140
E. Fraccaroli and D. Quaglia
system. This flexibility can be a source of interoperability. Furthermore, ISA100.11a
exploits all the potentialities of 6LoWPAN instead of designing a custom Network
Layer protocol.
3.3.17 Cellular Network Standards
Wireless devices such as mobile phones or data transmitters receive and send
radio signals with any number of cell site base stations fitted with microwave
antennas [66]. These sites are usually mounted on a tower, pole, or building, located
throughout populated areas, then connected to a cabled communication network and
switching system. The phones have a low-power transceiver that transmits voice and
data to the nearest cell site, normally not more than 8 to 13 Km away. In areas of
low coverage, a cellular repeater may be used, which uses a long-distance highgain antenna to communicate with a cell tower far outside of the normal range,
and a repeater to rebroadcast on a small short-range local antenna that allows any
cellphone within a few meters to function correctly.
When the mobile phone or data device is turned on, it registers with the mobile
telephone exchange, or switch, with its unique identifier, and can then be alerted by
the mobile switch when there is an incoming telephone call. The handset always
listens for the strongest signal being received from the surrounding base stations
and can switch seamlessly between sites. As the user moves around the network, the
“handoffs” are performed to allow the device to switch sites without interrupting the
call.
Cell sites have relatively low-power (often only one or two watts) radio transmitters which broadcast their presence and relay communications between the mobile
handsets and the switch. The switch, in turn, connects the call to another subscriber
of the same wireless service provider or to the public telephone network, which
includes the networks of other wireless carriers. Many of these sites are camouflaged
to blend with existing environments, particularly in scenic areas.
The dialogue between the handset and the cell site is a stream of digital data
that includes digitized audio. The technology that achieves this depends on the
system which the mobile phone operator has adopted. The technologies are grouped
by generation. The first-generation systems started in 1979 with Japan, are all
analog and include AMPS and NMT. Second-generation systems, started in 1991
in Finland, are all digital and include GSM, CDMA, and TDMA.
In an effort to limit the potential harm from having a transmitter close to the user’s
body, the first fixed/mobile cellular phones that had a separate transmitter, vehiclemounted antenna, and handset (known as car phones and bag phones) were limited
to maximum 3 watts Effective Radiated Power (ERP). Modern handheld cellphones
which must have the transmission antenna held inches from the user’s skull are limited to a maximum transmission power of 0.6 watts ERP. Regardless of the potential
biological effects, the reduced transmission range of modern handheld phones limits
E. Fraccaroli and D. Quaglia
system. This flexibility can be a source of interoperability. Furthermore, ISA100.11a
exploits all the potentialities of 6LoWPAN instead of designing a custom Network
Layer protocol.
3.3.17 Cellular Network Standards
Wireless devices such as mobile phones or data transmitters receive and send
radio signals with any number of cell site base stations fitted with microwave
antennas [66]. These sites are usually mounted on a tower, pole, or building, located
throughout populated areas, then connected to a cabled communication network and
switching system. The phones have a low-power transceiver that transmits voice and
data to the nearest cell site, normally not more than 8 to 13 Km away. In areas of
low coverage, a cellular repeater may be used, which uses a long-distance highgain antenna to communicate with a cell tower far outside of the normal range,
and a repeater to rebroadcast on a small short-range local antenna that allows any
cellphone within a few meters to function correctly.
When the mobile phone or data device is turned on, it registers with the mobile
telephone exchange, or switch, with its unique identifier, and can then be alerted by
the mobile switch when there is an incoming telephone call. The handset always
listens for the strongest signal being received from the surrounding base stations
and can switch seamlessly between sites. As the user moves around the network, the
“handoffs” are performed to allow the device to switch sites without interrupting the
call.
Cell sites have relatively low-power (often only one or two watts) radio transmitters which broadcast their presence and relay communications between the mobile
handsets and the switch. The switch, in turn, connects the call to another subscriber
of the same wireless service provider or to the public telephone network, which
includes the networks of other wireless carriers. Many of these sites are camouflaged
to blend with existing environments, particularly in scenic areas.
The dialogue between the handset and the cell site is a stream of digital data
that includes digitized audio. The technology that achieves this depends on the
system which the mobile phone operator has adopted. The technologies are grouped
by generation. The first-generation systems started in 1979 with Japan, are all
analog and include AMPS and NMT. Second-generation systems, started in 1991
in Finland, are all digital and include GSM, CDMA, and TDMA.
In an effort to limit the potential harm from having a transmitter close to the user’s
body, the first fixed/mobile cellular phones that had a separate transmitter, vehiclemounted antenna, and handset (known as car phones and bag phones) were limited
to maximum 3 watts Effective Radiated Power (ERP). Modern handheld cellphones
which must have the transmission antenna held inches from the user’s skull are limited to a maximum transmission power of 0.6 watts ERP. Regardless of the potential
biological effects, the reduced transmission range of modern handheld phones limits