution and
measurements required for handover form one of basic functions of RR management.
There are four different types of handover in the GSM system, which involve transferring
a call between:
• Channels (time slots) in the same cell
• Cells (Base Transceiver Stations) under the control of the same BSC.
• Cells under the control of different BSCs, but belonging to the same Mobile services
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Switching Centre (MSC)
• Cells under the control of different MSCs.
Intra-BSS handovers are known as Internal handovers as they involve only one Base
Station Controller (BSC). To save signalling bandwidth, they are managed by the BSC
without involving the Mobile services Switching Centre (MSC), except to notify it at the
completion of the handover.
Inter-BSS (either intra- or inter-MSC) are known as external handovers and are handled
by the MSCs involved. An important aspect of GSM is that the original (or anchor) MSC,
remains responsible for most call-related functions, with the exception of subsequent
inter-BSC handovers under the control of the new (or relay) MSC.
Handovers can be initiated by either the MS or the MSC (e.g. as a means of traffic load
balancing). During its idle time slots of a multiframe, the MS scans the BCCH of up to 32
neighbouring cells, and forms a list of the six best candidates for possible handover,
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based on the received signal strength. This information is passed to the BSC and MSC, at
least once per second, and is used by the handover algorithm.
Hand Over Causes:
Hand over can be initialised either by MSC or MS.
Hand over decision is based on following parameters:
o Received signal quality
o Received signal length
o Distance of MS from BTS
o Drops below power budget margin
Each parameter has an operator defined threshold and handover decisions can be
based on one or a combination of parameters.
Location update:
The network must always know our current location. For this, there is a timer in our
handset. BCCH provides with LAI & CGI. When mobile station moves from one place to
another, it searches BCCH, whichever BCCH is strong, mobile latches with it. BCCH
compares the new LAI with old LAI & same it does with CGI. If it is not the same, then
the location gets updated, otherwise it is slipped. Also, HLR & VLR also gets updated. In
idle state, handset monitors BCCH after intervals of time (keeps on comparing new & old
LAI). Temporary Mobile Subscriber Identity (TMSI) is used just for security reasons.
TMSI is just in VLR & not in HLR. IMSI is given to the user till it stays in that particular
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MSC. These are always sent in Radio link. When it reaches the new MSC, the earlier
MSC sends all the information to the new MSC, sending the TMSI, IMSI to it. The new
MSC has to send the acknowledgement to the early MSC that is being updated. Even
when we are in the same MSC, the LAI is compared. Now, if there are 2 different LAIs,
then the HLR is contacted, so it changes the LAI & gets updated. TMSI is always
allocated by VLR & always sends TMSI on radio link because it is not a secure link.
HLR has IMSI. If MSC wants data from HLR then it has to tell the IMSI to it. This IMSI
is given to it by the previous MSC. Pass information about the new subscriber to the new
MSC. The message contains a 64-bit ciphering key used as a Session Key (Kc), a 128-bit
random challenge (RAND) and a 32-bit Signed Response (SRES). These parameters will
be used in the authentication process. The new MSC replies back. Ask the Old MSC to
delete the record for this subscriber. The old subscriber's record is deleted. The TMSI
assigned to the mobile is also released. The Old MSC replies back to the HLR. The HLR
has updated all records, so it replies back to the new MSC.
Authentication in GSM:
Protects against intruders in air interface by maintaining authentication keys and
algorithms and provides security triplets (RAND, SRES, Kc). Authentication centre is
generally associated with HLR.The MSC VLR decides to authenticate the subscriber.
The RAND value received from the HLR is sent to the mobile. The SIM applies secret
GSM algorithms on the RAND and the secret key Ki to obtain the session key Kc and
SRES. The mobile passes the computed SRES value in the response. If the SRES
obtained from the mobile matches the SRES value obtained from the HLR, the subscriber
authentication procedure completes successfully. The MSC initiates ciphering of the data
being sent on the channel. The BSC sends the CIPHERING MODE COMMAND to the
mobile. Ciphering has already been enabled, so this message is transmitted with
ciphering. The BSC replies back to the MSC, indicating that ciphering has been
successfully enabled. The new MSC replies back to the mobile via the Virginia BSC. The
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message also assigns a new Temporary Mobile Subscriber Id (TMSI) to the terminal.
