PRESENTED BY
SHUJATHULLA SHARIFF

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INTRODUCTION
First generation:-
1. Almost all of the systems of this generation were Analog systems where voice was considered to be the main traffic.
2. 1G wireless networks used analog radio signals. Through 1G, a voice call gets modulated to a higher frequency of about 150MHz and up as it is transmitted between radio towers. This is done using a technique called Frequency-Division Multiple Access (FDMA).
3. These systems could often be listened to by third parties.
4. Drawbacks of 1G
1G compares unfavorably to its successors. It has low capacity, unreliable handoff, poor voice links, and no security at all since voice calls were played back in radio towers, making these calls susceptible to unwanted eavesdropping by third parties.
1G standards.
Advanced Mobile Phone System
(AMPS) was a 1G standard used in the United States.
Nordic Mobile Telephone (NMT) was a 1G standard used in Nordic countries (Denmark, Finland, Iceland, Norway and Sweden), as well as in its neighboring countries Switzerland and Netherlands, Eastern Europe, and Russia.
Italy used a telecommunications system called RTMI
Radio Telefono Mobile Integrato.
In the United Kingdom, Total Access Communication System (TACS) was used.
France used Radiocom 2000.
Second generation:-
2G refers to second generation wireless telecommunication technology. While its predecessor, 1G, made use of analog radio signals, 2G uses digital radio signals.
Based on what type of multiplexing (the process of combining multiple digital data streams into one signal) is employed, 2G technologies may be categorized by whether they are based on time division multiple access (TDMA) or code division multiple access (CDMA).
Around 60% of the current market is dominated by standards. of second Generation.
TDMA-based 2G standards
It includes the following:
Global System for Mobile communications (GSM), used worldwide;
Integrated Digital Enhanced Network (IDEN), developed by Motorola and used in the United States and Canada;
Interim Standard 136 (IS-136) or Digital Advanced Mobile Phone System (D-AMPS), used in North and South America; and
Personal Digital Cellular (PDC), used in Japan.
IS-95, on the other hand, is CDMA-based. It was developed by Qualcomm, and is alternately known as TIA-EIA-95 or cdmaOne.
2G cellphone units were generally smaller than 1G units, since they emitted less radio power.Another advantage of 2G over 1G is that the battery life of a 2G handset lasts longer, again due to the lower-powered radio signals. Since it transmitted data through digital signals, 2G also offered additional services such as SMS and e-mail. Its lower power emissions also made 2G handsets safer for consumers to use.
2.5 Generation
2.5G, which stands for "second and a half generation," is a cellular wireless technology developed in between its predecessor, 2G, and its successor, 3G.
"2.5G" is an informal term, invented solely for marketing purposes, unlike "2G" or "3G" which are officially defined standards based on those defined by the International Telecommunication (ITU). The term "2.5G" usually describes a 2G cellular system combined with General Packet Radio Services (GPRS), or other services not generally found in 2G or 1G networks.
GPRS is a service commonly associated with 2.5G technology. It has data transmission rates of 28 kbps or higher.
GPRS came after the development of the Global System for Mobile (GSM) service, which is classified as 2G technology, and it was succeeded by the development of the Universal Mobile Telecommunication Service (UMTS), which is classified as 3G technology.
Improved 2G networks (GPRS) manages to support few of applications like web browsing, emailing, video streaming, Multimedia messaging service etc. therefore GPRS can also be said that it is 2.5 generation technology.