1. Introduction: The Evolution of Mobile Telephone Systems

Cellular is one of the fastest growing and most demanding telecommunications
applications. Today, it represents a continuously increasing percentage of all new
telephone subscriptions around the world. Currently there are more than 45
million cellular subscribers worldwide, and nearly 50 percent of those
subscribers are located in the United States. It is forecasted that cellular systems
using a digital technology will become the universal method of
telecommunications. By the year 2005, forecasters predict that there will be more
than 100 million cellular subscribers worldwide. It has even been estimated that
some countries may have more mobile phones than fixed phones by the year
2000


The concept of cellular service is the use of low-power transmitters where
frequencies can be reused within a geographic area. The idea of cell-based mobile
radio service was formulated in the United States at Bell Labs in the early 1970s.
However, the Nordic countries were the first to introduce cellular services for
commercial use with the introduction of the Nordic Mobile Telephone (NMT) in
1981.
Cellular systems began in the United States with the release of the advanced
mobile phone service (AMPS) system in 1983. The AMPS standard was adopted
by Asia, Latin America, and Oceanic countries, creating the largest potential
market in the world for cellular.
In the early 1980s, most mobile telephone systems were analog rather than
digital, like today's newer systems. One challenge facing analog systems was the
inability to handle the growing capacity needs in a cost-efficient manner. As a
result, digital technology was welcomed. The advantages of digital systems over
analog systems include ease of signaling, lower levels of interference, integration
of transmission and switching, and increased ability to meet capacity demands.

Table 1. The Development of Mobile Telephone Systems

Year Mobile System
1981 Nordic Mobile Telephone (NMT) 450
1983 American Mobile Phone System (AMPS)
1985 Total Access Communication System (TACS)
1986 Nordic Mobile Telephony (NMT) 900
1991 American Digital Cellular (ADC)
1991 Global System for Mobile Communication (GSM)
1992 Digital Cellular System (DCS) 1800
1994 Personal Digital Cellular (PDC)
1995 PCS 1900—Canada
1996 PCS—United States