Telecommunications and Networks - Principles of Information Systems - page 246

business needs to develop an accurate monthly production forecast, a manager simply down-
loads sales forecast data gathered directly from customer databases. Telecommunications
provides the network link, allowing the manager to access the data quickly and generate the
production report, which supports the company's objective of better financial planning.
This section looks at some of the more significant telecommunications services and network
applications.

Cellular Phone Services
Cellular phones operate using radio waves to provide two-way communications. The cell
phone has become ubiquitous and is an essential part of life in the twenty-first century. It is
estimated that approximately 170 million landlines were in use in the U.S. at the end of
2007, compared to 250 million cell phones—including residential and business cell
phones. 47 In the United States, the largest wireless license holders run mobile networks that
are in near-constant transition; these companies include AT&T, Nextel, Sprint PCS, T-
Mobile, and Verizon.
With cellular transmission, a local area such as a city is divided into cells. As a person
with a cellular device such as a mobile phone moves from one cell to another, the cellular
system passes the phone connection from one cell to another (see Figure 6.13). The signals
from the cells are transmitted to a receiver and integrated into the regular phone system.
Cellular phone users can thus connect to anyone who has access to regular phone service,
such as a child at home or a business associate in London. They can also contact other cellular
phone users. Because cellular transmission uses radio waves, people with special receivers can
listen to cellular phone conversations, so they are not secure.

Figure 6.13

(5)

A Typical Cellular Transmission
Scenario
Using a cellular car phone, the
caller dials the number (1). The
signal is sent from the car's antenna
to the low-powered cellular antenna
located in that cell (2). The signal is
sent to the regional cellular phone
switching office, also called the
mobile telephoneswitching office
(MTSO) (3). The signal is switched to
the local telephone company
switching station closest to the call
destination (4). Now integrated into
the regular phone system, the call is
switched to the number originally
dialed (5), all without the need for
operator assistance.

(2)

(4)

(1)

(3)

Increasingly, workers rely on their mobile phones as their primary business phones.
However, they frequently encounter problems with poor in-building coverage and find it
difficult to place calls or conduct an extended conversation. A picocell is a miniature cellular
base station designed to serve a very small area such as part of a floor inside a building. Many
communications companies now offer picocell solutions to boost cell phone signals (e.g., the
Spotwave Zen) 48 or enable the cell phone to operate over other wireless networks (e.g.,
RadioFrame Picocell and Femtocell Base Stations), thus guaranteeing a strong, reliable cell
signal. 49 Picocells are being installed to provide service on aircraft registered in European,
Asian, and Middle Eastern countries to enable passengers to place calls and text messages.
Picocells are also enabling aircraft crew to update approach charts and access management
networks while parked at the gate. 50 The Ethical and Societal Issues sidebar describes how
data about cell phone usage can help direct drivers to avoid congested highways.