Since the TMSI assignment is being sent after ciphering is enabled, the relationship
between TMSI and the subscriber cannot be obtained by unauthorized users. The GSM
mobile replies back indicating that the new TMSI allocation has been completed. The RR
connection is released by the MSC. The BSC initiates RR release with the mobile. The
BSC informs the MSC that the RR connection has been released. The mobile sends a
disconnect message to release the LAPm connection. The BSC replies with an
Unnumbered Acknowledge message
Security in GSM:
On air interface, GSM uses encryption and TMSI instead of IMSI.
SIM is provided 4-8 digit PIN to validate the ownership of SIM
3 algorithms are specified :
- A3 algorithm for authentication- A5 algorithm for encryption- A8 algorithm for key generation
AUTHENTICATION IN GSM:
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KEY GENERATION AND ENCRYPTION:
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Chapter 8
NETWORK AND SWITCHING SYSTEMBHARTI AIRTEL LIMITED
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7.1 NSS (Network and switching system)
The switching system is responsible for performing call processing and subscriber-related functions. The switching system includes the following functional units:
Home location register (HLR)- the HLR is a database used for storage and management of subscriptions. The HLR is considered the most important database, as it stores permanent data about the subscribers, including a subscriber’s service profile, location information, and activity status. When an individual buys a subscription from one of the PCS operators, he or she is registered in the HLR of that operator.
Mobile services switching center (MSC) - the MSC performs the telephony switching functions of the system. It controls calls to and from other telephone and data systems. It also performs such functions as toll ticketing, network interfacing, common channel signaling, and others.
Visitor location register (VLR)- the VLR is a database that contains temporary information about subscribers that is needed by the MSC in order to service visiting subscribers. The VLR is always integrated with the MSC. When a mobile station roams into a new MSC area, the VLR connected to that MSC will request data the mobile station from the HLR. Later, if the mobile station makes a call, the VLR will have the information needed for call setup without having to interrogate the HLR each time.
Authentication center (AUC)- a unit called the AUC provides authentication and encryption parameters that verify the user’s identity and ensure the confidentiality of each call. The AUC protects networks operators from different types of fraud found in today’s cellular world.
Equipment identity register (EIR)- the EIR is a database that contains information about the identity of mobile equipment that prevents calls from stolen, unauthorized, or defective mobile stations. The AUC and EIR implemented as stand-alone nodes or
as a combined AUC\EIR node.
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7.2 The operation and support system
The operations and maintenance center (OMC) is connected to all equipment in the switching system and to the BSC. The implementation of OMC is called the operation & support system (OSS). The OSS is the functional entity from which the network operator monitors & controls the system. The purpose of OSS is to offer the customer cost-effective support for centralized, regional & local operational & maintenance activities that are required for a GSM network. As important function of OSS is to provide a network overview & support the maintenance organizations.
7.3 AXE SURVEY
The AXE architecture is an “open architecture” which is capable of supporting a whole range of communication services for large or small network operators in public fixed and mobile networks.
AXE is a future-proof solution based on continuous research and development in the field of communications and meets the demands of the future by incorporating advances such as
increased processor capacity, increased storage capacity, higher switching capacity and improved in-service performance (ISP). AXE is fully scalable and can be dimensioned to offer cost effective support for all sizes of network applications.
The main features of AXE are as follows:
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AXE modularity
Meeting network operators’ requirements
AXE is a telecommunication node.
AXE business communication services can be categorized as follows:
System and networking services
Analogue extension services
Digital extension service
Attendant services
Call distribution services
AXE System has:
System level 1: Highest system level at which nodes and networking configurations are defined.
