Page 204 - Antennas for Base Stations in Wireless Communications

5
Chapter

Antenna Issues and Technologies

for Enhancing System Capacity

Yasuko Kimura, NTT DoCoMo
Zhi Ning Chen, Institute for Infocomm Research

5.1 Introduction
Over the past three decades, we have all witnessed the rapid develop-
ment of mobile communications from devices to systems to infrastructure.
Japanese companies have played an important role in the development
of mobile communication technologies and services. Therefore, this chap-
ter first briefly reviews the historic evolution of technological innovation
and mobile communication systems in Japan. After that, general infor-
mation regarding wireless access systems is introduced with basic but
important concepts. Following the discussion of design considerations for
base station antennas in mobile communications systems, five typical
base station antennas will be discussed in depth.

5.1.1 Mobile Communications in Japan
As one of the key contributors, Japan has experienced all the stages of
development of modern mobile communications. Figure 5.1 shows the
evolution of technological innovations and generations of mobile com-
munication systems in Japan. 1–4
In 1979, the Japanese company Nippon Telegraph and Telephone
(NTT) Public Corporation started the first commercial land-mobile com-
munication service in the Tokyo district with the first-generation (1G)
automobile telephone. The system operated with analog transmission
technology. In 1984, NTT achieved countrywide service in Japan. One
year later, with the reduction in the size and weight of mobile phones,

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