GSM other services are also provided, including:” ·

 GSM ARCHITECTURE

 

 

“GSM is a mobile
communication modem; it represents the Global System for Mobile Communications
(GSM). The idea of ??GSM, developed at Bell Labs in 1970, is the most widely
used mobile communication system in the world. GSM is an open digital cellular
technology used to transport mobile voice and data services in the 850MHz,
900MHz, 1800MHz and 1900MHz bands.”

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“The GSM system was developed as a digital system that uses Time Division Multiple Access (TDMA) technology for communication. The GSM digitizes and reduces the data and then sends it over a channel with two different client data streams, each of which is in its own slot. The digital system can carry 64kbps to 120Mbps data rates.”

 

INTRO
LINK: https://www.elprocus.com/gsm-architecture-features-working/

 

A GSM network consists of the
following components:

·       
The Mobile Station (MS)

·       
The Base Station Subsystem (BSS)

·       
The Network
Switching Subsystem (NSS)

·       
The Operation Support Subsystem (OSS)

 

MOBILE STATION:

 

“MS by the radio
transceiver, display and digital signal processor and SIM cards and other
physical devices. It provides an air interface for users in the GSM network.
Therefore, other services are also provided, including:”

 

·       
Voice
teleservices

·       
Data
bearer services

·       
 The features’ supplementary services

 

 

THE
MOBILE STATION FUNCTIONS

 

“Mobile Station
also offers a receiver for SMS messages, allowing users to switch among data
and voice usage. Although, mobile helps to access the voice messaging systems.
Mobile Station also give the permission to different data services those are
available in GSM network. These data services include:”

 

·        The X.25 packet switches to PAD via PAD at 9.6 Kbps over a synchronous or asynchronous dial-up connection. ·        General Packet Radio Service (GPRS), which uses data transmission methods based on X.25 or IP at speeds up to 115 Kbps. ·        High-speed, circuit-switched data at speeds up to 64 Kbps.

 

LINK: https://www.tutorialspoint.com/gsm/gsm_mobile_station.htm

 

 

 

 

VOICE TELESERVICES

 

“The ability to carry traffic is used by Teleservice to transmit data. Further the services diverted by:”

 

·       
Voice
call

·       
Videotext
and Facsimile

·       
Short
text messages

 

“Video call:  The GSM phones supports most basic teleservice. That survices provides full-speed voice and emergency calls at 13 kbps.”

 

“Videotext and facsimile: Additional set of remote services contains video text access, Teletex transport, Copy alternative voice and Facsimile group 3, Auto Facsimile group 3, and more.”

 

“Short text messages: The Short Message
Service (SMS) service is a digital
writing service that give permission to send the messages and receive text
messages on GSM mobile phone. In addition to simple writing messages,
other written data, including bulletin, game, finance, languages, and
location-based data, can be transmitted.”

 

                            
Bearer Services

 

“Data services or bearer services are used over GSM phones. Receiving and sending data is a key cornerstone for a wide range of mobile Internet access and mobile data transfer. GSM current data transfer rate of 9.6k. New developments that will drive the transmission rate of GSM user data are now available for HSCSD (High Speed ??Circuit Switched Data) and GPRS (General Packet Radio Service).”

 

 

 

                        Supplementary Services

 

“Additional services are additional services provided in addition to remote       services and hosting services. These services include caller identification, call forwarding, call waiting, multiparty calls, and outgoing (international) calls.” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 

LINK: https://www.tutorialspoint.com/gsm/gsm_user_services.htm  

 

 

            BASE STATION
SUBSYSTEM (BSS)

 

The BSS is composed
of two parts:

·       
The Base Transceiver Station (BTS)

·       
The Base Station Controller (BSC)

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“The BTS and BSC communicate via the designated Abis interface, making it possible to operate between machineries made by different provider. The BSS radio components can consist of 4 to 7 or 9 cells. BSS can have more than one base stations. The BSS uses the Abs interface between BTS and BSC. Then connect from the BSS to a separate high-speed line (T1 or E1) of the mobile MSC.”