System level 2: This is further divided into AM based & Non-AM based systems.
Fig: NON-AM BASED AXE DIAGRAM
In Non-AM based, the AXE system is divided into two parts:
APT, which is the switching part. For example, APT provides the switching functions needed to implement a PSTN local exchange or node.
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APZ, which is the control part. APZ is the computer system that runs the software
programs controlling the operation of the switching part.
7.3.1 APZ:
Central Processor, CP is duplicated, thereby offering a high level of hardware fault tolerance as well as a high processor capacity. The two-processor sides operate such that, at any given time, only one of the processor sides controls the applications hardware. In the event of a fault in the operational side, control may be swapped to the other side (if the fault is considered serious) with minimum, or no, impact on traffic handling.
The CP is duplicated with an A-side and a B-side. The work of the two central processors is continuously compared so that any fault is detected immediately.
Regional processors, RP/RPG/RPP/RPI are used for routine repetitive processing, application hardware control and processing-intensive tasks such as protocol handling.
The architecture allows full scalability, which means, the number and type of regional processors are adapted to the need.
Group switch, GS is generally seen as the hub around which the system is built. The Group Switch performs functions such as selection, connection and disconnection of speech or signal paths that pass through the group switch as well as connection or disconnection of telephony devices to the speech or signal path.
7.3.2 APT:
GEM (GENERIC ERICSSON MAGAZINE):
The GEM sub rack is one of the cornerstones in the new APT hardware. GEM, which stands for Generic Ericsson Magazine, is the main building block in APT and it can hold many important and fundamental APT functions:
Group Switch
ET155
Transceivers
Echo Canceller
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Interfaces to GDM subracks
This means that the majority of hardware devices will be located in the GEM subracks. Hardware not included in GEM is located in the GDM, which is an older type of magazine.
GDM (GENERIC DEVICE MAGAZINE):
AXE equipment inside the older GDM subracks must in some way be able to co-exist with the new GEM magazines. This is achieved by means of duplicated interface boards called DLEB inside the GEM magazine. These boards interface the DL3 interface from the GDM subrack.
DLEB - “Digital Link multiplexer for Existing equipment Board”
DLHB -“Digital Link Handling Board.”.
Each DLEB board can connect up to 4 DLHB boards (up to 4 GDM subracks) and there is always a need for two DLEB boards, one for each plane in the group switch. The GDM consists of one pair of RP4s, one pair of DLHB boards and sixteen slots for device boards.The maintenance subsystem (MAS) handles the automatic maintenance functions in APZ, which are:
Fault detection
Recovery diagnostics
Alarm generation within APZ
The MAS is responsible for the supervision of both software and hardware faults. Hardware faults can be either temporary or permanent. Software faults are programming errors that can result in for log off or system restarts.
L3 switch (CS02/CS01)
1. It is being used as a router.
2. This is because it has supervisors (SUP1, SUP2) in it.
3. These sup1 and sup2 control the switches below.
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4. All the optic fibres are terminated here in the ports in the L3 switch.
5. Protocols are also implemented through this switch.
Supervisory engines can be placed in each and every slot. This is optional. We can use as many supervisors as we want. Normally 1 supervisor does the job but here at this site we use 2 supervisors in 1 LP3 switch.
Catalyst 4507
CS01
Both of them are redundant.
HSRP is implemented.
This is the other switch that is there in this site.
In this switch more amount of connections and ports are there if compared with the CS02.
JACK Panel
The jack is for knowing whatever connections this particular site has and from where are these connections coming and how long they are.
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7.4 MSC:
The Mobile-services Switching Centre is an exchange which performs all the switching and signaling functions for mobile stations located in a geographical area designated as the MSC area.
The main difference between a MSC and an exchange in a fixed network is that the MSC has to take into account the impact of the allocation of radio resources and the mobile nature of the subscribers and has to perform in addition, at least the following procedures:
· procedures required for location registration.
· procedures required for handover.
