GSM (Global System for Mobile Communication) is a widely used digital mobile telephony system that employs time division multiple access (TDMA) for voice and data communication. The architecture of a GSM network includes various components such as mobile stations, base stations, and service areas, allowing for efficient and mobile communication with applications in access control, transaction confirmation, and supply chain management. Although GSM offers advantages like diverse service options and better call quality, it has drawbacks, including higher roaming charges and data tampering risks.

1. TO STUDY ABOUT GSM
(GLOBAL SYSTEM FOR MOBILE COMMUNICATION)
GSM
GSM (Global System for Mobile communication) is a digital mobile telephony system
that is widely used in Europe and other parts of the world. GSM uses a variation of time
division multiple access (TDMA) and is the most widely used of the three digital wireless
telephony technologies (TDMA, GSM, and CDMA). GSM digitizes and compresses data,
then sends it down a channel with two other streams of user data, each in its own time
slot. It operates at either the 900 MHz or 1800 MHz frequency band.
The GSM standard was developed as a replacement for first generation (1G) analog
cellular networks, and originally described a digital, circuit-switched network optimized
for full duplex voice telephony. This was expanded over time to include data
communications, first by circuit-switched transport, then packet data transport via GPRS
(General Packet Radio Services) and EDGE (Enhanced Data rates for GSM Evolution or
EGPRS).
GSM ARCHITECTURE
A GSM network consists of several functional entities, whose functions and interfaces
are defined. The GSM network can be divided into following broad parts.
• The Mobile Station (MS)
• The Base Station Subsystem (BSS)
• The Network Switching Subsystem (NSS)
• The Operation Support Subsystem (OSS)

2. The added components of the GSM architecture include the functions of the databases
and messaging systems:
• Home Location Register (HLR)
• Visitor Location Register (VLR)
• Equipment Identity Register (EIR)
• Authentication Center (AuC)
• SMS Serving Center (SMS SC)
• Gateway MSC (GMSC)
• Chargeback Center (CBC)
• Transcoder and Adaptation Unit (TRAU)
Following is the diagram of GSM Networks along with added elements:
GSM network areas:

3. In a GSM network, the following areas are defined:
• Cell: Cell is the basic service area: one BTS covers one cell. Each cell is given a
Cell Global Identity (CGI), a number that uniquely identifies the cell.
• Location Area: A group of cells form a Location Area. This is the area that is
paged when a subscriber gets an incoming call. Each Location Area is assigned a
Location Area Identity (LAI). Each Location Area is served by one or more
BSCs.
• MSC/VLR Service Area: The area covered by one MSC is called the MSC/VLR
service area.
• PLMN: The area covered by one network operator is called PLMN. A PLMN can
contain one or more MSCs
GSM APPLICATIONS
Access control devices:
Now access control devices can communicate with servers and security staff through
SMS messaging. Complete log of transaction is available at the head-office Server
instantly without any wiring involved and device can instantly alert security personnel on
their mobile phone in case of any problem.
Transaction terminals:
EDC machines, POS terminals can use SMS messaging to confirm transactions from
central servers. The main benefit is that central server can be anywhere in the world.
Today you need local servers in every city with multiple telephone lines.
Supply Chain Management:
Today SCM require huge IT infrastructure with leased lines, networking devices, data
centre, workstations and still you have large downtimes and high costs. You can do all
this at a fraction of the cost with GSM M2M technology. A central server in your head
office with GSM capability is the answer, you can receive instant transaction data from
all your branch offices, warehouses and business associates with nil downtime and low
cost.
Multiple Remote Data Collection Points:
If you have multiple data collections points situated all over your city, state, country or
worldwide you will benefit the most. The data can be sent from multiple points like your

4. branch offices, business associates, warehouses, agents with devices like GSM modems
connected to PCs, GSM electronic terminals and Mobile phones.
High Uptime:
If your business require high uptime and availability GSM is best suitable for you as
GSM mobile networks have high uptime compared to landline, internet and other
communication mediums. Also in situations where you expect that someone may
sabotage your communication systems by cutting wires or taping landlines, you can
depend on GSM wireless communication.
Mobility, Quick installation:
GSM technology allows mobility, GSM terminals, modems can be just picked and
installed at other location unlike telephone lines. You can just purchase the GSM
hardware like modems, terminals and mobile handsets, insert SIM cards, configure
software and your are ready for GSM communication.
ADVANTAGES OF GSM
• There are numerous handsets and service providers available in the market. Hence the
buyers can choose from a variety of options.
• They come with a variety of plans with cheaper call rates, free messaging facility, and
limited free calls and so on.
• The quality of calling in GSM is better and also better secured than CDMA.
• A number of value-added services such as GPRS are making GSM a perfect choice.
• The consumption of power is less in GSM mobiles.
• With the tri-band GSM, one can use the phone anywhere around the world.
DISADVANTAGES OF GSM
• The per-unit charge on roaming calls is higher in GSM than in CDMA.
• Calls made through GSM mobiles can be tampered.
• If the SIM gets lost, one can lose all the data, if the same is not saved in the phone.