 

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THE BASE TRANSCEIVER STATION (BTS)

 

The
BTS accommodates the radio transceivers that present the cell and manage the radio
link protocol with the Mobile Station. In metropolitan areas, many BTSs can be
deployed.

 

 

“The BTS corresponds to the transceivers and antennas used in each
cell of the network. The BTS is normally placed in the middle of a cell. The
outcome of the power transmission. Each BTS has 1 to 16 transceivers, depending
on the density of users in the cell. Each BTS serves as a single cell. It also
includes the following features:”

 

Encoding,
encrypting, multiplexing, modulating, and feeding the RF signals to the
antenna
Transcoding
and rate adaptation
Time
and frequency synchronizing
Voice
through full- or half-rate services
Decoding,
decrypting, and equalizing received signals
Random
access detection
Timing
advances
Uplink
channel measurements

 

        THE
BASE STATION CONTROLLER (BSC)

 

“The BSC handles
more than one BTS radio resources. It mange’s radio channel settings, frequency
hopping as well switching. The BSC is the main source that has connection upon
mobile device and the MSC. The BSC has a program for translating the 13 Kbps
voice channel used over the radio link to a standard 64 Kbps channel used by
Public Switched Telephone Network (PSDN) or ISDN.”

 

“It allocates and releases MS frequencies and time slots. The BSC can
manage inter-cell handovers. It also manages the power transfer between BSS and
MS in its area. The function of the BSC is to allocate the necessary time slots
between the BTS and the MSC. It is a switching device that handles radio
resources. Other features include:”

 

Control
of frequency hopping

Performing
traffic concentration to reduce the number of lines from the MSC
Providing
an interface to the Operations and Maintenance Center for the BSS
Reallocation
of frequencies among BTSs
Time
and frequency synchronization
Power
management
Time-delay
measurements of received signals from the MS

LINK: https://www.tutorialspoint.com/gsm/gsm_base_station_subsystem.htm

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            NETWORK SWITCHING SUBSYSTEMS
(NSS)

 

“The important area is
the Mobile Switching center (MSC) Network Switching System (NSS) performs
mobile exchanges and call exchanges between other static or mobile network
users as well as the organization of mobile services such as verification.”

 

 

The exchange system includes the
following functional elements:

 

     
             HOME LOCATION REGISTER (HLR)

“HLR is a catalo for
storing and managing subscriptions. The HLR is known as the most important
database because it stores fixed information about users, along the
subscriber’s service profile, address data, and activity information. When any
person buys a subscription as a form of SIM, then all the operator information
will have registered at HLR.”

 

 

        
MOBILE SERVICES SWITCHING CENTER (MSC)

 

“The core part of the
network subsystem is MSC. The MSC performs call exchanges between mobile and
other fixed or mobile network users as well as the management of mobile
services such as roaming subscriber registration, authentication, location
updating, handoff and call routing. It also performs ticketing, network
interfaces, public channel signalling and more. Each MSC is defined by a particular
ID.”

 

       
      VISITOR LOCATION
REGISTER (VLR)

“The VLR is a database
that contains the user’s temporary identity that the MSC must needs to access
the user. The VLR is always works toghether with the MSC. When a mobile station
enters in new MSC area, the VLR connected to that MSC will request data about
that mobile station from the HLR. After that, if the mobile station makes a
call, the VLR will have the information needed for call setup without having to
question the HLR each time.”

 

      
      AUTHENTICATION CENTER (AUC)

 

“The Certification
Authority is a secured database that stores copies of the keys stored on each
user’s SIM card for confirmation and encryption of radio channels. AUC helps to
protects the operators network from any kind of scam found in today’s cellular
world.””

 

 

 

    
    

            EQUIPMENT IDENTITY REGISTER
(EIR)

“Device Identity
Registration (EIR) is a main area where all valid mobile devices on the network
is stored, with the International Mobile Equipment Identity (IMEI) identifying
each MS. If the IMEI is reported as stolen or not approved, the IMEI is marked
as invalid.”

