Page 205 - Antennas for Base Stations in Wireless Communications

178 Chapter Five

Data 1980s 1990s 2000s

Extended Enhanced
Period Dawn Grown quantity quality

Generation 1st 2nd 3rd 4th
The analog The digital IMT-
System mobile phone mobile phone IMT-2000 Advanced
LTE
Super-3G
Communication - Voice - Voice - Data at high speed - Multiband
- Data at a (< 100Mbps) - All data
low speed - Multimedia (Information)
(< 64kbps)
Figure 5.1 The evolution of Japan’s mobile access systems

people could carry them; however, the phones still weighed around 3 kg.
In 1987, people could actually use portable telephones, partially because
their size and weight were reduced dramatically. For example, handsets
then weighed approximately 700 g. NTT had a monopoly on the market
until 1985 when Japanese regulations allowed new operators to enter
the mobile communication market. At that time, the service systems
provided by operators differed from each other. In 1G systems, users
couldn’t employ roaming service because each operator had its own dis-
tinct wireless interface and signal system. If a person used Operator A’s
phone system, he or she couldn’t talk to his or her friend who was using
Operator B’s system. Therefore, a strong demand arose for unifying the
systems to allow operators to offer users roaming service. The Ministry
of Internal Affairs and Communications of Japan proposed standards
and received positive feedback.
As a result, in 1993, operators accepted a new standard, which was
called personal digital cellular (PDC) technology and which was used
as the second-generation (2G) technology, replacing the 1G analog net-
work. The 2G digital cellular network in Japan operated in 800-MHz
and 1500-MHz bands. Seamless roaming service was now available.
However, the 2G systems in Japan couldn’t be used by those employing
systems developed by foreign operators. Therefore, the next goal was
to develop the technology to provide users with a mobile communica-
tion service that could be used anywhere in the world with one mobile
terminal.
In Japan, the mobile communication system has been developed to
align with the global International Mobile Telecommunications-2000
(IMT-2000) standard for third-generation (3G) mobile telecommunication