18-12-2012, 12:11 PM
Evolution of Cellular Technology from 1G to 4G
1Evolution of Cellular.pptx (Size: 218.88 KB / Downloads: 27)
Introduction
First-generation (1G) mobile phones
had only voice facility.
These were replaced by second-generation (2G)digital phones with added fax, data, and messaging services.
The third-generation(3G) technology has added multimedia facilities to 2G phones.
The First Generation
1G mobile phones were based on the analogue system.
The Introduction of cellular systems in the late 1970s was a quantum leap in mobile communication especially in terms of capacity and mobility.
Semiconductor technology and microprocessors made smaller, lighter, and more sophisticated mobile systems a reality.
Advanced Mobile Phone System
AMPS is a first-generation cellular technology that uses separate frequencies, or "channels", for each conversation . It therefore required considerable bandwidth for a large number of users
Nordic Mobile Telephone
NMT is the first fully automatic cellular phone system
NMT is based on analog technology and two variants exist: NMT-450 and NMT-900. The numbers indicate the frequency bands uses.
An analog or analogue signal is any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal
The second Generation
2G phones using global system for mobile communications (GSM) were first used in the early 1990s in Europe.
GSM provides voice and limited data services, and uses digital modulation for improved audio quality.
The data services provided by GSM includes internet access, Circuit Switched data, SMS, Call forwarding, Call holding and Call waiting .
The development of 2G cellular systems was driven by the need to improve transmission quality, system capacity, and coverage.
Digital AMPS
IS-54 and IS-136 are second-generation (2G) mobile phone systems, known as Digital AMPS (D-AMPS). This system is most often referred to as TDMA.
D-AMPS uses existing AMPS channels and allows for smooth transition between digital and analog systems in the same area. Capacity was increased over the preceding analog design by dividing each 30 kHz channel pair into three time slots (hence time division) and digitally compressing the voice data, yielding three times the call capacity in a single cell. It provides services like text messaging, circuit switched data (CSD).
The 2G Architecture
The existing mobile network consists of the radio access network (comprising cells and backhaul communications)and the core network (comprising trunks, switches, and servers).
Mobile switching centres (MSCs) are intelligent servers and the whole network is data-driven, using subscription and authentication information held in the home location register (HLR) and authentication centre (AuC).