Slide 1
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Traffic
Signaling
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Separation of the whole spectrum into smaller frequency bands
A channel gets a certain band of the spectrum for the whole time
Advantages:
Disadvantages:
Time multiplex
A channel gets the whole spectrum for a certain amount of time
Advantages:
medium at any time
Time and Frequency Multiplex
Combination of both methods
A channel gets a certain frequency band for a certain amount of time
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k5
k6
k1
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. . .
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During the early 1980s
Analog cellular telephone systems were experiencing rapid growth in Europe (in Scandinavia, UK, France and Germany)
In 1982
The conference of European posts and telegraphs (CEPT) formed a study group called the group special mobile (GSM) to study and develop a pan-European public land mobile system
Requirements:
Support for international roaming
Support for range of new services and facilities
Spectral efficiency
ISDN compatibility
In 1983
In 1985
In 1986
Nordic Mobile Telephony (NMT) 900 developed
By 1993 there were 36 GSM networks in 22 countries [6] . Although standardized in Europe, GSM is not only a European standard. Over 200 GSM networks (including DCS1800 and PCS1900) are operational in 110 countries around the world. In the beginning of 1994, there were 1.3 million subscribers worldwide [18] , which had grown to more than 55 million by October 1997. With North America making a delayed entry into the GSM field with a derivative of GSM called PCS1900, GSM systems exist on every continent, and the acronym GSM now aptly stands for Global System for Mobile communications.
The developers of GSM chose an unproven (at the time) digital system, as opposed to the then-standard analog cellular systems like AMPS in the United States and TACS in the United Kingdom. They had faith that advancements in compression algorithms and digital signal processors would allow the fulfillment of the original criteria and the continual improvement of the system in terms of quality and cost. The over 8000 pages of GSM recommendations try to allow flexibility and competitive innovation among suppliers, but provide enough standardization to guarantee proper interworking between the components of the system. This is done by providing functional and interface descriptions for each of the functional entities defined in the system
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GSM responsibility was transferred to the European Telecommunication Standards Institute (ETSI)
In 1990
In mid-1991
In 1994
In 1995
PCS—United States
By 1993 there were 36 GSM networks in 22 countries [6] . Although standardized in Europe, GSM is not only a European standard. Over 200 GSM networks (including DCS1800 and PCS1900) are operational in 110 countries around the world. In the beginning of 1994, there were 1.3 million subscribers worldwide [18] , which had grown to more than 55 million by October 1997. With North America making a delayed entry into the GSM field with a derivative of GSM called PCS1900, GSM systems exist on every continent, and the acronym GSM now aptly stands for Global System for Mobile communications.
The developers of GSM chose an unproven (at the time) digital system, as opposed to the then-standard analog cellular systems like AMPS in the United States and TACS in the United Kingdom. They had faith that advancements in compression algorithms and digital signal processors would allow the fulfillment of the original criteria and the continual improvement of the system in terms of quality and cost. The over 8000 pages of GSM recommendations try to allow flexibility and competitive innovation among suppliers, but provide enough standardization to guarantee proper interworking between the components of the system. This is done by providing functional and interface descriptions for each of the functional entities defined in the system
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The fastest evolution
The highest demand
More than 747 million subscribers (more than 70% of all digital mobile phones use GSM)
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Date
No.of Countries/Areas on Air
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To Produce Telecommunications Standards
Active in all areas of ICT
Setting globally-applicable standards for
http://www.etsi.org
http://portal.etsi.org
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(NMT , AMPS , TACS)
(UMTS , IMT2000)
Parameter
Value




‌ ( (Roaming)
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GSM is:
A second generation cellular standard developed to cater voice services and data delivery using digital modulation
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GSM

ISDN.
GSM .

Max no. of user channels 124 * 8 = 992 channels
Channel BW 200 KHz
No, of channel/carrier 8 channels/carrier
Modulation Digital GMSK (Gaussian Minimum Shift Keying that is a type of phase modulation)
Speech Coding RPE-LTP (Regular pulse excited - long term prediction)
Speech coding bit rate 13 kbps
Data coding bit rate 12 kbps
Service Voice and Data
270.833 kb/s per carrier
Slow frequency hoping 217/hops/second.
Block and convolutional channel coding copuled with interleaving to combat channel perturbations- overall channel rate of 22.8 kb/s
Full rate channel 13 kb/s voice coder rate using regular pulse excitation/linear predictive coding RPE/LPC, half rate channel 6.5 kb/s using
Vector coder rate using vector sum excited linear predictivie coding VSELP
Overall full rate channel bit rate of 22.8 kb/s.
Each cell can have from 1 to 16 pairs of carriers.
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915MHz
935MHz
960MHz
890MHz
DOWN_LINK
UP_LINK
GSM_900
1785MHz
1805MHz
1880MHz
1710MHz
DOWN_LINK
UP_LINK
GSM_1800
F1
F2
F1'
F2'
Frequency
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Number of base stations is increased
Transmitter power is decreased correspondingly to avoid interference
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Cellular Concept
Cell size:
100 m in cities to 35 km on the country side (GSM)
even less for higher frequencies
Cell shape:
Practical footprint (radio coverage area) is amorphous
BS placement:
omni-directional antenna
Edge-excited cell: BSs on three of the six cell vertices
sectored directional antennas
One channel in each cell is set aside for signalling information between BS and mobiles
Mobile-to-BS: location, call setup for outgoing, response to incoming
BS-to-Mobile: cell identity, call setup for incoming, location updating
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less transmission power needed
interference with other cells
reduced concentration while driving
Important Issues:
Cell sizing
(Data)


CDMA


( )

( 144 Kbps 384 Kbps 2 Mbps)