Page 118 - Antennas for Base Stations in Wireless Communications

Base Station Antennas for Mobile Radio Systems 91

Figure 2.23 Microstrip feed network for a multi-user antenna with independently
controlled beamtilts (Photo courtesy of Quintel Ltd.)

organization, which may simply be a hardware facility provider rather
than a service operator. Sharing creates some constraints on the ways
in which the sharing organizations can design and optimize their net-
works, but it has an important contribution to make both to network
economics and also to minimizing the visual impact of mobile infra-
structure. Figure 2.23 shows an example of a dual-polar antenna with
a microstrip feed network and stacked-patch elements that can provide
individually controlled beamtilts to multiple network users. 39
In some countries, the radio and TV broadcasting industry has a clear
distinction between a small number of companies who operate the hard-
ware infrastructure; they competitively sell capacity to a much larger
number of companies who are responsible for the content. This pattern
of division reduces the total cost of operation while maintaining a wide
variety of choice for the consumer and may be one that mobile radio
systems follow increasingly in the future.

2.3.15 Future Directions
Network operators will continue to be under pressure to reduce costs,
while at the same time to provide increased capacity, better coverage, and
higher data rates to support new user services. The costs of new equip-
ment roll-out on new frequency bands are very high, and the greatest
challenge in many parts of the world will be to wring the highest possible
levels of optimization from the existing networks. The wide adoption
of RET techniques and the advent of remote azimuth steering (RAS)
and remote azimuth beamwidth control (RAB) provide new tools for the
dynamic optimization of network performance. The network software to
integrate these technologies with traffic dynamics is still under devel-
opment but will potentially have a major effect on network operation.
Once this layer of software becomes available, the antenna industry will