Page 19 - Antennas for Base Stations in Wireless Communications

xviii Introduction

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introduced the first portable mobile phone. Later, analog systems,
known as the first generation (1G) mobile phone systems, were accepted
as true personal mobile wireless communication systems.
In the 1990s, digital technology was employed for the development
of mobile phone systems, which were rapidly advancing and quickly
replacing the analog systems to become the second generation (2G) per-
sonal mobile phone systems. Benefiting from the huge progress seen in
integrated circuits (IC) and batteries as well as the deployment of more
base stations, the bricks (mobile phones) shrunk to become actual hand-
held devices. Meanwhile, cellular networks began to provide users with
additional new services such as text messaging (short message service
or SMS) and media content such as downloadable ring tones.
After the success of the 2G cellular network, extended 2G systems,
such as the CDMA2000 1xRTT and GPRS featuring multiple access
technology, were developed to enhance network performance and pro-
vide significant economic advantages. These systems are known as the
2.5 generation (2.5G). In theory, the 2.5G CDMA2000 1xRTT network
can achieve the maximum data rate of up to 307 kbps for delivering
voice, data, and signaling data.
The 2G and/or 2.5G networks provided users with quality of service
(QoS). With so many different standards, however, different technolo-
gies had to be developed. To achieve a worldwide standard, the third
generation (3G) systems have been standardized in the International
Telecommunication Union (ITU) family of standards, or the IMT-2000,
with a set of technical specifications such as a 2-Mbps maximum data
rate for indoors and 384-kbps maximum data rate for outdoors, although
this process did not standardize the technology itself. The first commer-
cial 3G CDMA-based network was launched by NTT DoCoMo in Japan
on October 1, 2001. Following this, many 3G networks have been set up
worldwide. By the end of 2008, global subscriptions to 3G networks
exceeded 300 million. For example, in China alone, the number of sub-
scribers had reached 118 million by the end of 2008.
After the 3G systems, the market is looking toward the next-generation
systems, which will be the fourth generation (4G) or beyond 3G (B3G).
The development of the 4G systems targets QoS and increasingly high
data rates to meet the requirements of future applications such as wire-
less broadband access, multimedia messaging service (MMS), video chat,
mobile TV, high-definition TV (HDTV) content, digital video broadcast-
ing (DVB-T/H), and so on.
Before the 4G systems are realized, however, many B3G systems are
being developed. For example, the 3GPP Long Term Evolution (LTE), an
ambitious project called the “Third Generation Partnership Project,” is
designed to improve the Universal Mobile Telecommunications System
(UMTS) in terms of spectral efficiency, costs, service quality, spectrum
usage, and integration with other open standards.