23-01-2013, 01:59 PM
Training Report On GSM (Global System for Mobile Communications) Network
[attachment=48172]
GSM :
Brief History
The Global System for Mobile communication (GSM) is an ETSI (European Telecommunication Standard Institute) standard for 2G pan European digital cellular with international roaming. The main purpose of the group was to develop a 2G standard to resolve the roaming problem in the six existing different 1G analog systems in Europe. In 1986, the task force was formed, and in 1987 a memorandum of understanding (MoU) was signed. In 1989, ETSI included GSM in its domain. In 1991, the specification of the standard was completed, and in 1992, the first deployment started. By the year 1993, thirty two operators in 22 countries adopted the GSM standard, and by 2001, close to 150 countries had adopted GSM for cellular adaptation
Definition
Global system for mobile communication (GSM) is a globally accepted standard for digital cellular communication. GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standard that would formulate specifications for a pan-European mobile cellular radio system operating at 900 MHz. It is estimated that many countries outside of Europe will join the GSM partnership
Frequency Bands
This GSM system is a frequency and time division system. Each physical channel is characterized by a carrier frequency and a time slot number. GSM system frequencies include two bands at 900 MHZ and 1800 MHz commonly referred to as the GSM 900 and DCS 1800 systems.
For the primary band in the GSM 900 system, 124 radio carriers have been defined and assigned in two sub-bands of 25 MHz each in the 890 – 915 MHz and 935-960 MHz ranges with channel width of 200 kHz (these sub-bands are always referred as downlink as well as uplink respectively, we will see this concept in detailed in “ channel concepts” later in this module). Each carrier (a total channel width of 200 KHz) is divided into frames of 8 time slots
For DCS – 1800, there are two sub bands of 75 MHz in the 1710 – 1785 MHz and 1805 – 1880 MHz ranges.
MOBILE STATION ISDN NUMBER (MSISDN):
The MSISDN is a number which uniquely identifies a mobile telephone subscription in the public switched telephone network numbering plan. These are the digits dialed when calling a mobile subscriber.
TEMPORARY MOBILE SUBSCRIBER IDENTITY (TMSI):
The TMSI is a temporary number used instead of IMSI to identify a MS. The TMSI is used for the subscriber’s confidentiality on the air interface. The TMSI has only local significance (that is, within the MSC/VLR area) and is changed at certain events or time intervals. The TMSI structure can be chosen by each operator but should not consist of more than four octets (8 digits).
CELLULAR TELEPHONY
1. A cellular telephone system links mobile subscribers into the public telephone system or to another cellular subscriber.
2. Information between the mobile unit and the cellular network uses radio communication. Hence the subscriber is able to move around and become fully mobile.
3. The service area in which mobile communication is to be provided is divided into regions called cells.
4. Each cell has the equipment to transmit and receive calls from any subscriber located within the borders of its radio coverage area.
Why “cellular”?
Radio spectrum is very limited, that’s why we have only 10-25MHz dedicated to wireless communication. Such narrow bandwidth allows 100-400 channels of reasonable quality, which is not rational and commercially not profitable to develop network for such small number of mobile subscribers. Genius idea lead to division of the whole geographical area to relatively small cells, and each cell may reuse the same frequencies by reducing power of transmission. Each cell has its own antenna (base station), and all base stations are interconnected using microwave or cable communication.
[attachment=48172]
GSM :
Brief History
The Global System for Mobile communication (GSM) is an ETSI (European Telecommunication Standard Institute) standard for 2G pan European digital cellular with international roaming. The main purpose of the group was to develop a 2G standard to resolve the roaming problem in the six existing different 1G analog systems in Europe. In 1986, the task force was formed, and in 1987 a memorandum of understanding (MoU) was signed. In 1989, ETSI included GSM in its domain. In 1991, the specification of the standard was completed, and in 1992, the first deployment started. By the year 1993, thirty two operators in 22 countries adopted the GSM standard, and by 2001, close to 150 countries had adopted GSM for cellular adaptation
Definition
Global system for mobile communication (GSM) is a globally accepted standard for digital cellular communication. GSM is the name of a standardization group established in 1982 to create a common European mobile telephone standard that would formulate specifications for a pan-European mobile cellular radio system operating at 900 MHz. It is estimated that many countries outside of Europe will join the GSM partnership
Frequency Bands
This GSM system is a frequency and time division system. Each physical channel is characterized by a carrier frequency and a time slot number. GSM system frequencies include two bands at 900 MHZ and 1800 MHz commonly referred to as the GSM 900 and DCS 1800 systems.
For the primary band in the GSM 900 system, 124 radio carriers have been defined and assigned in two sub-bands of 25 MHz each in the 890 – 915 MHz and 935-960 MHz ranges with channel width of 200 kHz (these sub-bands are always referred as downlink as well as uplink respectively, we will see this concept in detailed in “ channel concepts” later in this module). Each carrier (a total channel width of 200 KHz) is divided into frames of 8 time slots
For DCS – 1800, there are two sub bands of 75 MHz in the 1710 – 1785 MHz and 1805 – 1880 MHz ranges.
MOBILE STATION ISDN NUMBER (MSISDN):
The MSISDN is a number which uniquely identifies a mobile telephone subscription in the public switched telephone network numbering plan. These are the digits dialed when calling a mobile subscriber.
TEMPORARY MOBILE SUBSCRIBER IDENTITY (TMSI):
The TMSI is a temporary number used instead of IMSI to identify a MS. The TMSI is used for the subscriber’s confidentiality on the air interface. The TMSI has only local significance (that is, within the MSC/VLR area) and is changed at certain events or time intervals. The TMSI structure can be chosen by each operator but should not consist of more than four octets (8 digits).
CELLULAR TELEPHONY
1. A cellular telephone system links mobile subscribers into the public telephone system or to another cellular subscriber.
2. Information between the mobile unit and the cellular network uses radio communication. Hence the subscriber is able to move around and become fully mobile.
3. The service area in which mobile communication is to be provided is divided into regions called cells.
4. Each cell has the equipment to transmit and receive calls from any subscriber located within the borders of its radio coverage area.
Why “cellular”?
Radio spectrum is very limited, that’s why we have only 10-25MHz dedicated to wireless communication. Such narrow bandwidth allows 100-400 channels of reasonable quality, which is not rational and commercially not profitable to develop network for such small number of mobile subscribers. Genius idea lead to division of the whole geographical area to relatively small cells, and each cell may reuse the same frequencies by reducing power of transmission. Each cell has its own antenna (base station), and all base stations are interconnected using microwave or cable communication.