27-02-2013, 11:18 AM
GSM
GSM.ppt (Size: 452 KB / Downloads: 21)
Single Cell Systems
The first Mobile Telephone Service to offer duplex connections comparable to fixed network based telephone services started in 1946 as a car phone service in St. Louis, Missouri.
Comparable mobile telephone services appeared in post-war Europe some years later.
Cellular Mobile Radio Systems
The breakthrough in capacity was achieved with the introduction of the Cellular Radio System in the late 1970s/early 1980s.
The coverage of the supply area of a mobile communication operator involves many radio cells with cellular radio systems, in which the aforementioned limitation of the available HF frequency range is neatly circumvented through the repeated use of the HF channels.
‘1G’ Cellular Mobile Radio Systems
Information transmission of first generation cellular mobile radio system takes place via analogue radio interface.
These systems were tested in many countries in the end of the 70s.
‘2G’ Cellular Mobile Radio Systems
A further and very significant innovation in mobile radio communications took place with the introduction of the second generation cellular mobile radio system (e.g. GSM) in the early 90s.
Transmission via radio interface is now digital.
Portable Mobile Equipment
Mobile phones were first introduced in 1988. The weight of the equipment decreased from 1 kg to less than a 100 g within few years.
At the same time, mobility clearly improved despite decreasing weight owing to improvements in rechargeable batteries.
The GSM Recommendations
At the same time the Recommendations are flexible enough for the different realizations of various vendors.
The Recommendations are organized into 12 series according to different aspects.
This structure reflects the structure of the PLMN (Public Land Mobile Network) system and its interfaces.
The Evolutionary Concept
GSM Phase 2+: Individual topics are discussed separately and the update is added to the GSM standard in Annual Releases. Main topics are new Supplementary Services as the ASCI services, the IN feature CAMEL and VHE are very important. Especially the introduction of features to achieve higher data rates, i.e. HSCSD, GPRS and EDGE has received much attention. GSM Phase 2+ thus paves the way to 3G (UMTS).