Page 156 - Antennas for Base Stations in Wireless Communications

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Chapter

Advanced Antennas for Radio

Base Stations

Anders Derneryd and Martin Johansson
Ericsson AB Ericsson Research

The rapid growth in the number of mobile communications users, as
well as in the data rates required by more demanding applications such
as mobile Internet and streaming services, has generated a demand for
new and efficient ways of increasing capacity in cellular networks. At the
same time, the need to offer communication services for areas with low
traffic density, for example, in rural regions and developing markets with
initial focus on voice services, has made wide-area coverage solutions
essential. Solutions to either or both of these goals include increased
frequency band allocation, frequency-hopping techniques, micro cells,
underlay/overlay, and advanced antennas. There is an increasing inter-
est in deploying advanced antenna techniques at the radio base station
because these offer the potential to exploit the spatial domain and also
because many of the other available solutions either have been fully
utilized or are considered impractical or cost-inefficient.
The concept of advanced antennas for radio base stations is not well
defined but, in general, can be taken to mean any antenna or strongly
antenna-related solution more sophisticated than that of a conventional
three-sector base station. Such solutions include higher order sector-
ization, higher order receive diversity, and in-air combining, as well as
more elaborate techniques such as adaptive antennas. The latter means
that automatic adaptation to the environment is performed on a rela-
tively short time basis during transmission and/or reception. Examples
of adaptation techniques are dynamic sectorization and electrical beam-
tilt and antennas with beamforming capabilities on a user basis as

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