Standing up The Second Generation (2G)
The Second Generation of cellular technology was marked by a shift from analogue to digital systems.
Shifting to digital networks had many advantages. Firstly, transmission in the digital format aided clarity, since the digital signal was less likely to be affected by electrical noise. Secondly, transmitting data over digital network is much easier; data could also be compressed, saving a lot of time. And finally, with the development of new multiplexing techniques, the capacity of the cellular network could be increased manifold.
The technologies in a 2G cellular network are based on one of two concepts:
Time Division Multiple Access (TDMA)
Just like FDMA separated calls by assigning them different frequencies, TDMA separated calls by assigning them different time slots in the same frequency. TDMA was used in conjunction with FDMA, so if one frequency band had, say, three time-slots, it automatically multiplied the capacity of the network thrice.