This is divided into 2 parts:
1. Control unit:
This is the unit that controls the whole system or governs the system. This unit has 2 kinds of hardware same as the BSC but the only difference in this is that they run in parallel. Running in parallel means that the normal and the standby group of hardware work simultaneously but the signals sent by both of them have a time difference in between. This means that when the signal is passing through the main group of hardware to the traffic control this signal has a time difference between it and the signal of the standby unit so the signal of the main unit reaches faster or earlier so it is taken. But if the normal group malfunctions then the standby unit takes control.
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2. Traffic control:
This is the unit that controls the traffic. All the connections that are made while we are talking on the mob phone are made and controlled by it. This unit takes the signal from
the control unit. Here all the optic fibers terminate. The most important thing is that if the control unit malfunctions then the signals will keep on running. The network will be fine. And all the calls that the customers are making will not be affected. But we won’t be able
to control the network. But if the traffic control malfunctions then the whole network goes down. No calls can be made.
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Chapter 9
BASE STATION SUBSYSTEM (BSS)
The BSS consists of BTS, BSC and TRAU. It is capable of performing the configuration,
fault and maintenance task related activities. Operational & Maintenance Terminals
(OMT)s are used for installing the software in network elements. Antenna, rectifiers,
cabinets, feeders etc are required as transport essentials.
The BSS network architecture includes the following main components:
BTS
BSC
TRAU
1. BASE TRANSEIVER STATION EQUIPMENT
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• Radio Transmitter/Receiver (TRX)
• Signal processing and control equipment
• Antennas and feeder cables
The BTS comprises the entire radio network equipment
installed in a site for a single cell or a group of cells. In case of
sector cells, each cell refers to its own BTS, although all BTSs
are physically grouped together in the same site (BTS). The
BTS provides functions such as speech and channel
encoding/decoding, transmission and reception, etc.
The purpose of the BTS is to provide radio access to the mobile
stations and manage the radio access aspects of the system.
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2. BASE STATION CONTROLLER (BSC)
The BSC is the main component of the BSS system and it provides the interfaces to the
BTS and TRAU network elements and to the radio commander for operation and
maintenance functions. All the main components of the BSC are duplicated in order to
provide a fault-tolerant mechanism. The BSC allocates a channel for the duration of a call
and maintains the call also monitoring the call quality. It controls the power transmitted
by the BTS or MS. Thus administers the radio resources, it maps the radio channels to
terrestrial channels and it supports handover procedures between the connected cells.
3. TRANSCODING AND RATE ADAPTATION UNIT (TRAU)
For each traffic channel, the TRAU adapts the different transmission rates for speech and
data calls on the radio side to the PCM 64 Kbit/s transmission rate on the MSC side. It
also performs transcoding functions between the different speech coding algorithms used
on the radio interface (full rate, half rate, enhanced full rate) and the interface (PCMA or
μ law G.711) used within the terrestrial network.
HARDWARE USED
DXU-21 DISTRIBUTION SWITCHING UNIT
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DTRU- DOUBLE TRANSCEIVER UNIT
CDU &CXU
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1. DXU is the central control unit for BTS.
2. Flash card makes it possible to change a faulty DXU card
without the need of loading BTS software from the BSC.
3. OMT is the BTS configuration tool.
Functions:
1. Central function: control part of the TG.
2. Interworking Switch: connects time slots to transceivers.
3. Timing Function: synchronization with the PCM link and
generates the timing reference for the BTS.
4. Digital Path: associated object in each of the PCM systems
terminating in TG.
1. Contains 2 TRXs for transmission and reception
of carriers.
2. Built in combiner for combining 2 TX signals
into one output.
Functions:
1. TRXC: The transceiver controller controls
all the functions for signal processing, radio
receiving and transmitting.
2. RX: The receiver provides the radio
frequency reception functionality for 1
transceiver.
3. TX: The transmitter provides radio
frequency transmission one a time slot basis.
1. Combiners(CDU)
2. Interface between the transceivers (TRU)
and the antenna system.
