The document describes the key components of a Global System for Mobile Communications (GSM) network. It discusses the radio subsystem (RSS), which consists of mobile stations (MS) and base station subsystems (BSS). The BSS includes base transceiver stations (BTS) that establish radio coverage in cells, and base station controllers (BSC) that handle traffic and signaling between BTS and the network. The document also outlines the subscriber identity module (SIM) card, which securely stores a user's international mobile subscriber identity (IMSI) and authentication key.

1. Global System for Mobile
Communication(GSM)
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January 18, 2018
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2. Figure: GSM Overview
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3. Figure: GSM Overview
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5. Radio SubSystems(RSS)
Consist of Mobile Station (MS) and Base Station
Subsystems (BSS)
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6. Radio SubSystems(RSS)
Consist of Mobile Station (MS) and Base Station
Subsystems (BSS)
RSS connected with NSS via A Interface & to the OSS
via O Interface.
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7. Radio SubSystems(RSS)
Consist of Mobile Station (MS) and Base Station
Subsystems (BSS)
RSS connected with NSS via A Interface & to the OSS
via O Interface.
A interface is typically based on circuit switched PCM 3.0
Subsystems(2.048 M bit/s)
can carry 30 64 kbps connection.
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8. Radio SubSystems(RSS)
Consist of Mobile Station (MS) and Base Station
Subsystems (BSS)
RSS connected with NSS via A Interface & to the OSS
via O Interface.
A interface is typically based on circuit switched PCM 3.0
Subsystems(2.048 M bit/s)
can carry 30 64 kbps connection.
O interface uses signaling system no. 7 (SS7) based on
X.25 for carrying management data To and From.
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9. Base Station Subsystem (BSS)
Incharge of Transmission and Reception.
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10. Base Station Subsystem (BSS)
Incharge of Transmission and Reception.
Consist of BSC and one of more BTS.
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11. Base Station Subsystem (BSS)
Incharge of Transmission and Reception.
Consist of BSC and one of more BTS.
BSS Maintain radio connection to an MS and
MSC(Mobile Switching Centre).
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12. Base Station Subsystem (BSS)
Incharge of Transmission and Reception.
Consist of BSC and one of more BTS.
BSS Maintain radio connection to an MS and
MSC(Mobile Switching Centre).
Coding/ Decoding of voice , rate adaption to /from the
wireless network part.
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13. Base Station Subsystem (BSS)
Incharge of Transmission and Reception.
Consist of BSC and one of more BTS.
BSS Maintain radio connection to an MS and
MSC(Mobile Switching Centre).
Coding/ Decoding of voice , rate adaption to /from the
wireless network part.
BSS translates between wireless interface and fixed wired
infrastructure protocols.
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14. Base Transceiver Station(BTS)
Centre of Cell, Consist of all radio equipment (Antennas)
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15. Base Transceiver Station(BTS)
Centre of Cell, Consist of all radio equipment (Antennas)
Signaling equipment to operate over air interface.
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16. Base Transceiver Station(BTS)
Centre of Cell, Consist of all radio equipment (Antennas)
Signaling equipment to operate over air interface.
Hand - offs of calls between two BTSs under the control
of same BSC.
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17. Base Transceiver Station(BTS)
Centre of Cell, Consist of all radio equipment (Antennas)
Signaling equipment to operate over air interface.
Hand - offs of calls between two BTSs under the control
of same BSC.
Abis interface connect BTS to BSC, carries traffic and
maintenance data.
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18. Base Transceiver Station(BTS)
Centre of Cell, Consist of all radio equipment (Antennas)
Signaling equipment to operate over air interface.
Hand - offs of calls between two BTSs under the control
of same BSC.
Abis interface connect BTS to BSC, carries traffic and
maintenance data.
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19. Base Station Controller(BSC)
A Small Switch, incharge of Frequency administration,
maintains appropriate power levels of the signal and hand
off among BTSs inside BSS.
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20. Base Station Controller(BSC)
A Small Switch, incharge of Frequency administration,
maintains appropriate power levels of the signal and hand
off among BTSs inside BSS.
