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Technology Infrastructure: The Internet and the World Wide Web

protocol is backward compatible with several previous protocols, including 802.11b and
802.11g; however, a network that includes devices running the older protocols will
operate at the lower bandwidths of those protocols. 99
Wi-Fi devices are capable of roaming; that is, shifting from one WAP to another,
without requiring intervention by the user. Some organizations, including airports,
convention centers, and hotels, operate WAPs that are open to the public. These access
points are called hot spots. Some organizations allow free access to their hot spots; others
charge an access fee. A number of restaurants and fast food retailers, such as McDonald’s,
Panera, and Starbucks, offer hot spots. Hotels and office buildings have found that
installing a WAP can be cheaper and easier than running network cable, especially in
older buildings. Some hotels offer wireless access free; others charge a small fee. Users of
fee-based networks authorize a connection charge when they log in. There are Web sites
that offer hot spot directories that show hot spots by location, but these sites tend to open
and close frequently, so these directories become out of date rather quickly. The best way
to find hot spots (or a hot spot directory) is to use your favorite search engine.

Fixed-Point Wireless
In a growing number of rural areas that do not have cable TV service or telephone lines
with the high-grade wires necessary to provide Internet bandwidths, some small
companies have begun to offer fixed-point wireless service as an inexpensive alternative to
satellite service. One version of fixed-point wireless uses a system of repeaters to forward
a radio signal from the ISP to customers. The repeaters are transmitter−receiver devices
(also called transceivers ) that receive the signal and then retransmit it toward users’ roof-
mounted antennas and to the next repeater, which receives the signal and passes it on to
the next repeater, which can be up to 20 miles away. The users’ antennas are connected
to a device that converts the radio signals into Wi-Fi packets that are sent to the users’
computers or wireless LANs. Another version of fixed-point wireless directly transmits
Wi-Fi packets through hundreds, or even thousands, of short-range transceivers that are
located close to each other. This approach is called mesh routing. As Wi-Fi technologies
improve, the number and variety of options for wireless connections to the Internet
should continue to increase.

Mobile Telephone Networks
By the end of 2014, industry experts estimate that about 8 billion mobile phones and
other devices that use mobile telephone networks will be in operation around the world,
which is a little more than one for every person on Earth (although many people in the
world do not have a mobile phone, many more own multiple mobile phones and devices).
These phones are sometimes called cellular (or cell) phones because they broadcast
signals to (and receive signals from) antennas that are placed about 3 miles apart in a
grid, and the hexagonal area that each antenna covers within this grid is called a cell.
Many mobile phones have a small screen and can be used to send and receive short text
messages using a protocol called short message service (SMS). As you learned at the
beginning of this chapter, Internet-enabled mobile phones and smartphones are very
popular in highly developed countries as convenient ways to stay connected while on the go.

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