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Technology Infrastructure: The Internet and the World Wide Web

asynchronous transfer mode (ATM) connections and optical fiber (instead of copper
wire) connections with bandwidths determined by the class of fiber-optic cable used.
An OC3 (optical carrier 3) connection provides 156 Mbps, an OC12 provides 622 Mbps, 97
an OC48 provides 2.5 Gbps (gigabits, or 1 billion bits per second), an OC192 provides
10 Gbps, and an OC768 provides 40 Gbps.

Wireless Connections
For many people in rural areas, satellite microwave transmissions made connections to the
Internet possible for the first time. In the first satellite technologies, the customer placed a
receiving dish antenna on the roof or in the yard and pointed it at the satellite. The satellite
sent microwave transmissions to handle Internet downloads at bandwidths of around 500
Kbps. Uploads were handled by a POTS modem connection. For Web browsing, this was
not too bad, since most of the uploaded messages were small text messages (e-mails and
Web page requests). People who wanted to send large e-mail attachments or transfer files
over the Internet found the slow upload speeds unsatisfactory.
Companies now offer satellite Internet connections that do not require a POTS modem
connection for uploads. These connections use a microwave transmitter for Internet
uploads. This transmitter provides upload bandwidths in the range of 120–800 Kbps, with
some premium services offering up to 5 Mbps. Satellite download bandwidths have also
improved, with most in the 1–8 Mbps range and premium services ranging up to 17 Mbps.
Initially, installation charges for satellite were much higher than for other residential
Internet connection services because a professional installer was needed to carefully aim
the transmitter’s dish antenna at the satellite. As the accuracy of the antennas improved,
some of these companies offered a self-installation option that drastically reduced the
initial cost. For installations in North America, the antennas must have a clear line of sight
into the southwestern sky. This requirement can make these services unusable for many
people living in large cities or on the wrong side of an apartment building. In the United
States, about 4 million homes are connected to the Internet through a satellite broadband
service. Many airlines now provide Internet access to passengers in flight through a
combination of satellite and ground-based wireless connections.
Although satellite connections were once the only wireless Internet access media for
many years, many types of wireless networks are available now. People today use
Internet-capable mobile phones, smartphones, game consoles, and notebook computers
equipped with wireless network cards to connect to a variety of wireless networks that, in
turn, are connected to the Internet.

Personal Area Networks
One of the first wireless protocols, designed for personal use over short distances, is called
Bluetooth. (The protocol was developed in Norway and is named for Harald Bluetooth, a
tenth century Scandinavian king.) Bluetooth operates reliably over distances of up to 35
feet and can be a part of up to 10 networks of eight devices each. It is a low-bandwidth
technology, with speeds of up to 722 Kbps. Bluetooth is useful for tasks such as wireless
synchronization of laptop computers with desktop computers and wireless printing from
laptops or mobile phones. These small Bluetooth networks are called personal area
networks (PANs) or piconets.

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