Evolution of Cellular Systems 7
Some European countries implemented this system at that time. Subscribers of NMT‐400
were able to transmit up to 15 watts of power using car phones. Six countries – namely
Finland, Sweden, Norway, Austria, Spain, and Denmark – adopted NMT‐400.
The advanced mobile phone service (AMPS) and its alternative total access communication systems (ETACS and NTACS) were more successful for 1G. From the radio
standpoint these above systems were identical. The main difference was the length of
the channel bandwidth.
1.3.1 Advanced Mobile Phone Service
The advance mobile phone service (AMPS) was more advanced in comparison to the
other 1G systems in the United States. It was deployed in Europe and Japan by an
organization named Total Access Communication Systems (ETACS). As mentioned
above, from the radio standpoint, the above‐mentioned systems were identical, only
differing in the length of channel bandwidth. For example, AMPS was based on a
30 kHz bandwidth, while the ETACS and NTACS used 20 kHz and 12.5 kHz for the
channel bandwidth, respectively [11].
AT&T and Bell Labs first implemented the AMPS for commercial use in the year of
1983 in Chicago and its neighboring areas, then later in Israel in 1986, in Australia
in 1987, and in Pakistan in 1990. By the mid‐2000s, all commercial companies discontinued this system from the market around the world. This system was constructed using long base stations (height from 150 ft to 550 ft) with omnidirectional
antennas. In the beginning, the carrier to interference ratio (CIR) was kept to 18 dB
for better voice quality. Spectrum was assigned by FCC in the USA to two operators in
each market, one for the incumbent telecommunications carrier and another for the
non‐incumbent operator. 20 MHz of spectrum was assigned for each operator, which
could support a total of 416 channels. For voice communication, 395 channels were
used and the remaining 21 channels were for control information. There were 7‐cell
frequency re‐use patterns, where each sector consisted of 3 sectors per cell. The
AMPS is based on the Frequency Modulation for voice communication and used
Frequency Shift Keying (FSK) for managing the control channel. After the availability
of 2G systems, AMPS were continued by the operators in North America for the
purpose of a common fallback service for the entire region and for the roaming service between multiple operators that had implemented 2G systems.
1.3.2 Security in 1G
The first generation (1G) cellular system used analog communication, as stated before.
Due to the vulnerable nature of analog signal processing, it was difficult to provide
efficient security services for 1G. For example, eavesdropping was a pressing concern
for 1G phones, as it was possible for anyone to listen in to a private communication
between two users, because all it required was a simple receiver operating at the similar
frequencies. There was absolutely no confidentiality in communication in 1G networks.
Also, the identity of the cellphone could easily be duplicated, and all the call charges
made from the duplicate phone could be directed to the original owner. Since the scale
of the network was small, and a small number of users needed servicing, the 1G cellular
Some European countries implemented this system at that time. Subscribers of NMT‐400
were able to transmit up to 15 watts of power using car phones. Six countries – namely
Finland, Sweden, Norway, Austria, Spain, and Denmark – adopted NMT‐400.
The advanced mobile phone service (AMPS) and its alternative total access communication systems (ETACS and NTACS) were more successful for 1G. From the radio
standpoint these above systems were identical. The main difference was the length of
the channel bandwidth.
1.3.1 Advanced Mobile Phone Service
The advance mobile phone service (AMPS) was more advanced in comparison to the
other 1G systems in the United States. It was deployed in Europe and Japan by an
organization named Total Access Communication Systems (ETACS). As mentioned
above, from the radio standpoint, the above‐mentioned systems were identical, only
differing in the length of channel bandwidth. For example, AMPS was based on a
30 kHz bandwidth, while the ETACS and NTACS used 20 kHz and 12.5 kHz for the
channel bandwidth, respectively [11].
AT&T and Bell Labs first implemented the AMPS for commercial use in the year of
1983 in Chicago and its neighboring areas, then later in Israel in 1986, in Australia
in 1987, and in Pakistan in 1990. By the mid‐2000s, all commercial companies discontinued this system from the market around the world. This system was constructed using long base stations (height from 150 ft to 550 ft) with omnidirectional
antennas. In the beginning, the carrier to interference ratio (CIR) was kept to 18 dB
for better voice quality. Spectrum was assigned by FCC in the USA to two operators in
each market, one for the incumbent telecommunications carrier and another for the
non‐incumbent operator. 20 MHz of spectrum was assigned for each operator, which
could support a total of 416 channels. For voice communication, 395 channels were
used and the remaining 21 channels were for control information. There were 7‐cell
frequency re‐use patterns, where each sector consisted of 3 sectors per cell. The
AMPS is based on the Frequency Modulation for voice communication and used
Frequency Shift Keying (FSK) for managing the control channel. After the availability
of 2G systems, AMPS were continued by the operators in North America for the
purpose of a common fallback service for the entire region and for the roaming service between multiple operators that had implemented 2G systems.
1.3.2 Security in 1G
The first generation (1G) cellular system used analog communication, as stated before.
Due to the vulnerable nature of analog signal processing, it was difficult to provide
efficient security services for 1G. For example, eavesdropping was a pressing concern
for 1G phones, as it was possible for anyone to listen in to a private communication
between two users, because all it required was a simple receiver operating at the similar
frequencies. There was absolutely no confidentiality in communication in 1G networks.
Also, the identity of the cellphone could easily be duplicated, and all the call charges
made from the duplicate phone could be directed to the original owner. Since the scale
of the network was small, and a small number of users needed servicing, the 1G cellular