Telecommunications and Networks - Principles of Information Systems - page 229

phone calls and replace them with hair-thin strands of optical fiber in thousands of towns
and cities. When complete, the Verizon Fiber Optic Service (FiOS) network will take fiber
directly to subscribers' homes and provide downstream connection speeds (the speed that
data is transmitted to your computer) of 5 Mbps to 50 Mbps. The network will be used to
deliver high-speed Internet connection, telephone service, and TV including video on de-
mand. Verizon hopes that the new infrastructure will enable it to win customers from the
cable companies. 7

Broadband over Power Lines
Many utilities, cities, and organizations are experimenting with broadband over power lines
(BPL) to provide Internet access to homes and businesses over standard high-voltage power
lines. This form of BPL is called access BPL . A system called in-premise BPL can be used to
create a local area network using the building's wiring. A potential problem with BPL is that
transmitting data over unshielded power lines can interfere with both amateur (ham) radio
broadcasts and police and fire radios. However, BPL can provide Internet service in rural
areas where broadband access has lagged because electricity is more prevalent in homes than
cable or even telephone lines.
The U.S. Transportation Security Administration is testing the use of in-premise BPL at
selected airports to connect airport passenger and other screening systems, cameras at ticket
counters, and passport readers. 8 To access the Internet, BPL users connect their computer to
a special hardware device that plugs into any electrical wall socket. Comtrend Corporation
offers a PowerGrid 904 adapter that enables data transmission speeds of up to 400 Mbps. 9

Wireless Communications Options
Wireless communications coupled with the Internet is revolutionizing how and where we
gather and share information, collaborate in teams, listen to music or watch video, and stay
in touch with our families and coworkers while on the road. With wireless capability, a coffee
shop can become our living room and the bleachers at a ball park can become our office. The
many advantages and freedom provided by wireless communications are causing many or-
ganizations to consider moving to an all-wireless environment. Shopanista, a shuttle for
shoppers in Los Angeles, California, made the decision to move to wireless after tiring of the
hassles of moving wired devices. 10
Wireless transmission involves the broadcast of communications in one of three frequency
ranges: radio, microwave, or infrared frequencies, as shown in Table 6.2. In some cases, the
use of wireless communications is regulated and the signal must be broadcast within a specific
frequency range to avoid interference with other wireless transmissions. For example, radio
and TV stations must gain approval to use a certain frequency to broadcast their signals. In
those cases where wireless communications are not regulated, there is a high potential for
interference between signals.

Table 6.2

Technology Description Advantages Disadvantages

Radio frequency
range

Operates in the 3KHz-300
MHz range

Supports mobile users;
costs are dropping

Signal highly susceptible to
interception

Frequency Ranges Used for
Wireless Communications

Microwave—
terrestrial and
satellite frequency
range

High-frequency radio signal
(300 MHz-300 GHz) sent
through atmosphere and
space (often involves
communications satellites)

Avoids cost and effort
to lay cable or wires;
capable of high-speed
transmission

Must have unobstructed line
of sight between sender and
receiver; signal highly
susceptible to interception

Infrared frequency
range

Signals in the 300 GHz-400
THz frequency range sent
through air as light waves

Lets you move, remove,
and install devices
without expensive wiring

Must have unobstructed line
of sight between sender and
receiver; transmission effective
only for short distances

With the spread of wireless network technology to support devices such as PDAs, mobile
computers, and cell phones, the telecommunications industry needed new protocols to define
how these hardware devices and their associated software would interoperate on the networks
provided by telecommunications carriers. Today more than 70 active groups set standards