Telecommunications and Networks - Principles of Information Systems - page 232

Over 100 U.S. city governments have implemented municipal Wi-Fi networks for use
by meter readers and other municipal workers and to partially subsidize Internet access to
their citizens and visitors. Supporters of the networks believe that the presence of such net-
works stimulates economic development by attracting new businesses. Critics doubt the long-
term viability of municipal Wi-Fi networks because the technology cannot easily handle
rapidly increasing numbers of users. Also, because municipal Wi-Fi networks use an unli-
censed bandwidth available to any user and they operate at up to 30 times the power of
existing home and business Wi-Fi networks, critics claim interference is inevitable with these
networks. Competing Internet service providers (cable, telephone, and satellite, for example)
complain that municipal Wi-Fi networks are subsidized to such an extent that they have an
unfair competitive cost advantage.
Municipal Wi-Fi network projects for San Francisco, Chicago, Philadelphia, St. Louis,
and Houston were delayed or cancelled as the costs of the projects became too high for both
the cities involved and the builders of the networks. 16 Many of the other existing municipal
Wi-Fi networks have failed to achieve their goals for number of subscribers. 17 On the other
hand, when Denver International Airport switched its public Wi-Fi offering from paid ($7.95
per day) to advertising supported, the number of users increased ten-fold with some 8,000
connections to the network each day. 18
Several airlines plan to offer passengers with Wi-Fi enabled devices access to the Internet,
e-mail, and stored in-flight entertainment. 19 Surveys have shown that 80 percent of business
travelers and over 50 percent of leisure travelers want onboard Internet access. Southwest
spokeswoman Whitney Eichinger says, “We hope that the Internet will be expected on
airplanes just as it's expected in a hotel or coffee shop.” 20

Wide Area Wireless Network Options
Many solutions provide wide area network options including satellite and terrestrial
microwave transmission, wireless mesh, 3G, 4G, and WiMAX.

Microwave Transmission
Microwave is a high-frequency (300 MHz-300 GHz) signal sent through the air (see Figure
6.4). Terrestrial (Earth-bound) microwaves are transmitted by line-of-sight devices, so that
the line of sight between the transmitter and receiver must be unobstructed. Typically,
microwave stations are placed in a series—one station receives a signal, amplifies it, and
retransmits it to the next microwave transmission tower. Such stations can be located roughly
30 miles apart before the curvature of the Earth makes it impossible for the towers to “see
one another.” Microwave signals can carry thousands of channels at the same time.

Microwave
relay
station

Figure 6.4

Microwave
relay
station

Microwave
relay
station

Microwave Communications
Because they are line-of-sight
transmission devices, microwave
dishes are frequently placed in
relatively high locations, such as
atop mountains, towers, or tall
buildings.

Earth