3. Signals are filtered with Band Pass Filter
(BPF).
4. BTS 2206 has maximum 3 CDUs.
5. CDU-F used for Baseband hopping.
6. CDU-G is most commonly used for
synthesizer hopping.
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Other Standard Hardware Units:
1. AC connection unit.
2. DC connection unit
3. FCU: Fan control unit
4. IDM: For supply of 24V+ DC power to all units.
5. PSU: Power supply unit
6. DC filter
7. Battery Fuse Unit
8. Climate Unit
9. EPC bus: For alarm signaling.
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1. Distributes RX signal from CDU to DTRUs.
2. Built up software controlled switches.
3. Makes it possible to reconfigure a cabinet without cable moving.
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POWER SUPPLY:
The power is supplied from power plants and is sent to the distribution box which may be
single phase or three phase depending upon the kind of supply. Generally both types of
power are available at a site.
Then the power from distribution box is sent to the SMPS through which further supply
is carried out. The above diagram shows the general structure of power supply in a site.
Diesel Generator (D.G) rating is 45KV and if single sharing is there then 25KV.
Mains give power of 230 to 250KV, which if increased to 250KV then PIU
disconnects the power. It is provided with internal stabilization circuit.
Battery Bank (B.B) has a backup of 300A/H.
o -48 V supply is provided by B.B. This is to prevent acid accumulation
because -48V causes a current of 1A to flow in the reverse direction in the
circuit.
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o 48 V is converted to 24V when given to BTS.
Now a days BBS has been replaced by SMPS.
o There are two types of SMPS loads i.e. Critical and Non Critical.
Critical are concerned with Transmission rack.
Non Critical are concerned with BTS
All the equipments work on DC supply except the Air conditioning equipment
which works on AC supply.
Maximum capacity of Air conditioner is about 3 tonnes depending upon the
requirement.
Heat load is the factor from which we decide the power supply of AC.
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Chapter 10
Mobile station
Introduction:
The MS is the equipment used to access the network. The MS consists of two independent parts:
Subscriber Identity Module (SIM) card
Mobile Equipment (ME)
MOBILE S TA T ION F E A T URES
TYPES OF MS FEATURES:
MS features are defined as mandatory or optional. Mandatory features must be implemented as long as they pertain to the MS type. The choice of implementing optional features is left up to the manufacturers. Manufacturers are responsible for ensuring that the MS features neither conflict with the air interface nor interfere with the network, any other MS, or the MS itself.
Standardization of a minimum set of features is desirable to make a simple and uniform set of MS features independent of the MS manufacturer and type. This minimum set includes all the mandatory features.
There are three categories of MS features:
Basic: Basic MS features are directly related to the operation of basic telecommunication services. Each feature is classed as being mandatory or optional.
Supplementary: A supplementary MS feature is directly related to the operation of the supplementary service (e.g. display of calling line number). All supplementary MS features are optional.
Additional: Additional features are neither basic nor supplementary. All additional MS features are optional.
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Mandato r y Features:
1. Display of called number: This feature enables the caller to check that the selected number is correct before call set-up.
2. Dual Tone Multi Frequency function (DTMF): The MS must be able to send DTMF tones. There is a special function MSC to generate DTMF tones. MS just sends a digital signal to this function in MSC.
3. Indication of call progress signals: Indications are given such as tones, recorded messages or a visual display based on signaling information returned from the PLMN. On data calls, this information may be signaled to the Data Terminating Equipment (DTE).
4. Country/PLMN indication: The country/PLMN indicator shows in which GSM/PLMN the MS is currently registered. This indicator is necessary so that the user knows when roaming is taking place and that the choice of PLMN is correct. Both the country and PLMN are indicated. When more than one GSM/PLMN is available in a given area this information is indicated.
5. Country/PLMN selection: If more than one GSM/PLMN is available, the user must have the ability to select their preferred choice.