BSC also multiplexes the radio channels onto the fixed
n/w connections at the A interface.
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21. Base Station Controller(BSC)
A Small Switch, incharge of Frequency administration,
maintains appropriate power levels of the signal and hand
off among BTSs inside BSS.
BSC also multiplexes the radio channels onto the fixed
n/w connections at the A interface.
Traffic Measurement, Authentication, Location Registray,
Loction updates,, Handover Management, Encryption,
Decryption, Paging, Frequency hopping.
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22. Base Station Controller(BSC)
A Small Switch, incharge of Frequency administration,
maintains appropriate power levels of the signal and hand
off among BTSs inside BSS.
BSC also multiplexes the radio channels onto the fixed
n/w connections at the A interface.
Traffic Measurement, Authentication, Location Registray,
Loction updates,, Handover Management, Encryption,
Decryption, Paging, Frequency hopping.
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23. Mobile Station (MS)
Comprised of User equipment and Software for GSM
Communication.
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24. Mobile Station (MS)
Comprised of User equipment and Software for GSM
Communication.
MS has ME (Mobile Terminal) and SIM(Subscriber
Identification Module).
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25. Mobile Station (MS)
Comprised of User equipment and Software for GSM
Communication.
MS has ME (Mobile Terminal) and SIM(Subscriber
Identification Module).
SIM has flash memory and mobile network codes.
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26. Mobile Station (MS)
Comprised of User equipment and Software for GSM
Communication.
MS has ME (Mobile Terminal) and SIM(Subscriber
Identification Module).
SIM has flash memory and mobile network codes.
MS can be identified using IMEI(International Mobile
Equipment Identifier).
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27. Mobile Station (MS)
Comprised of User equipment and Software for GSM
Communication.
MS has ME (Mobile Terminal) and SIM(Subscriber
Identification Module).
SIM has flash memory and mobile network codes.
MS can be identified using IMEI(International Mobile
Equipment Identifier).
Authentication based on SIM and not Device.
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28. SIM Details
A subscriber identity module or subscriber identification
module (SIM) is an integrated circuit that is intended to
securely store the international mobile subscriber identity
(IMSI) number and its related key, which are used to identify
and authenticate subscribers on mobile telephony devices
(such as mobile phones and computers).
The most important part of the SIM card is its
Microcontroller. It is a paper sized chip which is a typical
ROM with a size between 64 KB to 512 KB. The RAM size
ranges between 1KB to 8KB while the EEPROM size is in
between 16KB to 512 KB. The ROM contains the OS or
operating system for the card, while the EEPROM contains
data called personalization that includes security keys, phone
book, SMS settings etc. The operating voltage of SIM maybe,
1.8V, 3V or 5V but the operating voltages of most of the
modern SIM support 5V, 3V and 1.8V.
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29. Vcc : Power supply voltage at VCC Vpp : Programming
voltage at VPP
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30. SIM cards store network-specific information used to
authenticate and identify subscribers on the network. The
most important of these are the ICCID, IMSI, Authentication
Key (Ki), Local Area Identity (LAI) and Operator-Specific
Emergency Number. The SIM also stores other carrier-specific
data such as the SMSC (Short Message Service Center)
number, Service Provider Name (SPN), Service Dialing
Numbers (SDN), Advice-Of-Charge parameters and Value
Added Service (VAS) applications.
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31. ICCID
Each SIM is internationally identified by its integrated circuit card identifier (ICCID). ICCIDs are stored in the SIM
cards and are also engraved or printed on the SIM card body during a process called personalisation.
IMSI
SIM cards are identified on their individual operator networks by a unique International Mobile Subscriber Identity
(IMSI). Mobile network operators connect mobile phone calls and communicate with their market SIM cards using
their IMSIs.
Authentication key (Ki)
The Ki is a 128-bit value used in authenticating the SIMs on a GSM mobile network.
Location area identity
The SIM stores network state information, which is received from the Location Area Identity (LAI). Operator
networks are divided into Location Areas, each having a unique LAI number.
SMS messages and contacts
Most SIM cards store a number of SMS messages and phone book contacts. It stores the contacts in simple ”name
and number” pairs.
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