TABLE OF CONTENTS The development of the cell phone systems has witnessed a tremendous improvement in technology since the first cell phones were introduced at the beginning of the 1980s. The first generation (1G) of mobile phone systems were based on analogue technology and provided voice communications only. The first commercial analogue system to be launched was the Nordic Mobile Telephone (NMT) and shortly after, the Advanced Mobile Phone Service (AMPS) was commercially launched in the US. The Total Access Communication System (TACS) developed by Motorola was introduced in the UK and many other countries. These were the main mobile systems of the 1G that were developed around the globe but various variants were developed in other individual countries to suit their needs.
The 1G mobile phone systems were very similar in concept; the voice information was carried on a frequency modulated carrier and a control channel enables the voice signal to be routed to an available channel. The channel spacing used in these systems was different: NMT used a channel spacing of 12.5 kHz, AMPS a 30 kHz spacing, and TACS used a 25 kHz spacing.
The penetration rate of mobile phone subscription was increasing rapidly around the world. However, since a limited spectrum was available for the mobile phone provision, the analogue technology could not meet the demand because of its inherent shortcomings. There was a great deal of research into the application of digital technology into mobile phone systems. The research has led to the development of the...