6. Service indicator: The user is informed that there is adequate signal strength (as far as can be judged from the received signal) to allow a call to be made and that the MS has successfully registered on the selected PLMN. This can be combined with the Country/PLMN Selection.
7. Subscription identity management: The IMSI is part of the SIM card and is physically secured and standardized in the GSM system. If the user can remove the SIM, its removal detaches the MS from the network causing a call in progress to be terminated, and preventing the initiation of further calls (except emergency calls).
8. International Mobile station Equipment Identity (IMEI): Each MS must have a unique identity and must transmit this if requested by the PLMN. The IMEI is incorporated into a module which is built into the MS and is physically secured. The implementation of each individual module is to be carried out by the manufacturer.
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9. Support of A5/1 and A5/2: Provisions are made for support of up to seven algorithms as well as the support of ‘no encryption’. It is mandatory for A5/1 and A5/2 and non-encrypted mode to be implemented, but other algorithms are optional.
10. Short message indication and acknowledgment: This feature allows delivery of short messages to a MS from a service center. Such messages are submitted to the service center by a telecommunications network user who can also request information on the message status from the service center. The service center then transmits the message to the active MS user.
The MS must therefore provide an indication to the user that a message has been received from the service center and must also send an acknowledgment signal to the PLMN, to show that this indication has been activated. The PLMN then returns this acknowledgment to the service center.
11. Short message overflow indication: An MS user using the short message service will be informed when an incoming message cannot be received due to insufficient memory.
12. Emergency call capabilities: It must be possible to make an emergency call even without a valid SIM.
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Chapter 11
OPERATIONS SUPPORT SYSTEMS (OSS)
The OSS is connected to the different components of the NSS and to the BSC, in order to
control and monitor the GSM system. It is also in charge of controlling the traffic load of
the BSS. However, the increasing number of base stations, due to the development of
cellular radio networks, has provoked that some of the maintenance tasks are transferred
to the BTS. This transfer decreases considerably the costs of the maintenance of the
system
11.1 OPERATION & MAINTENANCE TERMINAL (OMT)
OMT is the ERICSSON software which is used at the site. Rectification of faults is done
as per their severity and service affecting nature. This is the software which helps to
connect with the remote BTS with our laptop and then helps us to see whatever is
happening inside the hardware. This is usually plugged into the DXU. The DX has a flash
card in which the IDB (installation data base) are installed through this software. Now
IDBs are installed by this Software according to the traffic around that site and the
different amount of traffic in the 3 different sectors of the tower. Eg. If only one of the
sector has traffic in it and the other 2 point towards inhabitant areas then the IDB to be
installed will be 1X12 (this means 1 sector has all the 12 TRX for itself). Now if each
sector has equal traffic then the DB will be 3X4 (3 sectors having 4 TRX each).
This software also tells us about the faults and the alarms raised in the BTS.it even tells
us where the fault is in the hardware ans what type of fault is it.the full description is
given fault wise in this software. There are the two types of faults: internal and external
faults.
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11.2 MAP INFO PROFESSIONAL:
This is the software in which there is an outline of each and every site airtel has in a
particular area and how are the sites connected to each other and finally to the hub site.
Now the best thing about this software is that if a site is down then till the point where the
network isn’t fine it will show a red connecting line. So we will come to know where to
check for the problem.
11.3 ERICSSON WINFI OL
Winfiol is developed by Ericsson AB and is used by 102 users of Software Informer. The
most popular versions of this product among our users are: 7.0 and 7.1. The names of
program executable files are IconF26A7E5C.exe, winfiol.exe. To make automate login
with Winfiol, you should change properties on the channel where u will use ,and check
the enable login on the channel properties after that you should fill the IP
target(OSS,AXE etc..) and add the script file with adding new word for answer the login
prompt such as "login:" and "Password:".
Winfiol is a remote connection software developed by Ericsson. It is similar to telnet but
with little bit of graphical interface and at the same time with inbuilt command for scripts
and provision for macros.
WinFiol = command handling interpreter that is used for trouble shooting in Ericsson.
