First Generation Mobile Network (1st Generation)

The first generation of mobile telephony (written 1G) operated using analogue communications and portable devices that were relatively large. It used primarily the following standards. In the case of AMPS, the first 1G system to start operating in the USA (in July 1978), each channel was separated from the adjacent channels by a spacing of 30 kHz, which was not particularly efficient in terms of the available radio spectrum, and this placed a limitation on the number of calls that could be made at any one time. However, the system was a multiple access one, because a second caller could use the same channel, once the first caller had hung up. Such a system is called "frequency division multiple access" (FDMA).

The technological development that distinguished the First Generation mobile phones from the previous generation was the use of multiple cell sites, and the ability to transfer calls from one site to the next as the user travelled between cells during a conversation. The first commercially automated cellular network (the 1G generation) was launched in Japan by NTT in 1979. The initial launch network covered the full metropolitan area of Tokyo's over 20 million inhabitants with a cellular network of 23 base stations. Within five years, the NTT network had been expanded to cover the whole population of Japan and became the first nation-wide 1G network.

In 1984, Bell Labs developed modern commercial cellular technology (based, to a large extent, on the Gladden, Parelman Patent), which employed multiple, centrally controlled base stations (cell sites), each providing service to a small cell area. The sites were set up so that cells partially overlapped and different base stations operated using the same frequencies with little or no interference.
Vodafone made the UK's first mobile call at a few minutes past midnight on 1 January 1985.
The technology in these early networks was pushed to the limit to accommodate increasing usage. The base stations and the mobile phones utilised variable transmission power, which allowed range and cell size to vary. As the system expanded and neared capacity, the ability to reduce transmission power allowed new cells to be added, resulting in more, smaller cells and thus more capacity. The evidence of this growth can still be seen in the many older, tall cell site towers with no antennae on the upper parts of their towers. These sites originally created large cells, and so had their antennae mounted atop high towers; the towers were designed so that as the system expanded—and cell sizes shrank—the antennae could be lowered on their original masts to reduce range.