What is 1G or First generation of wireless telecommunication technology?

The First generation of wireless telecommunication technology is known as 1G was introduced in 1980. The main difference between then existing systems and 1G was invent of cellular technology and hence it is also known as First generation of analog cellular telephone. In 1G or First generation of wireless telecommunication technology the network contains  many cells (Land area was divided into small sectors, each sector is known as cell, a cell is covered by a radio network with one transceiver) and so same frequency can be reused many times which results in great spectrum usage and thus increased the system capacity i.e. large number of users could be accommodated easily.

Use of cellular system in 1G or First generation of wireless telecommunication technology resulted in great spectrum usage.  The First generation of wireless telecommunication technology used analog transmission techniques which were basically used for transmitting voice signals. 1G or  first generation of wireless telecommunication technology also consist of various standards among which most popular were Advance Mobile Phone Service (AMPS), Nordic Mobile Telephone (NMT), Total Access Communication System (TACS). All of the standards in 1G use frequency modulation techniques for voice signals and all the handover decisions were taken at the Base Stations (BS). The spectrum within cell was divided into number of channels and every call is allotted a dedicated pair of channels. Data transmission between the wire part of connection and PSTN (Packet Switched Telephone Network) was done using packet-switched network.

Different standards of 1G were used worldwide like:

In 1982 Advance Mobile Phone Service (AMPS) was employed in United States and later it was used in Canada, Central America, South America, Australia,  Argentina, Brazil, Burma, Brunei, Bangladesh, China ,Cambodia, Georgia, Hong Kong, Indonesia, Malaysia, Kazakhstan, Mexico, Mongolia, Nauru, New Zealand, Pakistan, Guinea, Philippines, Russia, Singapore, South Korea, Sri lanka, Tajikistan, Taiwan, Thailand, Vietnam, Western Samoa.

Total Access Communication System (TACS) / Extended Total Access Communication System (ETACS) was employed in United Kingdom, United Arab Emirates, Kuwait, Macao, Bahrain, Malta, Singapore.

Nordic Mobile Telephone-450 (NMT-450) was employed in Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Hungary, Poland, Russia, Spain, Sweden, Thailand, turkey and Ukraine.

Nordic Mobile Telephone-900 (NMT-900) was employed in Cyprus, Denmark, Finland, France, Greenland, Netherlands, Norway, Switzerland and Thailand.

C-NETZ (C-NETZ in German refers to C Network which was the first cellular wireless telephone network in Germany) was employed in Germany, Portugal and South Africa.

Radiocom2000 was employed in France.

Radio Telephone Mobile System (RTMS) was employed in Italy

Nippon Telephone and Telegraph (NTT) was first employed in Japan and later NTACS (Narrowband Total Access Communications System) and JTACS (Japanese Total Access Communication System) were also employed.

Use of Analog signals for data (in this case voice) transmission led to many problems those are:
1. Analog Signals does not allow advance encryption methods hence there is no security of data i.e. anybody could listen to the conversion easily by simple techniques. The user identification number could be stolen easily and which could be used to make any call and the user whose identification number was stolen had to pay the call charges.

2. Analog signals can easily be affected by interference and the call quality decreases.

References
1. For C-NETZ Reference taken from the book Der Telefon-Ratgeber (The Phone Guide )- Page 124 written by Fritz Jörn
2. Introduction to 3G mobile communications By Juha Korhonen
3. Wireless networks By P. Nicopolitidis