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Chapter 12
Project management.
12.1 SHIPMENT CYCLE DESCRIPTION (PROCESSES)
The entire project of GSM architecture consists of different type of equipments in it. For
example SDH, PDH, multiplexers, hops etc. It may happen that sometimes fault is
generated in the equipment. When the fault is generated at site, immediately serial no. of
the faulty equipment is generated. After generation of serial no. through software, order
is put forth about quantity and fault, giving all detail information about product, that
particular product goes to warehouse. Through warehouse information goes to
authorized personnel of Airtel. As this is case of Airtel, arrangement of vehicle is done,
which is sent to warehouse for collection of faulty equipments, which is sent to center
here the center is at Badlapur border. From center it sent to Singapore through coastal
area for lab test. At Singapore lab testing is carried out, on the entire faulty products and
then it decided whether product can be repaired or it should be replaced. And after this
process again same consignment is sent back through coastal area. The duration of this
shipment is 40 days, approximately 1month 10 days to and fro.
When this shipment is sent then at that time blue tag is attach to it containing all
information about product which is faulty which contain information about as shown in
tag format such as 1) prepared 2) Date 3) phone no. 4) Email-ID 5) service technician
company 6) country 7) company 8) customer name 9) product no. R-states 10) serial
no 11) magazine position etc as shown in the following format.
BHARTI AIRTEL LIMITED
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12.2 Block diagram of shipment carried out in GSM architecture Project
Fault generated
in
1 )Prepared: 9) Product no incl R state: 20)I instruction during fault situation
2 )Date: 3) Phone no: 10) serial no 21) fault code
4 )Email id:
5 )Service technician company:
11) superior or product no incl R states: 22) failure verified
Yes
No 6 )Country:
7 )Customer name : 12) magazine position 13) glot position
23) fault description
BHARTI AIRTEL LIMITED
site Serial no generation
Put order through software& quantity
Ware house
Authorized person of Airtel
Vehicle arrange ment
Center
Coastal area Singapore lab /test repair center
GSM-Global System for Mobile Communication 65
14) type if node 15) system sw release 8) Site identity :
16) product sw release 16)fault category
18) fault situation 19) unit failure
24) only replacement
25) CSR ref no.
12.3 BLUE TAG FORMAT
CONCLUSION
In this report, I have tried to give an overview of the GSM system. As with any overview, and especially one covering a standard there are many details missing. I believe, however, that I gave the general flavor of GSM and the philosophy behind its design. It was a monumental task. It is a standard that ensures interoperability without stifling competition and innovation among suppliers, to the benefit of the public both in terms of cost and service quality. For example, by using Very Large Scale Integration (VLSI) microprocessor technology, many functions of the mobile station can be built on one chipset, resulting in lighter, more compact and more energy-efficient terminals.
Telecommunications are evolving towards personal communication networks, whose objective can be stated as the availability of all communication services anytime,
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GSM-Global System for Mobile Communication 66
anywhere, to anyone, by a single identity number and a pocket able communication terminal. The economies of scale created by a unified system are enough to justify its implementation, not to mention the convenience to people of carrying just one communication terminal anywhere they go, regardless of national boundaries.
Another point where GSM has shown its commitment to openness, standards and interoperability is the compatibility with the Integrated Services Digital Network (ISDN) that is evolving in most industrialized countries and Europe in particular (the so-called Euro-ISDN). GSM is also the first system to make extensive use of the Intelligent Networking concept, in which services like 800 numbers are concentrated and handled from a few centralized service centers, instead of being distributed over every switch in the country. This is the concept behind the use of the various registers such as the HLR. In addition, the signaling between these functional entities uses Signaling System Number 7, an international standard already deployed in many countries and specified as the backbone signaling network for ISDN.
GSM is a very complex standard, but that is probably the price that must be paid to achieve the level of integrated service and quality offered while subject to the rather severe restrictions imposed by the radio environment.
BHARTI AIRTEL LIMITED