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Marconiâ„¢s innovative perception of electromagnetic waves and the air
interface in 1897 was the first milestone on the important road to shared use of the
radio spectrum. But only after almost a century later did mobile wireless
communication start to take off. Despite a series of disappointing false starts,
communication world in the late 1980â„¢s was rapidly becoming more mobile for a
much wider segment of communication users than ever before. With the advent of
wireless technology, a transition from point-to-point communication toward personto-
person communication (i.e.; independent of position) has begun. Testimony to this
is the rapidly increasing penetration of cellular phones all across the world. In
anticipation of the growing consumer demands, the next generation of wireless
systems endeavors to provide person-to-person communication of the circuit and
packet multi media data.
The first generation cellular networks, which were based on analog
technology with FM modulation, have been successfully deployed since the early and
mid 1980â„¢s. A typical example of a first generation cellular telephone system (1G) is
the Advanced Mobile Phone Services (AMPS). Second generation (2G) wireless
systems employ digital modulation and advanced call-processing capabilities. In view
of the processing complexity required for these digital systems, two offered
advantages are the possibility of using spectrally efficient radio transmission schemes
such as Time Division Multiple Access (TDMA) or Code Division Multiple Access
(CDMA), in comparison to the analog Frequency Division Multiple Access (FDMA)
schemes previously employed and the provision for implementation of a wide variety
of integrated speech and data services such as paging and low data rate network
access. Examples of 2G wireless systems include the Global System for Mobile
communication (GSM), TDMA IS-54/IS-136 and Personal Digital Cellular (PDC).
Third Generation (3G) wireless systems will evolve from mature 2G
networks with the aim of providing universal access and global roaming. More
important these systems are expected to support multi dimensional (multi-information
media, multi-transmission media, and multi-layered networks) high-speed wireless
communication- an important milestone toward achieving the grand vision of
ubiquitous personal communications. Introduction of wide band packet-data services
for wireless Internet up to 2Mbps will be the main attribute of 3G system.


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