First-generation (1G) wireless networks were established in the late 1970s
with the primary aim of providing voice telephony services to mobile sub-
scribers. 1Gsystems are basically characterized by the use of analog frequency
modulation (FM) for voice transmission and frequency division multiple ac-
cess (FDMA) as its multiple access architecture. Several 1G networks were
independently developed in various regions of the world, with the main
systems represented by the following major technologies: Advanced Mobile
Phone Service (AMPS) in North America; Total Access Communication Sys-
tem(TACS), European TACS (ETACS), and NordicMobile Telephone system
(NMT) in Europe; and Japan TACS (JTACS) and Nippon TACS (NTACS) in
Japa.