Page 59 - Antennas for Base Stations in Wireless Communications

32 Chapter Two

TABLE 2.1 Frequency Bands, Nomenclatures, and Uses
Frequency band Short reference Service
450–470 MHz 450 MHz Phone + data
824–890 MHz 850 MHz Phone + data
870 (880)–960 MHz 900 MHz Phone + data
824–960 MHz Low bands Phone + data
(850 and 900 MHz)
1710–1880 MHz 1800 MHz Phone + data
1850–1990 MHz 1900 MHz Phone + data
1900–2170 MHz 2100 MHz Phone + data
1710–2170 MHz (1800, 1900, High bands Phone + data
and 2100 MHz bands)

■ Intellectual property Many of the topics discussed in this chapter
relate to areas in which a wide variety of patents have been granted; it
should not be assumed that because a technique or physical structure
is described here it is free of patents or other commercial IP.
■ Frequency bands Table 2.1 includes most major worldwide assign-
ments but other frequency bands are allocated to mobile radio ser-
vices in some countries. Future bands for UMTS or additional 3G
services are not included. Following the transfer of broadcast TV ser-
vices to digital format, a significant amount of the present analog TV
spectrum will be reassigned to mobile services, although the extent
to which these may be common on an international basis is not clear
at the time of writing.

2.1 Operational Requirements

The dominant concerns of mobile radio operators are to optimize net-
work capacity within the allocated number of channels and to obtain
the maximum revenue generation from the installed equipment base.
These economic objectives imply securing the most intensive possible
frequency re-use and controlling the geographical distribution of chan-
nel capacity to match the distribution of user demand in space and
time. The physical location of base stations and the engineering of their
antenna systems are invaluable tools in this optimization. The develop-
ment of the network and the antenna systems employed will be deter-
mined both by current usage patterns and also by those foreseen in the
future. An important feature of modern antenna design is the increasing
availability of techniques that permit the adaptation of antenna char-
acteristics to current usage patterns in real time.
In the discussion that follows, we assume the reader has a general
understanding of how mobile radio air interfaces operate and is familiar