 

 
      GATEWAY MOBILE SWITCHING CENTER (GMSC)

“GMSC is the point at
which the ME terminates the call initially and do not have information about
mobile station area. Therefore, the GMSC is responsible for gaining the MSRN
(Mobile Station Roaming Number) from the HLR based on the MSISDN (Mobile
Station ISDN Number, MS’s “Telephone Number”) and routes the call to
the correct Visiting MSC. The term “MSC” part in the term GMSC is confusing
because the gateway operation does not require any link to the MSC.”

 

 

 

 

 

 

 

 

 

 

 

 

        
           OPERATION SUPPORT SUBSYSTEM (OSS)

“The Operations and
Maintenance Centre (OMC) connects to completely devices and BSCs in switching
system. The improvement of OMC is called Operations and Support System (OSS).”

 

Here are some of the OMC functions:

o    Administration and commercial operation
(subscription, end terminals, charging and statistics).

o    Security Management.

o    Network configuration, Operation and
Performance Management.

o    Maintenance Tasks.

 

Operation and maintenance roles built on the ITU-T Series M.30
standardized telecom management network (TMN) concept.

The diagram below displays the OMC system covering all GSM essentials:

 

“OSS is a functional object for network operator monitoring and
control systems. The motive of OSS is to provide cost-effective customer
support for the centralized, regional and local operations and preservation actions
required for GSM networks. A significant function of open source software is to
offer an overview of the network and support for the maintenance actions of
different operation and maintenance organizations.”

 

LINK: https://www.tutorialspoint.com/gsm/gsm_operation_support_subsystem.htm

 

 

Supplementary gears of the GSM architecture include database and
messaging system capabilities:

 

Home
Location Register (HLR)
Visitor
Location Register (VLR)
Equipment
Identity Register (EIR)
Authentication
Centre (AUC)
SMS
Serving Centre (SMS SC)
Gateway
MSC (GMSC)
Chargeback
Centre (CBC)
Transcoder
and Adaptation Unit (TRAU)

 

The figure below shows the GSM network
with additional elements:

 

 

With the help of Um interface, the MS and BSS communicate with each
other. It has one another name that is air interface or radio link. The BSS
communicates with Network Services Switching (NSS) centres over the A
interface.

 

    

 

                 GSM
NETWORK AREAS

 

In the GSM network, the following aspects are defined:

 

“CELL: Cell is the basic service area; a BTS covers a cell. Each
cell has a Cell Global Identification (CGI), a number that uniquely identifies
the cell.”

 

“LOCATION AREA:   A group of
cells form a location area (LA). This is the area the user called when they
received the call. Each LA is assigned a Location Area Identity (LAI). Each Los
Angeles is served by one or more BSCs.”

 

“MSC/VLR SERVICE AREA: An area covered by an MSC is called an MSC /
VLR service area.”

 

“PLMN:  The area covered by a
network operator is called the Public Land Mobile Network (PLMN). The PLMN may
contain one or more MSCs.”

 

                               
CONCLUSION

 

 

“The development of communication and the improvement of people’s
living standards are directly related to the use of mobile phones. Cellular
mobile radios – high-end, sophisticated technologies that allow everyone to
communicate with anyone. The rapid growth of the mobile phone industry has
become a pillar of business success and efficiency as part of a global modern
lifestyle.”

“In the work of this thesis, I try to reflect on the GSM system. I
hope I have given the overall style of GSM and the philosophy behind the
design. GSM is a standard that guarantees interoperability, and will not
benefit the public in terms of cost and service quality by not stifling
competition and innovation among suppliers.”

“Features and benefits of the GSM system include superior voice
quality, low end-of-line, operational and service costs, high levels of
security, international roaming support for low-power handsets, and new
business and networking facilities. In the coming days, 3G mobile phones will
be available worldwide, facilitating video conferencing for mobile phones.”